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ELECTRICIAN, NSQF LEVEL - 5, , 1st Semester, TRADE PRACTICAL, SECTOR: Electrical, , DIRECTORATE GENERAL OF TRAINING, MINISTRY OF SKILL DEVELOPMENT & ENTREPRENEURSHIP, GOVERNMENT OF INDIA, , NATIONAL INSTRUCTIONAL, MEDIA INSTITUTE, CHENNAI, Post Box No. 3142, CTI Campus,, Guindy, Chennai - 600 032, (i), , Copyright @ NIMI Not to be Republished
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Sector, , : Electrical, , Duration : 2 - Years, Trade, , : Electrician 1st Semester - Trade Practical - NSQF LEVEL - 5, , Copyright © 2018 National Instructional Media Institute, Chennai, First Edition :, , August 2018, , Copies : 1,000, , Rs.225/-, , All rights reserved., No part of this publication can be reproduced or transmitted in any form or by any means, electronic or mechanical, including, photocopy, recording or any information storage and retrieval system, without permission in writing from the National, Instructional Media Institute, Chennai., , Published by:, NATIONAL INSTRUCTIONAL MEDIA INSTITUTE, P. B. No.3142, CTI Campus, Guindy Industrial Estate,, Guindy, Chennai - 600 032., Phone : 044 - 2250 0248, 2250 0657, 2250 2421, Fax : 91 - 44 - 2250 0791, email : nimi_bsnl@dataone.in, chennai-nic.in, Website: www.nimi.gov.in, (ii), , Copyright @ NIMI Not to be Republished
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FOREWORD, The Government of India has set an ambitious target of imparting skills to 30 crores people, one out of every, four Indians, by 2020 to help them secure jobs as part of the National Skills Development Policy. Industrial, Training Institutes (ITIs) play a vital role in this process especially in terms of providing skilled manpower., Keeping this in mind, and for providing the current industry relevant skill training to Trainees, ITI syllabus, has been recently updated with the help of Mentor Councils comprising of various stakeholder's viz. Industries,, Entrepreneurs, Academicians and representatives from ITIs., National Instructional Media Institute (NIMI), Chennai has come up with instructional material to suit the, revised curriculum for Electrician 2nd Semester Trade Practical NSQF Level - 5 in Electrical sector, under Semester Pattern required for ITIs and related institutions imparting skill development. The NSQF, Level 5 will help the trainees to get an international equivalency standard where their skill proficiency and, competency will be duly recognized across the globe and this will also increase the scope of recognition, of prior learning. NSQF level 5 trainees will also get the opportunities to promote life long learning and skill, development. I have no doubt that with NSQF level 5 the trainers and trainees of ITIs, and all stakeholders, will derive maximum benefits from these IMPs and that NIMI's effort will go a long way in improving the, quality of Vocational training in the country., The Executive Director & Staff of NIMI and members of Media Development Committee deserve appreciation, for their contribution in bringing out this publication., Jai Hind, , RAJESH AGGARWAL, , Director General / Addl. Secretary,, Ministry of Skill Development & Entrepreneurship,, Government of India., , New Delhi - 110 001, , (iii), , Copyright @ NIMI Not to be Republished
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PREFACE, The National Instructional Media Institute (NIMI) was established in 1986 at Chennai by then Directorate, General of Employment and Training (D.G.E & T), Ministry of Labour and Employment, (now under Ministry, of Skill Development and Entrepreneurship) Government of India, with technical assistance from the Govt., of the Federal Republic of Germany. The prime objective of this institute is to develop and provide instructional, materials for various trades as per the prescribed syllabi (NSQF) under the Craftsman and Apprenticeship, Training Schemes., The instructional materials are created keeping in mind, the main objective of Vocational Training under, NCVT/NAC in India, which is to help an individual to master skills to do a job. The instructional materials are, generated in the form of Instructional Media Packages (IMPs). An IMP consists of Theory book, Practical, book, Test and Assignment book, Instructor Guide, Audio Visual Aid (Wall charts and Transparencies) and, other support materials., The trade practical book consists of series of exercises to be completed by the trainees in the workshop., These exercises are designed to ensure that all the skills in the prescribed syllabus are covered. The trade, theory book provides related theoretical knowledge required to enable the trainee to do a job. The test and, assignments will enable the instructor to give assignments for the evaluation of the performance of a trainee., The wall charts and transparencies are unique, as they not only help the instructor to effectively present a, topic but also help him to assess the trainee's understanding. The instructor guide enables the instructor to, plan his schedule of instruction, plan the raw material requirements, day to day lessons and demonstrations., In order to perform the skills in a productive manner instructional videos are embedded in QR code of the, exercise in this instructional material so as to integrate the skill learning with the procedural practical steps, given in the exercise. The instructional videos will improve the quality of standard on practical training and, will motivate the trainees to focus and perform the skill seamlessly., IMPs also deals with the complex skills required to be developed for effective team work. Necessary care, has also been taken to include important skill areas of allied trades as prescribed in the syllabus., The availability of a complete Instructional Media Package in an institute helps both the trainer and, management to impart effective training., The IMPs are the outcome of collective efforts of the staff members of NIMI and the members of the Media, Development Committees specially drawn from Public and Private sector industries, various training institutes, under the Directorate General of Training (DGT), Government and Private ITIs., NIMI would like to take this opportunity to convey sincere thanks to the Directors of Employment & Training, of various State Governments, Training Departments of Industries both in the Public and Private sectors,, Officers of DGT and DGT field institutes, proof readers, individual media developers and coordinators, but for, whose active support NIMI would not have been able to bring out this materials., , R. P. DHINGRA, EXECUTIVE DIRECTOR, , Chennai - 600 032, , (iv), , Copyright @ NIMI Not to be Republished
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ACKNOWLEDGEMENT, National Instructional Media Institute (NIMI) sincerely acknowledges with thanks for the co-operation and, contribution extended by the following Media Developers and their sponsoring organisations to bring out this, Instructional Material (Trade Practical) for the trade of Electrician NSQF LEVEL - 5 under Electrical Sector, for ITIs., , MEDIA DEVELOPMENT COMMITTEE MEMBERS, Shri. T. Muthu, , _, , Principal (Retd.),, MDC Member., NIMI, Chennai, , Shri. C.C. Jose, , _, , Training Officer (Retd.),, MDC Member,, NIMI, Chennai, , Shri. K. Lakshmanan, , _, , Assistant Training Officer (Retd.),, MDC Member,, NIMI, Chennai., , Shri. V. Gopalakrishnan, , _, , Assitant Manager,, Co-ordinator, NIMI, Chennai - 32, , NIMI records its appreciation for the Data Entry, CAD, DTP operators for their excellent and devoted services in, the process of development of this Instructional Material., NIMI also acknowledges with thanks the invaluable efforts rendered by all other NIMI staff who have contributed, towards the development of this Instructional Material., NIMI is also grateful to everyone who has directly or indirectly helped in developing this Instructional Material., , (v), , Copyright @ NIMI Not to be Republished
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INTRODUCTION, This manual for trade practical is intended for use in the ITI workshop. It consists of a series of practical exercises, that are to be completed by the trainees during the first semester of course is the Electrician trade under, Electrical Sector. It is National Skills Qualifications Framework (NSQF) - Level 5, supplemented and, supported by instructions/information to assist the trainees in performing the exercise. The exercises are designed, to ensure that all the skills prescribed in the syllabus are covered including the allied trades.The syllabus for the1st, Semester Electrician Trade under Electrical Sector Trade Practical is divided into six modules.The allocation, of time for the various modules is given below:, Module 1 - Safety Practice and Hand Tools, , 14 Exercises, , 75 Hrs, , Module 2 - Basic Workshop Practice (Allied Trade), , 09 Exercises, , 100 Hrs, , Module 3 - Wires, Joints - Soldering - U.G. Cables, , 10 Exercises, , 125 Hrs, , Module 4 - Basic Electrical Practice, , 11 Exercises, , 75 Hrs, , Module 5 - Magnetism and Capacitors, , 08 Exercises, , 50 Hrs, , Module 6 - AC Circuits, , 12 Exercises, , 100 Hrs, , 64 Exercises, , 525 Hrs, , Total, , The syllabus and the content in the modules are interlinked. As the number of workstations available in the electrical, section is limited by the machinery and equipment, it is necessary to interpolate the exercises in the modules to, form a proper teaching and learning sequence. The sequence of instruction is given in the schedule of instruction, which is incorporated in the Instructor's Guide. With 25 practical hours a week of 5 working days 100 hours of, practical per month is available., Contents of Trade Practical, The procedure for working through the 64 exercises for the 1st semester with the specific objectives as the learning, out comes at the end of each exercise is given is this book., The skill objectives and tools/instruments, equipment/machines and materials required to perform the exercise are, given in the beginning of each exercise.Skill training in the shop floor is planned through a series of practical, exercises/experiments to support the related theory to make the trainees get hands on trainning in the Electrician, trade along with the relevant cognitive skills appropriate for the level. A minimum number of projects have been, included to make the training more effective and develop attitude to work in a team. Pictorial, schematic, wiring and, circuit diagrams have been included in the exercises, wherever necessary, to assist the trainees broaden their views., The symbols used in the diagrams comply with the Bureau of Indian Standards (BIS) specifications., Illustrations in this manual, help trainess visual perspective of the ideas and concepts.The procedures to be followed, for completing the exercises is also given. Different forms of intermediate test questions have been included in the, exercises, to enhance the trainee to trainee and trainee to instructor interactions., Skill Information, Skill areas which are repetitive in nature are given as separate skill information sheets. Skills which are to be, developed in specific areas are included in the exercises itself. Some subexercises are developed to fulfill the, sequence of exercises in keeping with the syllabus., This manual on trade practical forms part of the Written Instructional Material (WIM). Which includes manual on, trade theory and assignment/test., , (vi), , Copyright @ NIMI Not to be Republished
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CONTENTS, Exercise No., , Title of the exercise, , Page No., , Module 1: Safety practice and hand tools, 1.1.01, , Visit various sections of the institutes and locations of electrical, installations, , 1, , 1.1.02, , Identify safety symbols and hazards, , 3, , 1.1.03, , Preventive measure for electrical accidents and practice steps to be, taken in such accidents, , 8, , 1.1.04, , Practice safe methods of fire fighting in case of electrical fire, , 10, , 1.1.05, , Use of fire extinguishers, , 11, , 1.1.06, , Practice elementary first - aid, , 14, , 1.1.07, , Rescue a person and practice artificial respiration, , *, , 16, , 1.1.08, , Disposal procedure of waste materials, , 21, , 1.1.09, , Use of personal protective equipment, , 23, , 1.1.10, , Practice on cleanliness and procedurse to maintain it, , 26, , 1.1.11, , Identify trade tools and machineries, , 27, , 1.1.12, , Practice safe methods of lifting and handling of tools and equipment *, , 30, , 1.1.13, , Select proper tools for operation and precautions in operation, , 31, , 1.1.14, , Care & maintenance of trade tools, , 37, , Module 2: Basic Workshop Practice (Allied Trade), 1.2.15, , Operations of allied trade tools, , 38, , 1.2.16, , Workshop practice on filing and hacksawing, , 45, , 1.2.17, , Prepare hand coil winding assembly, , 51, , 1.2.18, , Practice on preparing ‘T’ joint, straight joint and dovetail joint on wooden, blocks, , 68, , 1.2.19, , Practice sawing, planing, drilling and assembling for making a wooden, switchboard, , 81, , 1.2.20, , Practice in marking and cutting of straight and curved pieces in metal, sheets, making holes, securing by screw and riveting, , 88, , 1.2.21, , Workshop practice on drilling, chipping, internal and external threading, of different sizes, , 96, , 1.2.22, , Practice of making square holes in crank handle, , 106, , 1.2.23, , Prepare an open box from metal sheet, , 107, , (vii), , Copyright @ NIMI Not to be Republished
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Exercise No., , Title of the exercise, , Page No., , Module 3: Wires, Joints - Soldering - U.G. Cables, 1.3.24, , Prepare terminations of cable ends, , 111, , 1.3.25, , Practice on skinning, twisting and crimping *, , 114, , 1.3.26, , Identify various types of cables and measure conductor size using SWG, and micrometer, , 122, , 1.3.27, , Make a simple twist, married, Tee and western union joints, , 1.3.28, , Make a britannia straight, britannia Tee and rat tail joints, , 129, , 1.3.29, , Practice in soldering of joints/lugs *, , 132, , 1.3.30, , Identify various parts, skinning and dressing of underground cable, , 135, , 1.3.31, , Make a straight joint of different types of underground cables, , 136, , 1.3.32, , Test insulation resistance of underground cable using megger, , 140, , 1.3.33, , Test underground cable for faults and remove the fault, , 142, , *, , 125, , Module 4: Basic Electrical Practice, 1.4.34, , Practice on measurement of parameters in combinational electrical circuit, by applying Ohm’s Law for different resistor values and voltage sources and, analyse by drawing graphs, , 144, , 1.4.35, , Measure current and voltage in electrical circuits to verify Kirchhoff’s Law, , 146, , 1.4.36, , Verify laws of series and parallel circuits with voltage source in different, combinations, , 149, , 1.4.37, , Measue voltage and current against individual resistance in electrical, circuit, , 152, , 1.4.38, , Measure current and voltage and analyse the effects of shorts and, open in series circuits, , 154, , 1.4.39, , Measure current and voltage and analyse the effects of shorts and, open in parallel circuits, , 156, , 1.4.40, , Measure resistance using voltage drop method, , 158, , 1.4.41, , Measure resistance using wheatstone bridge, , 159, , 1.4.42, , Determine the thermal effect of electric current, , 161, , 1.4.43, , Determine the change in resistance due to temperature, , 162, , 1.4.44, , Verify the characteristics of series parallel combination of resistors, , 164, , Module 5: Magnetism and Capacitors, 1.5.45, , Determine the poles and plot the field of a magnet bar, , (viii), , Copyright @ NIMI Not to be Republished, , 165
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Exercise No., , Title of the exercise, , Page No., , 1.5.46, , Wind a solenoid and determine the magnetic effect of electric current, , 167, , 1.5.47, , Measure the induced EMF due to change in magnetic field, , 170, , 1.5.48, , Determine the direction of induced EMF and current, , 171, , 1.5.49, , Practice on generation of mutually induced EMF, , 173, , 1.5.50, , Measure the resistance, impedance and determine the inductance of, choke coils in different combinations, , 175, , 1.5.51, , Identify various types of capacitors - charging/discharging and testing, , 178, , 1.5.52, , Group the given capacitors to get the required capacity and voltage rating, , 182, , Module 6: AC Circuits, 1.6.53, , Measure the current, voltage and PF and determine the characteristics of, the R-L, R-C, R-L-C in AC series circuits, , 184, , 1.6.54, , Measure the resonance frequency in AC series circuit and determine its, effect on the circuits, , 189, , 1.6.55, , Measure current, voltage and PF and determine the characteristics of R-L,, R-C and R-L-C in AC parallel circuit, , 191, , 1.6.56, , Measure the resonance frequency in AC parallel circuit and determine its, effects on the circuit, , 194, , 1.6.57, , Measure power, energy for lagging and leading power factors in single, phase circuits and compare the characteristics graphically, , 196, , 1.6.58, , Measure current, voltage, power, energy and Power Factor (PF) in, 3 phase circuits, , 200, , 1.6.59, , Practice improvement of PF by use of capacitor in three phase circuit, , 202, , 1.6.60, , Ascertain use of neutral by identifying wires of 3-phase 4 wire system and, find the phase sequence using phase sequence meter, , 204, , 1.6.61, , Determine effect of broken neutral wire in three phase four wire system, , 206, , 1.6.62, , Determine the relationship between Line and Phase values for star and, delta connections, , 207, , 1.6.63, , Measure the power of three phase circuit for balanced and unbalanced, loads, , 209, , 1.6.64, , Measure current and voltage of two phases in case of one phase is, shortcircuited in three phase four wire system and compare with, healthy system, , 211, , Project Work, , 212, , * Steps to download and scan the Quick Response (QR) code, • Download QR Code app on your phone, • Run app and scan the QR code, • Your smartphone will read the code and navigate to the destination, , (ix), , Copyright @ NIMI Not to be Republished
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ASSESSABLE / LEARNING OUTCOME, On completion of this book you shall be able to, • Apply safe working practices, • Prepare profile with an appropriate accuracy as per drawing, • Prepare electrical wire joints, carry out soldering, crimping and, measure insulation resistance of underground cable, • Verify characteristics of electrical and magnetic circuits., , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - Safety practice and hand tools, , Exercise 1.1.01, , Visit various sections of the institutes and location of electrical installations, Objectives: At the end of this exercise you shall be able to, • visit the various sections/trade in your ITI and draw the layout of your ITI, • record the telephone numbers of the ITI office, hospitals, police station and fire station, • draw the layout of your section, • identify the locations that have electrical installations., , PROCEDURE, TASK 1: Visit various sections of the ITI and draw the layout of your ITI, Instructor will lead the new trainees to various sections of the ITI., 1 Visit the various sections in your ITI and identify the, sections of the ITI. List the trades and record it in your, note book., , 4 Collect the telephone numbers of the ITI office, nearest, hospitals, nearest police station and the nearest fire, station and record., , 2 Collect the information about the staff members in, each trade., , 5 Draw the layout of your ITI showing various trades., , 3 Identify the location of the ITI with details abouit the, railway and bus stations in the locality and note down, the list of bus route numbers which ply near the ITI., , Note :A Sample layout of the ITI (Fig 1) is given, for your reference. Now draw the new layout, of your ITI, with the trades/sections., , Copyright @ NIMI Not to be Republished, , 1
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TASK 2: Draw the layout of your section in the ITI, 1 Draw the plan of your section to a suitable scale in a, separate sheet of paper (A4 size)., 2 Take the length and the breadth measurements of, machine foundations, work benches, panels, wiring, cubicles, doors, windows, furniture, etc., 3 Draw the layout of the machines, work benches, panels, and furniture., , The section plan should be in the same scale, as in step 1 as per the actual placement of the, machine foundations, panels, furniture, work, benches etc., Note : The sample layout of a typical, electrician trade section is given for your, reference (Fig 2). You have to draw your, section's is layout using the sample as, reference., , TASK 3: Identify the locations of electrical installations, 1 Identify the main switch and mark its position in the, layout. (Fig 3), 2 Identify each of the sub-main switches, the area of, control in the section and mark them on the layout., 3 Identify 3 or 4 spots in various locations of the electrician, sections layout and identify the respective sub-main, switches., 4 Practice switching 'off' the control switches, depending, upon the area of control,imagining that victim are, etectrocuted in a specific location/spot., , 2, , Electrical : Electrician - Exercise 1.1.01, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - Safety practice and hand tools, , Exercise 1.1.02, , Identify safety symbols and hazards, Objectives: At the end of this exercise you shall be able to, • identify the safety symbols from the chart and their basic categories, • write their meaning and description mentioning where they are used, • identify road safety signs in traffic signals from the chart, • read and interpret different types of occupational hazards from the chart., , Requirements, Materials, •, •, , Basic safety signs chart, Road safety signs and traffic, signal chart, , - 1 No., , •, , Occupational hazards chart, , - 1 No., , - 1 No., , PROCEDURE, TASK 1: Identify safety symbols and interpret what thay mean with the help of their colour and shape, Instructor may provide charts with various safety, signs for the road safety signs in traffic signals., Then, explain the categories meaning and, colour. Ask the trainees to identify the signs, and record it in Table 1., , 1 Identify the sings and their categories from the chart., 2 Write the name, categories, meaning and description of, each sign and its place of use in Table 1., , Table 1, No., , Safety signs, , Name of the sign and category, , Place of use, , 1, , 2, , 3, , Copyright @ NIMI Not to be Republished, , 3
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No., , Safety signs, , Name of the sign and category, , Place of use, , 4, , 5, , 6, , 7, , 8, , 4, , Electrical : Electrician - Exercise 1.1.02, , Copyright @ NIMI Not to be Republished
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No., , Safety signs, , Name of the sign and category, , Place of use, , 9, , 10, , 11, , 12, , 13, , Electrical : Electrician - Exercise 1.1.02, , Copyright @ NIMI Not to be Republished, , 5
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TASK 2 : Identify the road safety signs and traffic signal signs., Instructor will explain all the road safety signs, and traffic signal signs, 1 Identify the sign and give details of its kind and meaning, in Table 2., 2 Get it checked by the instructor, , Table 2, Figure Number, , Kind of road sign, , Name of the signal, , Meaning of the sign, , 1, 2, 3, 4, 5, 6, 7, 8, , TASK 3: Read and interpret the different types of personal protective equipment (PPE) from the chart, Instructor may brief the various types of, occupational hazards and their causes., , 1 Identify the occupational hazard matching it to the, corresponding situation with the given potential in, Table 3., 2 Complete the details and get it checked by your, instructor., , 6, , Electrical : Electrician - Exercise 1.1.02, , Copyright @ NIMI Not to be Republished
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Table 3, Sl.No., , Source or potential harm, , 1, , Noise, , 2, , Explosive, , 3, , Virus, , 4, , Sickness, , 5, , Smoking, , 6, , Non-control device, , 7, , No earthing, , 8, , Poor housekeeping, , Type of occupational hazard, , Electrical : Electrician - Exercise 1.1.02, , Copyright @ NIMI Not to be Republished, , 7
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Electrical, Electrician - Safety practice and hand tools, , Exercise 1.1.03, , Preventive measures for electrical accidents and practice steps to be taken, in such accidents, Objectives: At the end of this exercise, you shall be able to, • practice and follow preventive safety rules to avoid electrical accidents, • rescue the electric shock victim., , Requirements, Materials, •, •, •, •, , Heavy insulated screwdriver 200 mm, Electrical safety chart (or) display, Gloves, Rubber mat, , - 1 No., - 1 No., - 1 No., - 1 No., , •, •, •, , Wooden stool, Ladder, Safety belt, , - 1 No., - 1 No., - 1 No., , PROCEDURE, TASK 1: Practice and follow preventive safety rules to avoid electrical accidents, 1 Do not work on live circuits. If unavoidable use rubber, gloves or rubber mats., 2 Do not touch bare conductors., 3 Stand on a wooden stool or an insulated ladder while, repairing live electrical circuits/appliances or replacing, fused bulbs., 4 Stand on rubber mats while working, operating switch, panels, control gears, etc., 5 Always use safety belts while working on poles or highrise points., 6 Use screwdrivers with wooden or PVC insulated handle, when working on electrical circuits., 7 Replace (or) remove fuses only after switching off the, circuit switches., , 8 Open the main switch and make the circuit dead., 9 Do not stretch your hands towards any moving part of, the rotating machine and around moving shafts., 10 Always use always earth connection for all electrical, appliances along with 3-pin sockets and plugs., 11 Do not connect earthing to the water supply electrical, lines., 12 Do not use water on electrical equipment., 13 Discharge static voltage in HV lines/equipment and, capacitors before working on them., 14 Keep the workshop floor clean and tools in good, condition., , TASK 2 : Rescue the electic shock victim, 1 Proceed with treatment as early as possible without, panic or becoming emotional., 2 Switch off the power or remove the plug or wrench the, cable free., 3 Move the victim from contact with the live conductor by, using dry non-conducting materials like wooden bars., (Fig 1 & 2), Avoid direct contact with the victim. Wrap your, hands with dry material if rubber gloves are not, available. If you are uninsulated, do not touch, the victim with your bare hands., , 8, , Copyright @ NIMI Not to be Republished
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8 Cover the burnt area with pure running water., 9 Clean the burnt area using a clean cloth/cotton., 10 Send someone to call the doctor immediately., In case of severe bleeding, 11 Lay the patient flat., 12 Raise the injured part above the body level. (If possible), 13 Apply pressure on the wound ,as long as necessary,, to stop the bleeding. (Fig 4), 4 Keep the patient warm and at mental rest., Ensure that there is good air circulation. Seek, help to shift the patient to a safer place. If the, victim is aloft, take steps to prevent him from, falling., 5 Loosen the clothing near the neck, chest and waist, and place the victin in a relaxed position, if the victim, is unconscious., 6 Keep the victim warm and comfortable. (Fig 3), , 14 cover the injured area with a clean pad and bandage, firmly, if it is a large wound. (Fig 5), , 7 Send someone to call the doctor, in case of electric, burns., If the victim has electrical burns due to shock,, it may be very painful and is dangerous. If a, large area of the body is burnt do not give, treatment. Give first-aid as given in step 8, , If bleeding is severe, use more than one, dressing., 15 initiate right methods of artificial respiration, if the person in unconscious, , Electrical : Electrician - Exercise 1.1.03, , Copyright @ NIMI Not to be Republished, , 9
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Electrical, Electrician - Safety practice and hand tools, , Exercise 1.1.04, , Practice safe methods of fire fighting in case of electrical fire, Objectives: At the end of this exercise you shall be able to, • demonstrate the ability of fire-fighting during electrical fire, • as a member of the fire-fighting team, • as a leader of the group., , Requirements, Equipment/Machines, •, , Fire extinguishers- CO2, , - 1 No., , PROCEDURE, General procedure to be adopted during electrical fire, 1 Raise an alarm. Follow the methods giving below to, raise an alarm signals when the fire breakes out., – Raise your voice and shout Fire! Fire! to draw, attention., – run towards fire alarm/bell to activate, – switch off the mains (if possible), 2 when you hear the alarm signal:, – stop working, – turn off all machinery and power, – switch off fans/air circulators/exhaust fans. (it's, good to switch off the sub-main), 3 If you are not involved in the fire fighting:, – leave the place using the emergency exit., – evacuate the premises, – assemble at a safe place along with others, – check, if anyone has called the fire services, – close the doors and windows, but do not lock or bolt, As a member of the fire-fighting team, 4 If you are involved in fire fighting:, – take instructions to extinguish fire in an organised, way., If taking instructions:, , 10, , – follow the instructions, and obey. Be safe and do not, get trapped., – do not use your own ideas., As a leader of the group, If you are giving instructions:, –locate and use co2 fire extinguisher, – seek for sufficient assistance and inform the fire, brigade, – locate locally available suitable means to put out the, fire, – judge the magnitude of the fire, Ensure that emergency exit paths are clear with no obstructions and, then attempt to evacuate the place. (Remove, explosive materials, substances that would easly, catch fire., – Put off the fire with assistance identifying people, with assigned responsibility for each activity., 5 Report the measures taken to put out the fire, to the, authorities concerned., Detailed reports on the fire accidents, even if, they are small accidents, shall help in, identification of the causes of the fire. The, identified causes shall help in taking preventive, measures to avoid similar occurences in the, future, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - Safety practice and hand tools, , Exercise 1.1.05, , Use of fire extinguishers, Objectives: At the end of this exercise you shall be able to, • select fire extinguishers according to the type of the fire, • operate the fire extinguisher, • extinguish the fire., , Requirements, Equipment/Machines, •, •, , Fire extinguishers-CO2, Scissors 100mm, , - 1 No., - 1 No., , •, , Cell phone, , - 1 No., , PROCEDURE, 1 Alert people in the surrounding area by shouting fire,, fire, fire when you see fire (Fig 1a & b)., 2 Inform fire service or arrange to inform them immediately, (Fig 1c)., 3 Open the emergency exit and ask the people inside, the area to go away (Fig 1d)., , 4 Switch "OFF" all electrical power supply., Do not allow people to go near the fire., 5 Analyze to identify the type of fire. Refer Table1., 6 Assume that is it type D fire (Electrical fire)., , Copyright @ NIMI Not to be Republished, , 11
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TABLE1, , Class 'A': Wood, paper, cloth, solid material, , Class 'B': Oil-based fire (grease, gasoline,oil) and, liquefiable solids, , Class 'C': Gas and liquefied gases, , Class 'D': Metals and electrical equipment, , 12, , Electrical : Electrician - Exercise 1.1.05, , Copyright @ NIMI Not to be Republished
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6 Select CO2 (carbon dioxide) fire extinguisher., 7 Locate and take the CO2 fire extinguisher. Check for, its expiry date., 8 Break the seal. (Fig 6), , 11 Slowly squeeze the handle lever to discharge the agent., (Fig 8), 12 Sweep from side to side approximately 15 cm over the, fuel fire until the fire is put off. (Fig 9), , Fire extinguishers are manufactured for use, from a distance., 9 Pull the safety pin from the handle. (Fig 7) (the Pin is, located at the top of the fire extinguisher.) (Fig 7), , 10 Aim the extinguisher nozzle or hose at the base of the, fire. (This will remove the source of the fuel fire.) (Fig 8), Keep your self low., , Caution, •, , While putting off fire, the fire may flare up., , •, , Do not panic so long as it is being put off promptly, , •, , If the fire does not respond well even after you have, used the fire extinguisher, move away from the fire, point., , •, , Do not attempt to put out a fire when it emits toxic, smoke. Leave it to the professionals., , •, , Remember that your life is more important than the, property. So do not take risks., In order to remember the simple operation of, fire extinguisher, remember P.A.S.S., This will help to use the fire extinguisher., P for pull, A for aim, S for squeeze, S for sweep, , Electrical : Electrician - Exercise 1.1.05, , Copyright @ NIMI Not to be Republished, , 13
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Electrical, Electrician - Safety practice and hand tools, , Exercise 1.1.06, , Practice elementary first aid, Objective : At the end of this exercise you shall be able to, • prepare the victim for elementary first aid., , Requirements, Equipment/Materials, •, , Number of Persons (Instructor can divide the trainees into suitable Number of groups.), , - 20 Nos., , PROCEDURE, Assumption: For easy manageability, Instructor may divide the trainees into groups and ask each group, to perform one method of resuscitation., TASK 1: Prepare the victim before giving first-aid treatment, 1 Loosen the tight clothing as it may interfere with the, victim’s breathing. (Fig 1), , 3 safely bring the victim to the level ground, taking the, necessary safety measures. (Fig 3), , 2 Remove any foreign material or false teeth from the, victim's mouth and keep the victim’s mouth open., (Fig 2), , Do not waste too much time in loosening the, clothes or trying to open the tightly closed, mouth., 4 Avoid violent operations to prevent injury victim's to the, victim’s internal parts., , 14, , Copyright @ NIMI Not to be Republished
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Task 2: Prepare the victim for artifical respiration, Observe the condition of electric shock victim., If breathing has stopped, try to provide artifical, respiration, 1 Send word for professional assistance. (If no other, person is available, you stay with the victim and help as, best as you can.), 2 Look for visible injury in the body and decide on the, suitable method of artificial respiration., -, , In the case of injury/burns on the chest and/or belly, follow the mouth to mouth method., , -, , In case the mouth is closed tightly, use Schafer's or, Holgen–Nelson method., , -, , In the case of burn and injury in the back, follow Nelson's, method., , All actions should be taken immediately., Delay by even a few seconds may be dangerous., Take extreme care to prevent injury to the, victim's internal organs., 4 Cover the victim with coat, sacks or improvise with your, own method. Help to keep the victim's body warm., 5 Proceed to perform the suitable artifical respiration, method., , 3 Place the victim in the correct position before giving, artificial respiration., , Electrical : Electrician - Exercise 1.1.06, , Copyright @ NIMI Not to be Republished, , 15
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Electrical, Electrician - Safety practice and hand tools, , Exercise 1.1.07, , Rescue a person and practice artificial respiration, Objective : At the end of this exercise you shall be able to, • rescue a victim from electric shock, • apply respiratory methods, - Nelson's arm - Lift back method, - Schafer's method, - mouth to mouth method, - mouth to nose method, - revive breathing during cardiac arrest., , Requirements, Equipment/Materials, •, •, •, , Control panel arrangement, Motor, Rubber mat, , - 1 No., - 1 No., - 1 No., , •, •, , Wooden stick, 2 persons for demonstration purpose, , - 1 No., , PROCEDURE, TASK 1: Rescue a person (mock victim) from live supply (simulated)., 2 Safety move the victim away from the `live` equipment, by disconnecting the supply or using any insulating, material., Do not run to switch off the supply that is far, away., Do not touch the victim with bare hands until, the circuit is made dead or the victim is moved, away from the equipment., Push or pull the victim away from the point of, contact of the live equipment, without causing, serious injury to the victim., 3 Physically move the victim to a nearby place., 1 Observe the person (mock victim) receiving an electric, shock. Interpret the situation quickly., , 4 Check for the victim's natural breathing and, consciousness., 5 Take steps to revive breathing if the victim is unconscious, and not breathing., , TASK 2 : Revive breathing in the victim by Nelson’s arm-Lift back pressure method, Nelson’s arm-lift back pressure method must, not be used when there are injuries to the chest, and belly., , 3 Place your hands on the victim’s back beyond the line, of the armpits, with your fingers spread outwards and, downwards, thumbs just touching as in Fig 2., , 1 Place the victim with his arms folded with the palms one, over the other and the head resting facing the ground, with his cheek over the palms., , 4 Gently rock forward keeping your arms straight until, they are nearly vertical, and steadily keep pressing the, victim’s back as shown in Fig 3 to force the air out of the, victim’s lungs., , 2 Kneel on one or both knees near the victim’s hand., , 16, , Copyright @ NIMI Not to be Republished
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5 Synchronise the above movement of rocking back, wards with your hands sliding downwards along the, victim’s arms, and grasp his upper arm just above the, elbows as shown in Fig 4. Continue to rock backwards., 6 As you rock back, gently raise and pull the victim’s, arms towards you as shown in Fig 5 until you feel the, tension in his shoulders. To complete the cycle, lower, the victim’s arms and move your hands up to the initial, position., 7 Continue artificial respiration till the victim starts to, breathe naturally. Please note, in some cases, it may, take hours., , 8 When the victim revives, keep the victim warm with a, blanket, wrapped around him or with hot water bottles, or warm bricks. Stimulate blood circulation towards the, heart by stroking the insides of the arms and legs., 9 Keep him in the lying position and do not let him exert, himself., Do not give him any stimulant, until he is fully, conscious., , TASK 3 : Revive breathing in the victim by Schafer’s method, Do not use this method when the victim has, injuries on the chest and belly., 1 Lay the victim on his belly, one arm extended direct, forward, the other arm bent at the elbow and with the, face turned sideward and resting on the hand or forearm, as shown in Fig 6., 2 Kneel when the victim is astride, so that his thighs are, between your knees with your fingers and thumbs, positioned as in Fig 6., Electrical : Electrician - Exercise 1.1.07, , Copyright @ NIMI Not to be Republished, , 17
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3 With the arms held straight, slowly swing forward so, that the weight of your body is gradually brought to bear, upon the lower ribs of the victim to force the air out of the, victim’s lungs as shown in Fig 7., , 4 Now immediately swing backwards removing all the, pressure from the victim’s body as shown in Fig 8, to, allow the lungs to fill with air., , 5 After two seconds, swing again forward and repeat the, cycle twelve to fifteen times per minute., 6 Continue it till the victim begins to breathe naturally., , TASK 4: Revive breathing in the victim by mouth-to-mouth method, 1 Lay the victim flat on his back and place a cloth roll, under his shoulders to ensure that his head is thrown, well back. (Fig 9), , 2 Tilt the victim’s head back so that the chin points, straight upwards. (Fig 10), , 3 Grasp the victim’s jaw as shown in Fig 11, and raise it, upwards until the lower teeth are higher than the upper, teeth you may also place your fingers on both sides of, the jaw near the victim's ear lobes and pull upward., Maintain this jaw position throughout the duration to, revivel respiration to prevent the tongue from blocking, the air passage., , 5 Blow into the victim’s mouth (gently in the case of an, infant) until his chest rises. Remove your mouth and, release the hold on the nose, to let him exhale, turning, your head to hear gushing the out of air. The first 8 to 10, breathings should be as rapid as the victim responds., Thereafter the rate should be slowed down to about 12, times per victim's minute (20 times for an infant)., If air cannot be blown in, check the position of, the victim’s head and jaw and recheck the, mouth for obstructions. Then, try again more, forcefully. If the chest still does not rise, turn the, victim’s face down and strike his back sharply, to dislodge obstructions., , 4 Take a deep breath and place your mouth over the, victim’s mouth as shown in Fig 12 making airtight, Sometimes air enters the victim’s stomach as, contact. Pinch the victim’s nose shut with the thumb, evidenced is the swelling of the stomach. Expel, and forefinger. If you dislike direct contact, place a, the air by gently pressing the stomach during, porous cloth between your mouth and that of the, the exhalation period., victim’s. For an infant, place your mouth over the, infant's mouth and nose. (Fig 12), 18, Electrical : Electrician - Exercise 1.1.07, , Copyright @ NIMI Not to be Republished
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TASK 5: Revive breathing in the victim by Mouth-to-Nose method, Use this method when the victim’s mouth will, not open, or has a blockage you cannot clear., 1 With the fingers of one of your hand that keep the, victim’s lips firmly shut. Seal your lips around the, victim’s nostrils and breath the air into him. Check to, see if the victim’s chest is rising and falling. (Fig 13), 2 Repeat this exercise at the rate of 10-15 times per, minute till the victim responds., 3 Continue this exercise till the arrival of the doctor., , TASK 6 : Revive breathing in a victim who is under cardiac arrest, In cases where the heart has stopped beating,, you must act immediately., 1 Check quickly whether the victim is under cardiac, arrest., Cardiac arrest could be ascertained by the, absence of the cardiac pulse in the neck, (Fig 14), blue colour around lips and dilated, pupil of the eyes., , 5 Keeping your arms straight, press sharply down on the, lower part of the breastbone. Then release the pressure., (Fig 17), , 2 Lay the victim on his back on a firm surface., 3 Kneel alongside facing the chest and locate the lower, part of the breastbone. (Fig 15), , 6 Repeat step 5, fifteen times at the rate of at least one, time per second., 7 Check the cardiac pulse (Fig 18)., 4 Place the palm of one of your hands on the centre of the, lower part of the breastbone, keeping your fingers off the, ribs. Cover the palm with your other hand and lock your, fingers together as shown in Fig 16., , 8 Move back to the victim’s mouth to give two breaths, (mouth-to-mouth revival of breathing) (Fig 19)., 9 Continue with another 15 compressions of the heart, followed by two breaths of mouth-to-mouth revival of, breathing. Check the pulse at frequent intervals., , Electrical : Electrician - Exercise 1.1.07, , Copyright @ NIMI Not to be Republished, , 19
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10 As soon as the heartbeat is revived, stop the, compressions immediately. Continue mouth-to-mouth, revival of breathing until natural breathing is fully, restored., 11 Place the victim in the recovery position as shown in, Fig 20. Keep him warm and quickly get medical help., , Other steps, 1 Send for a doctor immediately., 2 Keep the victim warm with a blanket around him or, wrapped up with hot water bottles or warm bricks., Stimulate blood circulation towards the heart by, stroking the insides of the arms and legs., , Scan the QR Code to, view the video for this, exercise, , 20, , Electrical : Electrician - Exercise 1.1.07, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - Safety practice and hand tools, , Exercise 1.1.08, , Disposal of procedure of waste materials, Objectives: At the end of this exercise you shall be able to, • identify the different type of waste material, • segregate the waste materials in the respecive bins, • sort non-saleable and saleable materials separately and maintain record., , Requirements, Materials, •, •, , Shawel, Plastic/Metal bins, , •, •, , - 1 No., - 4 Nos., , Trolly with wheels, Brush and gloves, , - 3 Nos., - 1 Pair, , PROCEDURE, 1 Collect all the waste materials in the workshop., 2 Identify and segregate them like cotton waste, metal, chips, chemical waste and electrical waste (Fig 1), separately and label them., , 3 Sort waste materials as saleable, non saleable, organic, and inorganic materials., 4 Record the sorted waste material and fill Table-1., , Table-1, SI.No., , Name of the waste material, , Quantity, , Saleable or non Saleable, , 1, 2, 3, 4, 5, 6, 5 Arrange at least 3 trolleys with wheels for disposal., Stick label on each trolly as "Cotton Waste", "Metal, Chips" and "others". (Fig 2), , 6 Put the cotton waste in the cotton trolly and similarly, put the metal chips waste and others in the respective, trolleys., , Copyright @ NIMI Not to be Republished, , 21
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7 Keep 4 more bins to collect saleable scrap, non, saleable scrap, organic waste and Inorganic waste and, label them. (Fig 3), Fig 3, , Saleable Material, , Non Saleable, Material, , Waste Material, ( Organic ), , Waste Material, ( Inorganic ), , Skill Sequence, Separate the cotton waste and dispose it, Objectives: This shall help you to, • separate and dispose cotton waste., 1 Collect the chips by hand shavel with the help of a, brush., , 5 Collect all the saleable material and non salable one, seperately and put them in the respective bins., , 2 Clean the floor if oil has been spilt., , 6 Collect all the non-saleable materials like cotton waste,, paper waste, wooden pieces, etc., and keep them in, the respective bin as in Fig 3., , Do not handle the chip with bear hand., Separate the chip according to the metal., 3 Separate the cotton waste and store it in the bin provided, for the purpose., 4 Store the each category in the assigned bins., Each bin have respective label., , 22, , 7 Check the non-saleable material (organic) and send it, for disposal by burning after getting approval., 8 Check the saleable material and segregate like, Aluminium, Copper, Iron, Screws, nuts and other items, separately and send it to the stores for disposal by, auction (or) as per recommended procedure., , Electrical : Electrician - Exercise 1.1.08, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - Safety practice and hand tools, , Exercise 1.1.09, , Use of personal protective equipment, Objectives: At the end of this exercise you shall be able to, • read and interpret different types of Personal Protective Equipment (PPE) from the chart (or) real PPE, • identify and name the PPEs corresponding to the type of protection and write their uses., , Requirements, Tools / Equipment, •, , Chart showing different types, of PPEs, , - 1 No., , •, , Real PPEs(available in section) - as required., , PROCEDURE, Instructor may arrange the available different, types of PPEs in the table or provide the chart, showing the PPEs. Instrcuter may also explain, the types of PPEs and their uses, and the, hazards for which each type is used., , 1 Identify the different types of PPEs and write their, names with the help of the chart and write in Table 1., 2 Write the type of protection and uses in the space, provided against each PPE in Table 1., , Table 1, Sl. No., , Sketches, , Name of, PPE, , Type of, protection, , Uses, , 1, , 2, , Copyright @ NIMI Not to be Republished, , 23
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Sl. No., , Sketches, , Name of, PPE, , Type of, protection, , 3, , 4, , 5, , 6, , 24, , Electrical : Electrician - Exercise 1.1.09, , Copyright @ NIMI Not to be Republished, , Uses
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Sl. No., , Sketches, , Name of, PPE, , Type of, protection, , Uses, , 7, , 8, , 9, , 3 Get it checked by your instructor., , Electrical : Electrician - Exercise 1.1.09, , Copyright @ NIMI Not to be Republished, , 25
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Electrical, Electrician - Safety practice and hand tools, , Exercise 1.1.10, , Practice on cleanliness and procedure to maintain it, Objectives: At the end of this exercise you shall be able to, • identify the places/machinery/equipment that are to be cleaned, • collect the cleaning materials/devices required for cleaning, • clean the machines/equipment and devices installed in your section., , Requirements, Materials, , Tools / Equipment, •, , Portable vacuum cleaner/blower, , •, •, •, , - 1 No., , Emery sheet-'O' grade, Dusting cloth, Dust bin, , - 1 No., - as required., - 3 Nos ., (labelled), , PROCEDURE, Do not remove lubricants in the machine while, wiping/cleaning., , Switch OFF all the machinery and equipment, before starting the cleaning process. Use a, mask or cover the mouth and nose., , 6 Use vacuum cleaners to suck dust from areas where a, brush or cloth cannot help., , Instructor has to brief the Japanese 5S concept, to the trainees before starting the work., , 7 Collect the waste materials found in the lab and put it, in the specified dustbin, as shown in Fig 1., , Sort, , Dusting and cleaning can be arranged by, dividing the trainees into groups under the, supervision of the instructor., , Set in order, Shine, , 8 Clean places where water or oil has been spilt on the, floor, , 5s - concept, , Standardise, , Note down abnormal things that you noticed, while cleaning and report it to the instructor to, take corrective action., , Sustain, 1 Identify the areas/equipment/machine that need to be, cleaned., 2 Keep the movable items in one place and group them., 3 Clean the dust carefully, without damaging any part/, connection in the machine / equipment, using a cloth., 4 Use wet dusting cloth on areas that are wired., , 9 Put all the materials and equipment used for cleaning, in their respective places., 10 Inspect and ensure that all machines are working after, cleaning in the presence of the instructor., 11 Discuss abnormal things that you came across while, cleaning with the instructor. Prepare a report if the, instructor asks for it, , 5 Remove rust on parts of the equipment (or) devices, using an emery sheet., , Instructor may assign trainees the responsibilty, of cleaning in batches. Disposal of waste may, be organised as a routine actvity by, coordinating with the stores., , Fig 1, , Organic, Waste, , 26, , Inorganic, Waste, , Metals, Scrap, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - Safety practice and hand tools, , Exercise 1.1.11, , Identify trade tools and machineries, Objectives : At the end of this exercise you shall be able to, • identify tools and draw their sketches, • identify the machineries in the lab and note down their names., , Requirements, Equipment/Machines, , Tools/Instruments, •, •, •, •, •, •, •, •, •, •, •, •, , Combination plier (150 mm), Long round nose plier (200 mm), Screwdriver (150 mm), Firmer chisel (12 mm), Wood rasp file (250 mm), Flat file bastard (250 mm), Bradawl (6 mm x 150 mm), Gimlet (4 mm x 150 mm), Ratchat brace (6 mm), Rawl jumper holder with bit No. 8, Triangular file bastard (150 mm), Saw-tooth setter, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , •, , Electric bench grinder, , - 1 No., , Materials, •, •, •, •, •, , Lubricating oil, Cotton waste, Cotton cloth, Grease, Emery sheet, , - 100 ml, - as required., - 0.50 m, - as required., - 1 sheet., , The instructor shall arrange for the necessary tool/equipment from other sections and also arrange for, the required materials from scrap for practising the use of tools., , PROCEDURE, TASK 1 : Identify tools with specification, Assumption - A set of trainees tool kit and, specified tools as given in this exercise are, displayed on the workbench. Trainees are, required to identify the tools from the, specifications given and draw the sketch of the, tools in the space allotted for the purpose., , 1 Identify the tools from the specification given., 2 Draw a neat sketch against each item., In case the specifications are different write, the correct specification of the items given to, you., , Copyright @ NIMI Not to be Republished, , 27
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Table 1, Sl. No., , Name of tool with specification, , i, , Combination plier with pipe grip, side cutter and, insulated handle - size 150 mm,, , ii, , Long round nose pliers 200 mm,, , iii, , Screwdriver 150 mm, , iv, , Firmer chisel 12 mm, , v, , Wood rasp file 250 mm, , vi, , Flat file bastard 250 mm, , vii, , Bradawl 6 mm x 150 mm square-pointed, , viii, , Gimlet 4 mm x 150 mm, , ix, , Ratchet brace 6 mm capacity, , x, , Rawl jumper holder with bit No.8, , xi, , Triangular file bastard 150 mm, , Sketch of tools, , 3 Get your sketches checked by your instructor., , TASK 2: Identify the machineries installed in the electrician section, Instructor shall explain the names of the, machineries installed in the electrician section, and their locations. Then ask the trainees to, write the name,and other details of each, machine in the section., , 28, , 1 Identify and locate the machines and their names in, your section., 2 Read and recognise the name plate of each machine., 3 Write the name and other details of each machine, against their names in Table 2., , Electrical : Electrician - Exercise 1.1.11, , Copyright @ NIMI Not to be Republished
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Table-2, Sl. No., , Name of the machine, , 1, , D.C. shunt generator, , 2, , Motor Generator set (A.C. motor with D.C, generator), , 3, , D.C. Compound generator, , 4, , D.C. Series motor, , 5, , D.C. Shunt motor, , 6, , D.C. Compound motor, , 7, , Motor generator set (D.C. motor with A.C, generator), , 8, , A.C.Squirrel cage induction motor, , 9, , A.C Slipping induction motor, , 10, , Universal motor, , 11, , Synchronous motor, , 12, , Diesel generator set, , 13, , Electrical machine trainer, , Name and other details, , 4 Get it checked by your instructor., , Electrical : Electrician - Exercise 1.1.11, , Copyright @ NIMI Not to be Republished, , 29
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Electrical, Electrician - Safety practice and hand tools, , Exercise 1.1.12, , Practice safe methods of lifting and handling of tools and equipment, Objectives: At the end of this exercise you shall be able to, • demonstrate how to lift and handle heavy equipment during working conditions while, • lifting from floor, • during lift, • carrying, • lowering to bench, • lifting from bench, • lowering to floor, , Requirements, Tools and equipment, •, , Single phase one HP 240V/50Hz, capacitor start induction motor, , •, •, , - 1 No., , D.E. Spanner set 5 mm to 20 mm - set of 8, Work bench or table, , - 1 No., - 1 No., , PROCEDURE, Instructor has to demonstrate, how to lift and handle heavy equipment and then ask the trainees to, practice., 4 Check for clear route to the location where the motor, is to be placed. Remove obstacles, if any., 5 Position yourself close to the equipment to be lifted., 6 Lift the equipment from the floor using the correct, posture., 7 Carry the equipment to the work bench safely, keeping the equipment close to your body., 8 place the equipment carefully on the bench, and, adjust it to the correct position., Assume that the overhauling work is over and, the motor is to be placed in its orginal place., Assume one single phase motor has to be lifted, and lowered to be placed on the floor., , 9 Lift the equipment correctly with a firm grip., , 1 Switch OFF the motor and remove the fuse carriers., Ensure that the equipment is disconnected, from power supply and that the base plate nuts, of the motor have been removed., , 10 Carry the equipment to its original place., 11 Safely lower the equipment with your feet apart,, knees bent, back straight and arms close to your, body., 12 Safely place the equipment on the floor., , 2 Ensure that you know the position where the equipment, is to be placed., , If you feel the equipment is too heavy, take, help from others., , 3 Assess whether you need any assistance to carry the, equipment., , Scan the QR Code to, view the video for this, exercise, , 30, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - Safety practice and hand tools, , Exercise 1.1.13, , Select proper tools for operation and precautions in operation, Objectives : At the end of this exercise you shall be able to, • select proper tools for specific uses., • follow care and maintenance and procedures with precaution for each tool., , Requirements, Tools, •, •, •, •, •, •, •, •, •, , Combination plier - 150 mm, Flat nose plier 150 mm, Diagonal cutting plier 150 mm, Round nose plier 150 mm, Screw driver 150 mm, Star-headed screw driver 100 mm, Neon tester, Electrician's knife 100 mm, Try square 150 mm, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , •, •, •, •, •, •, •, , Firmer chisel 12 mm, Tenon saw 300 mm, Plumb bob, Centre punch 50 mm, Cold chisel, Hacksaw frame with blade, Portable electric drilling machine, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , PROCEDURE, TASK 1: Select the proper tools for specific uses, 1 Identify proper tools for specific uses, Fig 1 to 16 ,, , from, , 2 Write the uses of each selected tool and the precautions, to be followed while handling in Table 1., , Table 1, Tool, , Uses/Operation, used for, , Care, Maintenance and, Precautions in operation, , 1 Combination pliers (Fig 1), , Copyright @ NIMI Not to be Republished, , 31
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Tool, , Uses/Operation, used for, , Care, Maintenance and, Precautions in operation, , 2 Pliers - round nose, , 3 Pliers - flat nose, , 4 Pliers - diagonal cutting, , 32, , Electrical : Electrician - Exercise 1.1.13, , Copyright @ NIMI Not to be Republished
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Tool, , Uses/Operation, used for, , Care, Maintenance and, Precautions in operation, , 5 Screwdriver, , 6 Screwdriver (Star), , 7 Electrician's knife, , 8 Neon tester, , Electrical : Electrician - Exercise 1.1.13, , Copyright @ NIMI Not to be Republished, , 33
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Tool, , Uses/Operation, used for, , Care, Maintenance and, Precautions in operation, , 9 Portable electric drilling machine, , 10 Hacksaw, , 11 Cold chisel, , 34, , Electrical : Electrician - Exercise 1.1.13, , Copyright @ NIMI Not to be Republished
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Tool, , Uses/Operation, used for, , Care, Maintenance and, Precautions in operation, , 12 Tenon saw, , 13 Try square, , 14 Firmer chisel, , Electrical : Electrician - Exercise 1.1.13, , Copyright @ NIMI Not to be Republished, , 35
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Tool, , Uses/Operation, used for, , Care, Maintenance and, Precautions in operation, , 15 Centre punch, , 16 Plumb bob, , 4 Get it checked by your instructor., , 36, , Electrical : Electrician - Exercise 1.1.13, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - Safety practice and hand tools, , Exercise 1.1.14, , Care and maintenance of trade tools, Objective : At the end of this exercise you shall be able to, • perform care and maintenance of tools., , Requirements, Equipment/Machines, , Tools/Instruments, •, •, •, •, •, •, •, •, •, •, •, •, , Combination plier (150 mm), Long round nose plier (200 mm), Screwdriver (150 mm), Firmer chisel (12 mm), Wood rasp file (250 mm), Flat file bastard (250 mm), Bradawl (6mm x 150 mm), Gimlet (4 mm x 150 mm), Ratchat brace (6 mm), Rawl jumper holder with bit No. 8, Triangular file bastard (150mm), Saw tooth setter, , - 1 Set., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , •, , Electric bench grinder, , - 1 No., , Materials, •, •, •, •, •, , Lubricating oil, Cotton waste, Cotton cloth, Grease, Emery sheet '00', , - 100 ml, - as reqd., - 0.50 m, - as reqd., - 1 sheet., , PROCEDURE, TASK 1: Perform care and maintenance of tools, Prevent rust formation, , Reshaping the screwdriver tip, , 1 Inspect all the tools. If the tools are rusted, use fine, emery paper to remove the rust., , 8 Check the tips of the flat tipped screwdrivers. If the tip, is blunt or disfigured report to the instructor., , While removing rust keep your hands safe from, sharp edges. Do not use emery paper on steel, rule or tape., , Observe how the screwdriver tip is ground to, form a perfect cornered tip for effective use., , 2 Apply a thin coat of oil over the surface of the rusted tool, and clean with a cotton cloth., A hammer should not have any trace of oil on, its striking surface., 3 Check and lubricate tools for easy movement of the, jaws of the pliers, blades of knives, jaws of wrench,, pincers, gears of the hand drilling machine., 4 Apply a drop of oil on the hinged/geared surface, if the, movement is hard., 5 Activate the jaws and gears till the muck/grim in the, surfaces are cleaned, 6 Apply a drop of oil again and clean the tools with a, cotton cloth., , Sharpen and set the saw-teeth, 9 Check the teeth of the Tenon saw., 10 If the saw-teeth are blunt, report to your instructor., Observe how the saw-teeth is filed to make the, saw-teeth sharp., 11 Check the saw-teeth setting., The teeth of the Tenon saw should be set to be, able to alternately remove dust while sawing., 12 If the setting is not proper report to the instructor., 13 Check how the teeth are set by a saw-setter., , Remove the mushroom, 7 Check the cold chisel and the hammer's striking face for, mushrooms. If you find mushrooms report to your, instructor to enable him to remove the mushroom, through grinding., , Copyright @ NIMI Not to be Republished, , 37
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Electrical, Electrician - Basic Workshop Practice (Allied Trade), , Exercise 1.2.15, , Operations of allied trade tools, Objectives : At the end of this exercise you shall be able to, • identify fitting, carpenter and sheetmetal tools, • write the names, specifications and operations of each tool., , Requirements, Tools, •, , Fitter, carpenter and sheetmetal tools - 1 set., , PROCEDURE, Instructor may display the fitter, carpenter and sheetmetal tools (allied trade) on the workbench in the, section and demonstrate how to identify the tools, their operation with specifications. Then ask the, trainees to record it in Table 1., TASK 1: Identify fitter, carpenter and sheetmetal tools and mention their operation/uses, 1 Identify fitter, carpenter and sheetmetal tools provided, on the workbench and recagnise them with their names., , 3 Write the operations / uses of each trade tool., , 2 Write the name of the tool against the visual shown in, Table 1 and mention the specifications., , Fitter, , -, , Fig 1 to 12, , Carpenter, , -, , Fig 1 to 11, , Sheet metal Worker, , -, , Fig 1 to 5, , Table 1, Fitter Tools, Sl. No., , Visual of tool, , Name of the tool, with specifications, , 1, , 2, , 38, , Copyright @ NIMI Not to be Republished, , Operation/, uses
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Sl. No., , Visual of tool, , Name of the tool, with specifications, , Operation/, uses, , 3, , 4, , 5, , 6, , Electrical : Electrician - Exercise 1.2.15, , Copyright @ NIMI Not to be Republished, , 39
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Sl. No., , Visual of tool, , Name of the tool, with specifications, , 7, , 8, , 9, , 10, , 11, , 40, , Electrical : Electrician - Exercise 1.2.15, , Copyright @ NIMI Not to be Republished, , Operation/, uses
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Sl. No., , Visual of tool, , Name of the tool, with specifications, , Operation/, uses, , Name of the tool, with specifications, , Operation/, uses, , 12, , Table 2, Carpentary tools, Sl. No., , Visual of tools, , 1, , 2, , 3, , 4, , Electrical : Electrician - Exercise 1.2.15, , Copyright @ NIMI Not to be Republished, , 41
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Sl. No., , Visual of tool, , Name of the tool, with specifications, , 5, , 6, , 7, , 8, , 9, , 42, , Electrical : Electrician - Exercise 1.2.15, , Copyright @ NIMI Not to be Republished, , Operation/, uses
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Sl. No., , Visual of tool, , Name of the tool, with specifications, , Operation/, uses, , Name of the tool, with specifications, , Operation/, uses, , 10, , 11, , Table 3, Sheetmetal tools, Sl. No., , Visual of tools, , 1, , 2, , 3, , Electrical : Electrician - Exercise 1.2.15, , Copyright @ NIMI Not to be Republished, , 43
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Sl. No., , Visual of tools, , Name of the tool, with specifications, , 4, , 5, , 4 Get it checked by the instructor., , 44, , Electrical : Electrician - Exercise 1.2.15, , Copyright @ NIMI Not to be Republished, , Operation/, uses
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Electrical, Electrician - Basic Workshop Practice (Allied Trade), , Exercise 1.2.16, , Workshop practice on filing and hacksawing, Objectives: At the end of this exercise you shall be able to, • file a surface flat and check it with straight edge and light gap, • file two adjacent sides to 90o and check it with Try square, • perform operations of marking a straight line, • mark parallel lines to the given dimension using Jenny caliper, • file and finish surfaces to an accuracy of 0.5mm, • fix the hacksaw blade in the correct position and saw the metal., , Requirements, Tools/Instruments, •, •, •, •, •, •, , File, flat bastred, double cut - 300 mm, File, flat second cut, double cut 300 mm, Try square - 150 mm, Jenny caliper - 150 mm, Ball peen hammer - 200 gm, Hacksaw frame (200 mm), with blade (24 TPI), • Mild steel square bar 25x25mx50mm, , Equipment/Machines, - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , • Bench vice - 50 mm Jaw size, , - 1 No., , Materials, • ISA 5555 Thickness, Length, , - 8 mm, -150 mm., , - 1 No., - 1 No., , PROCEDURE, TASK 1: Practice on filing, 1 Check the length and size of the given M.S.angle iron, as per the sketch using a steel ruler., 2 Fix at right angle with one side (surface 'A') at least 15, mm above the jaws of the bench vice., 3 File the reference side (surface 'A' indicated in Fig 1), with the bastard file., 4 Test the flatness with the blade of the Try square., Do not touch the surface of the job while filing., Use a vice clamp for protecting the finished, surfaces., 5 File the adjacent surface `B' with a bastard file., 6 Test the flatness and also check the right angle with the, Try square., 7 File the side 'C' at right angle to surfaces 'A', 'B'., 8 Evenly apply marking media (lump chalk) on the, surfaces 'A' and 'B'., 9 Place surface 'B' on the levelling plate and scribe a line, parallel to 'B' on surface A at a distance of 53 mm as, shown in Fig 1. Similarly on surface 'A' mark a line, parallel to 'B' at a distance of 53 mm., 10 Place surface 'C' on the levelling plate and scribe a line, parallel to 'C' on surfaces 'A' & 'B' at a distance of, 146mm from surface 'C'., 11 Punch all the scribed lines., , 12 File the sides 'D', 'E' and 'F' with a bastard file., 13 Finish the job with a second cut file. File within ± 0.5mm, and check the right angles with reference to surfaces 'A', and 'B'., , Copyright @ NIMI Not to be Republished, , 45
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14 Use an outside caliper for checking the finished sizes., 15 Deburr all sharp edges., , Do not overtighten the vice., Do not allow any pining of the file handle. Use, a file card for removing pining of the file., , Skill sequence, Types of filing, Objective: This shall help you to, • file a flat surface., Filing methoda : The method of filing adopted depends on, the type of surface profile to be filed, the type of surface, texture required and the amount of materials to be removed., Diagonal filing: This type of filing is done when heavy, reduction of material is required. The strokes are at an, angle of 45°. Because the stroke directions cross, the, surface texture formed clearly indicates the high and low, spots. Frequent checking of the level is not necessary,, particularly, after one has developed a steady movement of, the file. (Fig 1), Longitudinal filing: The file is moved parallel to the longer, side of the work. Usually all surfaces are smooth–finished, by this method. The filed surface texture will show uniform, and parallel lines. (Fig 3), , Transverse filing: In this method the file strokes are at, right angles to the longer side of the work. This is commonly, used to reduce material from the edges. Using this method,, the size of the workpiece is brought close to the finishing, size, and then final finishing is done by longitudinal filing., (Fig 2), , Checking flatness and squareness, Objectives: This shall help you to, • check flatness, • check squareness., Checking flatness: During the initial stages of filing the, evenness of the surface is visible to a reasonable degree of, perfection from the surface texture of diagonal filing. To, ensure perfection the surface should be checked with a, straight edge. To do this, the blade of a Try square can, serve as a straight edge. Flatness should be checked in all, directions to cover the entire surface. Light gap will indicate, high and low spots. (Fig 1), , 46, , Electrical : Electrician - Exercise 1.2.16, , Copyright @ NIMI Not to be Republished
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Checking squareness: While checking for squareness,, the larger finished surface serves as reference surface., Ensure that the reference surface is perfectly finished, before filing the other surfaces. (Fig 2), , Burrs, if any, should be removed before checking with the, Try square. While checking with the Try square, press the, stock against the reference face and then slowly bring the, blade down. (Fig 3) Pressure is always applied to the stock, against the reference surface., , Marking parallel lines with Odd Leg Caliper, Objective: This shall help you to, • mark parallel lines with reference to a datum edge using an odd leg caliper or Jenny caliper., •, , Hold the job in the left hand if the job is small., , •, , Hold the odd leg caliper in the right hand., , •, , Transfer the required dimension from the steel rule to, the odd leg caliper., The tip of the bent leg should touch the datum, edge of the job. The pointed leg should be on the, surface of the job. (Fig 1), The odd leg should be held at 45° from the surface, of the job., , Scribing of lines should always towards the, direction of marking person., , Method of using Centre Punch, Objectives: This shall help you to, • hold a centre punch over a scribed line, • punch by dot/centre punch., Hold the punch in a relaxed manner between your thumb, and your fingers. For centre/dot punching, place the, workpiece on a steel support plate. Place the punch in, position. Rest your hand on the workpiece while doing so., (Fig 1), , Place the point of the centre punch on the line of intersection., (Fig 2), , Electrical : Electrician - Exercise 1.2.16, , Copyright @ NIMI Not to be Republished, , 47
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Bring the punch in perpendicular position to the surface of, the workpiece. (Fig 3), , Tap the head of the punch with a light blow by a hammer., A heavier blow is required for marking the position of drilling, a hole. (Fig 4), , Practice in hacksawing, Objectives: At the end of this exercise you shall be able to, • file one face flat and check by straight edge and light gap, • file angle to 90o within Try square accuracy, • mark straight lines, • mark parallel lines using a surface gauge, • mark parallel lines using a Try square, • file and finish surfaces flat and parallel within ± 0.5mm, • file and finish radius, • saw M.S.flat along a straight line., , Requirements, Tools/Instrumentss, •, •, •, •, •, •, •, •, •, •, •, , File, flat bastard, double cut 300 mm, File, flat, second cut, double cut, 300 mm, Try square - engineer's rule 150 mm, Jenny caliper 150 mm, Engineer ball peen hammer 200 gm, Centre punch 100 mm, Dot punch, Steel rule 300 mm, Hacksaw blade 300 mm, Surface gauge, Radius gauge, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 set., , •, •, •, •, , File card, Vice clamp, Divider, Straight edge, , - 1 No., - 1 pair., - 1 No., - 1 No., , Equipment/Machines, •, •, •, , Bench vice 50 mm jaw, Surface plate, Angle plate, , - 1 No., - 1 No., - 1 No., , Materials, •, , 60 ISF 8 (Length - 350 mm.), , - 2 Nos., , PROCEDURE, 1 Check the raw material size with the sketch using the, steel ruler., 2 Securely fix the job in the bench vice., 3 File the reference face A (Fig 1) with a bastard file., 4 Check the flatness with the straight edge., 5 File adjacent edge or datum edge B (Fig 1) with a, bastard file., 48, , 6 Check the right angle with a Try square., 7 File adjacent edge or datum edge C (Fig 1) with a, bastard file., 8 Check the right angles to the datum edge B and, reference surface A., 9 Evenly apply chalk on the surface A., , Electrical : Electrician - Exercise 1.2.16, , Copyright @ NIMI Not to be Republished
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10 Place the job on the levelling plate and scribe the lines, by the surface gauge, parallel to the datum edge B (size, 58 mm) and on datum edge C (size 350 mm)., 11 Scribe the saw, cut parallel lines a, b, c & d as per the, sketch. (Fig 1), 12 Scribe two arcs of radius 10 mm with the divider at the, datum edge C as in the Fig 1., 13 Punch all the scribed lines and also the arcs by a dot, punch., 14 File the edges D and E with a file., 15 Check for the right angle between edges D and E and, also with the surface A., 16 Check the finished piece for length 350 mm and breadth, 58 mm with an outside caliper., 17 Saw the depth a, b, c, and finally saw part at 'd' in, Fig 1., 18 File and finish the saw - Cut surface of part 1 for a length, of 300 mm., 19 Saw the corners for removing the unwanted metal for, filing the radius., 20 File and finish two corners by radius filing on part 1., 21 Check the radius with a radius gauge., 22 File and finish the job with a second cut file within a, tolerance of ± 0.5 mm (use outside calipers for checking)., , Skill sequence, Fixing of hacksaw blade on the frame and sawing, Objectives: This shall help you to, • fix the hacksaw blade on the frame, • practice sawing with dimensions., The teeth of the blade should point from the, handle., 1 Fix the blade to the frame in good tension. (Fig 1), , 2 Set your thumb nail vertically to the location of the cut,, and this location should be at least 10 mm from the vice., (Fig 2), , Electrical : Electrician - Exercise 1.2.16, , Copyright @ NIMI Not to be Republished, , 49
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3 Hold and press the hacksaw straight. (Fig 3), Do not use force when pulling back., Occationally apply cutting compound while, cutting ., Use the full length of the hacksaw blade., , For this section use a fine grade blade. A, minimum of two to three teeth should be in, contact with the work. (Fig 5), , 4 Make the last few cuts holding the piece to be cut in, your left hand. (Fig 4), , 50, , Electrical : Electrician - Exercise 1.2.16, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - Basic Workshop Practice (Allied Trade), , Exercise 1.2.17, , Prepare hand coil winding assembly, Objectives: At the end of this exercise you shall be able to, • identify the component /part that matches with the given drawings, • prepare the parts required for assembly with the help of sub exercises, • assemble the components (with the specified method) to the appropriate fitness and complete the assembly, • test the working of the assembly to the required standard., , Requirements, Materials, , Tool/Instruments, •, •, •, •, •, •, , Four folded wooden scale 600 mm, Screwdriver 3 mm blade 150 mm, Screwdriver 10 mm blade 200 mm, DE spanner set of 8 pieces (Metric), Combination plier 150mm, Smooth jack plane, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , •, •, , - 1 No., , •, •, •, , Equipment/Machines, •, , Portable electric drilling machine ø 6 mm, capacity, , •, •, •, •, , •, , Completed exercise jobs from Ex. 1.2.16, Completed exercise jobs from sub exercises from, (S. Ex. from 1.2.17 - 1 to 1.2.17 - 5), Slotted cheese head screw M 6 20 mm - 1 No., Slotted cheese head screw, M 6 x 125 mm, - 1 No., T.W. plank 30 x 350 x 500, - 1 No., M 10 slotted cheese head, screw x 25 mm, - 4 Nos., M 10 Hexagonal bolt and nut 50 mm, - 4 Nos., Set screw M 3 x 8 mm, - 2 Nos., Washer outer diamrter ø 20 bore 7 mm,, thickness 1.5 mm, - 1 No., Hexagonal nut for M 6, - 2 Nos., , PROCEDURE, TASK 1: Preparation of the wooden base, Fig 1 shows the completed sketch of a hand coil, winding machine assembly., , 3 Plane the longer edge B (Fig 2). Check the straightness, using a straight edge., 4 Plane the shorter edge C (Fig 2) and check the right, angle with reference edge B., 5 Mark the length and breadth as per sketch. (Fig 2), 6 Plane the longer edge D as per the marked line, and, check 90° with reference to edge C., 7 Plane the shorter edge E as per the marked line, and, check right angle (90°) with reference to edge D. (Fig 2), 8 Check the length and breadth using a wooden scale, (folded)., 9 Polish the sharp edges and surface with sandpaper., , 1 Check the size of the wooden base with the dimensions. (Fig 2), 2 Plane the top surface A (Fig 2) using a planer., , Copyright @ NIMI Not to be Republished, , 51
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TASK 2: Assemble the hand coil machine, Note: The instructor shall give as sub exercises, of Ex. 1.2.17 (S. Ex. 1 to 5) and keep the finished, jobs done from these sub exercises securely., They must be required to assemble the hand, coil winding machine. So, before commencing, the assembling TASK 2, the trainees can be, instructed to complete the 5 sub exercises, given in this exercises 1.2.17., , handle) and fix using machine screw and washer, (Fig 4)., , 1 Fix the angle iron (done in sub exercise so S.Ex. 1.2.17, - 2 - internal threading) on the base of the vertical stand, (done in S. Ex. 1.2.17- 1 drilling and chipping) by bolt, and nut (Fig 1)., , 2 Mark on the wooden base for fixing of vertical stand, (Fig 2)., , 3 Fix the vertical stand on the wooden base using wood, screws (Fig 3)., , 5 Hold the steel tube (done in sub exercise S Ex - 1.2.17, - 5 pipe hacksawing, drilling and internal threading) in, one hand and the threaded rod in the other hand. Insert, the rod through the spacer and the stand (Fig 5)., , 6 Fasten the spacer tube on the rod using screws., 7 Assemble all the components on the base (Fig 6) and, finish the machine assembly., , 4 Insert the square end of the threaded rod (done in, exercise S. Ex. 1.2.17 - 3 external threading and, square slot filing) into the square slot (done in sub, exercise S Ex.1.2.17 - 4 making square hole in crank, 52, , Electrical : Electrician - Exercise 1.2.17, , Copyright @ NIMI Not to be Republished
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Note: Before commencing TASK 2 of this, exercise, complete the following sub exercises, S. Ex. 1.2.17 - 1 to 5 and reserve the jobs for, assembling in Task - 2., , Sub Exercise (S. Ex.) 1.2.17 - 1, Drilling and chipping practice, Objectives: At the end of this exercise you shall be able to, • file two adjacent sides to 90° and mark parallel lines for filing, • file and finish surfaces within ± 0.5mm, • mark by surface gauge for saw cut, • mark locations for drill hole centre using the surface gauge, • transfer measurements from steel rule to the divider, • scribe circles for holes by the divider, • make centre punch for centering drill bit, • make dot punch for saw line and circumference of the drill hole mark, • saw M.S. flat along a straight line, • chip flat surface using cold flat chisel, • drill through holes within ± 0.5 mm countersunk holes, • grind the cutting edge of the flat cold chisel., , Requirements, Tools/Instruments, •, •, •, •, •, •, •, , Flat cold chisel 20 mm, Engineer's ball peen hammer 400 gm., Surface gauge, Hacksaw frame 250 to 300 mm, Twist drill - ø 6, ø10, ø 11.5, ø18, Engineer's parallel blocks, C.S.K. bit ø 15, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 each, - 1 pair, - 1 No., , Bench vice, , Angle plate, Pillar drilling machine, Pedestal grinding machine, Drilling accessories, chuck, sleeve,, drift, , - 1 No., - 1 No., - 1 No., - 1 each, , Materials, •, •, , Equipment/Machines, •, , •, •, •, •, , 58 ISF 10, length 300 mm, Finished part of Exercise No.1.2.16, Hacksaw blade 300 mm, , - 2 Nos., - 2 Nos., , - 1 No., , PROCEDURE, 1 Check the dimensions of the finished job, (EX. 1.2.16 - hack sawing practice)., , 7 Punch mark the circle at four intersecting points with, centre lines., , 2 Evenly apply lump chalk on the job., , 8 Fix the job in the machine vice of the drilling machine to, drill holes marked in part A. (Fig 1), , 3 Mark all lines parallel to the finished datum edge C, (Fig 1) for saw cut and centre of drill holes as per the, drawing by placing the job on the levelling plate. (Refer, skill information - 1.2.16), 4 Scribe all the lines parallel to the finished datum edge, B for saw cut and centre of drill holes as per the drawing, by placing the job on the levelling plate., 5 Mark the intersection points of the centre lines of the, drill holes with the dot punch., 6 Scribe the circle of the drill hole using the divider. (Refer, skill information - 1.2.16), , 9 Drill holes of diameter. 6 mm, 10 mm and 15 mm., 10 Drill without altering the setting of the job, change the, drill bit to 18 mm and drill the hole., No holes should be drilled in the portion of the, job marked part D., 11 Repeat the steps 1 to 10 in the second portion of the, finished job in Exercise No 1.2.16, 12 Make the saw cut at a b, 252 mm from datum C., 13 Chip off the L shape to the dimensions using a flat cold, chisel and holding part A in the bench vice. (Refer skill, information - 1.2.17), , Electrical : Electrician - Exercise 1.2.17, , Copyright @ NIMI Not to be Republished, , 53
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Use goggles to protect your eyes., Dip the tip of the chisel in oil at frequent, intervals to keep the cutting edge cool., 14 Repeat steps 12 and 13 on the second piece., 15 File and finish the edge G opposite to the datum edge, C in both the pieces., 16 Clamp both the job pieces together and fix them in the, drill machine vice. (Refer skill information-1.2.17), 17 Drill 11.5 mm diameter. holes through both the pieces., 18 Drill a pilot hole for 18 mm diameter through both the, pieces., Do not disturb the setting in the drill machine., 19 Drill 18 mm hole through the pilot hole already drilled., 20 Separate both the job pieces., 21 Countersink the 11.5 mm holes (4 OFF) as per the, dimensions given in (Fig 1) in the two pieces of part A., 22 Countersink the 11.5 holes in part D of both the job, pieces as per the drawing in Fig 1., , Skill Information, Hints on chipping, Objective: This shall help you to, • chip metals adopting safe practices., Before commencing the chipping we must ensure the, following factors., , Oily substance, if any, is wiped off from the face of the, hammer., , The hammer head is properly secured. (Fig 1), , The chisel head is free from mushrooms. (Fig 2), , 54, , Electrical : Electrician - Exercise 1.2.17, , Copyright @ NIMI Not to be Republished
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Safety goggles are used., A chip guard is installed to prevent chips flying off. (Fig 3), , Chipping is stopped before the end of the surface to prevent, the edge of the job from breaking off. (Fig 6), , Chip from the end of the job from the opposite direction., (Fig 7), Bangles and wrist watches are removed., Work is properly gripped in the vice. If necessary, it is, supported on a wooden block. (Fig 4), , Hold the hammer at the end of the handle for maximum, leverage. (Fig 8), , The cutting edge of the chisel is looked at and not the head, of the chisel. (Fig 5), The chisel is positioned to cut the metal in uniform, thickness. (Fig 5), , Electrical : Electrician - Exercise 1.2.17, , Copyright @ NIMI Not to be Republished, , 55
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Inserting and removing taper shank drill bit, Objectives: This shall help you to, • insert a drill bit (taper shank) in the spindle of the drilling machine, • remove the inserted drill bit from the spindle., Wipe the drill taper and the sleeve hole clean with a rag., Align the slot in the sleeve with the drill bit tang and insert, it. (Fig 1), , Lower the main spindle far enough to see the wedge, insertion hole. Throw the main spindle vertical handle to the, right and stop the vertical movement of the main spindle ., , Insert the wedge into the sleeve slot. Lightly tap the top of, the wedge with a hammer. If you cannot support it with one, hand, place a wooden block at the bottom with the sleeve,, and then tap. (Fig 3), , Wipe the sleeve taper and the main spindle taper hole with, a rag. Align the sleeve tang with the main spindle slot, and, insert it. Start the main spindle, and make sure there is no, wobble. Turn the inclined edge of the wedge down, and, insert it into the main spindle slot., Support the bit with your left hand to prevent it from falling., Lightly tap the top of the wedge with a hammer. (Fig 2), , Drilling through holes, Objectives: This shall help you to, • fix drill bit in the chuck, • drill a hole., Hold the straight shank drill firmly in the chuck. Adjust and, check the speed of drill as per size. Hold the job deep in, the vice jaws., , 56, , Electrical : Electrician - Exercise 1.2.17, , Copyright @ NIMI Not to be Republished
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Support the job with suitable parallel blocks., Remember that the drill must clear the parallel, blocks when a hole is drilled., , Bring the drill point drawn for the correct centre punch, position marked on the work. Use coolant at the time of, drilling the hole. At the end of the drilling, apply less, pressure on the drill., , Sharpening of chisels, Objectives: This shall help you to, • Safetly operate a grinder., Sharpening of chisels: Chisels become blunt by use. For, efficiency in chipping, chisels need to be regularly, sharpened., Chisels are sharpened on grinding machines. (Fig 1), , Ensure that there is sufficient coolant in the container., While grinding, rest the body of the chisel on the tool rest, (A) and allow the point to touch the wheel. (Fig 4), Rock the point slightly on both sides in an arc (B) to provide, slight convexity at the cutting edge. This will save digging, in of the sides while chipping. (Fig 4), After grinding many times, the cutting edges of chisels, become very thick and are unsuitable for re-sharpening., They need to be forged and brought to shape before, grinding (Fig 2)., , Dip the chisel frequently in the coolant to avoid, overheating., Overheating will reduce the temper of the, chisel., , Before commencing grinding, the following procedure should, be observed., Ensure the wheel guards are in place and are securely, fastened., Inspect the condition of the grinding wheel for breakage and, cracks., , If the chisel head is mushroomed, it should be removed by, grinding. (Fig 5), , Wear safety goggles., When switching on the grinding machine, stand aside until, the wheel reaches the operating speed., Inspect the tool rest. If there is more gap between the tool, rest and the wheel, adjust it and position it as close to the, wheel as possible. (Fig 3), , Electrical : Electrician - Exercise 1.2.17, , Copyright @ NIMI Not to be Republished, , 57
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Use only the front face of the grinding wheel. (Fig 4) Do not, grind on the sides. (Fig 6), Any damage to the grinding wheel, if observed, should be, reported to the instructor., Do not use cotton waste or other material for holding the, chisel while grinding., , Off hand grinding with bench and pedestal grinders, Objectives: This shall help you to, • state the purposes of off-hand grinding, • name the machines with which off-hand grinding is done, • state the features of bench and pedestal grinders., Off-hand grinding is the operation of removing material by, pressing the workpiece against a grinding wheel. Work that, does not require great accuracy in size or shape is ground, in this manner. Work is held in the hands and manipulated, to the desired shape., Off-hand grinding is performed for, •, , rough grinding of a job, , •, , re-sharpening of scriber, punch, chisel, twist drill and, single point cutting tools., , Offhand grinding is performed with a bench grinder or, pedestal grinder. (Fig 1 & Fig 2), , support the work while grinding. These work-rests must be, set very close to the wheels. (Fig 3), , Bench grinders are fitted to a bench or table, and are useful, for light duty work. (Fig 1), Pedestal grinders are mounted on a base (pedestal) and, are fastened to the floor. These are used for heavy duty, work. (Fig 2), , Extra eye shields are also provided for the protection of the, eyes. (Fig 4), , These grinders consist of an electric motor and two, spindles for mounting the grinding wheels. On one spindle,, a coarse grained wheel and on the other fine grained wheel, are fitted. Wheel guards are provided for safety while, working (Fig 2)., A coolant container is provided for frequently cooling the, work. (Fig 2), Adjustable work-rests are provided for both wheels to, 58, , Electrical : Electrician - Exercise 1.2.17, , Copyright @ NIMI Not to be Republished
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Sub Exercise (S. Ex.) 1.2.17 - 2, Internal threading practice, Objectives: At the end of this exercise you shall be able to, • mark off parallel lines by surface gauge (R), • saw as per marking(R), • file and finish to 90o ± 1o and to the required length to ± 0.5mm (R), • mark for drilling holes (R), • drill holes using the pillar drilling machine (R), • form internal thread using hand tap and wrench., , Requirements, Tools/Instruments, •, •, •, •, •, •, •, , Equipment/Machines, , Surface gauge, Hacksaw frame 250 to 300 mm, Engineer's ball peen hammer 200 gm, M 10 tap and wrench, Steel rule 300 mm, Twist drill, ø 8.5 and ø11.5, Try square 150 mm, , - 1 No., - 1 No., - 1 No., - 1 set., - 1 No., - 1each., - 1 No., , •, •, •, •, •, , Bench vice 50 mm jaw, Drilling machine–pillar type, Angle plate, Surface plate, Drilling accessories, chuck,, sleeve and drift, , - 1 No., - 1 No., - 1 No., - 1 No., - as requried., , Materials, •, , Finished part of Exercise 1.2.02 (filed full surface), , PROCEDURE, TASK 1: Prepare the angle iron and drill through holes in it, 1 Check the dimension of the finished filed part of Exercise, 4 Punch scribed lines using dot punch., 1.2.16., 5 Saw centrally, and part into two pieces., 2 Apply lump chalk on the two flanges of the angle., 6 Mark off again for 60mm length. (Fig 2), 3 Mark off the length of the angle iron - 74 mm, using, 7 Saw, file and remove unwanted metals., surface gauge. (Fig 1), 8 File and finish one piece to 60 mm length., 9 Mark off in one flange for the tapping hole. Mark off the, other flange for the clearance hole. (Fig 2), 10 Drill ø 8.5 mm for two tapping holes., 11 Drill ø 11.5 mm for two clearance holes., After performing the above operations get it, approved your instructor., 12 Repeat steps 6 to 11 for finishing another piece., , Electrical : Electrician - Exercise 1.2.17, , Copyright @ NIMI Not to be Republished, , 59
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Skill Information, Internal threading of through holes using hand taps, Objectives: This shall help you to, • determine tap drill sizes for internal threading, • cut internal threads using hand taps., For cutting internal thread, it is necessary to determine the size of hole (tap drill size). This can be chosen, from the table of tap drill sizes., 1 Drill the hole to the required tap drill size., Remember give the chamfer required for, aligning and starting the tap. (Fig 1), , 4 Position the tap vertically in the chamfered hole that, ensuring the wrench is in the horizontal plane., 5 Exert steady downward pressure and turn the tap, wrench slowly in the clockwise direction to start the, thread., 6 Hold the tap wrench close to the centre. (Fig 4), , 2 Hold the work firmly and horizontally in the vice., The top surface should be slightly above the level of the, jaws of the vice. This will help to use the Try square, without any obstruction while aligning the tap. (Fig 2), , When you are sure of starting to thread, remove the tap, wrench without disturbing the tap alignment., Use soft jaws while holding the finished surface, on the vice., 3 Fix the first tap (taper tap) in the wrench., Very small wrenches need more force to turn, the tap. very large and too heavy tap wrenches, will not give the required feel to turn the tap, slowly as it cuts. (Fig 3), 60, , 7 Check that the tap is vertical, with the help of a small, Try square. (Fig 5) Place the Try square in two positions,, 90o to each other. (Fig 6), 8 Make corrections, if necessary., This is done by exerting slightly more pressure on the, opposite side of the tap inclination. (Fig 7), , Electrical : Electrician - Exercise 1.2.17, , Copyright @ NIMI Not to be Republished
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12 After the tap is positioned vertically, turn the wrench, lightly by holding the ends of the wrench handles, without exerting any downward pressure. (Fig 8), While turning the wrench the movement should, be well balanced. Any extra pressure on one, side will spoil the tap alignment, and can also, cause the tap to break., 13 Continue cutting the thread., 14 Turn backwards frequently about quarter reverse turn to, remove the chips. (Fig 9), , 15 Stop and turn backwards when some obstruction to the, movement is felt., Use a cutting fluid while cutting the thread., 16 Cut the thread until the tap is fully inside the hole that, is being threaded., 17 Finish and clean using the intermediate and plug tap., The intermediate and plug tap will not cut any, thread if the taper tap has fully entered the, hole., 18 Remove the chips from the work with a brush., Apply side pressure after giving a turning motion, to the tap., 9 Check the tap alignment again with a Try square., , 19 Check the threaded hole with a machining screw., 20 Clean the tap with a brush and place it back on the, stand. (Fig 10), , 10 Fit the wrench and tighten without disturbing the tap, alignment., 11 Make one or two turns and check the alignment., The tap alignment should be achieved within, the first few turns. This cannot be done, afterwards as the threads may break., , Electrical : Electrician - Exercise 1.2.17, , Copyright @ NIMI Not to be Republished, , 61
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Sub Exercise (S. Ex.) 1.2.17 - 3, External threading and square slot filing, Objectives: At the end of this exercise you shall be able to, • make internal thread in blind holes, • make external thread on M.S. rod, • make square slot on M.S. rod, • make square on one end of the rod., , Requirements, Tools/Instruments, •, •, •, •, •, •, •, •, •, •, , Square, second cut file 200 mm, Try square (Engineer's) 150 mm, Surface gauge, Dot punch, Engineer's ball peen hammer 200 gm., Outside caliper 150 mm, Steel rule 300 mm, Twist drill ø 5, M 6 tap, Round split die ø/18, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 set., - 1 No., - 1 No., , •, •, , Die stock, Odd leg caliper, , - 1 No., - 1 No., , Equipment/Machines, •, •, •, •, , Bench drill machine, Bench vice 50 mm jaw, 'V' block, Clamp (G), , - 1 No., - 1 No., - 1 No., - 1 No., , Materials, •, , ISRO 20 turned and finished to ø 18, length 270 mm., , - 1 No., , PROCEDURE, 1 Check the size of the raw material as per the sketch (Fig, 1) using an outside caliper and a steel rule., , 9 Mark off square with the surface gauge and Try square., , 2 Fix the job vertically in the bench vice at least 50 mm, from the jaw of the vice., , 11 Mark off open right angle slots (G) on the rod., , 3 File one end of the rod and check 90° with the Try, square., 4 Evenly apply the lump chalk on one end., 5 Set the job vertically on the surface plate supported by, the `V' block and clamp., 6 Mark off the centre of the round rod with the odd leg, caliper., 7 Punch for centering the tap drill hole., 8 Set the job horizontally on the `V' block., , 62, , 10 Punch the square scribed lines., 12 File the square on the end of the rod and check 90° with, a Try square., 13 Check from side to side of the square with an outside, caliper., 14 File the right angle slots (G)., 15 Check the depth and width of the slot with the steel rule., 16 Form blind hole tapping with hand tap and wrench., 17 Form external thread with die and stock., 18 Check the thread using the screw pitch gauge., , Electrical : Electrician - Exercise 1.2.17, , Copyright @ NIMI Not to be Republished
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Sub Exercise (S. Ex.) 1.2.17 - 4, Practice of making square holes in crank handle, Objectives : At the end of this exercise you shall be able to, • file on face to flatness using straight edge and light gap (R), • file angle to 90° within Try square accuracy (R), • perform operations of marking straight lines (R), • file and finish surfaces within ± 0.5 mm (R), • mark off for drill and square holes with surface gauges, • drill holes, • form internal thread using a hand tap, • file the surfaces of the inner square hole with a safe edge square file, • measure the inner square hole with an inside caliper., , Requirements, Tools/Instruments, •, •, •, •, •, •, •, •, , File flat, bastard, double cut 300 mm, File flat, second cut double cut, 300 mm, Try square (Engineer's) 150 mm, Surface gauge, Engineer's ball peen hammer 200 gm, Inside caliper 150 mm, M 6 tap and wrench, Square safe edge file 200 mm, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 set., - 1 No., , •, •, , Straight edge, Twist drill ø 5, , - 1 No., - 1 No., , Equipment/Machines, •, •, •, , Bench drill machine, Angle plate, Bench vice, , - 1 No., - 1 No., - 1 No., , Materials, •, , 30 ISF 6 (Length - 184 mm), , - 1 No., , PROCEDURE, 1 Check the size of the raw material as per the sketch, using a steel rule., , 16 Finish the job with a second cut file within an accuracy, of ± 0.5mm., , 2 Fix the job horizontally in the bench vice., 3 File the reference face No.1 to flatness and check the, flatness by straight edge and light gap., 4 File two datum edges 2 and 3 with reference to face, No.1 at right angles and check with a Try square., (Fig 1), 5 Evenly apply lump chalk on the job., 6 Mark off length and width using a surface gauge on, datum edges 2 and 3., 7 File and finish length and breadth as per dimensions., 8 Mark off in one end for tap drill hole and another end for, square hole as per dimensions., 9 Punch scribed lines., 10 Drill φ5mm for tap drill and square hole, for φ10.5 mm., 11 Form internal thread with M6 tap., 12 Finish square hole using square safe edge file and, warding file., 13 Check the inner square hole with an inside caliper., 14 Round the firm corners., 15 Deburr all the edges., Electrical : Electrician - Exercise 1.2.17, , Copyright @ NIMI Not to be Republished, , 63
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Sub Exercise (S. Ex.) 1.2.17 - 5, Hacksawing, drilling and internal threading on the pipe, Objectives: At the end of this exercise you shall be able to, • file one end of M.S. tube and check 90° at the end of the pipe, • perform marking on M.S. tube to different dimensions as per the sketch with the help of a surface gauge, • perform marking for different depths using the box square, • saw M.S. tube along straight lines and slant lines, • drill a hole on M.S.pipe., • form internal thread (small size on the M.S. tube)., , Requirements, Equipment/Machines, , Tools/Instruments, •, •, •, •, •, •, •, •, •, , File flat, second cut, double cut, 300 mm, Steel rule 300 mm, Try square (Engineer's) 150 mm, Surface gauge, Engineer's ball peen hammer 200 gm., Dot punch, Hacksaw frame, adjustable 250 to, 300 mm, Box square, Outside caliper, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , •, •, •, •, , Bench vice 50 mm jaw, Sensitive drilling machine, `V' blocks, Surface plate, , - 1 No., - 1 No., - 1 pair., - 1 No., , Materials, •, •, , Steel tube H.F.W ø 20, length 174 mm., Hacksaw blade 300 mm, 18 TPI, , - 1 No., - 1 No., , - 1 No., - 1 No., - 1 No., , PROCEDURE, 1 Check the size of the steel tube as per sketch (Fig 1), with an outside caliper and steel rule., 2 File one end of the tube and check 90° with the Try, square., 3 Apply lump chalk on the outside of the tube., , 64, , 4 Place it vertically on the surface plate., 5 Mark off the required length for part A - 60 mm length,, with a surface gauge., 6 Saw part A. (Fig 1), , Electrical : Electrician - Exercise 1.2.17, , Copyright @ NIMI Not to be Republished
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7 Mark off the other end as part B. (Fig 2), 8 File and finish the required length of part B., 9 Set part B vertically on the surface plate supported by, a `V' block., 10 Mark off the different heights as per the sketches with, the surface gauge by rotating the job for a saw cut., 11 Place the tube horizontally on the `V' block., 12 Mark off different depths of saw cut using box square or, key seat rule., 13 Punch the scribed lines., 14 Saw all cuts as per the marking., 15 Finish the job, part B by removing the burrs., 16 Mark off part A as per the required length 60 mm., 17 File and finish part A and check with the Try square., 18 Mark off for two tap drill holes on part A., 19 Fix the job on a `V' block and clamp it., 20 Drill ø 2.4 mm on the punch mark on one side of the steel, tube., 21 Form internal thread on the drilled hole., 22 Remove burrs and finish parts A and B., Part A will be kept for assembly fitting as a, spacer., , Skill Information, Hacksaw blade, Objectives: This shall help you to, • identify the set of hacksaw blades, • state the number of teeth in the sawing tubes., There are two sets of blades, •, , Staggered set (Fig 1), , Hacksaw blade section, Teeth per inch, (25.4 mm), , •, , Wavy set (Fig 2), , Material and shape, of workpiece, , 14 teeth, , Mild steel, brass,, , 18 teeth, , Cast iron, gas pipe,, , 24 teeth, , Hard steel, angle irons,, , 32 teeth, , Thin iron sheet, thin, steel pipe,, , Electrical : Electrician - Exercise 1.2.17, , Copyright @ NIMI Not to be Republished, , 65
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Select and use blades in such a way that the number of, teeth cutting the wall of the tube is at least two at a time., (Fig 3 & 4), , Less than two teeth will resuli in tearing of the, thin plate, or damage the blade's teeth., Saw thin plates at an angle such that a minimum of two or, three teeth are in cutting action., , Cutting pipes, Objective: This shall help you to, • cut a metal pipe., Metal pipes can be held firmly by a pipe vice for cutting at, the desired, marked position. (Fig 1), , Set the hacksaw blade at right angles to the conduit on the, spot to be cut., Set your left thumb on the conduit as a guide and make the, initial cut into the conduit by moving the hacksaw back and, forth across a small distance. (Fig 2), Pipe cutters are used to cut thin walled non-ferrous pipes., , Locate the spot to be cut, about 150mm outside the vice., Tighten the handle securely., Slide the handle forward so that it does not interfere with the, work area. (Fig 2), , 66, , Electrical : Electrician - Exercise 1.2.17, , Copyright @ NIMI Not to be Republished
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Hacksawing steel pipe/tube, Objectives: This shall help you to, • fix a steel pipe in a pipe vice, • saw steel pipes., For cutting steel pipes, a blade with a pitch of 24 teeth per, 25mm should be selected. (Fig 1), , The steel pipe should be fixed in a pipe vice., Set your left thumb on the pipe as a guide. (Fig 2), , After cutting the pipe you have to do the following things:, • Square the end of the pipe., • Remove the outside burrs. (Fig 5), • Remove the inside burrs with a half round file. (Fig 6), , Grip the hacksaw handle in the right hand. The blade, should be on the top of the cutting line. (Fig 3), , Hold the handle of the hacksaw in your right hand and the, front of the frame in your left hand. Gradually increase the, pressure on the forward stroke., To finish cutting, use your left hand to support the pipe end, and make the final cuts very tightly. (Fig 4), , Electrical : Electrician - Exercise 1.2.17, , Copyright @ NIMI Not to be Republished, , 67
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Electrical, Electrician - Basic Workshop Practice (Allied Trade), , Exercise 1.2.18, , Practice on preparing 'T' joint, straight joint and dovetail joint on wooden, blocks, Objectives: At the end of this exercise you shall be able to, • mark lines on wooden planks, • cut the given planks with hand saw and Tenon saw to the required sizes, • set the jack plane blade for rough and fine cut, • plane the surfaces and edges of the board using jack and smoothing plane, • make the pin and socket on the wood, • make half lap 'T' joint with pin and socket on the wood, • make a straight joint (half lap), • make dovetail angle, • make a half lap dovetail joint., , Requirements, Tools/Instruments/Equipment, •, •, •, •, •, •, •, •, •, •, •, •, , Pencil, - 1 No., Scriber 75 mm, - 1 No., Hand saw 450 mm, - 1 No., Try square 200 mm, - 1 No., Tenon saw 300 mm, - 1 No., Four fold wooden rule (600mm), - 1 No., Marking gauge, - 1 No., Firmer chisel 25 mm, 35 mm & 50 mm - 1 No, 300mm, each, Hammer (0.57 g & 200 gm), - 1 No., each., 'T' Bevel square, - 1 No., Dovetail saw, - 1 No., Mallet, - 1 No., , •, •, •, •, •, •, •, •, •, , 'G' clamp, Straight edge 600 mm, Steel rule 300 mm, Jack plane, Smoothing plane, Work bench with vice (10cm jaw), Paring chisel, Bench hook, Oil stone, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , Materials, •, •, , Hard wood 340 x 200 x 30 mm, (for sawing machine), - 1 Piece., Teak wood or any other hard wood, (360 x 60 x 25 mm) for planning practice, and 'T' joint, - 3 Piece., , PROCEDURE, Instructor shall demonstrate, marking, cutting (sawing) and planing operations on the given wooden, planks before making joints., TASK 1: Marking lines and cutting (sawing) on the marked lines on the wooden planks, Practice on marking lines on the wooden plank and, cutting (sawing) on the marked lines, 1 Check the raw material size., 2 Draw 4 lines parallel to the edge along the grain with 10, mm spacing between the lines and straight edge on one, face of the given wooden piece using pencil., 3 Extend these lines to both ends using a Try square and, connect them on the other face, using a straight edge., (Fig 1), 4 Draw 4 lines across the grains on one face from one end, with 20 mm spacing between the lines using a pencil, and try square and extend these lines on both edges, and the other face using a Try square. (Fig 2), , 68, , 5 Fix the piece on the workbench top with a `G' clamp., See that the cut along the grain-marked portion is clear, on the workbench top., Do not overtighten the `G' clamp., , Copyright @ NIMI Not to be Republished
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8 Remove the `G' clamp and fix the wooden piece such, that the marked portion across the grain is clear of the, workbench top., 9 Start cutting across the grain on the first line from the, end with a Tenon saw., 10 Repeat sawing on the remaining 3 lines, one after the, other. Check whether the board size is 260 x 160 mm, (Fig 3)., 6 Start cutting along the grain on the first line from the, edge with a hand saw., , 11 Repeat sawing practice on the wood everyday to, produce at least 6 mm thick and 300 mm long plank, from 25 mm thickn plank., , Use a well sharpened saw for good results., Saw with even strokes using the full length of, the saw blade., Keep your eye on the line being cut., Keep your left hand away from the cutting edge, of the saw while sawing., 7 Repeat sawing on the remaining 3 lines, one after the, other., TASK 2: Practice on sawing along the grains to the marked lines using hand and Tenon saw, 1 Identify the grain direction of the piece prepared under, Task 1., , Keep this finished wooden plank for Ex. 1.2.19, , 2 Draw a line parallel to the edge along the grain using a, steel rule/straight edge and a pencil keeping the width, of the board as 155 mm., , 6 Check the piece with a straight edge/steel rule and Try, square for squareness and size of 155 x 245 x 30 mm., (Fig 4), , 3 Draw a line across the grains from one end measuring, 245 mm length of the board., 4 Saw along the grains to the marked line with a hand, saw., 5 Saw across the grain to the marked line with a Tenon-saw., Saw with even strokes using the full length of, the saw blades., , Skill Information, Use of try square, Objectives: This shall help you to, • mark lines on wooden boards/battens, • test flatness and squareness using a Try square., A Try square is used for testing squareness and to mark, lines at right angles to the given surface and edges., The Try square has two parts. (Fig 1), – Stock or handle, – Blade, , Electrical : Electrician - Exercise 1.2.18, , Copyright @ NIMI Not to be Republished, , 69
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Common uses, To test surfaces: Hold the Try square in the reverse, position and keep one edge of the blade vertical on the, surface to be tested. Look through between the edge of the, Try square and the surface being tested (facing source of, light). This will show the high and low spots. (Fig 2), , To test the squareness of edges: Place the stock firmly, against the face. Then lower the inner edge of the blade on, the edge to be tested and look through between the surface, of the edge and the edge of the blade of the Try square., (Fig 3), , To mark lines: To mark lines on the edge or face at right, angles, hold the Try square as shown in Fig 6., Use a marking knife or pencil and draw the lines., , To test the squareness of ends: Test from the face and, the edge. Hold the Try square as shown in Figs 4 and 5., While testing the squareness hold the handle firmly against, the surface., , How to handle a hand saw, Objective: This shall help you to, • cut the given battens, boards etc, with a hand, saw., Saws are used to cut wood pieces to the required sizes., Proper holding of the saw gives ring better control during, use., How to hold?: Hold the handle by inserting 3 fingers, (little,ring and middle fingers) of the right hand in the, opening of the handle unit supporting the opposite side with, the thumb. Keep the index finger along the face of the, handle pointing towards the length of the blade. (Fig 1), , 70, , Electrical : Electrician - Exercise 1.2.18, , Copyright @ NIMI Not to be Republished
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For sawing along the grain, keep the cutting edge of the, saw at an angle of approximately 60 o to the face of the, board being cut. (Fig 2), , For sawing across the grain, keep the cutting edge of the, saw at an angle of 45o to the face of the board being cut., (Fig 3) Hold the piece with the left hand at the finishing cut., , How to handle a Tenon saw, Objective: This shall help you to, • cut the given board and batten to the required shape/size with a Tenon saw., A Tenon-saw is used for sawing both across and along the, grain, and is particularly suitable for fine cutting for light, jobs., , Initially, mark a `Kerf' at the starting point by taking one or, two back strokes, and then start sawing using forward, strokes. (Fig 3), , How to hold a Tenon saw? Hold the handle by inserting, 3 fingers tittle, ling and middle fingers of the right hand in, the opening of the handle, while holding the opposite side, with the thumb. Keep the index finger along the handle, pointing towards the length of the blade. (Fig 1), , When starting a cut, guide the saw's cutting edge to the, marked line with the thumb of the left hand as shown in Fig, 2., , Gradually, bring the cutting edge of the saw parallel to the, surface of the piece being cut. (Fig 4) Exert moderate, pressure on the forward strokes, but reduce the pressure, on the return strokes. Reduce the pressure and make, short and light strokes, while finishing the cut., Always use well sharpened saws. Hold the, material firmly while sawing. Saw with even, strokes., , Electrical : Electrician - Exercise 1.2.18, , Copyright @ NIMI Not to be Republished, , 71
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Method of using a steel rule, Objective: This shall help you to, • mark perfect lines on wooden boards/battens using a steel rule., A steel rule is graduated both in inches and millimeter, (Fig1)., , To mark the distance: Position the rule as shown in, Fig 4. The required scale graduation is in line with the, marked line. Use a sharp, pointed tool or scriber to mark., , A steel rule with mm and cm graduations is used for, checking distances, and for taking linear measurements., How to use?, To measure between lines: Position the front end, exactly on line `A' with the scale of the rule at 90o to line `B'., Read the distance where line `B' coincides with the, graduation on the scale. (Fig 2), , For accurate reading, you have to look straight, and vertical at the point where line `B' and the, graduation of the scale meet. Looking at this, point, from an angle from either side, will result, in a reading error. (Fig 5), , To measure between edges: Position the front end of the, rule exactly in line with edge `A' of the workpiece and the, scale at 90o to the edge. Read the distance between the, edges `A' and `B'. (Fig 3), , 72, , Electrical : Electrician - Exercise 1.2.18, , Copyright @ NIMI Not to be Republished
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TASK 3: Practice on planing the surfaces and edges of the board using jack and smoothing planes, 1 Fig 1 shows the size of the wooden piece after planing., Check the raw material size., , (, , 13 Plane one face of the board, used in the previous, exercise, flat., 2 Set the jack plane for planing. Use a well sharpened, plane blade., , 14 Check for its flatness (using a Try square) and also, check lengthwise and diagonally with a straight edge., , 3 Place the batten on the workbench against the bench, stop. Plane one face of the batten flat and straight., , 15 Plane the edge of the board flat and square to the face., , Maintain proper pressure on the plane, while, planing., , 16 Set the marking gauge for 150 mm and mark the line, for the width of the board on both the faces., , 4 Check the flatness with a Try square across the length,, and check the straightness with a straight edge along, the length., 5 Indicate the finished face as a reference surface by, marking with a pencil., 6 Hold the batten in the bench vice, and plane the edge, straight and square to the face., Lay the plane side ways to protect the cutting, edge of the blade, when not in use., 7 Check for squareness and straightness of the finished, edge and make a mark with a pencil to indicate it as the, reference edge., , 17 Plane the other edge to the marked line., 18 Set the marking gauge for 25 mm and mark for, thickness on both the edges., 19 Plane the other face to the marked line and check the, face for flatness., 20 Check the planed board to the dimensions of, 240 x 150 x 25 mm., 21 Firmly hold the board in a vertical position in a carpenter's vice, keeping the end of the board projecting 25, mm to 30 mm above the vice jaws., 22 Set the smoothing plane for a moderate cut., , 8 Set the marking gauge to 30 mm and mark a line for the, width of the batten on both the faces., , 23 Plane the end of the board half way from both the edges, using the smoothing plane., , 9 Plane the batten edge holding on the bench vice and, remove the excess material up to the marked line., , 24 Test the squareness of the end from the face and edge, using a Try square., , 10 Set the marking gauge for 25 mm. and mark for the, thickness of the batten on both edges., , 25 Mark the length of the board as per the drawing, using, steel rule, Try square and scriber on both faces and, both edges., , 11 Fix the batten in the vice and plane the other face to, remove the excess material up to the marked lines., 12 Check the planed batten for its dimensions, 255 x 30 x 25 mm. (Fig 2), , 26 Cut the extra portion using a Tenon saw, keeping the, saw thickness on the waste side., 27 Plane the other end (by repeating steps 21 to 24)., , Electrical : Electrician - Exercise 1.2.18, , Copyright @ NIMI Not to be Republished, , 73
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Skill Information, Setting a jack plane blade, Objective: This shall help you to, • set the jack plane blade for rough and fine cuts., A jack plane is used to plane the wood to the required, dimensions with smooth surface finish., It is neccessary to set and adjust the plane blade for even, and uniform cuts while planing., Steps in setting, , Adjust the plane blade parallel to the sole of the, plane: Check whether the cutting edge of the blade is, parallel to the bottom face of the plane. Gently, move the, adjusting lever to the left or right until it is parallel if it is not, parallel to the bottom face of the plane. (Fig 2), , The two steps in setting the plane blade are:, – setting the plane blade to the required depth of the cut, – adjusting the cutting edge of the plane blade parallel to, the plane sole or bottom face., Setting the plane blade to the required depth of cut:, Hold the plane in the left hand keeping the sole of the plane, in line with your view at a convenient distance., Turn the adjusting the nut in the anticlockwise direction to, the required depth of cut until the cutting edge of the blade, projects above the sole or bottom face of the plane. (Fig 1), , While setting the plane blade, face the source, of light., To protect of the cutting edge of the blade,, withdraw the plane blade into the plane before, replacing the jack plane in the tool kit., , Jack plane - Care and use, Objective: This shall help you to, • plane the surfaces and the edges of boards and battens using a jack plane., How to hold a jack plane? It is necessary to hold the, plane properly in both hands so as to maintain balance and, have better control of the plane while planing. While planing, hold the plane as shown in Fig 1., How to operate? Start of stroke Apply downward pressure on the knob with the left hand and push the plane, forward., Length of stroke: Apply equal pressure with both hands, on both the knob and the handle., , 74, , Electrical : Electrician - Exercise 1.2.18, , Copyright @ NIMI Not to be Republished
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End of stroke: Reduce the pressure on the knob while, applying pressure only on the handle (Fig 2) at the tail end, of the planing until the stroke is completed., , When setting down a plane on the bench, for example, between operations, ensure that the cutting edge is clear, of the bench. This can be done by:, – resting the front of the plane's body on a piece of wood,, or, – placing the plane on its side., If the cutting edges are allowed to come in, contact with the bench, it will be damaged or, become blunt., Any damage to the face of the plane will be transferred to, the workpiece. Ensure that the face is smooth and free from, burrs., , Use of marking gauge, Objective: This shall help you to, • mark lines on wooden boards and battens according to the drawing, using a marking gauge., A marking gauge is used for marking lines parallel to the, face or the edge at any given distance. Correct use of the, marking gauge will help to produce perfect and clear lines., How to set? Release the thumb screw., Hold the scale in the right hand and the marking gauge in, the left hand. (Fig 1), , Ensure that the stock or head of the marking gauge is firmly, touching with the reference edge or face., Push it forward to mark a line, parallel to the reference or, face, as required. (Fig 3), , Move the stem or beam to the required measurement, between the face of the stock and spur., Keep the scale away and tighten the thumb screw., Recheck the gauge setting for accuracy of measurements, before use., How to use? Hold the marking gauge in the right hand. Tilt, it forward in the direction of the marking. (Fig 2) Exert, minimum pressure for the spur to scribe a line., , While using a marking gauge, always give, forward strokes., , Method of checking flatness, Objective: This shall help you to, • check the faces and edges of boards for flatness., Wider surfaces of planed boards are checked for flatness., This is done at a number of places on the board while, planing to ensure that the surfaces planed are perfectly flat., How to check? Check the flatness by placing a Try square, across over the board. (Fig 1), , Repeat the above step at a number of places on the boand, along the length of the surface., Check the flatness by placing a straight edge over the, surface of the board and lengthwise and diagonally. (Fig 2), , Electrical : Electrician - Exercise 1.2.18, , Copyright @ NIMI Not to be Republished, , 75
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Never drag the Try square over the surface of, the board., While testing surfaces for flatness, face towards, the light., , TASK 4: Prepare a half lap 'T' joint on a wooden plank, Check the size of the given plank. (300 x 60 x 25, mm), , 3 Mark both the pin and socket pieces as per the drawing., (Fig 2), , 1 Plane the piece as per required size 50x20x300mm., 2 Saw it into two pieces of sizes 50x20x170 (socket) and, 50x20x120mm (pin). (Fig 1), , 4 Check the markings as per drawing., Pin piece, 5 Hold the piece in the vice., 6 Cut the shoulder line down to the centre of the face edge, using Tenon saw. (Fig 2), 7 Cut on the waste side on the line., 8 Hold the piece in the vertical position in the vice., (Fig 3), , 76, , Electrical : Electrician - Exercise 1.2.18, , Copyright @ NIMI Not to be Republished
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9 Cut the centre line down to the shoulder. (This cut, should be on the waste side of the line)., , 15 Chisel off the waste portions. (Fig 8 and 9), , 10 Complete the cut., 11 Smooth the surface with paring chisel as shown in, Figs 4 and 5 and complete it., , Socket piece, 12 Hold the socket piece in the vice., 13 Saw close to the marked line (shoulder line) up to the, depth of 10 mm using Tenon saw. (Fig 6), 16 Smooth the trench surface side and the side walls with, firmer or parting chisel. (Fig 10), , 14 Make several saw cuts as shown in Fig 7., , 17 Assemble the pin and socket pieces together. (Fig 11), , 18 Check the squareness of the job/joint., , Electrical : Electrician - Exercise 1.2.18, , Copyright @ NIMI Not to be Republished, , 77
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TASK 5: Prepare a straight joint on wooden block, 1 Check the measurement of wood piece of, 300 x 60 x 25 mm., 2 Plane into size 300 x 50 x 20 mm (socket and pin)., 3 Saw into two pieces of size 140 x 50 x 20 mm as in, Fig 1., , 9 Assemble the pin and socket pieces together (Fig 4),, in proper position without overlapping., 10 Fasten the assembly of straight joint by hammering, with four wire nails at equal distance as in Fig 4., , 4 Mark both the pin and socket pieces as per the drawing., 5 Check the markings as per the drawing., 6 Hold the piece in the vice., 7 Repeat from step 6 to 10 as in TASK 4 for both the, pieces (socket and pin)., 8 Smooth the surface with paring chisel as shown in, Figs 2 & 3., , While fixing the nail, the head of the nail, should not project on the other side. Avoid, fixing nails on the edges as it may cause, cracks., 11 Finish the straight joint by planing the joining surfaces, using smoothing plane., , TASK 6: Prepare dovetail (half lapped) joint, Preparation of material, Check the measurement, 300 x 60 x 25mm., , of, , wooden, , piece, , Plane it to size 300 x 50 x 20mm., Saw into two pieces of 170 x 50 x 20 and 110 x 50 x 20mm., 1 Mark dovetail pin and socket as per the drawing., (Fig 1), 2 Check the marking as per drawing., 3 Hold the pin piece in the vice vertically., 4 Cut near the marked lines up to half of the thickness, using Tenon saw. (Fig 2), 5 Cut the shoulders with Tenon saw. (Fig 3), , 78, , Electrical : Electrician - Exercise 1.2.18, , Copyright @ NIMI Not to be Republished
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9 Hold the socket piece in the vice., 10 Cut the shoulder lines down to the centre line. (Fig 7), , 6 Holding it vertically, cut the dovetail angle with Tenon, saw. (Fig 4), , 11 Cut on the waste side of the line., 12 Chisel off waste materials. (Fig 8), , 13 Smooth the trench surface with firmer chisel., 14 Fit the pin piece with the socket piece. (Fig 9), 7 Pare the dovetail pin and smooth the surfaces using, firmer chisel. (Fig 5), , 8 Place the dovetail pin over the socket piece and check, the marked dovetail socket as per drawing., (Fig 6), , 15 Finish it by chiselling excess material, plane it if, necessary., , Electrical : Electrician - Exercise 1.2.18, , Copyright @ NIMI Not to be Republished, , 79
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Skill sequence, Half lapped dovetail joint, Objective: This shall help you to, • mark the job for half lapped dovetail joints., Marking, Pin, Mark 50 mm from one end in the pin piece., Mark 6.25 mm (1/8th of total width) from both the face, ends., Mark shoulder line on the pin piece all around the end., Mark sloping sides by joining 6.25 mm line to the extreme, the corner of the end of the pin piece. (Fig 1), Set marking gauge to half thickness, gauge the thickness, of the pin from the face side to all sides., Socket, Mark 60 mm and 50 mm from one end in the socket piece., , Mark sloping sides by joining 6.25 mm line to the extreme, end of the socket piece., , Mark 6.25 mm (1/8th of total width) from both the ends of, the trench., , Set marking gauge to half the thickness, gauge the, thickness of the socket from the face side to the edges., , Mark shoulder line on the socket piece all around the, edges., , Mark the sinking line, edges and depth in the socket piece., , 80, , Electrical : Electrician - Exercise 1.2.18, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - Basic Workshop Practice (Allied Trade), , Exercise 1.2.19, , Practice sawing, planing, drilling and assembling for making a wooden, switchboard, Objectives: At the end of this exercise you shall be able to, • make the lines and saw on the grains on wooden blocks (R), • set the jack plane, flat surfaces on wooden blocks plane, • drill holes on boards and battens using hand drill, electric hand drilling machine and ratchet brace, • make countersink holes in wood., , Requirements, Tools / Instruments, •, •, •, •, •, •, •, , Steel rule 300 mm, Try square 200 mm, Marking gauge, `G’ Clamp No 6, Drill bit S.S 6 mm, Hand drill machine 6 mm, Ratchet brace, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , •, •, •, , Countersink bit 6 to 10 mm, Drill bit SS 3 mm, Four fold wooden rule 600 mm, , - 1 No., - 1 No., - 1 No., , Equipment/Machines, •, , Electric hand drilling machine (6 mm), , - 1 No., , Material, •, , Battern prepared in previous exercises, , - 1 No., , PROCEDURE, Note: Sawing and planing operation exercises are already dealt with in the previous exercise (Ex.1.2.04, (joints)) in TASKS 1 & 2. The exercise (sawing and planing) need not be repeated. The jobs prepared, in the previous exercise may be used for this exercise., TASK 1: Drill holes on the wooden batten, 1 Check the given material prepared in the previous, exercise EX.1.2.18 (planing practice TASK 2) as in Fig, 1., , 9 Punch the hole centres with centre punch/sharpened, nail at the markings that have already been made., , 2 Set the marking gauge for 15 mm., , 10 Fix the batten on the workbench top using a `G' clamp., Use a waste piece under the batten while clamping., , 3 Draw the centre line along the edge on both faces using, the marking gauge., 4 Mark points at 151 mm from one end of the batten and, 102 mm from the other end, using a steel rule and, scriber or pencil., 5 Draw lines across the points using a Try square and, scriber or pencil., 6 Extend the lines all round the batten with the Try square, and scriber or pencil., 7 Cut the batten with a Tenon saw between the lines., 8 File the cut ends and finish to the lines marked., Mark hole centres from any end as per drawing with a, steel rule and pencil on the centre line on both battens., (Fig 1), , 11 Drill 6 mm holes on the marked centres of the holes., Use well sharpened drill bits., Hold the drill machine vertically., 12 Fix the countersink bit in the ratchet brace., 13 Countersink all the drilled holes., Do not cut too deep., 14 Check the diameter of the countersunk holes with the, screw head., , Copyright @ NIMI Not to be Republished, , 81
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TASK 2: Drill the pilot holes on the wooden board, 1 Collect the piece prepared in Ex.No.1.2.18, on sawing, practice in TASK 1., , 4 Punch the hole centres with the centre punch / sharpened, nail., , 2 Mark lines with a marking gauge, 15 mm from each end,, as per the drawing for the centre line of pilot holes. (Fig, 2), , 5 Fix the board on the workbench with the `G' clamp., , 3 Mark hole centres as per the drawing with a steel rule, and pencil from one edge on these already drawn, central lines on both the faces., , 6 Drill 3 mm diameter pilot holes to a depth of 15 mm in, the locations already marked., Do not drill holes deeper than specified., , Mark hole locations within ± 0.5 mm accuracy., , 82, , Electrical : Electrician - Exercise 1.2.19, , Copyright @ NIMI Not to be Republished
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Sub Exercise (S.Ex.) 1.2.19 - 1, Make a frame for the test board, Objecitves: At the end of this exercise you shall be able to, • mark perfect lines on wooden planks or battens using a Try square, steel rule and marking gauge (R), • cut boards or battens to size by a hand saw or by a tenon-saw, • plane the surfaces and edges of the planks/battens by a jack plane or iron plane to the marked lines (R), • plane the surfaces of the battens using a smoothing plane, • chisel to remove materials, • mark and prepare half-lap joints using any given size of the batten., , Requirements, Materials, , Tools/Instruments, •, •, •, •, •, •, •, , Tenon-saw 350 mm, Firmer chisel 6 mm, Mallet, Try square 150 mm, Steel rule 300 mm, Jack plane, Marking gauge, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , •, , Teak wood or any hardwood, 260 x 35 x 30 mm, 295 x 35 x 30 mm, , - 2 Nos., - 2 Nos., , PROCEDURE, Take all the measurements carefully and, accurately., , 1 Check the material for its size., 2 Plane all the 4 pieces to size., 260 x 30 x 25 = 2 Nos A, , 4 Measure and mark 95 mm on either side on the centre, line., , 295 x 30 x 25 = 2 Nos B, , 5 Draw lines across the points where 95 mm is measured., , 3 Take the part `A' pieces and mark a centre line across, on one face with a Try square, steel rule and pencil., , 6 Extend the same line to both the edges., 7 Repeat the same for the other piece., , Electrical : Electrician - Exercise 1.2.19, , Copyright @ NIMI Not to be Republished, , 83
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8 Repeat steps 3 to 7 with the `B' pieces but taking 110, mm on either side of the centre line., , Never use a hammer on a chisel. Use only a, mallet., , 9 Set the marking gauge for 1/2 thickness i.e. 12.5 mm., Draw lines parallel to one face with the marking gauge, on both the edges, starting from the ends up to the, shoulder line., , Use well sharpened cutting tools., 17 Test for accuracy with a Try square., , 10 Repeat the same for the remaining three pieces., 11 Cut the shoulders with a Tenon saw up to the gauge line, keeping the saw thickness on the waste side., Always saw on the waste side of the line., 12 Repeat the same for the remaining three pieces., 13 Fix each piece in the vice., 14 Remove the waste material with the saw., 15 Repeat the same for the remaining 3 pieces., 16 Finish all the end-laps with a firmer chisel., , Sub Exercise (S.Ex.) 1.2.19 - 2, Make the back cover of the test board, Objectives: At the end of this exercise you shall be able to, • mark lines perfect on wood with a Try square, straight edge, steel rule, marking gauge (R), • set and plane the surfaces and edges of T.W. battens/boards with a jack plane (R), • cut rebates on the edges of planks/boards with a rebate plane, • mark dimensions on planks with a steel rule. (R)., , Requirements, Tools/Instruments, •, •, •, •, •, •, , Materials, , Try square 150 mm, Steel rule 300 mm, Marking gauge, Handsaw 450 mm, Jack plane, Rebate plane, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , •, , Teak wood plank., 275 x 130 x 25 mm, 275 x 190 x 25 mm, , - 1 No., - 1 No., , PROCEDURE, 5 Draw a line parallel to the face on one edge of each, piece., , 1 Check the material for size., 2 Plane both pieces to size, , 6 Extend the lines to end up to 20 mm length., , 275 x 130 x 25 and, , 7 Set the marking gauge for 20 mm., , 275 x 190 x 25, , 8 Draw a line parallel to the edge on one face of one piece, and on another face of a second piece and extend these, lines on both ends of each piece to half thickness., , 250 x 120 x 20 mm - (1), 250 x 180 x 20 mm - (2)., 3 Test the pieces for flatness, squareness and, straightness., 4 Set the marking gauge to 10 mm., 84, , 9 Set the rebate plane., Use a well sharpened blade with a straight, cutting edge., , Electrical : Electrician - Exercise 1.2.19, , Copyright @ NIMI Not to be Republished
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10 Place the piece on the workbench top and cut the, rebate with a rebate plane to the marked lines., , Keep the plane upright while cutting the rebate., , 11 Reset the rebate plane for smooth cut and finish the, rebates., , 12 Set the rebate edges together and check for accuracy., , Sub Exercise (S.Ex.) 1.2.19 - 3, Make the front panel for the test board, Objectives: At the end of this exercise you shall be able to, • mark lines on wooden boards or laminates using a steel rule, Try square (R), • mark profiles on laminates using dividers/compasses to fix electrical accessories, • make profiles with a fret saw/keyhole saw to house electrical accessories, • mark dimensions on laminates with a steel rule, • drill through holes using power drilling machines (R), • file the laminate to the finished shape with a rasp file., , Requirements, Tools/Instruments, •, •, •, •, •, •, •, , Steel rule 300 mm, Try square 150 mm, Dividers/compasses, Smoothing plane, Fret saw, Drill bit 6 mm, File half round 200 mm, , Equipment/Machines, -, , 1 No., 1 No., 1 No., 1 No., 1 No., 1 No., 1 No., , •, , Electric, portable drilling machine 6 mm., , - 1 No., , Materials, •, , Laminated sheet 250 x 280 x 3 mm, , - 1 No., , PROCEDURE, 1 Check the material for its size. 250 x 280 x 3 mm, 2 Mark the necessary centre lines on the sheet., 3 Mark the profiles for fixing electrical accessories with, dimensions as per the drawing., Take all the measurements accurately., 4 Drill four 6 mm holes in each profile within the corners., 5 Drill one 6 mm hole in the circular profile near the, marked area., 6 Insert a fret saw blade in one of the drilled holes of each, profile, one by one., Use a good saw blade., Select the proper size of blade., 7 Cut along the lines precisely., Keep the thickness of the blade on the waste, side. Keep the blade under tension., 8 Repeat the same for all the profiles marked., 9 Cut and remove the waste material., With the saw blade in motion, move the material, being cut., 10 Finish each profile with a file for accuracy., Saw with rhythmic strokes., Electrical : Electrician - Exercise 1.2.19, , Copyright @ NIMI Not to be Republished, , 85
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Sub Exercise (S.Ex.) 1.2.19 - 4, Assemble the test board, Objectives: At the end of this exercise you shall be able to, • mark dimensions on boards with steel rule, marking gauge (R), • make planks by joining with joint-nails for boards, • use proper size screws and nails according to the purpose, • drill through holes and pilot holes on boards or batten with a drilling machine (R), • bore holes on planks using a ratchet brace, • file wooden materials for proper finishing with a rasp file (R)., , Requirements, Tools/Instruments, •, •, •, •, •, •, , Equipment/Machines, , Hammer 200 mm, Screwdriver 200 mm, Try square 150 mm, Drill bit, 2, 4 and 6 mm, Steel rule 300 mm, G clamp, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , •, , Drilling machine 6 mm, , - 1 No., , Materials, •, , Materials prepared in the previous exercise., , PROCEDURE, , 1 Take all the four finished pieces already prepared for the, frame., 86, , 2 Place the frame on a flat surface and position all the lap, joints on the four corners., , Electrical : Electrician - Exercise 1.2.19, , Copyright @ NIMI Not to be Republished
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3 Check for overall frame dimensions., 4 Put identification marks on both the joints and keep, them separately., 5 Assemble each joint as identified in step 4 and, drive nails for their permanent assembly., 6 Check the assembled frame for squareness in all, the four corners with a Try square., 7 Check for the flatness of the frame by placing it on, a flat surface., 8 Cut off excess material on each joint using a Tenon, saw., 9 Mark pitch line for 15 mm from all the 4 edges on, the face of the front panel., 10 Mark a point at 35 mm from each corner and the, pitch line., 11 Mark centre points on the four sides of the front, panel on the pitch line., 12 Keep the front panel on a flat wooden surface and, fix with a clamp., , 14 Keep the front panel on the frame and adjust the frame., Check if the edges are accurate and clamp them with, a 'G' clamp., 15 Drill 2 mm pilot holes on the frame with the guidance of, the drilled through holes on the front panel., 16 Fix the front panel to the frame with 20 mm screws and, cup washers with a screwdriver., 17 Use the already prepared material in the previous, exercise for the back cover., 18 Keep the back cover on the frame and adjust all the, edges., 19 Fix the back cover to the frame using wire nails (35 mm, x 14 G)., 20 Mark the location for drilling a hole for cable on one edge, of the board widthwise., 21 Firmly hold the board in the vice., 22 Drill a through hole on the marking already done, vide, step No 20., 23 File and give proper finish and round off all sharp edges., , 13 Drill 4 mm through holes and remove the clamp., , Electrical : Electrician - Exercise 1.2.19, , Copyright @ NIMI Not to be Republished, , 87
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Electrical, Electrician - Basic Workshop Practice (Allied Trade), , Exercise 1.2.20, , Practice in marking and cutting of straight and curved pieces in metal sheets,, making holes, securing by screw and riveting, Objectives: At the end of this exercise you shall be able to, • mark straight lines of given dimensions using steel rule and scriber, • shear MS sheet using straight snip, • mark curved lines of given dimensions using divider, • shear along curved lines using bent snip and cut 90o notch, • make holes using a punch, • mark for making holes with drilling machine, • drill holes in the sheet metal with drilling machine, • rivet with a rivet set., , Requirements, Tools/Instruments, •, •, •, •, •, •, •, •, •, , Steel rule 300 mm, Scriber 200 mm, Straight snips 250 mm, Bent snip 250 mm, Divider 200 mm, Hammer ball peen 200g, Mallet (wood), Hatchet stake available size, `G' clamp 250 mm, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , •, •, , Hand drilling machine, Rivet set, , - 1 No., - 1 No., , Materials, •, •, •, , Sheet iron ISST 220 x 0.5 x 300., Sheet iron ISST 55 x 0.5 x 105, (for riveting Task - 4 same sheet can be, used for Tasks 1 to 3)), Trimmers rivets No. 14, , - 2 Nos., - 10 Nos., , PROCEDURE, TASK 1: Practice for marking in metal sheet, 1 Check the dimensions of the given raw material., 2 Take edges A and B as datum. Mark from edge B a, measurement 'V', mark for cut No. 2. Make at least 3, such 'V' marks along cut No.2. (Fig 1), , 4 Draw a line parallel to the scribed line at a distance of, 1 mm. (This line is drawn outside the measurement to, guide the snip, while cutting sheet metal.), 5 Repeat steps 2 and 3 for marking to cut along line 1., 6 Keeping edge A as reference, mark straight lines for, shearing along lines 3 and 4 respectively, repeating, steps 2 and 3., 7 Shear along the marked guidelines for 1, 2, 3 and 4 in, that sequence. The final piece is shown in Fig 2., , 3 Using a scale, draw a straight line with a scriber, connecting all the 3 'V' marks made., 88, , Copyright @ NIMI Not to be Republished
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Skill sequence, Mark straight lines using steel rule and scribers, Objective: This shall help you to, • mark the given dimensions on the sheet metal using a scriber, steel rule, Try square and straight edge., Generally, marking media is not applied on sheet iron, (metal) for marking lines. Instead, a scriber and steel rule, are used., A scriber is used to transfer measurement and to draw, lines., Place the steel rule on the sheet metal to transfer the, dimension from the datum edge or line. (Fig 1), , Lines that need not or must not be removed are scratched, on the material with the sharp point of the scriber., Hold the scriber in the correct angle to get into the corner, when scribing along a straight edge. (Figs 6 & 7), , Scribe a V-mark for the required distance. (Fig 2), Make at least two V-marks to draw a straight line parallel, to the datum. (Fig 3), , Scribe a line through both points of the V-marks (Fig 4),, using the straight edge and the scriber., Draw the line exactly through the points of the V-marks., (Fig 5), , Electrical : Electrician - Exercise 1.2.20, , Copyright @ NIMI Not to be Republished, , 89
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Cut sheet metal using straight snips, Objective: This shall help you to, • cut thin sheet metals with the help of straight snips., Hold the sheet in one hand, and with the other hand hold, the snip handle at the end, and place the upper blade of the, snip on the marked line with an initial angle measuring, lesser than 20°. (Fig 1), , Keep the blade perpendicular to the surface of the sheet., Hold the snips straight, up and down., While holding the snips on the sheet, allow lesser width on, your left side in every cutting, as shown in Fig 3., , Open and grip the sheet by the blade. The opening angle, of the blade should not be more than 20°. (Fig 2), , TASK 2: Practice on cutting curved pieces in metal sheets, 1 Check the dimension of the given sheet iron., , 4 Make indent mark with prick punch (tip angle, 30o)., , 2 Using the steel rule, mark the required dimension for, straight lines as per the diagram. (Fig 1), , 5 Transfer the radius measurement from steel rule to the, divider., , 3 Locate centre d1 for curve '4', as per the measurements, in the drawing., , 6 With the point d 1 as centre, scribe the curve 4., 7 With the same centre and radius reduced by 1 mm,, scribe the guide mark., 8 Repeat steps 3 to 7 for curve 5 with d2 as centre., 9 Shear along line 1 using straight snips., 10 Shear along line 2 using straight snips., 11 Shear along line 3 in part A using straight snips., 12 Shear along curve 4 using bent snip., 13 Shear along curve 5 using bent snip., 14 Mark the bending to 90o line as per the drawing. (Fig 1), Hold the part A along the bending line measurement, marked in the angle plate (fixed in bench vice)., 15 Clamp the extending end of the angle plate with G, clamp., 16 Hammer the projecting portions in stages (15o, 30o, 45o,, 60o and 90o) with a soft mallet. (Fig 2), , 90, , 17 Cut both the notches with the straight snip in part B., (Fig 3)., Electrical : Electrician - Exercise 1.2.20, , Copyright @ NIMI Not to be Republished
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Skill sequence, Marking curved lines using divider, Objective: This shall help you to, • scribe curved lines using dividers., On the sheet, mark a centre line using the scriber and steel, rule., Hold the centre punch on the marked line. First keep the, punch at an angle and then position it upright. Then hit on, it with a hammer. (Fig 1), , Set one point of the divider on the 1 cm mark of a rule, and, adjust the second leg to the required radius., Place the divider on the sheet with the point of one leg on, the centre punch mark. Hold the divider vertically. Swing, the divider clockwise exerting a little pressure. Incline the, divider in the direction of the line to be drawn to prevent, slipping. (Fig 3), , Curve-cutting using bent snips, Objective: This shall help you to, • shear internal and external curves in steel sheet using the bent snips., A bent snip can be used for cutting internal and external, curves., , For circular cutting, rotate the sheet while making a, continuous cut., , Bent snips are used for cutting holes. First, a rough cut is, made. Then the hole is finished off. (Fig 1), , First, a rough cut can be made. (Fig 2) for trimming a, cylinder, keep the lower blade outside the cut. (Fig 3), , Electrical : Electrician - Exercise 1.2.20, , Copyright @ NIMI Not to be Republished, , 91
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TASK 3: Practice on making holes using a punch, Holes in sheets are made either by drilling or by, punching. (Fig 1), , 1 Make location points with the help of a scriber and, punch on the sheet. (Fig 2), , A hole can become smaller than the punch size, when flattened. (Fig 5), Keep the punch vertical. Ensure that the point, of the punch coincides with the locating marks., 2 Use a lead slab as support. The end of a wooden block, can also be used as a support. (Fig 3), 3 Make a hole on the sheet using centre punch Fig 3., The sheet should be placed on the end of the, wood. Otherwise, distortion may be caused as, shown in Fig 4., , 92, , Electrical : Electrician - Exercise 1.2.20, , Copyright @ NIMI Not to be Republished
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Skill sequence, Join sheet metal pieces, Objective: This shall help you to, • join sheet metal using self-tapping screws., For joining two sheet metal pieces with the help of, self-tapping screws. Make pilot holes with the use of a solid, punch., Then select a screwdriver according to the screw to be, used., Finally, insert a self-tapping screw in the pilot hole, and, screw it using a screwdriver applying a downward force., (Fig 1), , TASK 4: Practice on rivetting with rivet sheet metal work, 1 Check the dimension of the given iron sheet., , 6, , 2 Mark a straight line for centre line of the rivet. (Fig 1), , 7 Draw the material and the rivet together tightly by, placing the hole in the rivet set and striking the set one, or two sharp blows with hammer., , Insert the rivet in the hole., , 8 Place the cup shaped hole on the rivet and give the rivet, set one or two sharp blows a the hammer to head the, rivet., 9 Rivet alternately in forward and reverse direction,, beginning with the nearest centre hole., 10 Insert the rivet in the holes that have been made in the, sheets., 11 Draw the rivet and the sheet together by striking one or, two sharp blows with a hammer., 12 Perform heading the rivet with the cup shaped hole of, the rivet set and hammer., , 3 Mark centres for drilling with the centre punch., 4 Drill holes using a hand drilling machine., 5 Place the two pieces of sheet metal together on a, suitable solid plate., , Electrical : Electrician - Exercise 1.2.20, , Copyright @ NIMI Not to be Republished, , 93
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Skill sequence, Joining sheet metal by using rivet set and snap, Objective: This shall help you to, • rivet the thin plates with a rivet set., In thin plates the holes for rivets are punched as shown in, Fig 1., , The shank is to be rounded by giving glancing blows with, the hammer (as shown in Fig 4) for firming the head., , Pass the rivet through the punched hole in the sheet as, shown in Fig 2., , To firmly set the rivet in the sheet, use a rivet set. The rivet, head is to be supported with a dolly. A dolly is used to, prevent the rivet head from expanding when it is struck with, the hammer., , Finally, place the rivet snap on the rivet (as shown in Fig 5), and finish the work by giving a few blows with the hammer., , Faults in riveted joints, Objective: This shall help you to, • identify the faults in riveted joints and the cause., The following faults may be noticed in riveted joints., , Incorrect alignment of punched holes in workpieces. (Fig 2), , Burrs between workpieces as shown in Fig 1., , Incorrect setting of the rivet with the rivet set. (Fig 3), 94, , Electrical : Electrician - Exercise 1.2.20, , Copyright @ NIMI Not to be Republished
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Rough rivet length may be found to be too long. (Fig 6), , Punched holes may be found to be too large. (Fig 4), Closed head may be found to be displaced. (Fig 7), , Rough rivet length may be found to be too short. (Fig 5), The rivet set and rivet snap must be free from burrs., , Removing rivets from metal sheet, Objective: This shall help you to, • remove the rivet from the metal sheet., The most satisfactory method of removing a, rivet on light gauge sheet metal is by drilling., Carry out the following steps:, 1 Flatten and centre punch exactly at the centre of the, formed head. (Fig 1), 5 Place the head of the rivet into a nut, a little larger than, the head of the rivet with a solid punch slightly smaller, than the size of the rivet shank. Punch the shank out of, the head. (Fig 4), , 2 Select a twist drill slightly smaller than the shank of the, rivet. (Fig 2), , Another simple method of removing rivets is to, cut off the formed head using a sharp cold, chisel. The remaining portion of the rivet is, removed by hammering, with a solid punch., 3 Drill into the head of the rivet up to the surface of the, metal. (Fig 3), 4 Remove the rivet head with a cold chisel. (Fig 3), , Precaution: The metal should not be distorted., The rivet hole should not be enlarged., , Electrical : Electrician - Exercise 1.2.20, , Copyright @ NIMI Not to be Republished, , 95
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Electrical, Electrician - Basic Workshop Practice (Allied Trade), , Exercise 1.2.21, , Workshop practice on drilling, chipping, internal and external threading of, different sizes, Objectives: At the end of this exercise you shall be able to, • drill pilot holes matching the sizes of screws with a hand drill machine or an electric hand drilling machine, • drill holes of larger diameter after pilot drilling., , Requirements, Tools/Instruments, •, •, •, •, •, •, •, , Equiment/Machines, , Steel rule 300 mm, Try square 200 mm, Marking gauge, `G' Clamp No.6, Hand drill machine 6 mm, Ratchet brace, Bench vice 50 mm jaw, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , •, •, , Portable electric hand drilling, machine (6 mm), Pillar electric drill machine, 12 mm capacity, , - 1 No., - 1 No., , Materials, •, •, •, •, , 58 ISP length 300 mm, (Finished part of previous exercise), Drill bit S.S.6 mm, Countersunk bit 6 to 10 mm, Drill bit SS 3 mm, , - 1 No., - 1 No., - 1 No., , PROCEDURE, TASK 1: Practice on drilling pilot holes using hand drilling machine, 1 Mark lines with a marking gauge, 15 mm from each end,, according to the drawing for the central line of pilot, holes. (Fig 1), 2 Mark hole centres as per the drawing with a steel rule, and pencil from one edge on the central lines already, drawn, on both the faces., Mark hole locations within ± 0.5 mm accuracy., , 96, , 3 Punch the hole centres with the centre punch / sharpened, nail., 4 Fix the job on the workbench with the bench vice `G', clamp., 5 Drill 3 mm diameter. pilot holes to a depth of 15 mm at, the locations already marked by using hand drilling, machine., Do not drill holes deeper than specified., , Copyright @ NIMI Not to be Republished
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TASK 2: Practice on drilling holes with larger diameter after pilot drilling, 1 Punch the centre of the hole to be drilled using a centre, punch (90°)., , 4 Fix the drill chuck into the spindle of the drilling machine, after cleaning the mating parts., , 2 Punch witness marks using a 60° prick punch on the, periphery of the hole to be drilled. (Fig 2), , 5 Select a smaller diameter drill as a pilot drill before, using the required large size drill., The diameter of the pilot drill/ hole should be, at least equal to the web thickness of the large, drill., Since, the web of large diameter drills are, thicker, the dead centres of those drills do not, seat in the centre punch marks. This can result, in the shifting of the hole location. Thick dead, centres cannot easily penetrate into the material, and will place severe strain on the drill., These problems can be overcome when we, drill pilot holes initially. (Fig 5), , These witness marks guide to ensure that the, hole drilled is exactly in its place., If the drilled hole is perfectly located, half, witness marks are visible at the circumference, of the hole. (Fig 3), , 6 Securely fix the drill deep into the drill chuck. (Fig 6), , 3 Set the job securely in the machine vice on the, parallels., Make sure that the largest size drill to be used, must clear the parallel during drilling. (Fig 4), 7 Determine the speed of the spindle (r.p.m.) from the, recommended cutting speed and the diameter of the, drill or use a table and get the r.p.m., 8 Open (or) remove the belt guard and change the belt to, the pulley of the required cutting speed or to the nearest, r.p.m. and replace the gaurd., , Electrical : Electrician - Exercise 1.2.21, , Copyright @ NIMI Not to be Republished, , 97
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Do not change the belt when the spindle is, rotating. (Fig 7), , 11 Recheck the alignment. Switch ON the machine and, feed the drill gently on to the work. Recheck the starting, of the drill., 12 Use a steady force and feed the drill gently into the job., 13 Provide continuous flow of cutting fluid to prevent, overheating of the drill., 14 Gradually reduce the feed force as the drill reaches the, bottom of the hole., 15 Withdraw the drill from the hole and switch OFF the, machine., 16 Remove the pilot drill and the drill chuck from the, machine. (Fig 6), 17 Fix a large diameter drill into the machine spindle, directly., , 9 Run the spindle and check that the drill is rotating and, in the clockwise direction (from right to left)., 10 Bring the drill point and centre punch mark in line by, adjusting the vice. When the alignment is satisfactory,, clamp the vice to the machine table. (Fig 8a & b)., , 18 Determine and reset the spindle speed (r.p.m.)., Note that the bigger the diameter of the drill is, lesser than the r.p.m. and greater than the feed., 19 Drill to enlarge the hole with steady feed. Stop the, machine, remove the job and clean the chips using a, brush., , Skill sequence, Method of fixing drill bits in a drilling machine, Objective: This shall help you to, • fix a drill bit and check for eccentricity., A drill bit should be firmly fitted for in the drilling machine,, so that straight and circular holes can be drilled. This, prevents accidents too., The drill bit must be centrally located and held firmly in the, chuck of the drilling machine., Fixing a drill bit in a hand drill machine: Hold the gear, of the drilling machine with one hand. (Fig 1), Unscrew, the sleeves of the chuck with the other hand to, provide sufficient clearance for the drill shank in the jaws., (Fig 1), Insert the drill shank into the chuck., Keep the drill centrally seated, and tighten the chuck., , To remove the drill, slacken the jaws by twisting the, hand in the opposite direction (from what was done for, fixing)., , Twist the hand holding the gear to the right to further tighten, the drill while firmly holding the chuck with the other hand., (Fig 1), Electrical : Electrician - Exercise 1.2.21, 98, , Copyright @ NIMI Not to be Republished
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Fixing a drill bit in an electric hand drill machine :, The same procedure used for fixing a drill bit in a hand drill, machine is followed except in the case of slackening and, tightening the jaws of the chuck.(Fig 2), , Slackening and tightening the jaws of the chuck is done, using a special drill chuck key provided with the machine., (Fig 3), , When using a power drill, make sure that the, material to be drilled is fixed firmly in a clamp/, vice., To prevent accidents never attempt to hold the, workpiece by hand., , Locating hole by drilling centre hole, Objective: This shall help you to, • drill centre holes with a drilling machine., Drilling centre holes using combination drills is an accurate, method of locating the position of the holes (i.e. within ±, 0.25 mm). In drilling operations, this method will be helpful, while drilling deeper holes, and holes in fairly accurate, locations. For doing centre drilling, follows the steps given, below., , 5 Remove the centre drill, hold the twist drill of the, required diameter. Check if it 'runs true'. Start drilling the, through hole., , 1 Hold the combination centre drill in the drill chuck and, check whether it runs true'. Adjust the spindle speed to, suit the combination drill., 2 Adjust the job together with the vice and align it with the, centre punch mark. (Fig 1), 3 Drill a centre hole up to a depth of 3/4th of the, countersink. Do not apply undue pressure on the centre, drill., 4 Apply sufficient quantity of cutting fluid., , Sharpening of drills, Objective: This shall help you to, • sharpen drills on an off hand grinder., A drill will loose sharpness of its cutting edges due to, continuous use. Improper use of drills will also spoil the, cutting edges., , Check the grinding wheel for loading, glazing, trueness and, cracks. Call your instructor for advice. Dress and true the, wheel if necessary., , Spoiled or blunt cutting edges of the drills must be, sharpened on a grinder., , Protect your eyes either with goggles or by lowering the, eye protecting shield near the tool rest and adjust the tool, rest at 2 mm closer to the wheel, if necessary., , Electrical : Electrician - Exercise 1.2.21, , Copyright @ NIMI Not to be Republished, , 99
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Check if enough coolant is there in the container., Switch the grinder on., Hold the shank of the drill lightly in one hand between the, thumb and the forefinger, and with the other hand hold the, portion near the point. (Fig 1), , Rotate the drill to the right by turning it between the thumb, and the forefinger. (Fig 4), This turning movement is not necessary for, drills of smaller diameters., While swinging and turning the drill make sure, you do not grind the other cutting edges., All movements of the drill for angular turning,, swinging and forward movements should be, well coordinated. They should result in one, smooth movement to produce a uniformly, finished surface., Repeat the process to re-sharpen the other cutting edges., Check both the cutting edges with a drill angle gauge, for, correctness of the lip angle and same in size of the lip, lengths. (Figs 5 & 6), , The hand near the point of the drill should be, pivoted lightly on the tool rest at 'x' for easy, manipulation. (Fig 2), , Hold the drill level (Fig 2) and turn it to 59° to the face of the, wheel and swing the drill slightly downward and towards the, left. (Fig 3 & 4), , Check the lip clearance angle in Fig 5 visually. The angle, should be between 8° to 12°., Practice on chipping exercise has already been, dealt in Ex. No. 1.2.17 as Sub Exercise 1.2.17- 1, , 100, , Electrical : Electrician - Exercise 1.2.21, , Copyright @ NIMI Not to be Republished
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Practice on making internal threading using hand taps, Objectives: At the end of this exercise you shall be able to, • form internal threads by hand tap and using wrench., , Requirements, Tools/Instruments, •, •, •, •, •, •, , Surface gauge, Hacksaw frame 250 to 300 mm, Ball pane hammer 200 gm, M10 tap and wrench, Steel rule 300 mm., Twist drill 8.5 and 11.5, , - 1 No., - 1 No., - 1 No., - 1 Set, - 1 No., - 1 No each., , Equiment/Machines, •, •, , Bench vice (100 mm), Drilling machine pillar type, , •, •, •, , Angle plate, Surface plate, Drilling accessories chuck, sleeve and drill, , - 1 No., - 1 No., - As required., , Materials, •, •, •, , Hexagonal nut (available size), Square nut (available size), Lubricant oil, , - 1 No., - 1 No., - As required., , - 1 No., - 1 No., , PROCEDURE, Drilling a hole, 1 Determine drill size for tapping using the table for doing, it., 2 Drill a blind hole using the depth stop arrangement., The depth of the tapping hole should be slightly more, than the depth of the required thread. (Fig 1), , Procedure for threading, 3 Remove metal chips, if any, from the blind hole by, turning it upside down and slightly tapping it on the, wooden surface., Do not clear the chips by blowing as it can, cause injury to your eyes., 4 Screw a matching hexagonal nut on the first tap to act, as the depth stop. (Fig 2), 5 Thread the blind hole until the nut touches the plate, surface., 6 Remove the chips from the hole frequently, using a, flattened and bent wire. (Fig 3), , 7 Finish tapping the hole with intermediate and bottoming, tap (Fig 4). Set the nut to control the depth of the thread., 8 Repeat and practice steps 4 to 7 for forming internal, thread on a square nut., , Electrical : Electrician - Exercise 1.2.21, , Copyright @ NIMI Not to be Republished, , 101
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Skill sequence, Hexagonal and square nut, Objective: This shall help you to, • use of hexagonal and square nuts., Hexagonal nuts, , Square nut, , This is the most commonly used type of nut in sructural and, machine tool constructions. (Fig 1), , Square bolts are provided with square nuts. In bolts for, coaches, mostly, square nuts are used. (Fig 3), , Hexagonal nuts are available in different thicknesses. Thin, nuts are used as lock-nuts. (Fig 2), , 102, , Electrical : Electrician - Exercise 1.2.21, , Copyright @ NIMI Not to be Republished
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Practice on making external threading by using stock & die set, Objectives: At the end of this exercise you shall be able to, • measure and cut the conduit pipe according to the requirement, • prepare the conduit pipe ends for threading and fastening in a pipe vice, • cut the threads on heavy gauge metal conduit according to the requirement using a conduit die set, • mark the position of bending on conduit pipes., , Requirements, Tools/Instruments, •, •, •, •, •, •, •, •, •, , Pipe vice 50 mm, Steel rule 600 mm, Hacksaw with a blade of 24 teeth, per 25mm (25 TPI), Flat file bastard 200 mm, Half round file bastard 20 0mm, Reamer 16 mm, Oil can 200 ml, Conduit stock and dies for 18 mm, conduit, Wire brush 50 mm, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , Materials, •, •, •, •, , Conduit pipe 19 mm diameter1m long, Lubricant - coconut oil, (for a batch of 16 trainees), Chalk piece, Cotton waste, , - 1 No., -100 grams, - 1 No., - as required., , - 1 set., - 1 No., , PROCEDURE, TASK 1: Preparation of conduit pipe for cutting., Assume that the job needs a 300 mm long, conduit drop while a 3000 mm standard length, pipe is only available. Normally both the ends, of a standard length pipe will have threads. To, make the required conduit drop, the available, 3000 mm pipe is to be cut for a length of 300 mm, and threaded again at the end where it is cut., Cutting could be done either using pipe cutters, or with hacksaws. Cutting with a hacksaw is, popular, and the method is explained below., 1 Measure 300 mm from the threaded end of the pipe and, mark it with chalk as shown in Fig 1., , 4 Close and tighten the vice jaw., 5 Select a hacksaw with a blade having 24 teeth per 25, mm (25 TPI), as shown in Fig 3., , 2 Open the jaw of the vice and insert the pipe so that it is, horizontal and parallel to the jaw serrations., 3 Keep the chalk mark of the pipe within 100 mm of the, vice as shown in Fig 2., , Ensure that the hacksaw blade is firmly, tightened in the frame and that the teeth point, in the forward direction., , Electrical : Electrician - Exercise 1.2.21, , Copyright @ NIMI Not to be Republished, , 103
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6 Take the hacksaw and position yourself, as shown in, Fig 4, with your left shoulder pointing in the direction of, the cut. Note the position of the feet, which allows for, free and controlled movement of the body while cutting., , 12 When getting near to the end of the cut, the conduit, must be supported with your left hand as shown in, Fig 8. Finish the cut., , 7 Grip the hacksaw handle with the right hand and, position the hacksaw blade on top of the cutting line., 8 Prepare to cut by guiding the blade with the thumb of, your left hand exactly on the cutting line against the saw, blade as shown in Fig 5., , Support the free end of the conduit to prevent, the blade of the hacksaw from being damaged., 13 Use a reamer or half round file to remove the inside burrs, as shown in Fig 9., , 9 When the initial cut has been made, move the left hand, to the front end of the hacksaw frame and use both, hands for the cutting operation as shown in Fig 6., 10 When sawing, use the full length of the blade, gradually, increasing the pressure on the forward stroke, and, releasing the pressure as the blade is drawn back., (Fig 6), 14 Use the flat portion of the half round file to smoothen the, sharp edges. (Fig 10), , 11 Saw with steady, even strokes, keeping the blade, upright and square to the cut as shown in Fig 7., , 104, , 15 Clean the hacksaw and vice in the end and keep them, in their respective places., , Electrical : Electrician - Exercise 1.2.21, , Copyright @ NIMI Not to be Republished
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TASK 2: Preparation of conduit pipe for threading., 1 Open the jaw of the vice and insert the pipe so that it is, horizontal and parallel to the jaw serrations., 2 Keep the end of the tube within 150 mm of the vice., 3 Close and tighten the vice as shown in Fig 11., , 4 File the end of the tube flat and chamfer the outer edge, to an angle of about 20 o as shown in Fig 12., , Make the depth of the chamfer equal to the, pitch of the thread (1.5 mm for conduit)., 5 Choose the correct dies and stock suitable for the pipe, to be threaded., Assembly drawing for the quick cut stock and, dies is given in Fig 13. The die size is engraved, on the die itself. Check the size with that of the, pipe. The handle of the stock is not shown in the, picture for clarity., 6 Insert each half of the die in the cap(stock) with the, chamferred threads positioned (leading faces) adjacent, to the guide., 7 Screw the guide into position., 8 Adjust each adjusting screw equally to make the die, halves centralized to the pipe axis., 9 Slide the stock guide over the end of pipe, adjust the, adjusting screws such that the dies grip the pipe evenly, on both sides., 10 Apply pressure to the stock and keep the handles at, right angles to the pipe as shown in Fig 14., 11 Rotate the handles clockwise in a plane at right angles, to the pipe axis as shown in Fig 15., 12 Apply the lubricant to the part to be threaded after the, thread has been started., , The lubricant allows the die to cool the heat, developed and thereby helps the edges to stay, sharp producing a better thread finish., 13 Make one or two complete turns in the clockwise, direction., Check whether the stock is at right angle to the, pipe axis., , Electrical : Electrician - Exercise 1.2.21, , Copyright @ NIMI Not to be Republished, , 105
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Electrical, Electrician - Basic Workshop Practice (Allied Trade), , Exercise 1.2.22, , Practice of making square holes in crank handle, Note: This exercise is already dealt in Ex. 1.2.17 as Sub Exercise S.Ex. 1.2.17 - 4. Refer it., , 106, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - Basic Workshop Practice (Allied Trade), , Exercise 1.2.23, , Prepare an open box from metal sheet, Objectives: At the end of this exercise, you shall be able to, • draw a development plan for a given open rectangular box in a single sheet, • drill hole of small diameter using hand drilling machine, • shear straight edge using straight snip, • make holes in sheet metal using cold punch, • make holes in sheet metal using hollow punch., , Requirements, Tools/Instruments, •, •, •, •, •, •, , Steel rule 300 mm, Scriber 200 mm, Divider 150 mm, Snips 250 mm, Hammer 200 g, Hatchet stake, , -, , 1 No, 1 No, 1 No, 1 No, 1 No, As available., , •, •, , Mallet wood, Hollow punches set 3 to 25 mm, , - 1 No, - 1 set, , Equipment/Machines, •, , Hand drilling machine, , - 6mm, , Materials, •, , Sheet iron ISST (in mm), , - 52 x 0.5 x 150, , PROCEDURE, 1 Check the dimension of the given sheet iron., 2 Mark all the dimensions as per drawing (Fig 1) for, cutting, bending and punching holes., 3 Drill 2 mm diameter holes on all corners of box using, hand drilling machine., 4 Shear over a length of 8.5 mm for bending indicated by, No. 1 in Fig 1., 5 Bend all the four corners to 90o. Bending width of 8 mm, is indicated by No. 2 in Fig 1., 6 Bend the sides B & D to 90 o using suitable stack., (Fig 2), Ensure the overlapping parts are well within, the bending line of side A and side C., , Copyright @ NIMI Not to be Republished, , 107
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7 Bend the sides A and C to 90 o . Use suitable stack., (Fig 3), , 11 Place sheet at the end of wood or lead cake., , 8 Repeat steps 1 to 8 and prepare another open box., , 12 Punch holes with correct size punches after exactly, locating their positions., , 9 Mark the centre lines as per the dimensions given in, (Fig 3), in one of the open end boxes., , 13 Flatten the surface by gently hammering with the soft, mallet., , 10 Make two marks on the holes of both the lines of at a, distance equal to the radius to locate punches., , Skill Information, Laying out development pattern of rectangular open box directly on sheet, metal, Objectives: This shall help you to, • draw a pattern for making a single open box., The steps to lay out the pattern remain the same., Check the sheet metal on which your pattern will be made., Check the bottom edge of the sheet with a straight edge., (Fig 1), , Square up the left hand end of the sheet. (Fig 2) The, ends of the sheet seldom remain a perfect square at, the edges. (Fig 3) The usual method is to draw a line, about 5 mm from the end using a square. (Fig 4), Always make your layout in the lower, left hand corner of, the sheet., Measurements should be from the bottom and left hand, square line., Never try to cut your metal to the exact size., Measure from all the four edges to make the, layout., , 108, , Electrical : Electrician - Exercise 1.2.23, , Copyright @ NIMI Not to be Republished
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Prick mark all bend lines. Before to Top forming the pattern,, prick mark all the bend lines about 5 mm from the end of, the line., Do not depend upon the corners of notches for, bend locations., Check the shape of the basic patterns., When the layoutis ready check the overall dimensions on, each side of the pattern. (Fig 6), , Make measurement at both ends of each line and draw a, line through the two points., Draw all the vertical and horizontal lines first. Then add lines, for metres, notches, seams, edges and laps. (Fig 5), , Making holes with a hollow punch in sheet metal, Objectives: This shall help you to, • make a hole on sheet metal with a hollow punch., Hollow punches are used for punching holes of 4 mm, diameter. or larger on soft sheet metal. First mark the, centre. Now, draw the circle with diameter equal to the, hollow punch., Place the sheet metal on a lead block or on a block of wood, with the end grains up. You should not use any other metal, block. If you use a metal block other than lead, it will spoil, , the cutting edge of the hollow punch., Position the hollow punch on the circle that has already, been drawn.Hold the punch upright. Strike gently on the, head of the hollow punch. Hit the punch until the disc is cut, from the material., , Drilling holes in sheet metal using hand drilling machine, Objectives: This shall help you to, • make holes on thin sheets using a solid punch, • drill holes using a hand drilling machine., In thin sheets, holes can be made using a solid punch., (Fig 1), A punching machine can also be used for this work. (Fig 2), , If the plate is thicker, about 1 mm, and hole diameter is, about 5 mm, cracks may be formed while punching and, ths may weakens the sheets. It is better to drill holes using, , Electrical : Electrician - Exercise 1.2.23, , Copyright @ NIMI Not to be Republished, , 109
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Centering is very important for using a hand drilling machine. It, is done with a centre punch. The centre punch should be held, in the inclined position. First check whether it has been, correctlyplaced in the point where the two lines intersect.(Fig, 4), , Hold the punch vertically and strike on the head of the, punch using a hammer (Fig 5). Fix the required straight, shank drill bit in the chuck of the drilling machine. The drill, can be tightened in the chuck. (Fig 6), , a hand drilling machine. The hand drilling machine (without, electricity) is provided with a gear transmission (Fig 3), which helps in a greater speed during drilling., , 110, , Electrical : Electrician - Exercise 1.2.23, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - Wires, Joints, Soldering - U.G. Cables, , Exercise 1.3.24, , Prepare terminations of cable ends, Objectives : At the end of this exercise you shall be able to, • prepare a loop termination, • prepare the cable end of fine multistranded wire, • identify the connecting parts of the socket of an appliance and connect it to cable with earth contact, • connect the appliance to the cable with earth contact, • identify the connecting parts of a 3-pole (plug) pin and connect the cable., , Requirements, Tools/Instruments, •, •, •, •, •, •, •, •, , Steel rule 300 mm, Electrician's knife 100 mm, Wire stripper (manual) 150 mm, Combination pliers 200 mm, Screwdriver 100/150 mm x 4 mm, Screwdriver 100 mm x 2 mm, Long round nose pliers 150 mm, Side cutting pliers 150 mm, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , •, •, , - as reqd., - as reqd., - as reqd., , •, •, , Multistrand cable 48/0.2 mm, Single pole plug (double banana plug), 4 mm screw type connection, Crocodile clips insulated 2A and 6A,, 250 V, Test lamp with bulb 40 W, 240 V, PVC cable 3-core copper 23/0.2 mm, -5m, Socket 2-pole with earthing contact, 6A, 250 V grade - each of different, rating and make, Plug 2-pole with earthing contact, Socket 2-pole with earthing contact 6A, , •, , PVC Cable 3-core 48/0.2 mm, , •, , Plug 3-Pole 6A, 250 V different, makes, Plug 3-Pole 16 A, 250 V different, makes, Meta/clad plug 2-pin with earth 20A, , Materials, •, •, •, •, •, •, , Pieces of 250 to 300 mm long, aluminium and copper, Single conductor cable 1.5 sq.mm, Single conductor cable 2.5 sq. mm, Bare copper wire No.10 SWG, - small pieces 300 mm long or as, available., Multistrand cable14/0.2 mm, - small pieces 300 mm long or as, available., Multistrand cable 23/0.2 mm, , •, •, •, •, , •, - as reqd., - as reqd., , •, , - 2 Nos., - 4 Nos., - 2 Nos., - 1 No., , - 4 pairs, - 4 pairs, - 5 Nos., - 3.5 m, - 2 Nos., - 2 Nos., - 2 Nos., , PROCEDURE, TASK 1: Preparation of loop termination (Solid conductor) (Fig 1), 1 Collect a single conductor cable of 1.5 sq.mm (copper), about 250 to 300 mm long from scrap., 2 Mark on the insulation the length 'L' from the cable end., The length 'L' is five times the diameter of the terminal, screw., 3 Loop in fine multistrand conductor. (Fig 2), 4 Make termination in screw on terminal. (Fig 3), , Copyright @ NIMI Not to be Republished, , 111
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The hook (loop) should go at least about three, quarters of the way around the screw., Check the inner diameter of the loop with, the terminal screw., Never make the hook long as the conductor, may overlap., , 5 Connect the terminated cable in different types of, connectors. (Fig 4 a,b,c,d)., , Keep the length of the exposed conductor to, the minimum, not more than 3 mm, to prevent, accidental contact with other wires. (Fig 8), , 10 Repeat the task for 2.5 sq.mm copper single conductor, cable., 11 Repeat the task for aluminium cable single conductor, of 1.5 sq. mm and 2.5 sq. mm., 6 Skin the insulation over the length 'L'. (Fig 5), , 12 Repeat the task for bare copper wire of 10 SWG and, other available sizes., Preparing a fine multistrand cable end for termination to screw-on terminal of terminal blocks, 13 Collect a piece of fine multistr and flexible copper cable,, of size 14/0.2 mm., , 7 Grip the bare conductor with the round nose pliers as, shown in Fig 6., , 14 Mark the length 'L' from the end of cable. Length 'L' is, equal to five times the diameter of the terminal screw., 15 Remove the insulation to the length 'L' (Fig 9) using a, pair of wire stripping pliers., , The diameter of the jaw at the gripping point of, the round nose pliers is little more than the, terminal screw diameter., 8 Turn the firmly gripped nose pliers to form the required, loop. (Fig 7), , 16 Retwist the bared strands in the same direction with, your fingers. (Fig 10) Note, that the strands are twisted, in the wire in a certain direction., , 9 Finally set the loops with the nose pliers as shown, in Fig 8., , 112, , Electrical : Electrician - Exercise 1.3.24, , Copyright @ NIMI Not to be Republished
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17 Repeat the steps No.4 to No.6 stated for solid conductor, to finalise the termination., , 23 Bend a loop at the end of the wire to the required, dimensions, with your fingers. (Fig 14), , 18 Repeat the task with other sizes of cables., 19 Repeat the task for terminating flexible cable end on, crocodile clips. (Fig 11), , 24 Push the wire through the cover of the plug. (Fig 15), , Prepare termination in a fine multistrand cable, for single pole plug., 20 Open the given single pole plug. (Fig 12), , 25 Insert the loop into the terminal (single pole plug)., (Fig 16), , 26 Assemble the plug by pushing its cover over the, terminal and by inserting and tightening the terminal, screw with a screwdriver. (Fig 17), 21 Measure with a steel rule the distance 'D' between the, outer edge of the terminal screw hole and the edge of the, terminal. (Fig 13), , 22 Remove insulation to the length equal to (2D + 1) mm., , Electrical : Electrician - Exercise 1.3.24, , Copyright @ NIMI Not to be Republished, , 113
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Electrical, Electrician - Wires, Joints, Soldering - U.G. Cables, , Exercise 1.3.25, , Practice on skinning, twisting and crimping, Objectives : At the end of this exercise you shall be able to, • skin the cable insulation using the electrician's knife, • skin the cable insulation using manual stripper, • skin the cable insulation using auto-stripper, • practice on making a straight twist joint, • prepare termination of cable lugs using crimping tool., , Requirements, Materials, , Tools/Instruments, •, •, •, •, •, •, •, , Electrician tool kit, Electrician's knife 100 mm blade, Wire stripper, manual 200 mm, Wire stripper auto–eject 150 mm, Combination pliers 150 or 200 mm, Steel rule 300 mm, Diagonal cutter or side cutting pliers, 150 mm, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , •, •, •, •, •, •, •, •, , Aluminium cables of the following sizes:, PVC single strand cable, 1/1.4, 1.5 sq. mm, -3m, PVC single strand aluminium cable, 1/1.8, 2.5sq. mm, -3m, Flexible cables with copper conductor of size:, PVC cable 14/0.2 mm, -3m, PVC cable 23/0.2 mm, -3m, PVC cable 48/0.2 mm, -3m, PVC cable 80/0.2 mm, -3m, PVC cable 128/0.2 mm, -3m, PVC cable,PVC sheathed cable, – assorted small pieces, -as reqd, , PROCEDURE, TASK 1 : Skinning cable insulation using the electrician's knife, 1 Mark the length of the 1.5 sq. mm cable at 400 mm from, its end., 2 Cut the cable using combination pliers on the mark., 3 Mark the length of insulation to be skinned from either, end. (Fig 1), , 7 Clean the surface of the bare conductor and show it to, the instructor., 8 Cut the cable at 12 mm from either end using a, combination plier., , 4 Check the sharpness of the knife blade and re-sharpen,, if necessary., Use an oilstone to sharpen the knife's blade., Visible thickness at the cutting edge of the, knife blade indicates a blunt edge. In the case, of a sharp edge, the thickness or end will not, be visible., 5 Remove the insulation of the cable for about 10 mm at, the ends using a knife. (Fig 2) Keep the knife blade at, an angle less than 20° to the cable., 6 Check for nicking over the conductor. Also check if the, cable is not shaved., 114, , 9 Repeat steps No.5 to No.8, until the cable is of 350 mm, length, 10 Mark the insulation that is to be removed as in Fig 3 and, repeat steps 5 and 6., , 11 Repeat the skinning of cable insulation of 2.5 sq. mm,, 14/0.2 mm, 23/0.2 mm, 48/0.2 mm, 80/0.2 mm and, 128/0.2 mm flexible cables., The length of the cable after skinning both the, ends shall be suitable for termination using, crimping and screw., , Copyright @ NIMI Not to be Republished
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12 The length of the finished skinned cable should be 300,, 500, 600, 800, 1000 mm., , In the case of flexible stranded cables to ensure, that the strands are not cut is essental., , These cable pieces are to be used for later, exercises., TASK 2: Skinning cable insulation using a manual stripper, 1 Mark the length of the cable to be trimmed off., 2 Trim the cable at the mark using a combination plier, diagonal cutter., 3 Straighten the ends where the insulation is to be, skinned., 4 Mark the point where the insulation is to be skinned., 5 Adjust the jaws of the manual stripper and set them to, suit the cable conductor., , Partially cut insulation can be removed only, with more force. Excessive force, indicates, improper cutting of insulation., 8 Repeat the skinning of insulation for 10 mm to develop, skill in the use of the wire stripper., 9 Remove insulation to the required extent at the ends as, per Fig 4., , 6 Set the jaws at the mark, press the handle of the, stripper and turn to cut the insulation., Do not nick the conductor. For better practice, try on a small waste piece., , 10 Be caeful with flexible cables to ensure that you do not, nick even a single strand., , 7 Pull the stripper to remove the insulation., TASK 3: Skinning cable insulations using auto-stripper, 1 Mark the length of the insulation to be removed from the, ends., 2 Straighten the cable ends., , 5 Press the stripper., Further pressing may damage the insulation from, the cable end, that is also to be removed., 6 Check that the cable conductor is not nicked., , 3 Select a proper set of stripper., 4 Locate the jaws of the stripper exactly on the mark., , 7 Repeat steps No 1 to 7 for different sizes of cables., , Skill sequence, Hand tools for skinning - knife, Objectives : This shall help you to, • identify the parts of the knife used for skinning, • perform care and maintenance in using the knife., The most frequently used tool for skinning is the knife, A knife may have a single or double blade. A single blade, knife is the most commonly used one. (Fig 1), •, , back of the blade, , •, , hanger, , •, , haft, , Becareful while using the knife., , •, , hinge pin, , •, , blade, , Always cut keeping the object to be cut away from your, body., Slice the insulation at an angle of approximately 15° to, avoid cutting into the conductor. (Fig 2), , Electrical : Electrician - Exercise 1.3.25, , Copyright @ NIMI Not to be Republished, , 115
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Knives should not be used to remove insulation, on very fine single or stranded conductors., Knives should not be used to cut conductors., , Hand tools for skinning - manual wire stripper, Objectives: This shall help you to, • identify the parts of the manual wire stripper, • perform care and maintenance of manual wire stripper., Hand operated wire stripping tools can be used to remove, P.V.C. or rubber insulation from a single core cable without, damaging the conductor. They are of two types manual, and auto-eject., , Often one cutter becomes sharper than the other, and cuts, more than halfway through the wires, damaging the conductors. In such an event, the blunt cutter should be, sharpened., , Manual wire stripper: The jaws have V shaped notches, to cut the insulation., , Fig 3 shows manual wire stripper., , The adjuster screw allows to cut a wide range of wire, diameters. (Figs 1 and 2)., , This tool has a series of sharp openings in its scissor blade, to allow stripping of wire in gauge of different sizes or, diameters. The gauge size of the wire must match with the, opening in the wire stripper to prevent cutting into the wire, and weakening it., Precautions:, •, , When using this tool, make sure that it is, correctly adjusted before trying to strip the, insulation from the cable so that it does not, damage the conductor., , •, , Do not use this tool to cut metallic conductors., , Hand tools for skinning - auto-eject stripper, Objectives: This shall help you to, • identify an auto-eject stripper, • take care while using an auto-eject stripper., Auto-eject strippers are used to cut the insulation from, electrical wire without damaging the wire strands. They, remove the insulation automatically. (Fig 1), , 116, , This stripper has two sets of jaws: one set grips the, insulation while the other set has cutting edges., When the handles are apart, both sets of jaws are open., (Fig 2), , Electrical : Electrician - Exercise 1.3.25, , Copyright @ NIMI Not to be Republished
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This stripper operates automatically when the correct, position on the blade matching the diameter of conductor, in mm is selected, and the handles are compressed, together., In an auto-eject stripper, we can select different of blades, sizes to match different sizes of conductors., , Precautions: While using this stripper the, cable insulation should be put in the proper, slot to avoid damage to the conductor., , Skinning - Using a knife, Objective : This shall help you to, • strip the wire insulation with the electrician's knife., Material:, , PVC insulated the wire 2.5 sq. mm - 1, metre., , Tools:, , Electrician's knife (100 mm) - 1 No., , 2 Cut the insulation. (Fig 3), , Pencil cut using a knife (Fig 1), 1 Set the knife to the wire, •, •, , Hold the section to be stripped on the ball of your, index finger., Hold the knife at about 20 degrees angle. (Fig 2), , •, , Move the knife forward as you saw it back and forth., , Be sure not to damage the core., •, , Move your index finger along the direction of cutting., , Electrical : Electrician - Exercise 1.3.25, , Copyright @ NIMI Not to be Republished, , 117
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Sub Exercise (S.Ex.) 1.3.25 - 1, Prepare termination of cable lugs by using crimping tool, Objectives: At the end of this exercise you shall be able to, • skin the cable end, • select the pressure terminal (compression connector) that suits the size of the wire and that of the terminal, • select the pressure pliers that match the size of the pressure terminal, • use the crimping tool to crimp the lugs at the cable end., • use an eyelet crimping plier for eyelet termination., , Requirements, Tools/ Instruments, •, •, •, •, •, •, •, •, •, , Pressure pliers 200 mm, Electrician's knife 100 mm, Wire stripper (manual) 200 mm, Combination pliers 200 mm, Crimping pliers 150/200 mm, Wire stripper auto-eject 200 mm, Steel rule 300 mm, Side cutting pliers 150 mm, Eyelet closing pliers 200 mm with, eyelets having inner diameter, of 3,4,5,6,7 mm., , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , Materials, •, •, •, •, •, •, , Crimping eyelet, eye hole dia. 6 mm, Crimping ferrule 4 mm,10 mm long, Crimping spade lug 6A, Crimping spade lug 10A, Crimping spade lug 16A, Conducting paste, , - 12 Nos., - 6 Nos., - 6 Nos., - 6 Nos., - 2 Nos., - 1 tube, , - 1 No., , PROCEDURE, TASK 2 : Crimping of lug connector, 1 Collect the cable (fine multi-strand copper conductor)., 2 Collect the spade connector suitable for the wire, thickness and terminal size of 6 mm diameter (Fig 1,, 2 & 3)., , 3 Select the wire stripper blade size to match the wires, thickness (auto-eject) or adjust the jaws of the, stripper. (Fig 4), , 4 Strip a length of insulation that suits the terminal size, (spade connector) (Fig 5), Be sure not to cut or damage the wire core., 118, , Electrical : Electrician - Exercise 1.3.25, , Copyright @ NIMI Not to be Republished
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Do not strip too much insulation. (Fig 10), , Adjust the length of the wire so that it does not, interfere with the terminal hole. (Fig 11), 5 Twist the strands of the wire lightly in the direction of, strands. (Fig 6), , 9 Apply light pressure to create a light impression on the, compression connector., 6 Select the crimping pliers that matches the terminal, size., 7 Clamp the spade connector with the crimping pliers, with the matching position of jaws., , 10 Check whether the press is located in the middle of the, band of compression connector and, if necessary,, make final adjustment., 11 Apply sufficient pressure in the handle to press the, compression connector fully, as shown in Fig 12., , 8 Insert the wire far enough in the compression connector., (Fig 7), , Do not clamp the insulation in the terminal., (Fig 8), , 12 Check whether the prepared compression/crimping, joint is firm by pulling the cable and compression, connector., 13 Repeat the crimping of compression in the connectors, of various sizes of copper and aluminium conductors of, different lengths., Trim the appropriate length of the skinned, cable ends to suit the compression connectors., , Strands must not stick out of the connector., (Fig 9), , The types of compression connectors to be, fixed at the cable ends will be as prescribed, by your instructor. Fig 2 shows the eyelet, lug compression connected/crimped on to, the flexible cable., , Electrical : Electrician - Exercise 1.3.25, , Copyright @ NIMI Not to be Republished, , 119
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TASK 3: Crimping an eyelet, 1 Collect the multi-strand cable., 2 Split the number of strands into two equal parts and, twist them. (Fig 13a), 3 Collect the eyelet. (Fig 13b), 4 Fix the eyelet by placing the eyelet between the, grouped strands close to the insulation and twist the, free ends of the strands as shown in Fig 13c., , 5 Trim the excess length of the multi-strand wire after, closing the eyelet using side-cutting pliers., 6 Repeat the exercise with different sizes of eyelets for, cable end termination., The eyelet is then pressed on to the wire end by, the two formers of the eyelet closing pliers., (Fig 14), , 7 Get it checked by your instructor., , TASK 4: Practice on twisting of single strand wires, 1 Take 30 mm of 1/1.5 mm2 aluminium wire, or 1/1.2 mm, P.V.C copper cable., , 6 Finish twisting the wires as shown in figure 3 & 4., , 2 Cut it into two pieces of 150 mm each., 3 Remove the insulation of 50 mm in each piece by using, stripper and clean it with cotton cloth., 4 Cross the bare wires at 45º and at a distance of 45 mm, from the cable end. (Fig 1), , 5 Twist the ends tightly at least 6-8 twists. (Fig 2), While twisting 2 wires together avoid gaps, between the twists. If it twisted with gap, it will, trigger sparks and overheat as shown in, Fig 2., , 120, , 7 Get it checked by your instructor., Joining of wires by twisting using plier., 8 Hold wires together near the plier. (Fig 5), , Electrical : Electrician - Exercise 1.3.25, , Copyright @ NIMI Not to be Republished
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9 Grab both the copper ends with pliers., , •, , Pull the stranded wire to make sure it is tight., , If the surrounded wire is of the same diameter,, , 10 Rotate your wrist while using pressure on pliers., When joining three large wires, strip the, insulation more., , •, , Cut both to the same length., , •, , Cover the wire with wire nut and twist it. (Fig 7 & 8), , Connecting a stranded wire to a solid wire., If the stranded wire is thinner than the solid wire, •, , Strip the stranded wire so that there is more copper, visible than solid wires., , •, , Wrap the stranded wire around solid copper, , •, , Leave the solid wire straight, , When connecting two solids that are stranded,, •, , First,twist the solids together, , •, , Wrap the stranded wire around the solids., , •, , Apply the wire nut tight. (Fig 6), , Scan the QR Code to, view the video for, this exercise, , Electrical : Electrician - Exercise 1.3.25, , Copyright @ NIMI Not to be Republished, , 121
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Electrical, Electrician - Wires, Joints, Soldering - U.G. Cables, , Exercise 1.3.26, , Identify various types of cables and measure conductor size using SWG and micrometer, Objectives: At the end of this exercise you shall be able to, • identify types of wires and cables, • verify their specifications referring to the data book, • measure wire sizes using SWG, • measure wire size using micrometers., , Requirements, Materials, , Tools / Instruments, •, •, •, •, •, , Standard Wire Gauge (SWG 0-36), Micrometer (0-25), Electrician's knife, Manual wire stripper 150 mm, Combination pliers 150 mm, , •, •, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , •, , Wires (assorted size), Cables (underground armoured, and unarmoured cable), Wire/ cable specification data book, , - as required., - as required., - 1 No., , PROCEDURE, TASK 1: Identify types of wires and cables, 5 Take any one cable from the table, note down its, alphabet., , The instructor will arrange and provide the, various types of cable and wire pieces (assorted, sizes) on the table and label them with alphabets, and explain them to trainees on, how to identify, the types of insulation, conductors, size of, wires. Demonstrate how to measure the size of, wires using SWG and micrometer., , 6 Identify the type of cable (unarmoured and armoured, cable) and note down in Table 1., 7 Identify the type of insulation, core and record in, Table 1., , 1 Take any one wire from the table, note down its aplhabet, in Table 1., 2 Identify the type of insulation, type of conductor material, and size of wires. Note it down in Table 1., , 8 Verify the specifications of the cable by referring with, the data book., 9 Repeat steps 1 to 8 for various wires and note the data, in Table 1., , 3 Take at least five different types of wires and repeat, steps 1 and 2 Note down the details in Table 1., 4 Verify the specifications of the wires by referring with, the data book., Table 1, Sl., No., , Alphabet, , Type of, Type of, insulation conductor, , Type of cable, Armoured, Unarmoured, , Type of core, single/3/3½, , material, 1, , A, , 2, , B, , 3, , C, , 4, , D, , 5, , E, , 122, , Copyright @ NIMI Not to be Republished, , Core, size in, mm
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TASK 2: Measuring the wire sizes by SWG in gauge number, 1 Skin the insulation of the cable., Exercise care to prevent from nicking., 2 Clean the surface of the wire with a cotton cloth., Remove insulation particles and any adhesive coating, from the surface of the conductor., Do not use abrasives to clean the conductor., Use of abrasive material, reduces the size of, the conductor., 3 Straighten the end of the conductor to be measured., Do not straighten conductors by directly using, hand tools on them., 4 Insert the conductor in the slot of the wire gauge and, determine its close fit. (Fig 1), 5 Read the marking at the slot, Fig 2. It gives the wire size, in SWG. The other side will give you the diameter. of the, wire in mm., 6 Record the measured size in Table 1., , TASK 3: Measuring the wire size, using micrometer, 1 Repeat steps 1-3 of TASK 2., 2 Check the micrometer for zero error by operating the, spindle., 3 Record the error value with the sign- +ve or –ve., , 7 Refer to the conversion table (Table 2) to get the size of, the conductor in the standard wire gauge., 8 Repeat the steps to find the measurement for the given, cables., , 4 Place the cleaned, straight portion of the conductor, between the jaws (anvil and spindle) of the micrometer., (Fig 3), 5 Close the spindle of the micrometer by turning the, thimble., Use the ratchet drive to avoid overtightening., 6 Read and record the diameter in Table 1 after computing, zero error., , Electrical : Electrician - Exercise 1.3.26, , Copyright @ NIMI Not to be Republished, , 123
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Table 2, Conversion table : SWG to inch/mm, , 124, , No., , Inch, , 7/0, , 0.500, , 6/0, , mm, , No., , Inch, , mm, , 12.7, , 23, , 0.024, , 0.61, , 0.464, , 11.38, , 24, , 0.022, , 0.56, , 5/0, , 0.432, , 10.92, , 25, , 0.020, , 0.51, , 4/0, , 0.400, , 10.16, , 26, , 0.018, , 0.46, , 3/0, , 0.372, , 9.44, , 27, , 0.0164, , 0.42, , 2/0, , 0.348, , 8.83, , 28, , 0.0148, , 0.38, , 0, , 0.324, , 8.23, , 29, , 0.0136, , 0.34, , 1, , 0.300, , 7.62, , 30, , 0.0124, , 0.31, , 2, , 0.276, , 7.01, , 31, , 0.0116, , 0.29, , 3, , 0.252, , 6.40, , 32, , 0.0108, , 0.27, , 4, , 0.234, , 5.89, , 33, , 0.0100, , 0.25, , 5, , 0.212, , 5.38, , 34, , 0.0092, , 0.23, , 6, , 0.192, , 4.88, , 35, , 0.0084, , 0.21, , 7, , 0.176, , 4.47, , 36, , 0.0076, , 0.19, , 8, , 0.160, , 4.06, , 37, , 0.0068, , 0.17, , 9, , 0.144, , 3.66, , 38, , 0.0060, , 0.15, , 10, , 0.128, , 3.25, , 39, , 0.0052, , 0.13, , 11, , 0.116, , 2.95, , 40, , 0.0048, , 0.12, , 12, , 0.104, , 2.64, , 41, , 0.0044, , 0.11, , 13, , 0.092, , 2.34, , 42, , 0.0040, , 0.10, , 14, , 0.080, , 2.03, , 43, , 0.0036, , 0.09, , 15, , 0.072, , 1.83, , 44, , 0.0032, , 0.08, , 16, , 0.064, , 1.63, , 45, , 0.0028, , 0.07, , 17, , 0.056, , 1.42, , 46, , 0.0024, , 0.06, , 18, , 0.048, , 1.22, , 47, , 0.0020, , 0.05, , 19, , 0.040, , 1.02, , 48, , 0.0016, , 0.04, , 20, , 0.036, , 0.91, , 49, , 0.0012, , 0.03, , 21, , 0.032, , 0.81, , 50, , 0.0010, , 0.02, , 22, , 0.028, , 0.71, , Electrical : Electrician - Exercise 1.3.26, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - Wires, Joints, Soldering - U.G. Cables, , Exercise 1.3.27, , Make simple twist, married, Tee and western union joints, Objectives : At the end of this exercise you shall be able to, • mark the length of the insulation to be removed, • skin the insulation, • prepare simple twist joint, • prepar married joint in stranded conductor, • prepare 'T' joint in multistranded conductor, • prepare western union joint in bare conductor., , Requirements, Tools/Instruments, •, •, •, •, , Electrician's knife with two folding, steel blades of 75 mm and 100 mm - 1 No., stainless steel rule 300 mm, with, graduations on either edge cm/mm, and inches, - 1 No., Diagonal cutting pliers 150 mm with, 660 volts grade insulated handle suitable, for cutting hard wires, - 1 No., Combination pliers 200 mm with, 660 volts grade insulated handles with, pipe grip, side cutter and two joint, cutters, - 1 No., , • Wooden mallet 75 mm, • Flat file - bastard 250 mm, • Hard vice 58 mm, Materials, •, •, •, •, •, •, •, •, •, , - 1 No., - 1 No., - 1 No., , PVC insulated copper cable 1/1.12, - 2 m., PVC insulated aluminium cable 1/1.40, - 2 m., Cotton cloth 30 cm square, - 1 No., Sandpaper `OO' (smooth), - 1 sheet, PVC insulated copper cable 7/0.914/600V - 1 m., PVC insulated copper cable 3/0.914/250V - 1 m., Bare copper wire 4 mm 30 cm, - 2 Nos., GI wire 4 mm 30 cm, - 2 Nos., Sand Paper 'O' grade, - 1 sheet, , PROCEDURE, TASK 1: Make simple (straight) twist joint as shown in Fig 1, , 1 Collect 2 pieces of 1/1.12 PVC copper cable of 0.5 m, length., 2 Straighten the cables., 3 Mark 80 mm length on one end of each piece of the, cable., 4 Use the knife at 20o as shown in Fig 2., , Avoid nicks in the conductor., 6 Clean the ends with the help of a cotton cloth., Use smooth sandpaper, if necessary, to clean, the conductor., 7 Place the conductors together, about 50 mm from the, ends. (Fig 4), , 5 Remove the insulation from each conductor for a length, of 50 mm. (Fig 3), , Copyright @ NIMI Not to be Republished, , 125
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8 Twist them tightly around each other in the opposite, directions. (Fig 1), Pliers can be used to just grip the crossed, conductors., Each side should contain about 6 turns., Each turn of the conductor should closely fit to, the adjacent turn., , Soldering the joint and insulating it with tape, should be completed before putting the jointed, cable in use., 11 Show the joint to your instructor., 12 Cut the joint after leaving 30 mm cable from the joint., (Fig 5), , 9 Cut the excess length of the conductor using side, cutters., 10 Press the sharp edge of the conductor end and smooth, it., , 13 Repeat steps 3 to 9 and make at least 4 more joints for, practice, using the remaining cable., , TASK 2: Prepare married joint in 7/0.914 stranded conductors as shown in Fig 1, , 1 Collect 2 pieces of PVC sheathed copper cable 7/0.914, 0.5 metre in leagth., 2 Mark both the the cables at 120 mm from the cable, ends., 3 Remove the insulation for 120 mm on both the cables., Carefully remove the insulation. Do not nick or, shave the conductor., 4 Open the strands, clean the wires, and re-twist the, strands in the original direction up to 50 mm from the, cable insulation. (Fig 2), , 8 Hold the cable end (that is without the binding) in one, hand and twist the strands of the other cable end over, it, one by one, closely and tightly. Each strand has to, be twisted half a turn at a time., The direction of twist to form the shoulder, should be the same as that of the cable twist ., 5 Cut the centre strand of both the cables close to the, twist (about 70 mm from the free end)., 6 Bind on the twisted part of one cable end as shown in, Fig 3., 7 Interlace the strands keeping the centres butt. (Fig 4), , 126, , 9 Remove the binding made in step 6., 10 Repeat the operation as in step 8 on the other side with, the 2nd cable end., 11 Complete the joint as shown in Fig 1 by rounding off the, twisted strands with a mallet or pliers, and cut the, excess wires., , Electrical : Electrician - Exercise 1.3.27, , Copyright @ NIMI Not to be Republished
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TASK 3: Prepare ‘T’ joint in multi-stranded conductor, Fig 1 shows a completed Tee joint in standard, conductors., , 7 Untwist the `through cable' to provide opening at the, point of tap. (Fig 6), 1 Collect two pieces of PVC insulated stranded copper, cable 7/0.91. Indicate one piece as `through cable' and, the other one as `tap cable'., 2 Mark the point of tap in the `through cable' and mark 60, mm on either side of the tap point for the insulation to, be removed as shown in Fig 2., , 3 Remove 60 mm insulation on either side of the `through, cable' from the point of tap. (Fig 3), , Do not nick or shave the conductor while, removing insulation., 4 Remove the insulation for 180 mm at the end of the `tap, cable'. (Fig 4), , 8 Insert the centre (middle) strand of the `tap cable' in the, opening of the 'through cable' as shown in Fig 7., , 9 Wrap 3 strands of the `tap cable' around the `through, cable' on either side of the tap point to form shoulder on, `through cable'., 10 Wrap the strands up to 50 mm to leave a 10 mm gap, between insulation and shoulders (Fig 1) and trim the, excess length of strands., 11 Remove the binding from the `tap cable', wrap the centre, strand of the `tap cable' around the `through cable' and, wrap it in the place of the binding. (Fig 1), 12 Round the ends with the combination pliers or mallet to, avoid sharp edges of the strands., , 5 Open the strands of the `tap cable' and clean it. Use, smooth `00' sandpaper, if necessary., 6 Re-twist the strands in the original direction up to 50, mm from insulation, and make a binding on the twisted, part of the `tap cable' as shown in Fig 5., , 13 Collect two pieces of PVC stranded aluminium cable, 19/1.12, or 19/1.63, 500 mm long and repeat working, steps 2 to 12., With 19/1.2, 19/1.63 mm cable, 9 strands of the, `tap cable' are to be wrapped on either side of, the `through cable'. Insulation that has to be, removed is 170 mm on the `through cable' and, 250 mm on the `tap cable'., , Electrical : Electrician - Exercise 1.3.27, , Copyright @ NIMI Not to be Republished, , 127
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TASK 4: Prepare western union joint in bare conductor, (A completed western union joint is shown in Fig 1.), , 1 Collect two pieces of bare copper conductor of 4 mm, diameter. and 30 cm long., 2 Straighten the conductor with a mallet., 3 Mark the conductor as shown in Fig 2., , 7 Wrap one conductor over the other conductor using, combination pliers. Make at least 5 to 6 turns as shown, in Fig 5., , 4 Clean both the conductors with `00' grade sandpaper to, a length of 250 mm from one end., 5 Bend both the pieces of conductors at a distance of 110, mm from one end to 45o as shown in Fig 3., , 8 Repeat the same procedure in the other end of the, conductor, but wrap the conductor in the opposite, direction., 6 Hold the conductors in the hand vice as shown in, Fig 4., To avoid nicks on the conductors while gripping, in a hand vice, always use soft materials like, aluminium sheets between the jaws., , 9 Cut the surplus conductor ends with a diagonal cutter., 10 Use a mallet to mesh the ends with the straight, conductor., 11 Smoothen the ends of the conductors with a flat file to, avoid sharp edges., 12 Repeat the Western union joint with G.I. wire of diameter 4 mm., , Scan the QR Code to, view the video for this, exercise, , 128, , Electrical : Electrician - Exercise 1.3.27, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - Wires, Joints, Soldering - U.G. Cables, , Exercise 1.3.28, , Make britannia straight, britannia ‘T’ (Tee) and rat tail joints, Objectives : At the end of this exercise you shall be able to, • make britannia straight joint in solid copper conductor, • make britannia ‘T’ (Tee) joint in solid copper conductor, • make rat tail joint., , Requirements, Tools/Instruments, •, •, •, •, •, •, , Steel rule 300 mm, Diagonal cutting plier 150 mm, Combination plier 200 mm, Hand vice 50 mm jaw, Flat file bastard 200 mm, Wooden mallet 75 mm diameter., , Materials, - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , •, •, •, •, •, , Hard drawn bare copper wire 4 mm, diameter 0.2 metre, Tinned copper wire of dia. 0.91 mm, Sandpaper `0 0', Cotton cloth 300 x 300 mm, PVC copper cable 1/1.2 mm 8.5 m, , - 4 Nos., - 4 m., - 1 sheet, - 1 No., - 2 Nos., , PROCEDURE, TASK 1: Make brittannia straight joint, (A completed britannia straight joint is shown in Fig 1.), , 1 Collect two pieces of 4 mm diameter Hard Drawn Bare, Copper (H.D.B.C) . wire, 0.2 m long., , 7 Start binding the wire tightly over the joint from position, `A' and continue till position `B'. (Fig 4), , 2 Straighten the conductors using a mallet and clean it, using fine sandpaper and cotton cloth., Use the mallet to make the wires straight. The, two pieces should be free from twists over the, entire length of the joint., 3 Bend each piece at one end for about 20 mm length at, 90o as shown in Fig 2., , 8 Insert the free end of the wire inside the loop as shown, in Fig 4., 9 Grip the 250 mm loose end of the wire with a pair of, pliers, and carefully pull it so that the loop and the free, end of the wire go inside the joint., 10 Wrap the free end and the loose end over the conductors, as shown in Fig 1., , 4 Collect the binding wire and straighten it without any, kink., , 11 Press the ends of the binding wire to the conductors, with pliers ., , 5 Hold the two ends of the bare copper wire to be joined, in the hand vice as shown in Fig 2., , 12 Smooth the sharp edges of the protruding wire ends, with a flat file., , 6 Form a loop of binding wire leaving one end about 250, mm at the right side of the joint. Place the binding wire, in the groove formed in between the main conductors as, shown in Fig 3., , 13 Repeat the above steps and make two or more joints to, get more practice., , Copyright @ NIMI Not to be Republished, , 129
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After completion the joint must be soldered, before putting it to use., , TASK 2: Make britannia ‘T’ joint, (A completed britannia `Tee' joint is shown in Fig 1.), , 8 Insert the free end of the wire inside the loop as shown, in Fig 4., 1 Collect two pieces of 4 mm diameter Hard Drawn Bare, copper (H.D.B.C) 0.2 m long., 2 Straighten the conductors using a mallet and clean it, with fine sandpaper and cotton cloth., 3 Bend and shape of one of the conductors according to, the size shown in Fig 2, with the help of combination, pliers., , 9 Grip the 250 mm loose end of the wire with a plier, and, carefully pull it so that the loop and the free end of the, wire go inside the joint., 10 Wrap the free end and the loose end over the conductors, as shown in Fig 1., 11 Press the ends of the binding wire to the conductors, with plier., , 4 Straighten the (0.914 mm diameter.) binding wire., , 12 Smooth the sharp edges of the binding wire ends with, a flat file., , 5 Hold the two copper conductors to be joined with the, help of a hand vice as shown in Fig 2 ., , 13 Repeat the above procedure to make two or more joints, to get more practice., , 6 Form a loop of binding wire leaving one end about 250, mm at the right side of the joint. Place the binding wire, in the groove formed between the conductors as shown, in Fig 3., , The joints need to be soldered before putting, them into use., , 7 Start binding the wire tightly over the joint from position, `A' and continue till the position `B'. (Fig 3), , 130, , Copyright @ NIMI Not to be Republished
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TASK 3: Make rat-tail joint (Fig 1), , The twist on the wire should be uniform and, close., 7 Make at least 6 twists. (Fig 3), , 1 Collect 2 pieces of 1/1.2 mm PVC copper cable of, 0.5 m length., 2 Straighten the cables., , 8 Fold the remaining wire back on the twists. (Fig 1), , 3 Skin both the cable ends for 50 mm., 4 Clean the conductor ends with the help of cotton cloth., , 9 Press the ends of the wire with the help of combination, pliers (Fig 1) to avoid sharp ends, and cut the excess, wire., , 5 Cross the bare wires at of 45o and at a distance of 45, mm from the cable end., , 10 Repeat the steps.3 to 8 of TASK 3 for at least 4 more, joints for practice, using the remaining cable., , 6 Tightly twist the ends as shown in Fig 2., , Copyright @ NIMI Not to be Republished, , 131
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Electrical, Electrician - Wires, Joints, Soldering - U.G. Cables, , Exercise 1.3.29, , Practice in Soldering of joints/lugs, Objectives : At the end of this exercise you shall be able to, • solder the copper conductor joints using a soldering iron and rosin solder, • solder the lugs in copper conductor with the help of a blow lamp., , Requirements, Tools/Instruments, •, •, •, •, •, •, •, •, •, •, , Materials, , Electrician tool kit, Combination piler 200 mm, Electric soldering iron 125W, 250V,, 50Hz, Flat file bastard 250 mm, Electrician's knife 100 mm, Steel rule 300 mm, Diagonal cutting plier 150 mm, Blowlamp 1 litre capacity, Tongs 300 mm, Sheet steel tray 150 x 150 x 20 mm, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , •, •, •, •, •, •, •, •, •, •, •, •, , Finished simple twist joint, - 1 No., Sandpaper ‘OO’ grade, - 9 Sq.cm, Resin-cored solder, - 25 gms, VIR or PVC copper cable 7/1.06 mm, or 7/0.914 - 250 mm long, - 2 pieces, Lug 30 amperes, - 1 No., Resin flux, - 10 gms., Solder stick 60/40, - 100 gms., Matchbox, - 1 No., Cotton tape or cloth, - as required., Sandpaper `O' grade, - 9 sq. cm., Blowlamp pin, - 1 No., Kerosene, - 1 litr., , PROCEDURE, TASK 1: Solder the copper joints, (A finished soldered joint will look like Fig 1.), , 1 Select a 60W, 240V AC 50 Hz. soldering iron (Fig 2) and, check that the iron has no physical damage, the body, is well insulated from the element and is of the correct, voltage and power rating., , A soldering iron should show continuity between, its terminals. Insulation resistance between, the terminal and the body should not be less, than 2 megohms. Report to your instructor in, case the insulation resistance is less than 2, megohms. Do not use the iron unless it is, cleared by your instructor., 2 Check the bit (Fig 3) to see whether the surface is, smooth and clean., , 132, , 3 If found corroded, file the tip with a flat file, so that the, surface is smooth and clean. (Fig 4), , 4 Connect the soldering iron to the supply and switch it, `ON'., 5 When the bit becomes sufficiently hot, apply a small, quantity of rosin-cored solder, and tin the bit. (Fig 5), , Copyright @ NIMI Not to be Republished
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If the bit is not completely and evenly covered, with solder, clean and tin it again., , 9 Keep the rosin-cored solder on the wire joint and allow, it to melt as shown in Fig 9., , Never flick excess solder off the bit. The hot, solder may cause burns to someone or fall 0n, the work and cause a short circuit., 6 Wipe the bit gently on the cleaning pad to remove, excess solder as shown in Fig 6., , 10 Melt the solder with the heat of the bit and make sure, that the solder flows freely and evenly on the joint., 11 Remove the soldering iron. use cotton cloth to wipe off, the excess solder from the surface of the joint when it, is still hot as shown in Fig 10., 7 Clean the joint to be soldered with the help of sandpaper, `0 0', grade as shown in Fig 7, and wipe the dust with, a wire brush., , 12 Allow the joint to cool naturally. Do not blow air for, cooling., 8 Keep the soldering iron bit on the joint and heat it for, soldering as shown in Fig 8., , A shining solder surface indicates good, soldering. Do not move the joint until the solder, solidifies., , TASK 2: Solder lug to a copper conductor, (A soldered lug should look as shown in Fig 1.), , 3 Put the cable lug to one end of the cable and mark the, cable according to the depth of the cable lug, as shown, in Fig 2., , 1 Collect a 30 amps cable lug, copper cable 7/1.06 or 7/, 0.914(6 sq.mm) of 250 mm length, blowlamp, matchbox, cotton cloth, solder stick, tray and flux., 2 Clean the inner and outer surfacses of the 30 amps, cable lug using `00' grade sandpaper., Electrical : Electrician - Exercise 1.3.29, , Copyright @ NIMI Not to be Republished, , 133
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4 Add about 2 mm to the marking, remove the insulation, from the cable (Fig 3) and clean the strands., , Pouring out the molten solder from the lug, socket a couple of times will make the tinning, perfect., 10 Apply some flux to the cable end and the interior of the, socket., 11 Fill the socket of the lug with molten solder. (Fig 6), , Avoid damage to the strands of the cable while, skinning. Clean the tray thoroughly. The tray, should be free from dirt and water., 5 Wrap a cloth/cotton tape on the insulation of the cable, to a length of 30 mm as shown in Fig 4, and wet it with, water., , 12 Monitor the blowlamp flame on the socket, insert the, cable in the socket and hold the cable vertically as, shown in Fig 7., , Use minimum water to wet the cloth/tape. Do, not allow water to drip., 6 Light the blowlamp and let it emit a blue flame., 7 Apply a thin coat of flux to the cable end., 8 Tin the cable end by monitoring the blowlamp on the, solder stick and allowing the molten solder to fall on the, bare stranded cable end as shown in Fig 5., , 13 Remove the blowlamp and firmliy hold the cable and, socket without shaking., 14 Remove the extra solder from the lug and cable by, wiping it with a piece of cotton cloth while the solder is, still hot., 15 Keep on holding the cable and lug as in Fig 7 and allow, the solder to solidify., A thin coating of tin should be on the stranded, cable end., , Do not use water to cool the lug. This will, crystallize the solder and make it weak., , 9 Apply a small quantity of flux inside the lug socket. Tin, the lug by melting the solder stick to fill the socket and, pour the molten solder in the tray., , Scan the QR Code to, view the video for this, exercise, , 134, , Electrical : Electrician - Exercise 1.3.29, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - Wires, Joints, Soldering - U.G. Cables, , Exercise 1.3.30, , Identify various parts, skinning and dressing of underground cable, Objectives: At the end of this exercise you shall be able to, • identify the voltage grade of the cable, • skin the UG cable, • dress the UG cable., , Requirements, Tools/Instruments, •, •, •, •, , Insulated combination piler 200 mm, DE Electrician's knife 100 mm, Hacksaw adjustable 300 mm, with blade, Handvice 50 mm jaw, , Materials, - 1 No., - 1 No., , •, •, , UG cable multicore eu/Al. 30 cm, Binding wire 16 SWG, , - 1 piece, - as required., , - 1 No., - 1 No., , PROCEDURE, Paper insulated 3, 31/2 core cable may taken., This instructor has to demonstrate the steps for, skinning and dressing of cables in this exetcise., , 7 Repeat steps 2-6 to skin all other layers till it is visible, as shown in Fig 2., , 1 Collect the UG cable piece and examine it for physical, damage., 2 Bind the winding wire at 20 cm (20 m at one side) of the, UG cable., 3 Mark 18 cm at one end near the binding wire knot from, the end where skinning is to be done, as shown in, Fig 1., , 4 Cut the overall serving using the knife and remove the, overall serving., 5 Mark 3 cm from the cutting edge and cut the single wire, armouring using hacksaw., 6 Mark 3 cm from cutting edge and cut the bending using, knife/hacksaw., , Carefully examine the skinned portion for any, damage/excess cutting., 8 Dress the protruding parts of the cable using a knife for, a better finish., 9 Get your work approved by your instructor., , Copyright @ NIMI Not to be Republished, , 135
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Electrical, Electrician - Wires, Joints, Soldering - U.G. Cables, , Exercise 1.3.31, , Make straight joint of different types of underground cable, Objectives: At the end of this exercise, you shall be able to, • cut the cable according to requirement, • prepare the cable as per measurement, • join the cables using split sleeves or ferrules and epoxy compound, • insulate the wires, cable joints., , Requirements, Tools/Instruments, •, •, •, •, •, •, •, •, •, •, •, •, , Insulated combination plier 200 m, Screwdriver 200 mm, D.E. Spanner 6mm to 25 mm, DE Electrician's knife 100 cm, Melting pot with 1 set of ladles, Blow lamp 1/2 litre capacity, Tongs 300 mm, Triangular file smooth 200 mm, Hacksaw adjustable 300 mm with, 32 TPI blade, Hammer ball pein 250 g, Plier round nose 150 mm, Hand vice 50 mm, , -, , 1 No., 1 No., 1 set, 1 No., 1 No., 1 No., 1 No., 1 No., , - 1 No., - 1 No., - 1 No., , Materials, •, •, , UG cable multi-core copper/, aluminium, Binding wire 16 SWG, , - as required., - 200 g, , •, •, •, •, •, •, •, •, •, •, •, •, •, •, •, •, •, •, , Lead and tin alloy 60/40, Kerosene oil, Cotton tape 25 mm10mm long, Bitumen compound, (‘epoxy’compound), Jute thread 3 mm, Impregnated cotton tape, Porcelain barrier, Coupling sleeve of suitable size, Metal connectors of suitable size, Slit sleeve of suitable size, Insulating paste board or yarn tape, Match box, Asbestos thread, Alca ‘P’ solder, Soldering flux, Bricks, Cotton cloth, Eyre flux, , - asrequired, - 2 litre., - 1 roll, - as required, - 100 g., - as required., - as required., - as required., - as required., - as required., - as required., - 1 No., - 50 g., - 1/2 kg., - 100 g., - as required., - as required., - 100 g., , PROCEDURE, TASK 1 : Make straight joint using sleeves in U.G cable, 1 Cut the given cable into two pieces as in Fig 1., Fig 2 is given here for your guidance. Actual, measurement for the cable insulation removal, depends upon the type of cable joint box and, cable sealing compound. Conventional method, of cable jointing is done with bitumen compound for sealing the joint , brass glands at the, ends of the joint box for sealing the joint entry, and plumbing to finish the job. Modern joints, with epoxy compounds are done by sealing the, joint entry either with special tapes or with, special compounds. According to the method, chosen, the measurement has to be made and, the insulation has to be removed at specified, points. For procedural convenience in this, sheet, L1 is taken as 200 mm and so on., , 136, , 2 Bind 16 SWG GI binding wire on the serving (PILC, cable) of the cables at a distance of 210 mm from one, end as shown in Fig 3 to avoid loosening of the serving, and damaging of the armour., 3 Remove the armour and serving of the cables to a, length of 200 mm from the end of each cable as shown, in Fig 4., , Copyright @ NIMI Not to be Republished
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Some prefer staggering of the joint position to, have maximum efficiency of the joint. In such, cases, the cable insulation should be removed, accordingly. Fig 8 shows such a joint., 6 Twist the bare conductors tightly and tin the conductors., (Fig 6), , Wrap the end of the paper insulation near the, bare conductor with lightly wetted cotton tape, or asbestos tape to protect against excess heat., 7 Wrap the portion of the paper insulated cable with, impregnated cotton tape to protect it from moisture and, hot solder. (Fig 6), , 4 Remove the lead sheath to a length of 150 mm from the, end of each cable as shown in Fig 5 and also remove, the impregnated paper., , Provide colour coding marks on cables at this, stage., 8 Clean the split copper sleeves and the brass glands, thoroughly and tin them., 9 Clean the joint box and keep the bottom cover on the, floor., 10 Insert the brass glands in the cables and position the, bare end of the cable and gland inside the joint box as, shown in Fig 2., 11 Insert the tinned portion of the cable ends into the split, sleeve with the help of the colour code of the cables., (Fig 2), 12 Insert barriers (separators) between the three individual, cables at both sides of the cable as shown in Fig 7., , Avoid nicks or cuts on the core. Do not remove, the paper insulation of individual cables., 5 Remove the paper insulation from both the cables to a, length of 15 mm from the end., , 13 Turn the split portion of the sleevves in the upward, position to facilitate pouring of the solder., , Electrical : Electrician - Exercise 1.3.31, , Copyright @ NIMI Not to be Republished, , 137
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14 Remove the bottom cover of the joint box and push the, brass glands apart and keep it in staggered position as, in Fig 8., , 19 Stop pouring the solder when the sleeve is filled up, and, the colour of the solder is bright., 20 Repeat this procedure to other joints one after another., Do not shake or disturb the position of the, cables during the soldering process as it will, result in dry joints., , 15 Apply soldering flux to the split sleeves and the bare, portion of the conductor., 16 See that the ladles are dry and then start alternately, scooping the molten solder with the ladles till the ladles, are sufficiently hot., , 21 After the joint is cold, wrap with at least 2 layers of, impregnated PVC tape over the joints., 22 Preheat the joint box before filling the preheated sealing, compound., 23 Close the top and bottom parts of the joint box together, and, position the brass glands., , 17 Keep one of the empty ladles underneath the split, sleeve that has to be soldered., , 24 Use the solder lead to make proper plumbing joints, between the lead sheath and the brass gland., , 18 Pour the molten solder on the sleeve such that the, solder enters the joint through the split as shown in, Fig 9., , 25 Pour molten sealing compound through the cover inlet, as shown in Fig 10., , When the compound is filled up to the mouth of, the inlet, stop pouring and allow it to cool., After sufficient cooling, the compound will, shrink, and now fill the available space with, more molten compound., , After the joint is sufficiently heated, increase, the time between the pourings to allow the, solder to solidify inside the joint., , 26 Fix the cover inlet of the joint box after the joint is, sufficiently cooled., 27 Cheek for cracks, melting due to heat or any other, mechanical damage., , TASK 2 : Make joints with epoxy compound in U.G cable, 1 Use the joint box, compound and, specified by the manufacturer., , crimping tool, , 2 Repeat the same procedure as in TASK 1 and note the, additional points stated below:, , • Joint box is of special PVC material., • A solder rarely is used for joints. Mostly, joints are, crimped with the help of a crimping tool using special, copper sleeves., , 138, , • No heating of compound or boxes is necessary as the, epoxy compound serves both as a jointing compound, and hardener. Both of these are to be mixed thoroughly, in specified quantities just before it is poured into the, joint box., , • No plumbing work is necessary as there is no brass, , gland. However, to maintain continuity of earthing a, special jumper fitting is to be made between lead sheath, of the cables which will be supplied on request. Refer, Fig 11., , Electrical : Electrician - Exercise 1.3.31, , Copyright @ NIMI Not to be Republished
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3 Follow the rest of the procedures outlined in TASK 1 to, complete the joint., , TASK 3: Aluminium cable joint, 1 Follow the procedure as explained in Tasks 1 and, 2 except that the solder to be used is Alca ‘P’ and, the flux is Eyre ‘7’., , Electrical : Electrician - Exercise 1.3.31, , Copyright @ NIMI Not to be Republished, , 139
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Electrical, Electrician - Wires, Joints, Soldering - U.G. Cables, , Exercise 1.3.32, , Test insulation resistance of underground cable using Megger, Objectives : At the end of this exercise, you shall be able to, • measure the insulation resistance between conductors of an armoured cable using Megger, • measure the insulation resistance between earth and conductors of an armoured cable., , Requirements, Tools/Instruments, •, , Materials, , Insulation resistance tester, (Megger) 500 V, , - 1 No., , •, •, , Testing prods, Armoured cables of different sizes, and length, , - 3 Nos., - 2 Nos., , PROCEDURE, TASK 1: Measure the insulation resistance between conductors of an armoured cable, 1 Connect the armoured cable as shown in Fig 1., , Table 1, Measurement, , Insulation, resistance, in megohms, , Between conductors, Conductor 1 and conductor 2, Conductor 2 and conductor 3, Conductor 1 and conductor 3, Between earth and conductors, Conductor 1 and earth, Conductor 2 and earth, Conductor 3 and earth, Conductor 1, 2, 3 shorted and earth, Connect the guard terminal of the meter with, the armour (metal sheath) of the cable., 2 Measure the insulation resistance between the, conductors and record the readings in Table 1., , Steadily rotate the insulation tester's handle at, a constant speed (160 r.p.m) at least for one, minute duration before recording the meter, reading., , TASK 2: Measure the insulation resistance between earth and conductors of an armoured cable, 1 Connect the armoured cable as shown in Fig 2., If the armoured cable is buried in the ground,, connect the Megger as shown in Fig 2. If the, cable is not buried but kept at the ground level, or on the working table, the earth connection, should be made as shown in Fig 3., , 140, , 2 Measure the insulation resistance between earth and, each conductor and record the readings in Table 1., 3 Measure the insulation resistance between earth and, all the three conductors by shorting them together and, record the reading in Table 1., , Copyright @ NIMI Not to be Republished
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Discuss the required insulation resistance value, of the cable with your instructor, , The Instructor may demonstrate the use of, transistorised Megger for various tests., , Electrical : Electrician - Exercise 1.3.32, , Copyright @ NIMI Not to be Republished, , 141
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Electrical, Electrician - Wires, Joints, Soldering - U.G. Cables, , Exercise 1.3.33, , Test underground cables for faults, and remove the fault, Objectives: At the end of this exercise you shall be able to, • locate open circuit faults in the cable, • locate short circuit faults in the cable, • locate the leakage fault in the cable and rectify the fault., , Requirements, Tools/Instruments, •, •, •, •, •, , Equipments/Machine, , Combination plier 200 mm, Connector Screw driver 100 mm, Screw driver 200 mm with, blade of 4 mm width, D.E electrician’s knife 100 mm, Megger 500V, , - 1 No., - 1 No., , •, , - 1 No., - 1 No., - 1 No., , •, •, •, , Wheatstone bridge, , - 1 No., , Materials, Connecting Prod for Megger, Connecting Prod for Wheatstone bridge, Connecting Cables (flexible, uniform,, cross sectional area), , - 1 set, - 1 set, - as reqd., , PROCEDURE, TASK 1: Locate open circuit faults in underground cable, This test is made to check whether the cable, insulation is in open condition and to identify, the exact location of the open circuit., 1 Switch 'OFF' the mains. Remove the fuse and the, neutral links in the main switch and keep them in safe, custody., 2 Select 500 V Megger and connect one terminal of the, Megger, say L, to the one end of cable as shown in, Fig 1., , 4 Rotate the megger at 160 r.p.m., 5 Observe the megger reading. If the megger shows, infinity, there is open circuit in the cable., Open circuit may be due to open in the cable., If the megger shows ‘0’ reading, it indicates no, open in the cable., 6 Connect the ‘E’ terminal near the middle of the cable, and repeat the above procedure for open circuit., If it shows ‘0’ reading, there is no open in, between ‘L’ and the middle of the cable., 7 Repeat the above procedure, connecting the ‘E’, terminal to beyond the middle point of the cable at, varied distances., When the megger shows infinity in a parhcilar, place, that is the point of open., , 3 Connect the other terminal of the Megger say ‘E’ to, the other end of the cable., , 8 Locate the faulty portion and make fresh straight joint, to the UG cable., , TASK 2: Locate the short circuit fault in U.G cable, This test is made to locate the short circuit in the, cable by Murray loop test., , 142, , 1 Switch 'OFF' the main switch. Remove the fuse of the, main switch and keep it in safe custody., , Copyright @ NIMI Not to be Republished
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2 Select a Wheatstone bridge and connect one end of, the cable to the meeting point of P and Galvanometer, and another cable end to the meeting point of Q and, Galvanometer as shown in Fig 2., , 3 Measure the length of each cable., 4 Connect the other two ends of both the cables by, means of low resistance wire., 5 Take the battery terminal (negative) wire and place it, at any point of the cable and observe the deflection in, the Galvano meter., The area of the cable where the Galvanometer, shows ‘0’ reading is the exact location of the short, circuit. It can be calculated with the formula given, below., (i.e), , x, p, , =, , Q, P, , or, , X, R+X, , =, , Q, P+Q, , where X is the length of the fault from the test end., L is length of each cable., 6 Locate the fault while measuring the length of the, cable and clear the short circuit in the UG cable., , TASK 3: Locate the ground fault in U.G cable, This test is also done to locate ground fault in, the cable by Murray Loop test., 1 Connect the cables as shown in the Fig 3 and repeat, the steps explained in the short circuit test (TASK 2)., The area of the cable where the Galvanometer, shows ‘0’ reading is the exact location of the, ground fault., 2 Calculate and locate the place of the ground fault as, given below., X=, , Q, x 2L, P+Q, , Where ‘X’ is the length of the fault from the test end., , 3 Locate the place where the ground fault is by measuring, the length from the test end and repair the fault., , Electrical : Electrician - Exercise 1.3.33, , Copyright @ NIMI Not to be Republished, , 143
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Electrical, Electrician - Basic Electrical Practice, , Exercise. 1.4.34, , Practice on measurement of parameters in combinational electrical circuit, by applying Ohm’s Law for different resistor values and voltage sources, and analyse by drawing graphs, Objectives: At the end of this exercise you shall be able to, • verify the relation between voltage and current when resistance is constant, • verify the relation between current and resistance when keeping voltage is constant, • plot the graph in both conditions illustrating the behaviour of current with respect to resistor., , Requirements, Tools/Instruments, •, •, •, •, , Materials, , Screwdriver 150 mm, MC Ammeter 0 to 500 mA, MI Ammeter 0 to 1A, MC Voltmeter 0 15 V, , - 1 No., - 1 No., - 1 No., - 1 No., , •, •, •, •, •, , - 1 No., , •, , Equipment/Machines, •, •, •, , 12 Volts battery 60 AH capacity OR, DC variable power supply, 0 - 30 V 2 amperes, Rheostat 20 ohms - 3.7A, , S.P.Switch, 6A, 250V, Resistors 10, 20, 50 Ohms 5 watts, Resistor 20 ohms,2W, Connecting leads 14/0.2 mm, P.V.C. insulated copper wires of, assorted length, Graph sheet, , - 1 No., - 1 each., - 1 No., - 1 No., - 8 Nos., - 1 No., , - 1 No., - 1 No., , PROCEDURE, TASK 1: Verify the relation between current and voltage when resistance is constant, 1 Check the voltmeter from the dial marking ‘V’., 2 Check the ammeter from the dial marking ‘A’., 3 Identify the fixed and variable terminals of the rheostat., 4 Connect the circuit elements as shown in Fig 1., , 6 Close the switch keeping the variable rheostat at the, minimum value of output., 7 Apply different voltages by varying the rheostat arm of, the potential divider in succession across the resistance., 8 Measure the voltage and the corresponding current, from the instruments., 9 Record the measured values in Table 1., To avoid parallax error:, Position your eye in line with the pointer and, also in front level of the instrument, Position your eye to coincide with the mirror, image of the pointer in instruments having antiparallax mirror., 10 Refer the recorded value and plot a graph. Write your, conclusion considering the calculated R values., V in Y Axis; I in X axis as shown in Fig 2., , 5 Check the value of each major division and minor, division of the scales of the meters., 144, , Copyright @ NIMI Not to be Republished
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Conculsion, Write your findings and conclusion by interpreting the, current and voltage, ______________________________________________, ______________________________________________, , TASK 2: Verify the relation between current and resistance: Voltage is constant and resistance is variable., 1 Connect the circuit elements as shown in Fig 3 with, 0 -1A ammeter. Adjust V at 10 volts keep it constant., , 4 Open the switch (OFF). Change the ammeter to 0-500, mA and repeat steps 2 and 3 by replacing 10 - ohm, resistance by 20 and 50 ohms., 5 Refer the recorded value and plot the graph. Write your, conclusion considering the calculated I values., R in Y Axis; V in X Axis as shown in Fig 4., , Write your findings and conclusion by interpreting the, current and resistance., 2 Close the switch ‘S’ and measure the current and, voltage., , Conculsion, , 3 Read and record values in the given Table 2., , ______________________________________________, , ______________________________________________, , Electrical : Electrician - Exercise 1.4.34, , Copyright @ NIMI Not to be Republished, , 145
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Electrical, Electrician - Basic Electrical Practice, , Exercise. 1.4.35, , Measure current and voltage in electrical circuits to verify Kirchhoff’s Law, Objectives: At the end of this exercise you shall be able to, • verify Kirchhoff’s current Law in two and three branch currents, • verify Kirchoff’s voltage Law with one voltage and two voltage source., , Requirements, Tools/Instruments/Equipment, , Materials, , •, •, •, •, •, , •, •, •, •, •, •, •, •, , Trainees kit, - 1 No., Variable DC power supply unit 0-30V/1A- 2 Nos., Milliammeters 0 - 500 mA, - 3 Nos., Milliammeters 0 - 30 mA, - 1 No., Power supply unit 0 - 30 V, - 1 No., , Resistors 1K, Resistors 2.2K, Resistors 3.3K, Resistors 4.7K, Lug board, Toggle switch, SPST, 1amp., Patch cords, SPST switch 6A, 250V, , - 4 Nos., - 1 No., - 1 No., - 1 No., - 1 No., - 2 Nos., -as required., -as required., , PROCEDURE, TASK 1: Verify the Kirchhoff’s current law with two branch currents, 1 Connect the PSU, milliammeters, SPST switch and, resistors as illustrated in the schematic circuit and the, layout diagram as shown in Fig 1., Keep the SPST and PSU in the OFF position, while making circuit connections., 2 Switch ‘ON’ PSU and set output to 12 volts., 3 Simplify the circuit in Fig 1 and calculate the theoretical, total circuit current and branch currents of the circuit for, a set DC supply of 12 volts. Record values in Table 1., Check if the connected ammeters can measure, the calculated current. Change the meter, if, necessary., 4 Get the circuit connections checked by your instructor., 5 Switch ON SPST., 6 Measure and record the total circuit current (IT) and, branch currents I and I in Table 1., S1, , 7 Switch OFF the SPST., , S2, , 8 Set the output of the RPSU to 9 volts., 9 Calculate the theoretical circuit currents for the set, supply voltage of 9V., 10 Record values in Table 1., 11 Repeat steps 4 and 6., 12 Switch OFF SPST and PSU., 13 Write Kirchhoff’s current equations for the nodes P and, Q., 14 Verify the equation substituting the measured current, values., 146, , 15 Get the readings and equations checked by your, instructor., , Copyright @ NIMI Not to be Republished
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Table 1, Set, circuit, voltage, , Calculated values of circuit current, Total circuit, current (I ), T, I =I +I, T, , B1, , IB1, , Measured values of circuit currents, , IB2, , Total circuit, current (I ), T, I =I +I, , B2, , T, , B1, , I B1, , IB2, , B2, , 12V, 9V, , TASK 2 : Verify the Kirchhoff’s current Law with three branch currents, 1 Make circuit connections on the lug board as per the, schematic circuit in Fig 2., Make it a practice to keep the SPST and PSU, switches in the OFF position while making, circuit connections., 2 Get the wired circuit checked by your instructor., 3 With the SPST in OFF position, set the output of PSU, to 12 volts., 4 Switch ON the SPST switch. Measure and record, currents I , I , I and I in Table 2., T, , B1, , B2, , B3, , 5 Switch OFF SPST and PSU., 6 Write Kirchhoff’s current equations at nodes P and Q., Verify the equation using measured current values., 7 Get the readings and equations checked by your, instructor., , 8 Record your findings and conclusions after verifying the, recorded and calculated values and check if it is same, as per the theoretical conclusions., , Table 2, Set circuit, voltage, , Total circuit, current (IT), I =I +I +I, T, , B1, , B2, , Branch currents, B3, , IB1, , IB2, , IB3, , 12 V, , TASK 3: Verify the Kirchhoff’s voltage Law with one voltage source, 1 Measure and record in Table 3, values of resistors R ,, 4, R and R soldered on the lug board., 5, , 6 Switch OFF SPST and PSU., , 6, , 2 Make the circuit connections as shown in Fig 3., 3 Mark the polarity of the voltage drops across resistors, R , R and R in the copy of Fig 3., 4, , 5, , 6, , 4 Get the circuit connections and polarities marked and, checked by your instructor., 5 Switch ON PSU and set output to 12V. Switch ON, SPST. Following the voltage polarities marked across, the resistors, measure and record the drop in voltage, across resistors R , R & R in Table 3., 4, , 5, , 6, , Electrical : Electrician - Exercise 1.4.35, , Copyright @ NIMI Not to be Republished, , 147
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7 Write Kirchhoff’s loop equations for the closed paths ac-d-b-a, a-e-f-b-a and c-e-f-d-c. Substitute the voltage, readings recorded in Table 3 in the equations for, verification., , 8 Get your readings and equations checked by your, instructor., , Table 3, Set circuit, , Measured values of, , voltage, , R4, , R5, , Voltage measured across, R6, , V, , V, , R4, , R5, , V, , R6, , TASK 4: Verify the Kirchhoff’s voltage Law with two voltage sources, 1 Modify the circuit connections made in TASK 3, to, obtain a circuit as shown in Fig 4., Keep both the PSU’s and the two SPST’s in the, OFF position while making circuit connections., 2 Mark the polarity of the voltage drops across the, resistors R , R and R in the copy of Fig 4., 4, , 5, , 3 Set the output of PSU-1 to 12 volts and PSU-2 to 6 volts., 4 Switch ON both SPSTs. Following the voltage polarities, marked across the resistors, measure and record the, voltage drop across the resistors R , R & R in, 4, 5, 6, Table 4., Note: While measuring voltage across resistors,, if the meter deflects below zero, recheck the, polarity marked at step 2 and repeat step 4., , 6, , 5 Switch OFF the SPSTs and PSUs., 6 Write Kirchhoff’s voltage equations for the closed paths, a-c-d-b-a, a-e-f-b-a and c-e-f-d-c., 7 Get your readings and equations checked by your, instructor., 8 Record your findings and conclusion after verifying the, recorded and calculated values and check if it is same, as per the theoretical conclusions., Table 4, Set output of, RPSU 1, , 148, , Set output of, RPSU 2, , Voltage measured across, VR4, , Electrical : Electrician - Exercise 1.4.35, , V, , R5, , Copyright @ NIMI Not to be Republished, , V, , R6
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Electrical, Electrician - Basic Electrical Practice, , Exercise 1.4.36, , Verify law’s of series and parallel circuits with voltage source in different, combinations, Objectives: At the end of this exercise you shall be able to, • verify the laws of series circuits, • verify the laws of parallel circuits, , Requirements, Equipment/ Machines, , Tools/ Instruments, •, •, •, •, •, •, •, •, •, , Electrician tool kit, Ammeter MC 0-500 mA, Rheostat - 100 ohms, 1A, Voltmeter MC 0-15V, Multimeter, Rheostat 0 - 25 ohm, 2A, Potentiometer 60 ohm, 1A, Rheostat 0 - 300 ohm, 2A, Rheostat 0 - 10 ohm,5A, , - 1 Set, - 3 Nos., - 1 No., - 1 No., - 1 No., - 2 Nos., - 1 No., - 2 Nos., - 2 Nos., , •, , DC source, 0 - 6V/30AH (battery),, Battery 12V, 90AH - 1 No. OR DC 0-30V, variable voltage supply source with, current limiting facility 0-1 ampere - 1 No., , Materials, •, •, •, •, , Switch SPT 6A 250V, Resistor 10 ohm 1 W, Resistor 20, 30, 40 & 60 ohm 1 W, Connecting cables, , - 1 No., - 2 Nos., - 1 No. each, - as required., , PROCEDURE, TASK 1: Verify the characteristics of series circuits, 1 Construct/ assemble the circuit as shown in Fig 1., (R1 = 10 Ω, R2 = 20 Ω , R3 = 10 Ω), , 5 Switch OFF the supply. Reconnect the voltmeter and, ammeter as shown in Fig 3 and measure the voltage, (V2) and current (I2) in R2., , 2 Close the switch ‘S’, measure the current (I) and voltage, (V)., 3 Enter the measured value in Table 1., 4 Switch OFF the supply. Reconnect the ammeter and, voltmeter as shown in Fig 2 and measure voltage (V1), and current I1 through R1., , 6 Draw the circuit diagram showing the position of A and, V in the circuit to measure the current (I3) and voltage, (V3) across R3., 7 Connect and measure the I3 and V3 across R3., 8 Enter the measured values in Table 1., 9 Record the relationship between I1, I2, I3 and I., , 10 Write down the mathematical form of current law of a, series circuit., , Copyright @ NIMI Not to be Republished, , 149
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13 Calculate resistance from the measured values, record, the results with the values indicated on the resistors., 14 Record the relationship between R and R 1, R2, R3., 11 Record the relationship between V1, V2, V3 and V., , 15 Write down the mathematical form of resistance law of, a series circuit., , 12 Write down the mathematical form of voltage law of a, series circuit., , R=, 16 Get it checked by the instructor, , V=, , Table 1, Values, , Total, , Current, Voltage, Resistance, , R1=10, , R2=20, , I=, , I1 =, , I2 =, , I3 =, , V=, , V1 =, , V2 =, , V3 =, , R =, , =, , R1=, , =, , R2=, , R3=10, , =, , R3=, , =, , TASK 2 : Verify the characteristics of parallel circuits, 1 Use an Ohm meter to set the values of a rheostat or, resistor R1 = 40 ohms, R2 = 60 ohms and R3 = 30 ohms., While using multimeter to measure resistance, values see that the supply is OFF and the supply, source is disconnected from the circuit., 2 Connect the resistors (Rheostats) in parallel with the, switch S, ammeter A, voltmeter V and battery B as in, Fig 4 and measure the current Is and Vs. Record the, valuesin Table 2., 3.Get it checked by the instructor, , Table 2, , Measured Value of RT = ----------Ohms, , 1, Sl.No., , R1, , R2, , R3, , Calculated RT =, , 4 Measure the voltages VS, V1 , V2 & V3 and record them, in Table 3., 5 Calculate the current through each resistor taking into, consideration VS, applying Ohm's law and enter the, values in Table 3., , 150, , 1, R1, , +, , 1, R2, , +, , 1, R3, , IS, , VS, , RT =, , VS, IS, , 6 Measure the currents IS, I1, I2 & I3 and record them in, Table 3., 7 Compare the calculated values with the measured, values. Record your observation., , Electrical : Electrician - Exercise 1.4.36, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - Basic Electrical Practice, , Exercise 1.4.37, , Measure the voltage and current against individual resistance in electrical, circuit, Objectives: At the end of this exercise you shall be able to, • connect individual resistor in series and measure current and voltage, • connect individual resistor in parallel and measure current and voltage, • compare the theoretical values with actuals in the circuit., , Requirements, Materials, , Tools/ Equipments, •, •, •, •, •, •, , Cutting plier 150 mm, Screw driver 150 mm, Voltmeter MI 0-300V, Ammeter MI 0 - 1A, Multimeter, AC source 240V/6A, , •, •, •, •, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - as required., , Connecting leads, Lamp 250V/ 40W, Lamp 250V/ 60W, Switch 240V/6A, , - as required., - 2 Nos., - 2 Nos., - 2 Nos., , PROCEDURE, TASK 1: Measure the voltage and current of resistors in series, 1 Construct the circuit as shown in Fig 1., 2 Record the cold resistor value of lamps in Table 1., 3 Connect two 40W lamps in series and switch ‘ON” AC, 240V/6A. Measure and record the current and voltage, V1 and V2 in Table 1 as per Fig 1A., 4 Switch ‘OFF’ and replace One 40W lamp and connect, 60W lamps in series and repeat the step 3 process after, switch ‘ON’ (Fig 1B)., 5 Switch OFF and connect 2 lamps of 60W in series and, repeat step 4. (Fig 1C)., 6 Get the work checked by the instructor, , Table 1, Cold resistor, , 40W - 40W, , 40W - 60W, , 60W - 60W, , 40W, , In series, , In series, , In series, , 60W, A, , V1, , V2, , A, , V1, , V2, , A, , V1, , V2, , Value, Measured, Value, Calculated, 152, , Copyright @ NIMI Not to be Republished
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TASK 2: Measure the voltage and current of resistors in parallel, 1 Connect the circuit as shown in Fig 2., , 2 Connect two 40W lamps in parallel and switch ‘ON’ AC, 240V/6A. Record the current, voltage V1 and V2 in Table, 2 as per Fig 2A., 3 Switch ‘OFF’ and replace one 40W Lamp with 60W, Lamp. Switch ‘ON’and repeat the step 2 (Fig 2B)., 4 Switch OFF and use two 60W Lamps and repeat step, 3 (Fig 2C)., 5 Record the reading in Table - 2 and write the conclusion., 6 Get the work checked by the instructor., , Table 2, Cold resistor, 40W, , 60W, A, , 40W - 40W, , 40W - 60W, , 60W - 60W, , In parallel, , In Parallel, , In Parallel, , V1, , V2, , A, , V1, , V2, , A, , V1, , V2, , Value, measured, Value, calculated, , Electrical : Electrician - Exercise 1.4.37, , Copyright @ NIMI Not to be Republished, , 153
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Electrical, Electrician - Basic Electrical Practice, , Exercise 1.4.38, , Measure current and voltage and analyse the effects of shorts and opens, in series circuits, Objectives: At the end of this exercise you shall be able to, • examine the effects of short circuited resistors in series circuits, • analyse the effects of open circuited resistors in series circuits., , Requirements, Materials, , Tools/ Instruments, •, •, •, •, •, •, •, , Screwdriver 150 mm, Voltmeter MC 0-15V, (Sensitivity 20K Ω/V), Voltmeter 0 - 15V MC, Ammeter 0 - 500mA, Multimeter, Rheostat 100/120 Ω, 300 Ω,1A, DC voltage source variable 0-15V,, 1 amp or Battery lead acid 12V, 60AH, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , •, •, •, , Resistors 2K, 1 Watt, Connecting leads, Switch 6A 250V, , - 3 Nos., - as required, - 2 Nos., , - 1 No., , PROCEDURE, TASK 1: Examine the effects of short and open circuitated resistors in series circuits, 1 For the circuit in Fig 1, calculate the nominal values, for the voltages VA, VB and VC and record them in, Table 1., , 4 Repeat steps 3 and 4 for each resistor in turn., 5 Consider now removing R1, calculate and record the, resulting voltages at A, B and C., 6 Enter the calculated values in the fourth column of, Table 1 under the heading `Fault conditions'., 7 Repeat this for each resistor in turn., Note: Only one fault is simulated., 8 Verify your calculations in steps 3 and 6 by connecting, a piece of wire across each resistor in turn, simulating, a short circuit across that resistor, and then removing, each resistor, simulating an open at the location., 10 Measure voltage for each fault condition and be sure to, check consistency with the calculated values., 11 Record all measured data in the corresponding, columns of Table 1., , Note: All voltages are with respect to ground., 2 Considering resistor R1 as shorted, calculate and record, the resulting voltages at A, B and C, if this were to, occur., , 12 Analyse the readings in healthy condition (normal, condition) and faulty (OC and SC) condition and record, the findings., 13 Get the work checked by your instructor., , 3 Enter the calculated values in the first column of, Table 1 under the heading `Fault conditions'., , 154, , Copyright @ NIMI Not to be Republished
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Table 1, Fault conditions, Voltages Nominal, Value, , R1, Cal, , S/C, Meas, , R2, Cal, , S/C, Meas, , R3, Cal, , S/C, Meas, , R1, Cal, , O/C, Meas, , R2, Cal, , O/C, Meas, , R3, Cal, , O/C, Meas, , VA, VB, VC, Cal - Calculated S/C - Short circuited, Meas - Measured, , O/C - Open circuited, , Electrical : Electrician - Exercise 1.4.38, , Copyright @ NIMI Not to be Republished, , 155
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Electrical, Electrician - Basic Electrical Practice, , Exercise 1.4.39, , Measure the current and voltage and analyse the effects of shorts and open, in parallel circuits, Objectives: At the end of this exercise you shall be able to, • examine the effects of short and open circuited resistors in parallel circuits, • analyse the effects of short and open circuited resistor in parallel circuits., , Requirements, Tools/ Instruments, •, •, •, •, •, •, •, , Materials, , Screw driver 150 mm, MC Voltmeter 0-15V, (Sensitivity 20K Ω/V), MC Voltmeter 0 - 15V, MC Ammeter 0 - 500mA, Multimeter, Rheostat 0 - 300 Ω, 2A, DC voltage source variable 0-15V,, 1 amp or Battery lead acid 12V, 80AH, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , •, •, •, , •, , Connecting leads, Switch 6A 250V, Resistors, carbon composition 62KΩ, 1/4 W, ± 5%, • 33KΩ, • 22KΩ, Resistors, carbon composition, • 220Ω, • 1/2 W, ± 5%, • 330 Ω, • 470 Ω, , - as required, - 2 Nos, - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , PROCEDURE, TASK 1: Analyse the effect of short and open circuited resistors in parallel circuits, 1 Calculate the nominal values for the currents, I, I1 and I23, I2 and I3 for the circuit in Fig 1 and record them, in Table 1., 2 Construct the circuit (shown in Fig 1) and adjust RS,, source voltage series resistor, to a value that produces, 12 volts across the parallel set of resistors., , 4 Measure and record the values of currents (I, I1, I23, I2,, and I3). (Use Multimeter DC milliamperes range)., Record them in the 'nominal' column in Table 2., 5 Now consider a shorted R1. Estimate and record the, resulting currents if this were to occur. Enter the, calculated values in the first column in Table 1 under the, heading `Short resistor'., 6 Repeat step 5 for each resistor in turn., 7 Now consider removing R1. Calculate and record the, resulting currents if this were to occur. Enter the, calculated values in the last column in Table 1 under the, heading `Open resistor'., 8 Repeat step 7 for each resistor in turn., , 3 Set the current limit to 100mA, if the DC power supply, with current limiting feature is used as Vs. Omit the, series resistor RS. (Fig 2), , Only one fault is simulated., 9 Verify the calculations in steps 5 and 6 by connecting, a piece of wire across each resistor in turn to simulate, a short circuit across that resistor. Measure and record, the current for each fault condition in Table 2., 10 Check the measured value of current consistency with, the calculated values in Table 1., 11 Verify the calculation in steps 7 and 8 by removing each, resistor in turn to simulate an open circuit at that, location., , 156, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - Basic Electrical Practice, , Exercise 1.4.40, , Measure resistance using voltage drop method, Objectives: At the end of this exercise you shall be able to, • determine unknown high resistance by voltage drop method, • test unknown low resistance by voltage drop method., , Requirements, Tools/Equipments, •, •, •, •, •, , Cutting plier 150 mm, Screwdriver 100 mm, Ammeter MC 0-500 mA, Multimeter, DC power supply unit 0-30V (RPS), , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , Materials, •, •, , Resistor high value, Resistor low value, , - 2 Nos., - 2 Nos., , PROCEDURE, TASK 1: Measure the high value resistance by voltage drop method., 1 Construct the circuit as diagram. shown in, Fig 1 and connect the high value resistor., , 4 Replace with another high value resistor and repeat, step 3., The true value and the measured value of R, will be equal if we provide “0Ω resistance”, ammeter and infinite voltmeter resistance., Table 1, SI.No., , 2 Switch ON power supply and adjust the DC volt to 30V., 3 Note the current and record it in Table 1., , V, , I, , R, , m, , =, , V reading, , =, , V reading, , A reading, , 1, 2, , TASK 2: Measure low value resistance by voltage drop method, Table 2, , 1 Costruct the circuit as per shown in Fig 2 and connect, the low value resistor., SI.No., , V, , I, , R, , m, , A reading, , 1, 2, , 2 Repeat step 2 in TASK 1., 3 Record the current and voltage in Table 2., , The true value and measured value of R will be, equal if we provide “0Ω resistance” ammeter, and infinite voltmeter resistor., 4 Write your conclusion _________________________., 5 Get the work approved by the instructor., , 158, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - Basic Electrical Practice, , Exercise 1.4.41, , Measure resistance using wheatstone bridge, Objectives: At the end of this exercise you, shall be able to, • identify the terminals of a Wheatstone bridge, • complete the bridge with resistors, • operate a wheatstone bridge to get ‘Null’ deflection, • calculate the value of unknown resistance using the wheatstone bridge., , Requirements, Equipment/Machines, •, , Wheatstone bridge, , - 1 No., , Materials, •, •, , Resistor 2 ohms 5 W, Resistor 50 ohms 5W, , - 1 No., - 1 No., , •, •, •, •, , Resistor 10 ohms 5W, Resistor 1K ohms 2W, Resistor 330K ohms 2W, Torch cells/battery for Wheatstone, bridge, , - 1 No., - 1 No., - 1 No., - as reqd., , PROCEDURE, TASK 1: Measuring an unknown resistance using Wheatstone bridge, 1 Identify the ratio arm (PQ), variable resistance (S),, sensitivity control (SC), switch (S1), galvanometer (G),, connecting terminal (x, xx) and battery compartment of, the Wheatstone bridge and correlate it with the schematic, diagram in Fig 1., , 9 Close the switch and watch the deflection of the, galvanometer., 10 Adjust the variable arm by closing the switch, to get a, minimum deflection in the galvanometer. (In case the, galvanometer needle overshoots, reset the ratio arm.), 11 Increase the sensitivity and repeat step 10., 12 When `Null' deflection is achieved in the galvanometer,, note the value of the ratio arm and position of the variable, resistance. Enter the values in Table 1., 13 Apply the formula given below and calculate the, resistance., Unknown resistance in ohms = ____________, Reading of ratio arm setting X value of variable, resistance, , 2 Check the battery for its condition., 3 Check the values of the ratio arm., 4 Check the minimum and maximum values of the variable resistance., , P S, =, Q R, , R=, , S, xQ, P, , 5 Connect the unknown resistor across terminals x and, xx., , 14 Enter the values in Table 1., , 6 Set the ratio arm to the approximate value of the, unknown resistor., , 15 Repeat the procedure for measuring at least four unknown, resistors and enter their respective values in Table 1., , 7 Set the variable resistor knob in the middle., , 16 Get the work approved by the instructor., , 8 Set the sensitivity control to `Low'., , Copyright @ NIMI Not to be Republished, , 159
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Table 1, Sl.No., , 160, , Type of resistor, , Setting of ratio arm, , Value of variable, resistance, , Electrical : Electrician - Exercise 1.4.41, , Resistor value in ohms, = Ratio arm x value of, variable resistance, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - Basic Electrical Practice, , Exercise 1.4.42, , Determine the thermal effect of electric current, Objectives: At the end of this exercise you shall be able to, • connect the ammeter in circuit, • read the ammeter, • connect the circuit element in series, • test the electrical continuity, • analyse the effects of electric current - thermal effect., , Requirements, Tools/Instruments, •, •, •, , Ammeter 0-15A MC, Battery lead acid 90 AH 12 V, Rheostat 10 ohms, 2A, , Materials, - 1 No., - 1 No., - 1 No., , •, , •, •, •, , Connecting leads, 48/0.2mm 1m, 80/0.2mm 1m, 128/0.2mm 1m, Resistance wire Nichrome/constantine, diameter. 0.2 to 0.3mm 250 to 500 mm., S.P.T.Switch 16A 250V, Connecting terminal post 16A, , - 8 Nos., - 8 Nos., - 8 Nos., - 1 No., - 2 Nos., , PROCEDURE, 1 Connect the resistance wire to the connecting terminal, post. (Fig 1), , 4 Close the switch and adjust the potential divider for, current. (Approximately.1 ampere.), 5 Observe the ammeter reading., 6 Touch the resistance wire and feel., 7 Conclusion, When the current flows in a resistive wire, ________________ is generated., 8 Gradually increase the current by varying the potential, divider., , 2 Form the circuit with the resistance wire, ammeter,, switch potential divider and battery. (Fig 2), , Note: For every change in current value switch OFf and allow the wire to cool down to, the room temperature., For every change of current, the time duration, to feel the heat must be the same, say 5, minutes., 9 Observe the value of the current through the resistance, wire., Note: Feel the heat at a distance without, touching the wire. Be cautious not to burn your, fingers., 10 Conclusion, When current increases ______________________, increases in the resistive wire., , 3 Keep the potential divider point C at B., , 11 When current is too high the resistance wire becomes, ___________________________________________., , Copyright @ NIMI Not to be Republished, , 161
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Electrical, Electrician - Basic Electrical Practice, , Exercise 1.4.43, , Determine the change in resistance due to temperature, Objectives: At the end of this exercise you shall be able to, • measure cold resistance of the incandescent lamp using ohmmeter, • measure hot resistance of the incandescent lamp with supply by voltmeter and ammeter, • identify the colour of the filament with respect to the voltage variation, • determine the relation between resistance and changes in temperature., , Requirements, Materials, , Tools/Instruments, •, •, •, •, •, , Connector screwdriver 100 mm, MI Voltmeter 0-300V, MC Ammeter 0-1A, Ohmmeter (shunt type), MC Voltmeter - 5 volts or, multimeter (digital), , - 1 No, - 1 No., - 1 No., - 1 No., - 1 No., , •, •, •, •, •, •, •, •, •, , Double-pole switch 250V,6A, Lamp 15W, 250V, Lamp-holder B.C.batten, Candle, Potentiometer 500 ohms, 0.5A, Iron wire 0.2 mm diameter., Connecting leads, Terminal post 16A, Lamp 40W, 250V, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 2.5m., -11 Nos., - 2 Nos., - 1 No., , PROCEDURE, TASK 1: Measuring of cold resistance of the incandescent lamp by using ohmmeter, 1 Set the ohmmeter to ‘zero’ and touch the two leads on, the pins of the lamp., , 5 Get the circuit checked by the instructor. Keep the, potential divider point C at B., , 2 Measure the resistance of the given incandescent lamp, using ohmmeter (Fig 1)., , 6 Fix the incandescent lamp in the lamp-holder and close, the switch., Note: Switch off the supply before fixing the, lamp., 7 Adjust the potentiometer at 50 volts., 8 Close the switch and read the voltmeter and ammeter., 9 Record the values in Table 1., , 3 Record the value in Table 1., , 10 Observe the colour of the filament and feel the temperature on the lamp’s glass., Table 1, , 4 Form the circuit with the lamp-holder, voltmeter, ammeter, potentiometer, D.P.S.T. switch and supply as per, the circuit diagram. (Fig 2), , Measurement, 1, , Cold resistance of bulb, measured by ohmmeter, V in volts, , 162, , R in Ω Colour of, filament, , 2, , 50 V, , 3, , 100 V, , 4, , 150 V, , 5, , 240 V, , I in mA, , Copyright @ NIMI Not to be Republished, , U
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Conclusion, , 10 Repeat steps 6 to 8 for 100V, 150V and 240V., 11 Calculate the resistance using the formula R =, for every set of reading., , E, I, , 12 Record the calculated values of resistance in the Table., , TASK 2: Determine the relation between resistance and changes in temperature using a candle, 1 Make a coil of iron wire of length 0.5 m and diameter 0.2, mm., , 7 The result is:, , =, , A, , VD =, , 2 Fix the coil between the two terminal posts mounted on, a piece of insulating board., 3 Build the circuit according to Fig 3., , I, , Therefore, RD =, , V., , VD, I, , 8 Now, warm the coil by heating it in candle flame record, and the measurement for calculation of resistance. Do, not change the potential divider movable arm position., 9 This now results in :, , Therefore, RD =, , 4 Increase the supply voltage to the iron coil by adjusting, the potentiometer so that the current (I) reaches a value, of 450mA., 5 Measure the voltage drop VD across the coiled wire., 6 From both the values (I and VD) calculate the resistance, of the coil., , VD, I, , I, , A, , VD, , V., , = .......... ohms, , The result may vary considerably due to different temperatures of the wire., Conclusion, What is the relationship between resistance and, temperature?, , Electrical : Electrician - Exercise 1.4.43, , Copyright @ NIMI Not to be Republished, , 163
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Electrical, Electrician - Basic Electrical Practice, , Exercise 1.4.44, , Verify the characteristics of series parallel combination of resistors, Objectives: At the end of this exercise you shall be able to, • form series parallel combination circuits, • verify characteristics of series and parallel circuits., , Requirements, Equipment/ Machines, , Tools/ Instruments, •, •, •, •, •, •, •, •, •, , Electrician tool kit, MC Ammeter 0-500 mA, Rheostat - 100 ohms, 1A, MC Voltmeter 0-15V, Multimeter, Potentiometer 60 ohm 2A, Rheostat 25 ohms 2A, Rheostat - 40 ohms,2A, Rheostat - 300 ohms, 2A, , •, , - 1 Set, - 3 Nos., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 2 Nos., - 1 No., , DC source,Battery, 12V,80AH or DC 0-60V, variable voltage supply source with, current limiting facility 0-1 ampere, , - 1 No., - 1 No., , Materials, •, •, •, •, , Switch SPT 6A 250V, Resistor 22 ohms 1 W, Resistor 10 ohms 1 W, Connecting cables, , - 1 No., - 1 No., - 1 No., - as reqd., , PROCEDURE, TASK 1: Verify the characteristics of series parallel combination of resistors., 1 Calculate the voltage and currents for the series parallel, circuit shown in Fig 1. Enter the values in, Table 1., , 2 Calculate the total resistance RT and total current IS for, VS = 50V and enter in Table 2., 3 Set the value of the rheostat resistances equal to the, values given in Fig 1 (i.e. R1 = 25 ohms, R2 = 300 ohms,, R3 = 40 ohms and R4 = 60 ohms) by measuring the, resistance value between one end and the variable point, of the rheostat., 4 Form the circuit and measure the voltages and current., Record them in Table 1., 5 Calculate the value of RT from Vs and Is and enter in, Table 2. Compare with the value obtained in step 2., , Table 1, VRI, VS = 50V, R1 = 25Ω, R2 = 300Ω, R3 = 40Ω, R4 = 60Ω, , IS, , I2, , VR2, , I3, , VR3, , R3+R4, , Calculated, Values, Measured, Values, Table 2, Calculated, Values, Measured, Values, , 164, , RT = R1 + {R2 || (R3 +R4)} =, RT=, , VS, =, IS, , Copyright @ NIMI Not to be Republished, , R2 ||(R3+R4)
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Electrical, Electrician - Magnetism and Capacitors, , Exercise 1.5.45, , Determine the poles and plot the field of a magnet bar, Objectives: At the end of this exercise, you shall be able to, • identify the polarity of the magnetic compass, • determine the polarity of a permanent magnet, • trace the magnetic field of the given magnetic bar, • trace the magnetic lines with the aid of a compass needle and iron fillings., , Requirements, Tools/Instruments, •, •, , Bar magnet 12 x 6 x 100 mm, Compass needle 10 mm diameter., , - 2 Nos., - 1 No., , Materials, •, , M.S.bar 12 x 6 x 100 m or, (make a M.S. bar to the size, of the bar magnet available), , - 1 No., , •, •, •, •, •, •, •, •, , Thread (tensionless), Iron fillings, Iron nails, Aluminium wire, Copper wire, Cotton thread sleeve, Wood chips, Paper pins, , -1m, - 25 gms, - 25 gms., - a few pieces, - a few pieces, - a few pieces, - a small quantity., - as required., , PROCEDURE, TASK 1: Trace the magnetic field of the given magnetic bar, 1 Keep the magnetic compass on the table as shown in, Fig 1., 2 Observe the needle ends., 3 Turn the position of the compass and observe the, position of the needle., 4 Result: The needle end seeking the geometrical north, direction is the north seeking pole, or in general called, a ________________ pole. The other end is called a, _______________ pole., , TASK 2: Determine the polarity of a permanent bar magnet, 1 Suspend the magnet as shown in, tensionless thread., , Fig 2 with a, , 2 Observe the direction of the poles of the suspended, magnet., 3 Mark the polarity N on the free end of the suspended, magnet that points (seeks) at the north direction of the, earth., 4 Reorient the position of the suspended magnet to, cofirm the polarity., 5 Check the identified polarity with a magnetic compass., The compass needle must not be taken near, the poles of the bar magnet., , Copyright @ NIMI Not to be Republished, , 165
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TASK 3: Trace the magnetic path of the given magnetic bar, 1 Place the bar magnet's north pole underneath the paper, as shown in Fig 3. Sprinkle some iron filings on the, paper., , 5 Place another thin card over the bar magnet as shown, in Fig 6. Trace the magnetic lines using a compass, needle by positioning the needle in the required areas.., 2 Tap the paper gently on all the corners. Observe the, random filings getting oriented into a definite pattern., 3 Gently draw lines along the orientation of the iron, filings with a pencil. Repeat the expriment for the, other pole as shown in Fig 4., , For steps 4 and 5, the bar magnet should be, oriented in the geometrical north-south direction., Do not use a strong bar magnet for mapping, the field with a compass., , 4 Place the bar magnet underneath a thin cardboard as, shown in Fig 5. Sprinkle some iron filings. Gently tap, the paper to orient the iron filings and trace the magnetic, path with a pencil., , 166, , Electrical : Electrician - Exercise 1.5.45, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - Magnetism and Capacitors, , Exercise 1.5.46, , Wind a solenoid and determine the magnetic effect of electric current, Objectives: At the end of this exercise you shall be able to, • prepare a bobbin, • select the suitable wire and make the winding for solenoid, • determine the pulling strength of a solenoid., , Requirements, Tools/Instruments, •, •, •, •, •, •, •, •, , Combination pilers 150 mm, Screwdriver 100 mm, Screwdriver 150 mm with 3 mm blade, Magnetic compass 12 mm diameter, Rheostat 10 Ohms, 20A, MC Ammeter 0-10A, MC Ammeter 0-30A, MC Voltmeter 0-15/0-25V, , - 1 No., - 1 No., - 1 No., - 8 Nos., - 1 No., - 1 No., - 1 No., - 1 No., , Equipment/Machines, •, , Battery 12V, 80 or 100AH or variable, voltage source DC 0-25V, 30A, , - 1 No., , Materials, •, •, •, •, •, •, •, , Iron filings, Connecting leads, DPST knife switch 16A/ 250V, Enamelled copper wire 16SWG, Paper pins, Terminal post 16A, SPST knife switch 16A / 250V, , - 50 gms, - as reqd., - 1 No., - 50 cm, - a few, - 2 Nos, - 1 No., , •, •, •, •, •, •, •, •, •, •, •, •, •, •, •, •, •, , PVC insulated cable 4 sq.mm, 250V grade, - 4 m., Barrator resistor 0.48 ohms 250W, - 1 No., Cardboard A4 (R 48) size, - 1 No., Bare copper wire 4 sq.mm, - 1 m., Porcelain connectors 2-way 32A, - 2 Nos., Transparent sheet of plastic,, A4 size, 3 mm thick, - 1 No., PVC saddles 50mm, - 2 Nos., PVC pipe 25 mm 100 mm long, - 1 piece., PVC washer 25mm inner diameter., 50 mm outside dia., - 2 Nos., PVC adhesive tape, - as reqd., Super-enamelled copper wire, 22 SWG, - 50m., 4–way terminal pad, - 1 No., T W plank 150 mm x 300 mm, - 1 No., Soft iron piece 22 mm dia 75 mm long, with hook on one end, - 1 No., SPST Knife switch 16A, - 1 No., Adhesive paste for fixing washers, - as reqd., PVC/Empire sleeve 2 mm, - as reqd., , PROCEDURE, TASK 1: Make the solenoid and determine its polarity for the given direction of current, 1 Fix the PVC washers at both ends of the PVC pipe to, make the bobbin. (Fig 1), 2 Fix the bobbin suitably in a hand drilling machine., 3 Secure the lead-out wire to the bobbin by means of, an adhesive tape after inserting the lead wire with, sleeve through the hole in the side wall of the bobbin., 4 Find the number of turns wound over the bobbin for one, rotation of the drilling machine handle., 5 Calculate the number of handle rotations required for, winding 200, 400 and 600 turns., , Copyright @ NIMI Not to be Republished, , 167
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6 Complete the windings by taking tapping at an interval, of every 200 turns (200, 400 and 600) such that the, common and three terminals are taken out through the, holes provided in the side wall (PVC washer)., (Fig 2), , 7 Insulate the top layer with an adhesive insulation tape., (Fig 3), , Carefully remove the enamel insulation without, damaging the conductor., 10 Check the continuity with an Ohmmeter., 11 Connect the ends of the solenoid to the 12V battery, through switch S, variable rheostat and ammeter 0 10A. (Fig 5), , 8 Fix the solenoid on a 150 mm x 300 mm wooden board, using a plastic saddle. (Fig 4), 9 Connect the drawn out ends with sleeves to the 4-way, terminal pad, fixed on the board. (Fig 4), , 12 Close the switch S and test the polarity of the solenoid, with a bar magnet which is, suspended with a thread., , TASK 2: Determine the magnetic effect of electric current, 1 Vertically mount the coil on a stand., 2 Suspend the spring balance from the stand and hook, it vertically to the (plunger) soft iron piece. (Fig 6), Check for the free movement of the plunger, inside the solenoid., , 9 Calculate the pulling power for strength in all the 3, cases., 10 Ascertain the relationship between the number of turns, and magnetic strength when the solenoid carries the, same current, and record the conclusion accordingly., 11 Connect the coil to 600 turns tappings., , 3 Take the initial reading of the spring balance., , 12 Close the switch., , 4 Connect the solenoid to the first tapping, say 200, turns, through an ammeter, knife switch and rheostat, as shown in Fig 5. Get the circuit checked by the, instructor., , 13 Keep the current at 1 ampere by adjusting the rheostat., (Fig 6), , 5 Close the switch and adjust the current to 5 amperes., , 15 Repeat step 14 for different current values (in steps of, 1 ampere up to 5 amperes)., , 6 Note the reading of the ammeter and spring balance, and record in Table 1., 7 Open the switch., 8 Repeat operations 4 to 7 for tappings 400 and 600 by, keeping the current constant at 5A, adjusting the, rheostat., , 168, , 14 Note and record the spring balance readings in, Table 2., , 16 Calculate the pulling power for strength in all the, 5 cases., 17 Ascertain the relationship between the current and the, magnetic strength when the number of turns of the, solenoid is constant. Record the conclusion, accordingly., , Electrical : Electrician - Exercise 1.5.46, , Copyright @ NIMI Not to be Republished
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18 Get it checked by the instructor., Conclusion, , Table 1, Magnetic strength with respect to the number of turns (Current kept constant), Sl.No., , No.of turns, , Current, , 1, , 200, , 5 amps, , 2, , 400, , 5 amps, , 3, , 600, , 5 amps, , Initial reading of, balance W1, , Spring balance, reading W2, , Strength of pulling, power (W3 = W2 - W1), , Table 2, Magnetic strength with respect to the current, (Turns kept constant = 600 turns), Sl.No., , Current, , 1, , 1 amp, , 2, , 2 amps, , 3, , 3 amps, , 4, , 4 amps, , 5, , 5 amps, , Initial reading of, the balance W1, , Spring balance, reading W2, , Electrical : Electrician - Exercise 1.5.46, , Copyright @ NIMI Not to be Republished, , Strength of pulling, power (W3 = W2 - W1), , 169
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Electrical, Electrician - Magnetism and Capacitors, , Exercise 1.5.47, , Measure induced E.M.F due to change in magnetic field, Objectives: At the end of this exercise you shall be able to, • test and install a solenoid, • select a bar magnet and insert it into the solenoid, • measure the e.m.f for the change in magnetic field., , Requirements, Materials, , Tools/Equipment, •, •, •, , Voltmeter (100 mv - 0 - 100 mv), (centre zero), Bar magnet 100 mm, Solenoid (Assembled), (prepared in previous exercise), , - 1 No., - 1 No., - 1 No., , •, •, , Connecting wires, Wooden board with stand, , - as required., - 1 No., , PROCEDURE, 1 Check the physical condition of the solenoid and check, the continuity of the coil., 2 Fix it on a board on shown in Fig 1., 3 Connect the galvanometer to the solenoid terminals as, shown in Fig 1., , 9 Record the voltmeter reading in Table 1., 10 Tabulate all the readings and show it to the instructor for, T approval., A, V, K, Table 1, 4 Insert the bar magnet into the solenoid and slowly, initiate to and fro movement as shown in Fig 2., 5 Record the corresponding reading in Table 1., 6 Gradually Increase the movement of the bar magnet., (Medium speed), 7 Record the reading in Table -1., , sLSl. No., , Speed of bar, magnet, , 1., , Slow, , 2., , Medium, , 3., , High, , 8 Increase the speed of bar magnet to the maximum, to, get higher voltage reading., , 170, , Copyright @ NIMI Not to be Republished, , Voltages, reading
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Electrical, Electrician - Magnetism and Capacitors, , Exercise 1.5.48, , Determine direction of induced E.M.F and current, Objectives: At the end of this exercise you shall be able to, • determine the direction of e.m.f induced in the circuit, • determine the direction of the current by the induced e.m.f., , Requirements, Materials, , Tools/Equipment, •, •, •, •, •, , Voltmeter (100 mv - 0 - 100 mv), Bar magnet 4”, Solenoid (Assembled) fitted on, board, (prepared in previous exercise), Multimeter, Magnetic campass, , - 1 No., - 1 No., , •, •, , Connecting leads, PVC transparent sheet with drilled, holes (4” x 3”), , - as required., - 1 No., , - 1 No., - 1 No., - 1 No., , PROCEDURE, 1 Connect the centre zero voltmeter to the solenoid and, test the continuity of the coil as shown in Fig 1., , 3 Extend one end of the coil wire and make 10 turns at, equal distance in a drilled hole made on a transparent, sheet on it as shown in Fig 3., , 4 Place the compass at one entry point of the conductor, by pointing ‘N’ to the entry of the coil as shown in, Fig 3. Record your findings in Table 1., 2 Check whether the induced voltage is present in the coil, by mounting bar magnet as shown in Fig 2., , 5 Insert the magnet into the coil and move the magnet to, and fro as in the earlier exercise. Note the deflection in, the compass needle., 6 Change the polarity of the magnet and repeat, step 4. Note the deflection in the compass needle., The current direction shown in Fig 4 is for your, reference., The direction of the current in a conductor’s, cross-section is shown by the (+) plus symbol, inside a conductor or a (.) dot symbol outside a, conductor. (Fig 4), 7 Interpret your findings and record the conclusion in, Table 2. (A sample result is given for reference), , Copyright @ NIMI Not to be Republished, , 171
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Table 1, , sLSl. No., , Compass N towards, entry, , Compass S, towards entry, , 1, 2, 3, , Table 2, (POLARITY OF INDUCED EMF), Case, , Operation, , Figure, , 1., , Magnet is moved inside the coil, , 2., , Magnet is moving away from the coil, , 3., , Magnet with changed polarity is moved, inside the coil, , 4., , Magnet with changed polarity is moving, away from the coil, , 172, , Electrical : Electrician - Exercise 1.5.48, , Polarity of induced voltage, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - Magnetism and Capacitors, , Exercise 1.5.49, , Practice on generation of mutually induced E.M.F, Objectives: At the end of this exercise, you shall be able to, • prepare a solenoid having two sets of winding, • wind the solenoid with both primary and secondary windings, • measure the induced voltage in the secondary wrinding., , Requirement, Materials, , Tools/Equipments, •, •, •, •, •, , Voltmeter (100 MV - 0 - 100 MV), Bar magnet 100 mm, Solenoid (Assembled) fitted on, board, (prepared in previous exercise), Multimeter, Magnetic compass, , - 1 No., - 1 No., , •, •, , - 1 No., , •, •, , Connecting wires, PVC transparent sheet with drilled, holes 100 x75 mm, Super Enamelled copper wire 22 SWG, Supporting stand, , - as reqd., - 1 No., - 25 m, - 1 Pair., , - 1 No., - 1 No., , PROCEDURE, Use the solenoid, used in exercise 1.5.47 and, 1.5.48., 1 Take the two ends of the coil, and check its resistance, using ohmmeter and record in table 1., 2 Wrap the tape over the solenoid from one end., 3 Wind the copper wire (22 SWG) over the solenoid from, one end to the half the length of the coil and wrap it with, the tape., , 7 Apply 10V AC to the inner winding (primary) and, measure the secondary winding voltage as shown in, Fig 1., 8 Note down the reading of the voltmeter in table 1., The voltmeter may show a very minimal, reading. If the reading does not increase when, the primary wrinding is used, set it to the, secondary winding, , 4 Take the two terminals of the copper wire and check its, resistance and record in table 1., , 9 Insert the soft iron core into the solenoid. Now the, voltage will increase. Note down the voltage in Table 1., , 5 Fix the solenoid, which already has two windings in the, board using clamps and screws as shown in Fig 1., , 10 Switch OFF and insert a non-magnetic cylindrical core, inside the coil. Switch ON the 10V supply. Note down, the voltage in Table 1., , 6 Set the secondary winding of step down transformer, tapping to 10V., , 11 Switch OFF and tabulate all the readings., , Copyright @ NIMI Not to be Republished, , 173
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12 Get the work approved by the instructor., , Note down the primary and secondary number, of turns in Table - 1 Measure the value of the, resistance in primary and secondary windings, and record in Table 1, , 13 Note down the result and conclusions., , Table 1, Primary, , Secondary, , Without soft iron core, , Turn, , Turn, , Primary, Voltage, 10, , 174, , Secondary, Voltage, , With soft iron core, Primary, Voltage, , Secondary, Voltage, , 10, , Electrical : Electrician - Exercise 1.5.49, , Any other core, Primary Secondary, , 10, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - Magnetism and Capacitors, , Exercise 1.5.50, , Measure the resistance, impedance and determine the inductance of choke, coils in diffrerent combinations, Objectives: At the end of this exercise, you shall be able to, • measure the resistance of the coil, • measure the impedance in AC circuit using the voltmeter and ammeter, • determine the inductance of the coil., , Requirements, Materials, , Tools/Instruments, •, •, •, •, •, , MC Voltmeter 0-15V, MI Voltmeter 0-300V, MC Ammeter 0-500mA, MI Ammeter 0 500mA, Ohmmeter 0 - 2 K ohms, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , •, •, •, •, , SPT switch 6A 250V, Connecting leads, Wound choke, (Solenoid coil), Tube light choke 40W, 240V, , - 1 No., - 7 Nos., - 2 Nos., - 2 Nos., , Equipment/Machines, •, •, •, , Potential divider 480 ohms 1A, 12 volts DC source (RPS), 240 volts AC source, , - 1 No., , PROCEDURE, TASK 1: Measure the resistance of the coil, 1 Connect the elements and form a circuit as shown in, Fig 1., , 2 Show the connections to the instructor and get it, approved., 3 Close the switch `S' and adjust the potentiometer, for 100mA current. Record the value of I and V in, Table 1., 4 Adjust the potentiometer to obtain the current, 200, and 300mA. Record I and the corresponding voltages., 5 Calculate the resistance of the coil applying Ohm's, Law. Record the result in Table 1. Find the average, value of resistance in ohms ie. R = V/I, 6 Disconnect one coil i.e. terminals 3 and 4. Repeat the, experiment to get the resistance measured for single, coil with terminals 1 and 2. (Fig 1b), 7 Connect terminal 3 at 1 and 4 at 2. Read and record the, V and I in Table 1. (Fig 1c), 8 Result: Resistance of the 2 choke coils in series =, ......... ohm, Resistance of one choke coil = ......... ohm, Resistance of two coils chokes in parallel = ........., ohm, ............................................................................, 9 Verify the above results with the help of an ohmmeter., , Keep terminal `C' at `B' in the potentiometer/, voltage divider for minimum output voltage, , Copyright @ NIMI Not to be Republished, , 175
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Table 1, Sl.No., , DC voltatge across coils, , current in mA, , Resistance R = V/ICoils connected, , 1, 2, 3, 4, 5, 6, 7, , Two in series, One coil only, Two in parallel, , Average resistance of both coils, Average resistance of the single coil, Average resistance of the parallel coils, , = ______________ ohms, = ______________ ohms, = ______________ ohms, , TASK 2: Measure the impedance of the coil in AC supply, 1, , Replace the voltmeter and ammeter with MI of, type 0-300V and 0.5 ampere respectively. Connect, the circuit to AC 240V 50 Hz supply source as, shown in Fig 2., , 3, , Close the switch `S' and adjust the potentiometer, to obtain a current of 100mA. Record the I and V, in Table 2., , 4, , Adjust the potentiometer for a current of 200mA., Record the corresponding voltage. Repeat it for, 300mA., , 5, , Calculate the value of R = V/I for each case. Record the, value under the column ` impedance ' and find the, average value of impedance ___________ohm, , 6, , Disconnect one coil (i.e. terminals 3 and 4). Repeat, steps 2 to 4 to determine impedance of one coil., , Conclusion, i) When both coils are in series the impedance is, Keep the terminal of the potentiometer `C' at `B', for the minimum output voltage., 2, , Show the connections to the instructor and get his, approval., , ii) Impedance of one coil is, , ohms., , TASK 3: Determine the inductance of the choke, Calculate the inductance (L) in the method shown below:, Average value of resistance (R) of the choke from, Table 1 =, ohms., Average value of impedance (Z) of the choke from, Table 2 =, ohms., Impedance = Z = R +X, 2, , \, , 176, , L, , 2, , 2, , L, , XL, , = Z2 - R2 ohms., , XL, , = 2p fL, =, , ohms, , where, , p, , =, , 3.142 (22/7), , f, , =, , Frequency of supply in Hz, , L, , =, , Inductance in Henry, , Inductance of the choke coil is L =, L, , =, , 2 πf, , Henry (H), , _________Henry, , XL, 2 πf, , Electrical : Electrician - Exercise 1.5.50, , XL, , Copyright @ NIMI Not to be Republished
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Table 2, Sl.No., , AC voltage across coils, , Impedance Z = V/I, , AC current in mA, , 1, 2, 3, 4, 5, 6, , Coils connected, Two in series, One coil only, , Average value of impedance of both coils, Average value of impedance of single coil, , = ______________ ohms, = ______________ ohms, , TASK 4: Verify the effect of the direction of the current in coils with a common core, 1 Connect the elements and the terminal of the circuit as, shown in Fig 3. Get the approval of the instructor and, then close the switch and adjust the potentiometer to, get 100mA., 2 Read and record the values for I and V in Table 3., Calculate the impedance and record in Table 3., 3 Switch OFF the supply and interchange the terminals, 3 and 4 as shown in Fig 3., , Table 3, Sl.No., , AC voltatge across both the coils, , AC current in mA, , Impedance Z = V/I Direction of current, , 1, , Two coils with, current in the, same direction, , 2, , Two coils with, current in the, opposite coils, , By interchanging the terminal connection, the, direction of the current is reversed in the coil., 4 Close the switch `S' and record the new values of I at, Sl.No.2. of Table 3., Ensure that the voltage remains at the set, value., 5 Calculate the value of impedance by the formula Z, = V/ I . Do you observe any change in the value of, impedance from the previous value?, Is the value close to the resistance value calculated in Task 1?, ., 6 Verify and compare the impedance with the previous, values., , 7 Compare the impedance values in to following two, conditions, – coils carrying current in the same direction, – coils carrying current in the opposite direction., Conclusion, 1 The impedance value when coils carry current in same, direction., __________________________________________, __________________________________________, 2 The impedance value when coils carry current in the, opposite direction., __________________________________________, __________________________________________, , Electrical : Electrician - Exercise 1.5.50, , Copyright @ NIMI Not to be Republished, , 177
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Electrical, Electrician - Magnetism and Capacitors, , Exercise 1.5.51, , Identify various types of capacitors, charging/discharging and testing, Objectives: At the end of this exercise, you shall be able to, • identify the type of capacitor by visual inspection, • identify the capacitor's value and rating from the marking, • test the capacitor with DC supply for insulation and leakage, • test the capacitor for charge and discharge., , Requirements, Tools/Instruments, , Materials, , •, •, •, , •, , Ohmmeter (multimeter - ohms range) - 1 No., MC Voltmeter (0 - 15V), - 1 No., MC Ammeter (100mA - 0 - 100mA), - 1 No., , Equipment/Machines, •, , DC source 12 V or 0-30V variable, (R.P.S), , - 1 No., , •, •, , Capacitors - paper, mica, electrolytic,, mylar, tantalum,variable air core and, mica – assorted values and different, voltage ratings, - as required., Potentrometer 100 k ohm, - 1 No., Single pole, double throw switch, 16A 250V, - 1 No., , PROCEDURE, TASK 1: Identification of capacitors, 1 Look at Figs 1(a) to 1(t). Identify the capacitors and, record your observations in Table 1., 2 Read the value of capacitance and working voltage from, the markings, if indicated, and record in, Table 2., 3 From the capacitor provided by the instructor read the, value of the capacitor and identify its type., , 178, , Copyright @ NIMI Not to be Republished
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Table 1, Fig.No., , Name of component, , Symbol, , Type, , Capacitance value, , Voltage rating, , Table 2, Sl.No., , Type, , Value of C in μf, , Voltage V, , TASK 2: Test the capacitor for charge and discharge, 1 Initially touch both leads of the capacitor with the, voltmeter (suitable range)., , 2 Form the 12V circuit for testing the capacitor circuit, elements as shown in Fig 2. Keep the switches open., , If there is any deflection, contact both leads, through a resistance for sufficiently a long, time., , 3 Keep the switch S connected to the battery. Observe, the deflection in the ammeter and voltmeter., , Do not touch the capacitor leads by hand., High voltage retained by a charged capacitor, will give a severe shock., , 5 Observe the voltmeter reading at equal intervals of time., (At least 4 readings from zero to the maximum deflection.), , 4 Record the deflection in the ammeter when the switch, S is closed to position 1., , Electrical : Electrician - Exercise 1.5.51, , Copyright @ NIMI Not to be Republished, , 179
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6 Record the time and voltage in Table 3., 7 Repeat steps 1 to 5 by changing the value of the series, resistor ‘R’ (increasing the value of R increases the, time)., 8 Open the switch ‘S’ and observe the voltmeter reading, for 5 minutes., , 9 Result, The voltage across the capacitor remains _________, because of _____________ condition of the capacitor., 10 Close the switch S to position 2 and observe the, voltmeter and ammeter readings., 11 Observe the deflection of the voltmeter:, (a), , The voltage of the capacitor gradually decreases., , (b, , The current shoots to maximum at the instant, switch S is closed to position 2, then it decreases, gradually, indicating that the capacitor is losing, charge., , 12 Repeat the test for different values of capacitance rated, for different voltages., The testing voltage should be close to the, voltage rating of the capacitor., Table 3, Sl., No., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, , Value of, Capacitor, Resistor, μF, kW, 470, , Time, in, seconds, , Voltage, volts, , 500, , 4370, , 470, , TASK 3: Testing of capacitor with ohmmeter, 1 Discharge the given capacitor., 2 Connect the ohmmeter to test the capacitor (Fig 3) and, observe the deflection in the meter., Set the ohmmeter selector switch at a higher, range., While testing with a polarised capacitor, the, positive terminal of the capacitor is to be, connected to the positive terminal of the, ohmmeter and the negative terminal to the, negative terminal of the ohmmeter., 180, , While testing with non-polarised capacitor, (mica, ceramic, etc) the low values in fractions, of micro-farad will not show any deflection in, the ohmmeter., 3 Assess the condition of the capacitor under test, using, the information available in Fig 3 and record the findings, in Table 4., , Electrical : Electrician - Exercise 1.5.51, , Copyright @ NIMI Not to be Republished
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4, , Discharge the capacitor., , 5 Perform the test in different capacitors., Table 4, Sl., No., , Value of, Capacitor, , Meter, reading, , Result, , 1, 2, 3, 4, 5, For electrolytic capacitor only., , Electrical : Electrician - Exercise 1.5.51, , Copyright @ NIMI Not to be Republished, , 181
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Electrical, Electrician - Magnetism and Capacitors, , Exercise 1.5.52, , Group the given capacitors to get the required capacity and voltage rating, Objectives: At the end of this exercise you shall be able to, • identify the capacitor's value and rating from the markings, • test the capacitor with DC supply for its insulation and leakage, • determine the capacitive reactance, • select capacitors and connect in series, • select capacitors and connect in parallel, • test combinations of capacitors., , Requirements, Tools/Instruments, •, •, •, , Materials, , MI Voltmeter 0 to 300V, MI Ammeter 0 to 500mA, Rheostat, about 300 ohms 2A, , - 1 No., - 1 No., - 1 No., , Equipment/Machines, •, , •, •, •, •, •, , Switch SPT 6A 250V, 2 MFD 240V/400V, 4 MFD 240V/400V, 8 MFD 240V/400V 50 Hz., Connecting leads, , - 1 No., - 2 Nos., - 1 No., - 1 No., - as required., , 240V AC source., , PROCEDURE, TASK 1: Measure capacitive reactance (Xc), 1 Form the circuit as shown in Fig 1 with a 2 - μF, capacitor. (Fig 1), , Table 1, Sl.No. Value of, , Voltage, , Current X C =, , Capacitor, , V, I, , 5 Compare the calculated value using the formula, Discharge the capacitor before handling., , XC =, , 1, 2πfC, , 2 Close the switch S and adjust the potential divider for, the rated voltage of the capacitor (240 V)., , 6 Find the capacitive reactance value for 4 μF repeating, steps 1 to 5., , 3 Note the voltmeter and ammeter readings and record, in Table 1., , 7 Conclusion, , V, 4 Calculate the reactance X C =, I, , and record the, , result in Table 1, , i, , When capacitance increases the capacitive, reactance, , ii Increased reactance, capacitance., , means, , TASK 2: Connect capacitors in series, 1 Form the circuit with two capacitors in series as shown, in Fig 2. (2 MFD, 2 MFD), , 182, , 2 Determine the XC value for the series combination, performing steps 2 to 5 of TASK 1. Fill XC values in, Table 2 under the appropriate columns., , Copyright @ NIMI Not to be Republished
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Result, When capacitors are connected in series, i, , the total reactance, , ii, , the net capacitance value, , 5 Measure the voltage across each capacitor and record, it in Table 2 under column 3., 3 Calculate, , 1, C, , =, , total, , the, , 1, C, , +, , 1, , total, , capacitance, , C total, , as, , 1, C, , 6 Repeat steps 1 to 5 for series grouping of capacitors., a) 2 & 4 MFD, , b) 4 & 8 MFD, , 7 Get it checked by the instructor., Conclusion, , 2, , 4 Calculate the Ctotal from the Xc., confirmity., , The voltage across the capacitor and the value of, capacitor in series., , Check for its, , Table 2, Sl., No., , Value of, Value of, Capacitor Capacitor, C1, C2, in μf, , in μf, , 1, , 2, , 2, , 2, , 2, , 4, , 3, , 4, , 8, , Voltage, across, C1, , Voltage, across, C2, , V1, , V2, , Current in, mA, , Voltage, V, , Total, , 1, C, , =, , 1, C, , 1, , +, , 1, C, , 2, , Capacitive, reactance, , XC=, , 1, 2Πfc, , TASK 3: Connect capacitors in parallel, 1 Form the circuit with two capacitors in parallel as shown, in Fig 3 (2 MFD, 2 MFD)., , 3 Calculate the total capacitance Ctotal = C1 + C2. Record, Ctotal in table 2., , 2 Determine the reactance X C of the parallel combination performing steps 2 to 5 of TASK 1. Fill up XC, in Table 3., , 4 Calculate the Ctotal from XC. Check for its confirmity., Result, In parallel combination of capacitance, i, , the total reactance _________________________, , ii the total capacitance _______________________., Discharge the capacitors at the end of each, experiment / test, 5 Repeat steps 1 to 5 for parallel grouping of capacitors., TABLE 2, Sl., Value of, No. Capacitor, C1, , Value of, Capacitor, C2, , Voltage, across, C1, , Voltage, across, C2, , in mf, , in mf, , V1, , V2, , 1, , 2, , 2, , 2, , 2, , 4, , 3, , 4, , 8, , Current in, mA, , Voltage, V, , Electrical : Electrician - Exercise 1.5.52, , Total, Ctotal= C1 + C2, , Copyright @ NIMI Not to be Republished, , Total, reactance, , XC=, , 1, 2Πfc, , 183
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Electrical, Electrician - AC Circuits, , Exercise 1.6.53, , Measure current, voltage and PF and determine the characteristics of the, RL, R-C, R-L-C in AC series circuits, Objectives: At the end of this exercise, you shall be able to, • measure the current, voltage, power and P.F in R-L series circuits, • measure the current voltage, power and P.F in R-C, series circuits, • measure the current voltage, P.F in R-L-C series circuits, • measure the power and P.F. in R-L-C series circuits, , Requirements, Tools/Instruments, •, •, •, •, , Materials, , MI voltmeter 0 - 300 V, MI ammeter 0 - 1.5 A, Wattmeter 250 V, 2.5 amps, Power factor meter (0.5 lag to, 0.5 lead) 250 volts, 2.5 amps, , - 3 Nos., - 1 No., - 1 No., - 1 No., , Equipment/Machines, •, , Auto transformer 0-270V/8A, , - 1 No., , •, •, •, •, •, •, •, , Connecting cables, Choke (tube light) 40 W, 0.43 A,, 250 V, I.C.D.P. switch - 16 amps, 250 volts, Wire wound resistor 500Ω/0.5A, Wire wound resistor 100Ω/1.5A, Electrolytic capacitor 8μFd/400V, Electrolytic 1μFd, 2μFd, 4μFd/400V, , - as required., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 each, , PROCEDURE, TASK 1: Measure the current, voltage, power and P.F in R-L series circuit, , 1 Assemble the circuit by connecting instruments, resistor, R, inductor L as in Fig 1. Switch ON the supply., , •, , Keep current as the reference vector., , •, , Select a suitable scale for the voltage., , 2 Measure the voltage VR, VL, supply voltage VT and the, circuit current and record in Table 1., , •, , Draw the voltage vector (VR) in-phase with current (Ι)., , •, , Draw the voltage vector VL leading-current I by, 90°., , •, , Add vector VR and VL to get VT1, , 3 Read power (W1) and power factor (cos φ) and record, it in Table 1., 4 Calculate the apparent and the true power consumed in, the circuit and compare them., 5 Calculate the power factor and compare it with the, measured power factor., 6 Draw the vector diagram to add the voltage drops across, R and L., , 184, , 7 Compare the above with the measured supply voltage., 8 Calculate the power factor from the true power and, apparent power Cos φ2 =, , W, = ......................W, VT × I, , 9 Compare the calculated power factor with the measured, power factor., , Copyright @ NIMI Not to be Republished
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11 Get it checked by the instructor., , 10 Repeat the steps changing two values for the resistor, and inductor and record them in Table 1 in columns 2, and 3., , Table 1, Measured value, Sl., No., , Circuit Supply, current voltage, , I, , VT1, , Calculated value, , Power, consumed, (Wattmeter, reading), , W1, , Voltage Voltage, across across, resis- inductance, tance, , VR, , VL, , Power, factor, (reading, of P.F., meter), Cos φ1, , Vector Difference, Power, Difference, between, addition, in VT1 consumed, of VR, and VT2 in circuit, measured, and VL, & calculated, power factor, VT1, , VT – VT1, , W2= VT X, I X Cos φ1, , Cos φ1–, Cos φ2, , 1, Resistance =, , Inductance =, , Resistance =, , Inductance =, , Resistance =, , Inductance =, , 2, , 3, , Conclusion, The difference between vector addition of VR and VL with, respect to VT is due to, , TASK 2: Measure the current voltage, power and P.F in R-C series circuit, 1 Test the capacitor with an ohmmeter for its condition., Discharge the capacitor before testing., 2 Check the value of the given resistance with a digital, multimeter for its value., Check the suitability of the selected wattmeter, and P.F. meter with respect to the circuit, specifications., , 4 Close switch ‘S’ and adjust the auto-transformer output, voltage to 100V., 5 Measure the circuit current, voltage power consumed, and power factor and note the readings in Table 2., 6 Calculate cosφ and impedance., 7 Compare the calculated P.F with measured P.F., 8 Measure the voltages across R and C and note in, Table 3., , 3 Construct the circuit as per diagram. (Fig 2) Keep the, switch ‘S’ open., , 9 Compare the arithmetical sum of VR and VC with the, supply voltage and observe that this is a wrong procedure., , Set the auto-transformer output to zero, voltage., , 10 Add VR and VC by the vector method (graphically), selecting a suitable scale and compare with the, measured supply voltage., 11 Adjust the output voltage to 200 V and repeat steps 5, to 10., , Electrical : Electrician - Exercise 1.6.53, , Copyright @ NIMI Not to be Republished, , 185
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12 Get it checked by the instructor., , Conclusion, , Table 2, Measured, V supply, , I, , W, , Calculated, PF, , PF =, , W, VI, , Z=, , Table 3, , V, I, , 100 V, , V supply, , VR, , VC, , VR + VC, (Arithmetic), , V R + VC, (Vector), , 100 V, , 200 V, , 200 V, , TASK 3: Measure the current voltage, P.F, in R-L-C series circuit, , 1 Assemble the circuit as per circuit diagram (Fig 3) with, the instruments and components collected., Before forming the circuit, confirm that the, capacitor is discharged., 2 Switch ‘ON’ the supply and adjust the auto-transformer, until the voltmeter indicates 240 volts., , Table 4, Supply, , VR, , V, , L, , 240 v, , 3 Measure the voltage across each element and note it in, the Table 4., 186, , Electrical : Electrician - Exercise 1.6.53, , Copyright @ NIMI Not to be Republished, , V, , C, , I
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4 Measure the current and note the same in Table 4., Switch off the circuit., , 8 Replace the capacitor with another value, say 8.0, MFD and repeat the steps 2 to 7., , 5 Draw the vector diagram (say 1cm = 50 V and 1cm, = 0.1A) taking the current as the reference vector., , 9 Replace the capacitor with another value, say 1.0, MFD and repeat the steps 2 to 7., , 6 Determine the supply voltage from the vector diagram., , 10 Result: Total measured voltage is, , Supply voltage (vector sum) =..................V, Assumption: The resistance of the choke is, negligible in this case., 7 Compare the value of the resultant vector voltage with, reading of the voltmeter across the mains., If the vector sum of voltages VR VC VL is not, exactly equal to the measured supply voltage,, it may be due to--•, , observation error, , •, , drawing of the vector diagram incorrectly, , •, , assumptions made., , 11 Get it checked by the instructor., Conclusion, A The voltage across individual component and total, supply voltage, B The circuit current, C The phase angle of current with supply voltage (from, voltage vector), , TASK 4: Measure the power and P.F. in R-L-C series circuit, , 1 Form the circuit as shown in Fig 4., Discharge the capacitor. With an ohmmeter, check the resistance for its value, the inductor, for its continuity and the capacitor for leakage., 2 Set the auto-transformer to have zero output. Switch, ‘ON’ the supply., 3 Gradually increase the output voltage until it is 100V., 4 Measure the corresponding current. Note down the, readings in Table 5. Also read the Wattmeter and the, power factor meter and record it in Table 5., 5 Calculate the apparent power from voltmeter and, ammeter reading., Apparent power = V x I in volt amp (VA), 6 Determine the power factor by using the formula, and record it in Table 5., , Cos φ =, , True power, Apparent power, , 7 Verify the measured power factor with the calculated, power factor., 8 Increase the voltage to 200 volts and repeat steps 4, to 7., Do not increase the voltage beyond 200V for, this circuit., 9 Reduce the output voltage back to zero and switch off, the supply., 10 Repeat the experiment (steps 2 to 9) with, i) the capacitor removed, ii) a 2 micro-farad capacitor connected, iii) a 8 micro-farad capacitor connected keeping the, voltage at 200 V., , Electrical : Electrician - Exercise 1.6.53, , Copyright @ NIMI Not to be Republished, , 187
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11 Compare the readings of the power factor in all the four, cases. Record your observation., 12 Result, The change of the capacitor in the R-L-C series circuit, for given R-L (value), , TABLE 5, Sl., , V Volt, , No., , I Amp., , W, , AP = V xI in VA, , True power, , Apparent power, , cos φ =, , W, AP, , P.F. Meter, reading, , Capacitor, value in MFD, , 1, , 100 V, , 4, , 2, , 200 V, , 4, , 3, , 200 V, , 0, , 4, , 200 V, , 2, , 5, , 200 V, , 3, , 13 Get it checked by the instructor., , 188, , Electrical : Electrician - Exercise 1.6.53, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - AC Circuits, , Exercise 1.6.54, , Measure the resonance frequency in AC series circuit and determine its, effect on the circuit, Objectives: At the end of this exercise you shall be able to, • determine the resonance frequency of a given LC series circuit and circuit current, • plot a graph of frequency versus circuit current, • test the working of a series LC as a wave trap, • determine the effect of the resonance on the circuit., , Requirements, Materials/Components, •, •, •, •, •, , General purpose Lug board, Capacitor 0.1 μF, Inductor coil, around 40mH (Use the, solenoid coil made in Ex. 1.5.46), LED with holder, Hook-up wires, , Tools/Equipments/Instruments, - 1 No., - 1 No., - 1 No., - 1 No., - as reqd., , •, •, •, •, , Trainees kit, CRO, 20 MHz, Function generator, MI Ammeter 0 - 30 mA, , - 1 No., - 1 No./batch, - 1 No./batch, - 1 No., , PROCEDURE, TASK 1: Finding Resonance frequency and circuit current, 1 Solder the components as shown Fig 1 to obtain a, simple series resonance circuit. Connect instruments, as shown in Fig 1., , LED may not be glow or may be very dim,, because the set frequency of 1 KHz may not be, the resonance frequency of the circuit., 5 Gradually increase the frequency and record the, resonance frequency fr at which the circuit current, becomes maximum (LED glows brightly)., This is the resonance frequency of the series, resonance circuit because at series resonance,, current I through the LC circuit will be, maximum., , The LED in the circuit is to get a visual indication, of the current through the circuit at different, frequencies., 3 Calculate and record the resonance frequency of the, series resonance circuit with known values of L and C, 4 Set the output of the signal generator to 10Vrms and, frequency to 1KHz. Record the current, I through the, circuit in Table 1., , 6 Compare and record the difference in the resonance, frequency calculated in step 3 and that measured in, step 5., 7 Vary the input frequency in steps of 500 Hz around the, resonance frequency and in each step record the value, of circuit current in Table 1., 8 From the recorded readings of current in step 6, plot a, graph of frequency versus current and mark the, resonance frequency of the LC series circuit. (Fig 2), 9 It may appear as in Fig 2 working of the circuit, Record, readings and plot the graph and get it checked by the, instructor., , Copyright @ NIMI Not to be Republished, , 189
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Table 1, Frequency, , +500HZ, , +1KHZ, , +1.5KHZ, , +2KHZ, , Sine wave, , TASK 2: To use series LC circuit as wave-trap to determine the effect on the circuit, 1 Using known values of L and C make the circuit, connections as shown in Fig 3., , 3 Increase the frequency till the output of the trap circuit, is minimum. Record this frequency as the trap frequency, and its the effect on the circuit., At trap frequency, which is the resonance, frequency of the Shunt connected LC circuit,, the impedance of the circuit will be minimum, and hence the voltage across the circuit will be, minimum. Ideally, this should be zero. But,, because of the internal resistance of the coil,, the output voltage will not be zero but, will be, minimum., 4 Get your work checked by the instructor., , 2 Set the output of the signal generator to 3 volts, 50KHz,, sine wave., , 190, , LAB ASSIGNMENT: Change the value of the, capacitor used in the LC circuit to 0.01μF and, redo TASK 2 to find the new wave-trap, frequency., , Electrical : Electrician - Exercise 1.6.54, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - AC Circuits, , Exercise 1.6.55, , Measure current, voltage and PF and determine the charactertics of R-L, RC and R-L-C in AC parallel circuits, Objectives: At the end of this exercise you shall be able to, • measure the current, voltage in R-L parallel circuit, • measure the current and voltage in each branch circuit of R-C parallel circuits, • determine the characteristics of R-L-C in parallel circuits., , Requirements, Tools/Instruments, •, •, •, •, •, , Digital multimeter, MI Ammeter 0 to 2 ampere (0-5A), MI Ammeter 0 to 3 amperes (0-5A), MI Voltmeter 0-250 V, Frequency meter 50Hz/±5, , •, - 1 No., - 2 Nos., - 1 No., - 1 No., - 1 No., , Equipment/Machines, •, , Auto-transformer - input 240 V, - output 0 to 270 V, 8 amps, , - 1 No., , Rheostar 400Ω/1A, , - 1 No., , Materials, •, •, •, •, , Connecting cables, I.C.D.P switch 250V, 16 A, Wire wound resistor - 200 ohms, Choke coil of 40 watts, 240V, 50 Hz. tube light, E.capacitor 8μFd/4μFd/400V, E.capacitor 2μFd/400V, , •, •, , - as reqd., - 1 No., - 1 No., - 1 No., - 1 each., - 1 each., , PROCEDURE, TASK 1: Measure the current, voltage in R-L parallel circuit, 1 Assemble the circuit with the instruments, inductance, coil and resistance. (Fig 1), , 4 Measure the branch and total currents and record in, Table 1. Repeat this step for different voltages say, 100V, 125V, 150V, and 175V., Table 1, Sl.No., , V, , 1, , 50, , 2, , 100, , 3, , 125, , 4, , 150, , 5, , 175, , Measured, IR, IL, , IT, , Graphical, IT Value, , 5 Draw the vector diagram with suitable scale for currents, taking voltage as reference vector in your practical, record., 6 Determine the total current graphically., 2 Set the auto-transformer output at zero position., 3 Switch ‘ON’ the supply and gradually increase the, output voltage to 50V., , The calculated values of total current and the, actual measured value of current may vary due, to instrument error, observational error and, non-availability of pure inductance. Hence,, about 5% error is permissible., , Copyright @ NIMI Not to be Republished, , 191
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7 Compare the total current measured with the calculated, value entered in table 2., TABLE 2, Sl.No. Measured, V, 1, , 50, , 2, , 100, , 3, , 125, , 4, , 150, , 5, , 175, , I, , Calculated, I =, , T, , T, , (I2 R + I2 L ), , 8 Find the Impedance of the circuit from the supply, voltage and measured current. Calculate Z =, , V, IT, , Conclusion, , V, Z= I, T, , Total current in an AC parallel circuit is the vector, of IR and IL and not, addition., , TASK 2: Measure the current and voltage in each branch circuits of R-C parallel circuits, 1 Test the capacitor with an ohmmeter for its condition., Discharge the capacitor before testing., , 6 Calculate the impedance ‘Z’ and record in Table 3., 7 Calculate the capacitive reactance (Xc = V/I3) and record, your result in Table 3., , 2 Test the resistor with an ohmmeter for its value., , 3 Build the circuit as per diagram. (Fig 2) Keep the switch, open. Set the auto-transformer to the minimum output, voltage., 4 Switch ON the supply. Adjust the auto-transformer for, an output voltage of 200V., 5 Record the frequency, voltage and the three ammeter, readings in Table 3., , 8 Calculate the capacitance from the values recorded, in Table 3., 9 Establish that the arithmetical sum of the branch, current is not equal to the main circuit current., 10 Graphically add the currents I2 and I3 and determine the, value of I1. Compare this value with the measured value., 11 Calculate the power factor from the recorded readings, and enter the value in the space given below., Table 3, , Sl.No., , V, , f, , I1, , I2, , I3, , Z=, , V, I, , 1, , 192, , Electrical : Electrician - Exercise 1.6.55, , XC =, , V, I, , 3, , Copyright @ NIMI Not to be Republished, , C=, , 1, 2πfXc
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12 Adjust the supply voltage to about 100 V and repeat, steps 5 to 10., , iii The vectorial sum of the branch currents and the, measured value of the total current., , Discharge the capacitor after the experiment., 13 Repeat the exercise for changed values of R and C in the, circuit., Conclusions, i, , The calculated value and the indicated value of the, capacitor, , iv The determination of PF from the vector diagram, , I, Cos φ = 2 = ....................... =, I1, , ii The arithmetic sum of the branch current and the, measured value of total current., , Cos–1 = P.F. =, , TASK 3 : Determine the characteristics of R-L-C in parallel circuits, 1 Form the circuit as shown in Fig 3., , Conclusion, , 2 Repeat steps 2 to 13 of TASK 2 and record the readings, in Table 4., , i, , Effect of change of supply voltage in R-L-C parallel, circuit as regards power factor of circuit, , 3 Compare the readings of the power factor in all the, cases. Record your observations., ii Effect of change in capacitance in RLC parallel circuit., , Table 4, Sl., , V Volt, , No., , I Amp., , W, , AP = V xI, , cos φ =, , True power Apparent power, in Watt, in VA, , P.F. Meter, reading, , Capacitor, value in, , 1, , 100 V, , 4, , 2, , 200 V, , 4, , 3, , 200 V, , 0, , 4, , 200 V, , 2, , 5, , 200 V, , 3, Electrical : Electrician - Exercise 1.6.55, , Copyright @ NIMI Not to be Republished, , μFD, , 193
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Electrical, Electrician - AC Circuits, , Exercise 1.6.56, , Measure the resonance frequency in AC parallel circuit and determine its, effects on the circuit, Objectives : At the end of this exercise you shall be able to, • determine the resonance frequency of a given LC parallel circuit, • determine the circuit current for different frequencies, • plot a graph of frequency versus circuit current, • calculate the value of unknown C using LC parallel resonance, • determine the effect of LC parallel circuit on the circuit., , Requirements, Tools/Equipment/Instruments, •, •, •, •, , Trainees kit, CRO, 20 MHz, Function generator, MI Ammeter 0-50mA, , Materials/Components, - 1 No./batch, - 1 No./batch, - 1 No., , •, •, •, •, •, , General purpose Lug board, Capacitor 0.1 μF, Inductor coil, around 40mH, (Use the solenoid coil made in unit 5), LED with holder, Hook-up wires, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - as reqd., , PROCEDURE, TASK 1: Determine parallel resonance frequency and circuit current, 1 Solder the components as shown Fig 1 to obtain a, simple parallel resonance circuit. Connect the, instruments as shown in Fig 1., , The LED in the circuit is to get a visual indication, of the current through the circuit for different, frequencies., 2 Calculate and record the resonance frequency of the, parallel resonance circuit from the value of L and C., 3 Set the output of the signal generator to 4Vrms and, frequency to 1KHz in Table 1. Record the current, I, through the circuit., Ensure that the current through the circuit is, around 10 to 12 mA and not more. If current, flowing is more, reduce the output level of the, signal generator. LED will glow at all, frequencies except at the resonant frequency., , Table 1, Frequency, , +500HZ, , +1KHZ, , +1.5KHZ, , Sine wave, , 194, , Copyright @ NIMI Not to be Republished, , +2KHZ
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4 Gradually increase the frequency and record the, resonance frequency fr at which the circuit current, becomes minimum (LED does not glow or glows very, dimeter)., This is the resonance frequency of the parallel, resonance circuit because at parallel, resonance, current I through the parallel LC, circuit will be minimum., 5 Compare and record the difference in the resonance, frequency calculated in step 2 and that measured in, step 4., , 6 Vary the input frequency in steps of 500 Hz around the, resonance frequency and in each step record the value, of circuit current in Table 1., 7 From the recorded readings of current in step 6, plot a, graph of frequency versus current and mark the resonance frequency of the LC parallel circuit., 8 Mark the -3dB points on the plotted graph. Find the, bandwidth (BW) and quality factor Q., 9 Get the working of the circuit, recorded readings and the, graph checked by the instructor., , TASK 2: Determine the inductance value of an unknown inductor, Note : You may use the solenoid coil used by, another trainee in Task,1 in Ex. 1.5.46 as an, unknown value inductor., 1 Connect the unknown value inductor in the place of the, coil., 2 Set the output level of the signal generator around 4Vrms., gradually increase the output frequency from 50 Hz and, record the resonance frequency fr at which the circuit, current becomes minimum (LED does not glow or, glows very dim)., This is the resonance frequency of the parallel, resonance circuit formed by the unknown, values of C and L., 3 Calculate and record the inductance value of the unknown, inductor using the formula given below with known, values of L and C., , At resonance, XL = XC, or 2πf r l =, , 1, 2πf r c, , or L =, , 1, 2, , 2, , 4π f r C, , 4 From the found value of L recalculate the resonance, frequency fr to reconfirm the found value of L., 5 Get your work checked by the instructor., Lab Assignment: Connect a known value, inductor in circuit as in Fig 1 and a capacitor of, unknown value. Repeat Task 2 to find the value, of the unknown capacitor., Note : The value of an unknown capacitor can, be found using series resonance circuit too., , Electrical : Electrician - Exercise 1.6.56, , Copyright @ NIMI Not to be Republished, , 195
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Electrical, Electrician - AC Circuits, , Exercise 1.6.57, , Measure power, energy for lagging and leading power factors in single, phase circuits and compare the characteristics graphically, Objectives: At the end of this exercise you shall be able to, • measure power and energy for lagging P.F., • measure power and energy for leading P.F., • draw a graph to compare lagging and leading P.F., , Requirements, Tools and Instruments, •, •, •, •, •, •, •, , M.I Ammeter 0-5A/10A, M.I Voltmeter 0-300V, Wattmeter 250V/5A, P.F. meter 250V/ 2A, Variac 0-270/5A, AC source 0-240V/5A, Energy meter 5A 250 V, , •, •, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , Stop watch, Lamp load 240 V/5A - 1KW, , - 1 No., - 1 No., , Materials, •, •, •, , Choke (T.L) 40W/250V, Electrolytic capacitor, 2.5μFd/415V, Connecting leads, , - 2 Nos., - 2 Nos., - as reqd., , PROCEDURE, TASK 1: Measure the power for lagging P.F, 1 Assemble the circuit as shown in Fig 1., , 2 Before giving supply disconnect one end of both the, chokes and set the variac ouput voltage at 250V., , 4 Switch ‘OFF’ and connect one choke and record the, readings (W and P.F. )., , 3 Switch ‘ON’ and note down the wattmeter and P.F. meter, readings in Table 1., , 5 Switch ‘OFF’ and connect the second choke, record, the readings in Table 1., , Table 1, S.No., , 196, , Voltage, (V), , Current, (I), , W, (w), , PF +/Lag/Lead, , No. of Chokes, , 1, , With one choke, , 2, , With two chokes, , Copyright @ NIMI Not to be Republished
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TASK 2: Measure the power for leading P.F., 1 Switch ‘OFF’ and modify the circuit as shown in Fig 2., , 2 Disconnect one end of both the capacitor and switch, ‘ON’. Record the W and P.F. reading in the Table 2., , 4 Switch ‘OFF’ and connect second capacitor and switch, ‘ON’., , 3 Switch OFF and connect one capacitor and switch, ‘ON’. Record the W and P.F. reading in the Table 2., , 5 Record the W and P.F. reading in the Table 2., , Table 2, S.No., , Voltage, V, , Current, I, , W, w, , PF +/-, , Condition, , 1, , With one capacitor, , 2, , With two capacitor, , 6 Compile all the readings and plot a graph with volt to, current for both leading and lagging PF., Note: A sample graph is shown for reference., in Fig 3., 7 Get your work approved by the instructor., , TASK 3: Measurement of energy with lagging and leading P.F., 1 Identify the energy meter terminals - line and load, after, removing the terminal cover., Always mount the meter vertically., 2 Associate the circuit diagram (inside) with the terminal, markings of the instrument., 3 Connect the energy meter terminals (line and load) in, the circuit as shown in Fig 4., 4 Note the meter constant from the nameplate of the, energy meter. (Fig 5), 5 Record the initial meter readings., 6 Switch ON the circuit with load., 7 Record the reading after 30 minutes in Table 3., , Electrical : Electrician - Exercise 1.6.57, , Copyright @ NIMI Not to be Republished, , 197
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Table - 3, SI. No., , Volt, , Current, , (V), , (I), , Rev. Constant, , Time, (Secs), , 8 Connect the inductive load (Lagging power factor) and, record the reading (Fig 6) in Table 4, , Energy, Wh, (Measured), , Wh, (Calculated), , 9 Calculate the energy for lagging PF., , Table 4, SI. No., , 198, , Volt, , Current, , (V), , (I), , W, , Rev. Constant, , Time, (Secs), , Electrical : Electrician - Exercise 1.6.57, , Energy, Wh, (Calculated), , Copyright @ NIMI Not to be Republished, , Wh, (Measured)
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9 Switch Off the power and remove the inductive load., , 10 Connect the capacitive, reactance (Fig 7) load and, record the reading in Table 5., , Table 5, SI. No., , Volt, , Current, , (V), , (I), , W, , Rev. Constant, , Time, (Secs), , 11 Calculate the energy for leading P.F. compile all the, values and record the findings., , Energy, Wh, (Calculated), , Wh, (Measured), , Space for Graph, , 12 Plot the graph for lagging and leading P.F. for energy, with respect to load current in the space provided, 13 Get it checked by the instructor., Result :, , Electrical : Electrician - Exercise 1.6.57, , Copyright @ NIMI Not to be Republished, , 199
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Electrical, Electrician - AC Circuits, , Exercise 1.6.58, , Measure current, voltage, power, energy and power factor (PF) in 3 phase, circuits, Objectives: At the end of this exercise, you shall be able to, • connect voltmeter, ammeter, wattmeter and power factor meter and 3 phase energy meter in 3 phase circuits, • measure the voltage, current, power and power factor and 3 energy in 3 phase circuits with lamp load, • measure the voltage, current, power and P.F and energy in 3 phase circuits with inductive lead (Induction, motor)., , Requirements, Tools and Instruments, •, •, •, •, •, •, •, , Equipment/Machines, , Insulated screw driver 200 mm, Insulated cutting plier 150 mm, M.I Voltmeter 0-300V/600V, M.I Ammeter 0-5A/10A, Wattmeter 250V/500V, 5A/10A, Power Factor meter 415V/20A, 3 phase 4 wire energy meter 415V/20A, , - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., - 1 No., , •, •, , 3-phase induction motor 415V, 50 Hz,, 5 HP (3.75 KW), 3-phase lamp load 100 W, , - 1 No., - 6 Nos., , Materials, •, , PVC insulated copper cable, 2.5 mm2 650V grade TPIC 16A/500V, • 200 Watt/250V, lamps, , - 20 m., - 6 hrs., , PROCEDURE, TASK 1: Measure three phase current, voltage, power and power factor in 3 phase circuit with lamp load, 1 Select and collect the proper range of meters and lamp, load for 3 phase circuit., The lamp load should have equal wattage in, all three phases, , 2 Make the connections of the meters and load as per the, circuit diagram (Fig 1)., Connect the current coils of wattmeter, energy, meter and P.F meter in series with the load., 200, , 3 Switch ‘ON’ the power supply momentarily after getting, the approval of the instructor and observe all themeter, deflections. Keep the switch closed if nothing is, abnormal., , 4 Note down the initial reading of the energy meter., 5 Note down the meter readings and enter in Table 1., 6 Keep the load in ‘ON’ position for at least 10 minutes, and then note and record the final reading and calculate, the energy consumption (i.e) F.R - I.R., , Copyright @ NIMI Not to be Republished
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Table 1, Load Line, Voltage, VL, , Phase, Voltage, Vph, , Line, Current, IL, , Phase, Current, IPH, , Power, in, Watt, , Power, factor, , Initial, reading, in energy, meter, , Final, reading, after 10, min in, energy, meter F.R, , Energy, consumption, F.R - I.R, in KWh, I.R, , Lamp, load, for, 100W, Lamp, load, for, 200W, 3φ, Ind., meter, load, 7 Swtich ‘OFF’ the power supply., 8 Replace the 100 Watt lamp with 200V lamp load., 9 Repeat steps 3 to 6 and record the readings in, Table 1., , 11 Repeat steps 3 to 6 and record the readings in, Table 1., 12 Get it checked by the instructor., , 10 Switch ‘OFF’ power supply and disconnect the lamp, load and connect 3 phase induction motor 3.75 KW/, 4.5V/50 Hz to the circuit., , Electrical : Electrician - Exercise 1.6.58, , Copyright @ NIMI Not to be Republished, , 201
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Electrical, Electrician - AC Circuits, , Exercise 1.6.59, , Practice improvement of PF by use of capacitor in three phase circuit, Objectives: At the end of this exercise you shall be able to, • connect 3 phase balanced inductive load and measure the P.F., • connect 3 phase capacitor bank to inductive load and measure the P.F., • calculate and record the improvement of P.F, after connecting the capacitor bank., , Requirements, Equipment/Machines, , Tools and Instruments, •, •, •, •, •, •, •, , Insulated combination pliers 200 mm, Insulated screwdriver 200 mm, 3 φ P.F. meter 240V/440V ;, Wattmeter 250/500 V, 5A/10A, M.I Ammeter 0-5A/10A, M.I Voltmeter 0-300V/600V, Power factor improving capacitor bank, 3 phase 415V, 1.5 KVAR, , - 1 No., - 1 No., - 1 No., - 2 Nos., - 1 No., - 1 No., , •, , - 1 No., , •, , •, , 3-phase induction motor 415V,, 2.25 KW (with loading arrangement), 3-phase lamp load 0-3KW, , - 1 No., - 1 No., , Materials, •, , PVC insulated copper cable, 2.5 Sq, MM, 650V grade, T.P.I.C.Switch 16A, 500V, , - 20 m., - 2 Nos., , PROCEDURE, TASK 1: Connect 3 phase unbalanced inductive load and measure the P.F., 1 Connect two Wattmeters to 3 phase P.F. meter, voltmeter and ammeter to 3 phase motor with load as, shown in Fig 1., , 4 Switch OFF and connect the capacitor bank as shown, in Fig 2., 5 Switch ON and adjust 60% of the load and verify the, readings as in step 3. The readings will be same., 6 Switch ON the capacitor bank and record the readings, in Table 1 for the load conditions., 7 Calculate the P.F. in each case using the following formula., a) P.F. calculated 1 = cos ϕ = =, , W1 + W2, 3EPH IPH, , b) P.F. calculated 2 = Cos • where the angle • is, , 2 Get the connection checked by the instructor., 3 Switch ‘ON’ and load the motor to 60% of its load, capacity and note the readings in Table 1., , derived from the formula Tan • = 3, , W1 - W2, , W1 + W2, 8 Enter the values in Table 1. Determine the percentage, of error., , (Calculated P.F. - Measured P.F.) x 100, % error = -------------------------------------------------------Calculated P.F, Write your conclusion and reasons for if any., 9 Get it checked by your instructor., , 202, , Copyright @ NIMI Not to be Republished
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Copyright @ NIMI Not to be Republished, , Electrical : Electrician - Exercise 1.6.59, , 203, , Wattmeter, 3-phase, reading, apparent, W1 watts, power in, volt amperes, 3 x EPH x IPH, Wattmeter, reading, W2 watts, , W1 + W2, , 3-phase, true power, , =, 3EPH IPH, , W1 + W2, , Cos ϕ P.F., , P.F. Calculated 1, P.F., Calculated 2, , After connecting the capacitor bank, the effect in value of P.F. is _________________________________________, , Conclusion:, , Motor with, load and, capacitor, bank, , Motor with, load, , Condition, , Ammeter Voltmeter, reading reading, IPH, EPH, , Table 1, P.F., measured, , Percentage, of error
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Electrical, Electrician - AC Circuits, , Exercise 1.6.60, , Ascertain use of neutral by identifying wires of a 3-phase 4 wire system and, find the phase sequence using phase sequence meter, Objectives: At the end of this exercise, you shall be able to, • test the phase wire and identify neutral with the use of test lamp, • identify, check and confirm the neutral wire with a meter, • connect and verify the phase sequence with 3-phase sequence meter., , Requirements, Tools and Equipment, •, •, •, •, •, , Materials, , Connector/Screw driver 100 mm, Combination plier 150 mm, Test lamp (40W/250V), Voltmeter 0-600V M.I., Phase sequence meter, , - 1 No., - 1 No., - 2 Nos., - 1 No., - 1 No., , •, , Connecting wires, , - as reqd., , PROCEDURE, TASK 1: Test the phase line and identify the neutral with the use of test lamp, 1 Prepare a line test lamp by connecting two lamps in, series., 2 Mark the terminals as 1, 2, 3 and 4 and connect one, lead of lamp to the marked 1 and other lead of the, earth point provided in the frame as shown in Fig 1 and, record the condition of lamp in Table 1., , 5 Connect one lead, No:4 (Identified as N) and connect, the other lead of test lamp to 1, 2, 3. (Fig 2). Record, the glow condition of the lamp in Table 2., , Table 2, SI.No. Terminals, , Table 1, Terminals, , Glowing, , Glowing, , Not glowing, , 1 to E, , 1, , 4-1, , 2 to E, , 2, , 4-2, , 3 to E, , 3, , 4-3, , Not glowing, , 1-2, , 4 to E, 3 Repeat the above step for other terminals 2, 3 and 4, and record the conditions in Table 1., 4 Mark the terminal where the lamp is not glowing as, neutral. (N), The three terminals at which the test lamp, glows are the phase leads., 204, , Lamp condition, , 1-3, 2-3, 6 Refer to Table 2, mark the terminals where the lamp is, glowing dim as neutral. If the lamp glows bright in the, other three terminals i.e. 1-2, 1-3, 2-3 are phase terminal, , Copyright @ NIMI Not to be Republished
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7 Repeat steps 1 to 5 by replacing lamps in series by, connecting the voltmeter (0-600v) and record the readings in Table 3 as shown in Fig 3., , Table 3, SI.No., , Test terminals, , 1, , 4 -1, , 2, , 4-2, , 3, , 4-3, , 4, , 1-2, , 5, , 1-3, , 6, , 2-3, , High, , Voltage, , Low, , TASK 2: Identify the phase sequence in 3-phase 4 wire system by using phase sequence meter, 1 Read and record the marking of the phase sequence, indicator direction: (Fig 4), , RYB Sequence, RBY Sequence, , Arrow marking to be, indicated, , Arrow in clockwise - , Arrow in anti-clockwise - /, 2 Switch ‘OFF’ the supply and connect the corresponding, terminals (R, Y & B) to the phase sequence Indicator ., 3 Mark leads as I, II, III. Connect them, such that I is, connected to R, II to Y, III to B,, You can connect any lead (phase) to any, terminal in the sequence indicator., 4 Switch ‘ON’ and observe the rotation of the disc and, record the direction of rotation., 5 If the direction is anticlockwise switch ‘OFF’ the supply, and interchange the terminals 1 and 2. Switch ‘ON’, and see that the rotation is reversed., 6 Mark the leads corresponding to the letters on the Phase, Sequence Meter. (PSM), , Rotation, , Remarks, , Same as arrow of the disc, Opposite to the arrow of disc, , If you connect any wire to any terminal, the, disc will rotate anticlockwise if the RYB, sequence is reversed, and it will be in the, clockwise direction when RYB is connected in, sequence., 7 Get it checked by your instructor., , Electrical : Electrician - Exercise 1.6.60, , Copyright @ NIMI Not to be Republished, , 205
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Electrical, Electrician - AC Circuits, , Exercise 1.6.61, , Determine effect of broken neutral wire in three phase four wire system, Objectives: At the end of this exercise you shall be able to, • test a healthy neutral wire in the 3-phase 4 wire system, • check the effect of broken neutral wire in 3-phase 4 wire system., , Requirements, Tools and Instruments, •, •, •, •, •, , Combination plier 150 mm, Connector screw driver 150 mm, Three phase test board with netural, link, Lamp 40/240 V, M.I Voltmeter 0-600V, , •, •, , - 1 No., - 3 Nos., - 1 No., , M.I Ammeter 0-5A, Line tester 500V/5A, , - 3 Nos., - 1 No., , Materials, •, •, , - 3 Nos., - 1 No., , Connecting wires, ON-OFF switch, , - as reqd., - 4 Nos., , PROCEDURE, 1 Connect the circuit as shown in Fig 1., , 5 Switch ‘ON’ 3-phase supply. Switch ‘ON’ S1, S2, S3., Switch ‘OFF’ S4. Check if the lamps are glowing., Record all the readings in the Table 1. (L1 will not glow, L2 and L3 will glow - Step 2), 6. Switch ‘OFF’ 3-phase supply. Link ‘B-E’. Follow the, step 3 in Table - 1. Record the readings, 7. Repeat the above step while linking ‘C-E’ (step 4 in, Table 1). Record all the readings, , 2 Switch ‘OFF’ all the switches S1, S2,S3,S4 and switch, ON the 3-phase supply., , It is evident that when neutral is broken the, current does not flow So lamp will not glow,, even though supply is available., , 3 Check whether the lamps are glowing. Lamps do not, glow, 4 Switch ‘OFF’ 3-phase supply. Connect the terminal ‘B, to D’, ‘C to D’ and ‘A to E’, Table 1, S. No., , 206, , Switch position, , A1, , A2, , A3, , V1, , V2, , V3, , Links, , Links, , 1, , S1,S2, S3, S4, OFF, , 0, , 0, , 0, , 0, , 0, , 0, , −, , −, , 2, , S1,S2, S3 ON, S4 OFF, , 0, , A-E, , B to D, C to D, , 3, , S1,S2, S3 ON, S4 OFF, , B-E, , A to D, C to D, , 4, , S1,S2, S3 ON, S4 OFF, , C-E, , A to D, B to D, , 0, 0, , 0, 0, , 0, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - AC Circuits, , Exercise 1.6.62, , Determine the relationship between Line and Phase values for star and, delta connections, Objectives: At the end of this exercise you shall be able to, • verify the relationship between Line and Phase values in star connection, • verify the relationship between Line and Phase values in delta connection., , Requirements, Tools/Instruments, •, •, •, •, •, , Screw driver 150 mm, Combination plier 150 mm, M.I Ammeter type 0-1 amp, M.I Voltmeter type 0-500V, ICTPN switch 16A 500V, , Materials, - 1 No., - 1 No., - 2 Nos., - 2 Nos., - 1 No., , •, •, •, •, , Connecting leads, Lamp BC - 40W 240V, 100W 240V, 200W 240V, , - as reqd., - 6 Nos., - 6 Nos., - 6 Nos., , PROCEDURE, TASK 1: Verify the relationship between Line and Phase values in star connection of three phase system, 1 Form the circuit as per the given circuit diagram., (Fig 1) with one lamp each connected to all the 3 phases, (40/100/200 W)., , 7 Measure the Line and Phase current and enter the, readings in Table 1., Switch ‘OFF’ supply before, change in load., , effecting any, , 8 Repeat steps 3 to 7 for different loads., 9 Calculate the ratio between the Line voltage and Phase, voltage., , VUV, VUN, VVW, 2 Identify the 3-phase (L1, L2, L3) and neutral (N) of supply, terminals., 3 Switch ‘ON’ the 3-phase supply., 4 Measure the line voltage VUV by placing the voltmeter, leads between the two lines and enter the reading in, Table 1., 5 Repeat for the other line voltages VVW, VWU., 6 Measure the phase voltages by placing the voltmeter, leads between one line and star point N, and enter the, readings in Table 1., , VVN, VWU, VWN, , =, =, =, , 10 Verify the ratio between Line current and Phase, current, i.e., , ILU, , I, I, = LV = LW =, IPU IPV IPW, 11 Get it checked by the instructor., , Copyright @ NIMI Not to be Republished, , 207
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Table 1, Sl., , Load in watts, , Line voltage, , No., , per phase, , VUV, , 1, , 40W, , 2, , 100W, , 3, , VVW, , Phase voltage, VWU, , VUN, , VVN, , VWN, , Line current, IU, , IV, , Phase current, , IW, , IUN, , IVN, , IWN, , 200W, , TASK 2: Verify the relationship between Line and Phase values in delta connection in three phase system, 1 Form the circuit as per the given circuit diagram. (Fig 2), Two lamp in series to be connected between two, phases of same voltage., , 4 Record the Line voltages and Phase voltages measured, under the appropriate column in Table 2., 5 Measure the Line and Phase currents and enter the, readings in Table 2., An ammeter connected between supply and, load indicates Line current. An ammeter, connected in series with single load (two lamps, in series) indicates Phase current., 6 Repeat steps 2 to 5 for different loads., Switch off the supply before effecting any, change in the load., 7 Verify the relationship between Line and Phase value of, current and voltage. Enter in Table 3., Result, , 2 Switch ON the 3-phase supply. Measure the line, voltages by connecting the voltmeter leads between, two of the terminals U1, V1, W1., 3 Measure the phase voltage by placing the voltmeter, leads across the lamps, i.e. U1, U2 or V1, V2 or W1, W2., , In star : Line current and Phase current are, whereas Line voltage =, x Phase voltage., In delta :Line voltage and Phase voltages are, whereas Line current =, x Phase current., 8 Get it checked by the instructor.., Table 2, , Sl., , Load in watts, , No., , per phase, , 1, , 40W, , 2, , 100W, , 3, , 200W, , Line voltage, , Phase voltage, , Line current, , VU1V1 VV1W1 VW1U1, , VU1U2 VV1V2 VW1W2, , IU, , IV, , Phase current, , IW, , IU1U2 IV1V2, , IW1W2, , Table 3, Load, , VU V, 1 1, , VV W, , VW U, , VU U, , VV V, , VW W, 1 2, , 1 2, , 1 1, 1 2, , 1 1, , I LU, I PU, , I LV, I PV, , 40W, 100W, 200W, 208, , Electrical : Electrician - Exercise 1.6.62, , Copyright @ NIMI Not to be Republished, , I LW, I PW
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Electrical, Electrician - AC Circuits, , Exercise 1.6.63, , Measure the power of 3-phase circuit for balanced and unbalanced loads, Objectives: At the end of this exercise, you shall be able to, • identify and connect the terminals of a single-phase Wattmeter, • connect single wattmeter in star, balanced load and measure the power, • connect two wattmeters in the circuit as per the given diagram, • connect two wattmeters in unbalanced, star-connected load and measure the power, • identify and connect 3-phase wattmeter and measure the power in star., , Requirements, Materials, , Tools/Instruments, •, •, •, •, •, , Single-phase wattmeter 250V/5A, Wattmeter 500V/5A, PF meter, single phase 250V,5A, Voltmeter 0-500 V M.I., Ammeter 0-5A M.I., , •, •, •, •, •, , - 1 No., - 2 Nos., - 1 No., - 1 No., - 1 No., , 200W, 250V lamps, 100W, 250V lamps, Capacitor 400V AC 4 MFD, Connecting leads, Pendent-holders 6A 250V, , -, , 3 Nos., 3 Nos., 2 Nos., as reqd., 6 Nos., , Equipment/Machines, •, , 3-phase, 415V AC induction motor, 3 HP coupled with DC generator, , - 1 No., , PROCEDURE, TASK 1: Connect balanced load in star and measure the power with one single element Wattmeter., 1 Form the circuit as per the given circuit diagram. (Fig 1), Connect proper voltage and current ranges of, Wattmeters suitable to the given load., 2 Switch ON the 3-phase supply and read the wattmeter, and record the wattmeter readings in Table 1., 3 Measure the power in the other two phases by, connecting the wattmeter in turns and record the, redings., 4 Total the readings of the wattmeters and check its, confirmity with the calculated total power., 5 Repeat steps 1 to 4 for different load conditions., , Table 1, Type of, Load, , Wattmeter connected, in the line, WL1, , WL2, , WL3, , Calculated, Total power, VL, , ΙL, , P.F, , Total power = Total of three, wattmeter readings, , W= 3 VLΙL Cos θ, , WL1 + WL2 + WL3 = W, , 1, 2, 3, 4, , Copyright @ NIMI Not to be Republished, , 209
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TASk 2: Power measurement by two-wattmeter method in 3-phase load, 1 Form the circuit as per the given circuit diagram., , 4 Read the wattmeters W1 and W2 and record in Table 2., Add the readings W1 and W2 and record the total power;, Go to step 6., , (Fig 2), Connect proper ranges of meters suitable for, the given load., , 5 Switch on the supply and read the wattmeters W1 and, W2. Record the values in the Table. Record the, readings of the wattmeter with the changed potential, coil as negative quantity., 6 Measure the 3-phase power for different load conditions, specified below:, a) L1 = 400 W bulb, L2 = 400 W bulb parallel 4 MFD capacitor, L3 = 200 W bulb, b) Water load to take a current maximum of 3 amps., , 2 Switch ‘ON’ the 3-phase supply and check whether the, deflection of wattmeter is correct. If both wattmeters, deflect properly, go to step 4, otherwise continue from, step 3., 3 Switch ‘OFF’ the supply, if any one wattmeter deflects, in the reverse direction. Change the connection of the, potential coil of the reverse deflection wattmeter. Go to, step 5., , c) Induction motor 3 HP on no load, d) Induction motor 3 HP with load, The instructor may connect the three-phase, motor to ensure it is running properly., 7 Calculate the power factor in all the above cases and, enter them in Table 2., 8 Get it checked by the instructor., , Table 2 2, Type of, Load, , Wattmeter, W1, , Wattmeter, , Total, , W2, , W1 + W2, , Calculated Power factor Cos θ, , Tan • = 3, , W1 + W2, Determine Cos θ, , 1, 2, 3, 4, 5, , Conclusion : ____________________________________________________, , 210, , Electrical : Electrician - Exercise 1.6.63, , W1 − W2, , Copyright @ NIMI Not to be Republished
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Electrical, Electrician - AC Circuits, , Exercise 1.6.64, , Measure current and voltage of two phases in case of one phase is shortcircuited in three phase four wire system and compare with healthy system, Objectives: At the end of this exercise, you shall be able to, • connect and test the circuit, • measure the current and voltage in healthy conditions, • check the condition of the two phase, when one phase is overloaded/short-circuited, • record the current and voltage in both conditions., , Requirements, Materials, , Tools/Instruments, •, •, •, •, •, , M.I Ammeter 0-10A, M.I Ammeter 0-20A, M.I Voltmeter 0-300V, Load 1500W/ 240V, 3 Phase supply board 3ϕ, 4 wire, , •, •, •, , - 2 Nos., - 1No., - 3 Nos., - 4 Nos., - 1 No., , PROCEDURE, , S.P. switch 240V/16A, Connecting wires, TPIC - 415V/16A, , - 2 Nos., - as reqd., - 1 No., , 2 Switch 'ON' the 3 Phase supply and ON the switch, SW1. Record the current and voltage the tabular column., , We cannot manually make a short circuit in, the phase line as it is dangerous and it may, trip the circuit. In order to make a short circuit, condition load current is doubled in one phase., , 3 Switch ‘OFF’ the 3 Phase in supply and SW2 switch, 'ON'., , 1 Connect the circuit as per the diagram shown in Fig 1., , 4 Switch ‘ON’ the 3 Phase supply and record the, readings of the current and voltage in the tabular column., 5 Switch ‘OFF’ all the supply lines, and disconnect the, wiring and return all the materials and equipment., 6 Get it checked by the instructor., Conclusion : ___________________________________, , Table 1, SI.No., , SW1 - ON, , SW1 - ON & SW2 ON, , 1, , A1, , V1, , A1, , V1, , 2, , A2, , V2, , A2, , V2, , 3, , A3, , V3, , A3, , V3, , Copyright @ NIMI Not to be Republished, , 211
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Project Works, Objectives: The Trainees/Participants shall be able to, • select a project work of their choice, • prepare the list of materials required and collect them, • list out the tools required, • prepare a brief note on the project, • complete the project and submit the project report with all the details., Note: Instructor has to explain in detail, regarding the project works to the carried out, in the section. The trainees may be divided in, groups according to the strength available in, section and give all details how to prepare and, finish the work with complete workmanship, and accuracy., •, , Step to start and follow the project work, , •, , Motivate the group by emphasising the technical work, involved and its future influences., , •, , Divide the work equally and make sure inyoke, participating with full interest., , •, , Start the project work, test of stage by stage and, complete it., , •, , Test the completed project job for its functional and its, utility., , •, , Prepare a project report containing its technical, parameters, specification, material requirement and its, cost, operational procedure, maintenance, utility and, marketting etc., , •, , •, , Get it checked with your instructor., , •, , The project him to complete with all operational, instructions and carry necessary procedure with, switches, controls, labels, symbols etc., , •, , Safety devices has to be placed according to the project, and its functions., , •, , Maintenance and repair instructions has to be indicated, clearly., Note : Instructor has to evaluate the project, work with all records and reports. Marks to be, awarded for the Project working, Accuracy,, Workmanship, Safety features and its work, performance related to the viva question., , Project work, 1 Prepare and assemble a test board with switches plug, socket, lamp holder etc., 2 Temperature controlled system for switchning ‘ON ‘and, ‘OFF’ of any circuit using bi-metallic strip., 3 Series/Parallel combinational circuits., , Indicate his scope of future expansion, easy conversion, to other project for advanced version in the report., , 212, , Copyright @ NIMI Not to be Republished
