BSIEC/IEEE 61869-21:2025 BSl Standards Publication Instrument transformers Part 21: Uncertainty evaluation in the accuracytest of instrument transformers bsi. BSIEC/IEEE61869-21:2025 BRITISH STANDARD Nationalforeword This British Standard is the UK implementation of IEC/IEEE61869-21:2025. TheUKparticipationinitspreparation was entrustedtoTechnical CommitteePEL/38,Instrumenttransformers. A list of organizations represented on this committee can be obtained on requestto its committee manager. Contractual andlegalconsiderations This publication has been prepared in good faith, however no representation, warranty, assurance or undertaking (express or implied) is or will bemade, and no responsibility or liability is or will be reasonableness of this publication. All and any such responsibility and liability is expresslydisclaimed tothe full extent permitted bythe law. This publication is provided as is, and is to be used at the recipient's own risk. The recipient is advised to consider seeking professional guidance with respectto itsuseofthispublication. This publication is not intended to constitute a contract. Users are responsibleforits correctapplication. @TheBritishStandards Institution2025 Published byBSI Standards Limited 2025 ISBN9780539283969 ICS 17.220.20 Compliancewith aBritish Standard cannot confer immunityfrom legal obligations. This British Standard was published under the authority of the StandardsPolicyandStrategyCommitteeon31December2025 Amendments/corrigenda issued sincepublication Date Textaffected BSIEC/IEEE61869-21:2025 IEC IEEE IEC/IEEE61869-21 Edition 1.02025-12 INTERNATIONAL STANDARD Instrumenttransformers Part 21: Uncertainty evaluation in the accuracy test of instrument transformers IEC/IEEE 61869-21:2025-12(en) ICS 17.220.20 ISBN 978-2-8327-0784-5 BSIEC/IEEE61869-21:2025 THIS PUBLICATIONIS COPYRIGHTPROTECTED Copyright2025IEC,Geneva,Switzerland Copyright2025IEEE All rights reserved. Unless otherwise specified, no 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 being secured. Requests for permission to reproduce should be addressed to either IEC at the address below or IEC's member National Committee in the country of the requester or from IEEE. IECSecretariat Institute of Electrical and Electronics Engineers, Inc. 3, rue de Varembe 3Park Avenue CH-1211 Geneva 20 New York, NY 10016-5997 Switzerland United States of America Tel.: +41 22 919 02 11 [email protected] [email protected] www.ieee.org www.iec.ch Aboutthe IEC The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes International Standards for all electrical, electronic and related technologies AbouttheIEEE IEEE is the world's largest professional association dedicated to advancing technological innovation and excellence for the benefit of humanity. IEEE and its members inspire a global community through its highly cited publications, conferences, technology standards, and professional and educational activities. AboutIEC/lEEEpublications The technical content of IEC/IEEE publications is kept under constant review by the IEC and IEEE. Please make sure that you have the latest edition, a corrigendum or an amendment might have been published. IEC publications search-webstore.iec.ch/advsearchform IEc Products & Services Portal -products.iec.ch The advanced search enables to find IEC publications by a Discover our powerful search engine and read freely all the varietyof criteria(referencenumber,text, technical publications previews, graphical symbols and the glossary. With a committee, ...). It also gives information on projects, replaced subscription you will always have access to up to date content and withdrawn publications. tailored to your needs. IEc Just Published - webstore.iec.ch/justpublished Electropedia-www.electropedia.org Stay up to date on all new IEC publicati