TheJ&P Transformer Book

1 TheJ&PTransformer BookJ & P BooksThe J&P Transformer BookandThe J&P Switchgear Bookwere published originally by Johnson& Phillips Ltd, and have for many years been accepted as standard works of reference byelectrical engineers concerned with transformers and switchgear. They now appear under theNewnes BookTwelfth editionA PRACTICAL TECHNOLOGY OF THEPOWER TRANSFORMERM artin J. Heathcote, CEng, FIEEN ewnesOXFORD BOSTON JOHANNESBURG MELBOURNE NEW DELHI SINGAPOREN ewnesAn imprint of Butterworth-HeinemannLinacre House, Jordan Hill, Oxford OX2 8DP225 Wildwood Avenue, Woburn, MA 01801-2041A division of Reed Educational and Professional Publishing LtdA member of the Reed Elsevier plc groupFirst published 1925 by Johnson & Phillips LtdNinth edition 1961 Reprinted by Iliffe Books Ltd 1965 Tenth edition 1973 Reprinted 1967 (twice)

2 , 1981 Eleventh edition 1983 Reprinted 1985, 1988, 1990, 1993, 1995 Twelfth edition 1998 Reed Educational and Professional Publishing Ltd 1998 All rights reserved. No part of this publication maybe reproduced in any material form (includingphotocopying or storing in any medium by electronic means and whether or not transiently orincidentally to some other use of this publication) without the written permission of the copyrightholder except in accordance with the provisions of the Copyright, Designs and Patents Act 1988or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 TottenhamCourt Rd, London, England W1P 9HE.

3 Applications for the copyright holder s written permissionto reproduce any part of this publicationshould be addressed to the Library Cataloguing in Publication DataA catalogue record for this book isavailable from the British 07506 1158 8 Library of Congress Cataloguing in Publication DataA catalogue record for this book isavailable from the Library of by Laser Words, Madras, IndiaPrinted in Great BritainContentsForewordixPrefacexiAcknow ledgementsxiii1 Transformer The ideal transformervoltage Leakage reactancetransformer Losses in core and Rated Regulation112 Design Types of Phase relationshipsphasor Volts per turn and flux Multi-winding transformers including tertiary Zero-sequence Double secondary General case of three-winding transformers353 Basic Core Winding Transformer oil744 Transformer Core Transformer Disposition of Impulse Thermal Tappings and Winding forces and

4 Performance under Tanks and ancillary Processing and drying out280viContents5 Testing of Testing and quality assurance during Final Possible additional testing for important Transport, installation and commissioning3846 Operation and Design and layout of Transformer neutral Transformer Parallel Transient phenomena occurring in Transformer Maintenance in Operation under abnormal The influence of Transformer connections upon third-harmonicvoltages and currents6367 Special features of transformers for particular Generator Other power station Transmission transformers and transformers for HVDC Phase shifting transformers and quadrature System Interconnected-star earthing Distribution Scott and Le Blanc connected

5 Rectifier AC arc furnace Traction Generator neutral earthing transformers for electrostatic Series reactors7588 Transformer enquiries and Transformer Assessment of Economics of ownership and operation, cost of losses793 APPENDICES1 Transformer equivalent circuit8032 Geometry of the Transformer phasor diagram8143 The Transformer circle diagram820 Contentsvii4 Transformer regulation8255 Symmetrical components in unbalanced three-phase systems8296 A symmetrical component study of earth faults intransformers in parallel8517 The use of finite element analysis in the calculation ofleakage flux and dielectric stress distributions9048 List of National and International Standards relating topower transformers9319 List of principal CIGRE reports and papers relatingto

6 Transformers93410 List of reports issued by ERA Technology Limited relating totransformers and surge phenomena therein937 Index941 ForewordThe J & P Transformer Bookhas been in print for 75 years and during thattime it has been a rewarding work of reference for students, young engineers,older engineers who have changed the direction of their careers to becomeinvoled with transformers , practising designers and for generations of applica-tions engineers. In the previous eleven editions the publishers endeavoured torevise the work, extend it and to bring it up to date. The fact thatThe J & PTransformer Bookis still in demand is a tribute to the publishers and to theauthors who have carried the torch to light our way for 75 years.

7 The firstedition was prepared by Mr H. Morgan Lacey in 1925, based on a series ofpamphlets entitledTransformer Abstractsthat were first printed in 1922. Thebook was welcomed as a key reference, giving a guide to British experience ata time of great change in Transformer technology. It was reprinted and revisedmany times during the next three ninth edition was produced in 1958 by Mr A. C. Franklin togetherwith his co-author Mr S. A. Stignant. The tenth edition was produced in1961 by the same authors, and was revised in 1965. Mr Stignant later retiredleaving Mr Franklin, as the main author of the eleventh edition, to carry onthe work.

8 This edition was published in 1983 with some assistance fromMr D. P. Franklin, who had been appointed as his current twelfth edition has been prepared by Martin J. the previous authors, Mr Heathcote has experience as both amanufacturer and a purchaser. His most recent appointment was withPowerGen, a successor company to CEGB, where he gained a wide experiencein the design and manufacturing techniques adopted by many differenttransformer manufacturers both in Britain and overseas. His strong relationshipwith manufacturers and users has allowed him access to a wide range ofinformation that has been included in this edition.

9 In particular he hascompletely rewritten many sections of the book to bring it up to date andreflect current experience. The latest information on Transformer materials hasbeen included, the modern trend to design transformers with the lowest lifetimecosts has been addressed, and interface problems with other equipment hasbeen considered in each section. Mr Heathcote s extensive experience in theoperation and maintenance phases of Transformer life has been included in thisedition, together with a more complete analysis of the many specialist typesof Transformer that are installed on supply systems and in industrial edition contains a wealth of new technical information that has beenfreely made available by Transformer manufacturers, the electrical supplyxForewordindustry, learned institutions and industrial associations such as CIGRE.

10 Itis intended that the information contained in this twelfth edition ofThe J & PTransformer Bookwill update the knowledge of the current generation ofengineers and will be of as much use to new generations of engineers as theprevious editions have been to their Dennis J. Allan FEngStafford, 16 March 1998 Preface to the twelfth editionA brief history of theJ & P Transformer Bookand of its many distinguishedprevious authors appears elsewhere in this volume. From this it will be seenthat most were chief Transformer engineers or chief designers for major manu-facturers. The effect of this has been twofold.