C37.91

IEEE Power Engineering Society
Sponsored by the
Power System Relaying Committee

C37.91

TM

IEEE
3 Park Avenue
New York, NY 10016-5997, USA

IEEE Std C37.91™-2008
(Revision of
IEEE Std C37.91-2000)

30 May 2008

Copyright The Institute of Electrical and Electronics Engineers, Inc.
Provided by IHS under license with IEEE
No reproduction or networking permitted without licensefrom IHS

Licensee=Petroleos Mexicanos/5948636001, User=teca, Norma
Not for Resale, 09/08/2008 09:42:30 MDT

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IEEE Guide for Protecting Power
Transformers

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Copyright The Institute of Electrical and Electronics Engineers, Inc.
Provided by IHS under license with IEEE
No reproduction ornetworking permitted without license from IHS

Licensee=Petroleos Mexicanos/5948636001, User=teca, Norma
Not for Resale, 09/08/2008 09:42:30 MDT

IEEE Std C37.91™-2008
(Revision of
IEEE Std C37.91-2000)

IEEE Guide for Protecting Power
Transformers
Sponsor

Power System Relaying Committee
of the
IEEE Power Engineering Society
Approved 31 January 2008

IEEE-SA Standards Board--````````,````,,``,,,`,``,`,,-`-`,,`,,`,`,,`---

Copyright The Institute of Electrical and Electronics Engineers, Inc.
Provided by IHS under license with IEEE
No reproduction or networking permitted without license from IHS

Licensee=Petroleos Mexicanos/5948636001, User=teca, Norma
Not for Resale, 09/08/2008 09:42:30 MDT

--````````,````,,``,,,`,``,`,,-`-`,,`,,`,`,,`---

Abstract: Thisguide is intended to provide protection engineers and other readers with
guidelines for protecting three-phase power transformers of more than 5 MVA rated capacity and
operating at voltages exceeding 10 kV. In some cases, a user may apply the techniques
described in this guide for protecting transformers of less than 5 MVA ratings or operating at
voltages less than 10 kV. Information toassist protection engineers in applying properly relays
and other devices to protect transformers used in transmission and distribution systems is
provided in this guide. General philosophy, practical applications, and economic considerations
involved in power transformer protection are discussed. Emphasis is placed on practical
applications. Types of faults in transformers are described. Technicalproblems with the
protection systems, including the behavior of current transformers during system faults, are
discussed. Associated problems, such as fault clearing and reenergization, are discussed as well.
Keywords: analysis of dissolved gases in transformer oil, application of multifunction relays for
transformer protection, differential protection, failures of transformers, overcurrentprotection,
protection of phase-shifting transformers, protection of transformers, volts-per-hertz protection

•

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Copyright © 2008 by the Institute of Electrical and Electronics Engineers, Inc.
All rights reserved. Published 30 May 2008. Printed in the United States of America.
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Engineers, Incorporated.
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Engineers, Inc.
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PDF:
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ISBN 978-0-7381-5388-9
ISBN 978-0-7381-5389-6

STD95767
STDPD95767

No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission
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Copyright The Institute of Electrical and Electronics Engineers, Inc.
Provided by IHS under license with IEEE
No reproduction or...