IEEE IEEESTANDARDSASSOCIATION IEEE Guide for Grounding of Instrument Transformer Secondary Circuits and Cases IEEE Power and Energy Society Sponsoredbythe PowerSystemRelayingCommittee IEEE IEEEStdC57.13.3TM-2014 3Park Avenue (Revision of NewYork,NY10016-5997 IEEE Std C57.13.3-2005) USA IEEEStdC57.13.3TM-2014 (Revisionof IEEEStdC57.13.3-2005) IEEE Guide for Grounding of Instrument Transformer Secondary Circuits and Cases Sponsor PowerSystemRelayingCommittee of the IEEEPowerand EnergySociety Approved 10 December 2014 IEEE-SAStandardsBoard Abstract:General and specific recommendations for grounding current and voltage transformer secondary circuits and cases of connected equipment are covered in this guide. Although most diagrams included in this guide show relaying applications, the recommended practices apply equally to metering and other areas where instrument transformers are used. Grounding practices presently used, and practices that were not previously reported, are included in this Keywords: Capacitive voltagetransformer,combined metering unit, ,current transformer, grounding of cases of instrument transformers, grounding secondary circuits of instrument transformers, IEEEC57.13.3TM,instrument transformer, linear coupler, low energy transducer, resistive voltage transformer, voltage transformer. The Institute of Electrical and Electronics Engineers, Inc. 3ParkAvenue,NewYork,NY10016-5997,USA Copyright2015 by The Institute of Electrical and Electronics Engineers, Inc. All rightsreserved,Published23January2015.Printed intheUnitedStatesofAmerica. IEEEandNESC are registeredtrademarks in the U.S.Patent &Trademark Office,owned byThe Institute ofElectrical and Electronics Engineers, Incorporated. National Electrical Code, NEC, and NFPA 70 are registered trademarks of the National Fire Protection Association, Inc. PDF: ISBN978-0-7381-9423-3 STD20038 Print: ISBN978-0-7381-9424-0 STDPD20038 IEEEprohibitsdiscrimination,harassment,andbullying Formoreinformation,visithttp://www.ieee.orq/web/aboutus/whatis/policies/p9-26.html. ofthepublisher. ImportantNoticesandDisclaimersConcerningIEEEStandardsDocuments IEEE documents are made available for use subject to important notices and legal disclaimers. These heading“Important Notice"or"Important Notices and Disclaimers Concerning IEEE Standards Documents." Notice and Disclaimer ofLiabilityConcerningthe Use of IEEE Standards Documents IEEE Standards documents (standards, recommended practices, and guides), both full-use and trial-use, are developed within IEEE Societies and the Standards Coordinating Committees of the IEEE Standards Association ("IEEE-SA") Standards Board. IEEE ("the Institute") develops its standards through a consensus development process, approved by the American National Standards Institute ("ANSI"), which brings together volunteers representing varied viewpoints and interests to achieve the final product. Volunteers are not necessarily members of the Institute and participate without compensation from IEEE. While IEEE administers the process and establishes rules to promote fairness in the consensus development process, IEEE does not independently evaluate, test, or verify the accuracy of any of the information or the soundness of any judgments contained in its standards. IEEE does not warrant or represent the accuracy or content of the material contained in its standards, and expressly disclaims all warranties (express, implied and statutory) not included in this or any other document relating to the standard, including, but not limited to, the warranties of: merchantability; fitness for a particular purpose; non-infringement; and quality, accuracy, effectiveness, currency, or completeness of material. In addition, IEEE disclaims any and all conditions relating to: results; and workmanlike effort. Use of an IEEE standard is wholly voluntary. The existence of an IEEE standard does not imply that there are no other ways to produce, test, measure, purchase, market, or provi