Electrical Installation Calculations: Advanced

231 Pages·2013·3.71 MB·English

by  Christopher Kitcher

Electrical Installation Calculations: Advanced
Electrical Installation Calculations:
Advanced
For technical certificate and NVQ level 3
Christopher Kitcher and A.J. Watkins
Eighth Edition
Eighth edition published 2014
by Routledge
2 Park Square, Milton Park, Abingdon, Oxon OX14 4RN
and by Routledge
711 Third Avenue, New York, NY 10017
Routledge is an imprint of the Taylor & Francis Group, an informa business © 2014 Christopher
Kitcher and A. J. Watkins The right of Christopher Kitcher and A. J. Watkins to be identified as
authors of this work has been asserted by him/her in accordance with sections 77 and 78 of the
Copyright, Designs and Patents Act 1988.
All rights reserved. No part of this book may be reprinted or reproduced or utilised in any form or
by any electronic, mechanical, or other means, now known or hereafter invented, including
photocopying and recording, or in any information storage or retrieval system, without permission
in writing from the publishers.
Trademark notice: Product or corporate names may be trademarks or registered trademarks, and
are used only for identification and explanation without intent to infringe.
First edition published 1957
Seventh edition published by Elsevier 2009
British Library Cataloguing in Publication Data A catalogue record for this book is available from
the British Library Library of Congress Cataloging in Publication Data
Kitcher, Chris.
Electrical installation calculations : advanced : for technical certificate and NVQ level 3 /
Christopher Kitcher and A. J. Watkins. – Eighth edition. pages cm 1. Electric wiring–Mathematics.
2. Electric wiring–Standards–Great Britain. 3. Electrical engineers–Certification–Great Britain. 4.
National Vocational Qualifications (Great Britain) I. Watkins, A. J. (Albert James), 1925-II. Title.
TK3221.K57 2014
621.319’24—dc23
2013021029
ISBN: 978–0–415–81003–6 (pbk) ISBN: 978–1–315–86312–2 (ebk)
Table of Contents
Preface
1 Use of Calculators
2 Simple Transposition of Formulae
3 SI Units
SI derived units
SI unit prefixes
4 Conductor Colour Identification
5 Alternating Current Circuit Calculations
Impedance
Inductive reactance
Capacitive reactance
Impedance in series circuits
Impedance triangles and power triangles
Waveform and Phasor Representation of Alternating Currents and
6
Voltages
Alternating e.m.f. and current
Phasors
7 Parallel Circuits Involving Resistance, Inductance and Capacitance
8 Power Factor Improvement
Calculation without p.f. correction
Calculation with p.f. correction
9 Three-phase Circuit Calculations
Star connected motors
Delta connected motors
Resistance and inductance in three-phase circuits
Three-phase circuits
Three-phase power
Voltage drop in three-phase circuits
10 Voltmeters and Ammeters: Changing the Use and Extending the Range
Voltmeters
Ammeters
11 Alternating Current Motors
12 Application of Diversity Factors
13 Cable Selection
Earthing conductor calculation
Voltage drop and cable selection calculations
Earth leakage protection calculations
14 Lighting Calculations
Lighting units and quantities
Lighting calculations using inverse square law
Lighting calculations using the cosine law
15 Mechanics
Moment of force
Torque
Power
Surface speed, pulley diameter and speed ratios
16 Miscellaneous Examples
D.c. generators
D.c. motors
Alternators and synchronous motors
Induction motors
Insulation resistance
17 Photovoltaic Calculations
18 Formulae
Three-phase calculations
Pythagorus-type calculations
Synchronous speed and slip calculations
Calculations associated with cable selection

Glossary
Answers to Exercises
General Questions and Answers
Additional Questions and Answers
Preface
Being able to carry out mathematical calculations is a vital part of
electrical installation courses and indeed electrical installation work.
The structure of electrical installation courses continually changes as do
the course titles and numbers, however electrical science remains the
same, and like it or not anyone wanting to become an electrician will
need to have a good understanding of how to carry out electrical
calculations.
The calculations which need to be performed vary from those which an
electrician needs almost on a daily basis, such as cable calculation or the
amount of energy required to run a particular piece of equipment, to more
complex calculations such as those required for electromagnetism.
This book will show you how to carry out these calculations as simply as
possible using electronic calculator methods. These methods will be
useful both in the classroom and the workplace. It is not necessary for
you to have a deep understanding of how the mathematical functions are
performed. Each topic is shown using a step-by-step process with lots of
exercises provided to give you the opportunity to test yourself at the end
of each chapter.
This edition has been completely updated to the 17th edition of BS 7671
amendment 1: 2011 and the IET On-Site Guide, useful references are
made to these documents throughout.
It does not matter which electrical course you are attending, this book
along with the basic calculations book will be invaluable.
1
Use of Calculators
Throughout books 1 and 2 the use of a calculator is encouraged. Your
calculator is a tool, and like any tool practice is required to perfect their
use. A scientific calculator will be required, and although they differ in the
way the functions are carried out, the end result is the same.
The examples are given using a Casio fx-83MS.
The character printed on the button is the function performed when the
button is pressed. To use the small letter functions on the top of any
button the shift button must be used.
Practice is important.
Syntax error: will appear when the figures are entered in the wrong
order.
x2: will multiply a number by itself, eg 6 × 6 = 36. On the calculator this
would be 6 x2 = 36. When a number is multiplied by itself it is said to be
squared.
x2: will multiply a number by itself and then the total by itself again, eg
when we enter 4 on calculator x3 = 64. When a number is multiplied in
this way it is said to be cubed.
: will give you the number which achieves your total by being multiplied
by itself, eg This is said to be the square root of a number, and is
the opposite of squared.
: will give you the number which when multiplied by itself three times
will be your total This is said to be the cube root.
−1
x : will divide 1 by a number, eg . This is the reciprocal button
and is useful in this book for finding the resistance of resistors in parallel
and capacitors in series.
EXP: is for the powers of 10 function, eg 25 × 1000 = 25 EXP × 103 = 25
000.
Enter into your calculator 25 EXP 3 = 25000. (Do not enter the × or the
number 10.)
If a calculation shows 10−3, eg 25 × 10−3, enter 25 EXP −3 = (0.025)
(when using EXP if a minus is required use the button (−)).
Brackets: these should be used to carry out a calculation within a
calculation. Example calculation
Enter into calculator 32 ÷ (0.8 × 0.65 × 0.94 = 65.46)
Remember Practice makes Perfect.