IEEE Std C57.13.1 pdf download IEEE Guide for Field Testing of Relaying Current Transformer
1. Overview1.1 Scope
The scope of this guide is to describe field test methods that assure current transformers (CTs) are connectedproperly, are of marked ratio and polarity, and are in a condition to perform as designed both initially and afterbeing in service for a period of time.
Annex A describes wiring integrity checks， the use of test jacks, current-shorting switches, andrelay test equipment.
Annex B illustrates excitation voltage measurement differences between rms responding voltmeters(commonly used under field conditions) and average responding voltmeters (commonly used in laboratorytests) and also discusses the effect of the source impedance.
Annex C describes the characteristics, and other pertinent information, of optical current sensor systems usedwith protective relaying. lt provides an overview of the components used in an optical sensor system, discussesthe differences from conventional CTs, and provides testing information.
Annex D is the bibliography for this guide.
The purpose of the guide is to provide information on the current technology for field testing of instrumenttransformers and to more closely coordinate the information with the other industry standards, for example,the National Electrical Safety CodeR(NESCR)(Accredited Standards Committee C2).3
2. Normative references
The following referenced documents are indispensable for the application of this document (i.e., they mustbe understood and used, so each referenced document is cited in text and its relationship to this document isexplained).For dated references, only the edition cited applies.For undated references, the latest edition of thereferenced document (including any amendments or corrigenda) applies.
Accredited Standards Committee C2, National Electrical Safety CodeR(NESCR).”
IEEE Std C37.110TMA，IEEE Guide for Application of Current Transformers Used for Protective RelayingPurposes.
IEEE Std C57.13TM4,IEEE Standard Requirements for Instrument Transformers.5.6
IEEE Std C57.13.3 TM,IEEE Guide for Grounding of lnstrument Transformer Secondary Circuits and Cases.
For the purposes of this document, the following terms and definitions apply. The lEEE Standards DictionaryOnline should be consulted for terms not defined in this clause.7
4.Consideration of American National Standards Institute (ANSI) accuracyclasses
Relaying accuracy classes have been established in lEEE Std C57.13 to specify the performance of relayingCTs. During faults on the electric power system, relaying CTs must operate at high overcurrent levels.ANSIclassifications , therefore,define minimum steady-state performance at these levels. Performance is describedby using a two-term identification system consisting of a letter and a number as follows: C100,C200,C400,c8oo,T10,T20,T50,T100,T200,T400,T800.
The first term of this identification describes performance in terms relating to construction; C representscalculated and T represents tested. The second term specifies the secondary voltage that can be deliveredby the secondary winding at 20 times rated secondary current through a standard burden without exceeding10% ratio error.As an example, a C100 rating means that the ratio error will not exceed 10% at any currentfrom 1 to 20 times the rated current with a standard 1.0 Q burden.(1.0 Q times 5 A times 20 times ratedsecondary current equals 100 V.)The ANSl voltage rating applies to the full secondary winding only. lfother than the full winding is used, the voltage rating is reduced in approximate proportion to turns usedonly if the windings are evenly distributed. For more details and discussions on windings, ratings, and CTclasses (see lEEE Std C37.110).
Details of low-energy devices, such as opto-electronic transducers, are not discussed in this guide.Somedetails are provided inAnnex C.Analog input issues are discussed in IEEE Std C37.92TM [B4].8
5. Precautions in field testing current transformers(CTs)