IEC_60076-8ed1.0en-d.pdf

Power transformers Application guideReference numberIEC 60076-8:1997(E)INTERNATIONALSTANDARDIEC60076-8First edition1997-10This English-language version is derived from the originalbilingual publication by leaving out all French-languagepages.Missing page numbers correspond to the French-language pages.Publication numbering As from 1 January 1997 all IEC publications are issued with a designation in the 60000 series.For example,IEC 34-1 is now referred to as IEC 60034-1.Consolidated editions The IEC is now publishing consolidated versions of its publications.For example,edition numbers 1.0,1.1 and 1.2 refer,respectively,to the base publication,the base publication incorporating amendment 1 and the base publication incorporating amendments 1 and 2.Further information on IEC publications The technical content of IEC publications is kept under constant review by the IEC,thus ensuring that the content reflects current technology.Information relating to this publication,including its validity,is available in the IEC Catalogue of publications(see below)in addition to new editions,amendments and corrigenda.Information on the subjects under consideration and work in progress undertaken by the technical committee which has prepared this publication,as well as the list of publications issued,is also available from the following:IEC Web Site(www.iec.ch)Catalogue of IEC publications The on-line catalogue on the IEC web site(www.iec.ch/searchpub)enables you to search by a variety of criteria including text searches,technical committees and date of publication.On-line information is also available on recently issued publications,withdrawn and replaced publications,as well as corrigenda.IEC Just Published This summary of recently issued publications(www.iec.ch/online_news/justpub)is also available by email.Please contact the Customer Service Centre(see below)for further information.Customer Service Centre If you have any questions regarding this publication or need further assistance,please contact the Customer Service Centre:Email:custserviec.ch Tel:+41 22 919 02 11 Fax:+41 22 919 03 00 Power transformers Application guideFor price,see current catalogue IEC 1997 Copyright-all rights reservedNo part of this publication may be reproduced or utilized in any form or by any means,electronic or mechanical,including photocopying and microfilm,without permission in writing from the publisher.International Electrotechnical Commission,3,rue de Varemb,PO Box 131,CH-1211 Geneva 20,SwitzerlandTelephone:+41 22 919 02 11 Telefax:+41 22 919 03 00 E-mail:inmailiec.ch Web:www.iec.chINTERNATIONALSTANDARDIEC60076-8First edition1997-10XCCommission Electrotechnique InternationaleInternational Electrotechnical Commission PRICE CODE60076-8 IEC:1997 3 CONTENTSPageFOREWORD.5Clause 1General.7 2Characteristic properties of different three-phase winding combinations andmagnetic circuit designs.9 3Characteristic properties and application of auto-connected transformers.17 4Zero-sequence properties neutral load current and earth fault conditions,magnetic saturation and inrush current.25 5Calculation of short-circuit currents in three-winding,three-phase transformers(separate winding transformers and auto-connected transformers)with earthed neutrals.51 6Parallel operation of transformers in three-phase systems.81 7Calculation of voltage drop for a specified load,three-winding transformer load loss.93 8Specification of rated quantities and tapping quantities.125 9Convertor applications with standard transformers.14710Guide to the measurement of losses in power transformers.151Annex A Basic relations for single-phase and two-phase earth faults.16560076-8 IEC:1997 5 INTERNATIONAL ELECTROTECHNICAL COMMISSION_POWER TRANSFORMERS APPLICATION GUIDEFOREWORD1)The IEC(International Electrotechnical Commission)is a worldwide organization for standardization comprisingall national electrotechnical committees(IEC National Committees).The object of the IEC is to promoteinternational co-operation on all questions concerning standardization in the electrical and electronic fields.Tothis end and in addition to other activities,the IEC publishes International Standards.Their preparation isentrusted to technical committees;any IEC National Committee interested in the subject dealt with mayparticipate in this preparatory work.International,governmental and non-governmental organizations liaisingwith the IEC also participate in this preparation.The IEC collaborates closely with the International Organizationfor Standardization(ISO)in accordance with conditions determined by agreement between the twoorganizations.2)The formal decisions or agreements of the IEC on technical matters express,as nearly as possible,aninternational consensus of opinion on the relevant subjects since each technical committee has representationfrom all interested National Committees.3)The documents produced have the form of recommendations for international use and are published in the formof standar