IEEE C57.13.5-2003 pdf download IEEE Standard of Performance and Test Requirements for Instrument Transformers of a Nominal System Voltage of 115 kV and Above
3. Definitions
For the purposes of this standard, the following terms and definitions apply. IEEE 100, The AuthoritativeDictionary ofIEEE Standards Terms, Seventh Edition (B4], should be referenced for terms not defined inthis clause.
3.1 capacitive insulation system: An arrangement of internal insulation and electrodes to distribute boththe alternating and impulse voltages along the bushing of the instrument transformer with capacitivedielectric layers and/or electrode(s) to achieve an improved coordination between the internal and externalinsulation for the purpose of increasing the overvoltage withstand capability.
3.2 internal arc protection class l: A special transformer design with a feature that, during an internal lineto-ground arc test with the arc taking place at a location, which is technically the most probable, the debris ofthe transformer will be confined to a circle, centered at the transformer. The diameter of this circle is equalto the sum of twice the length of the transformer and the diameter of the transformer.
3.3 internal arc protection class Il: A special transformer design with a feature that, during an internaine-to-ground arc test with the arc taking place at a location, which is technically the most probable, will notfracture the insulator or housing of the transformer.
NOTE–The above definitions (3.2 and 3.3) regarding the classification of internal arc protection apply only to the testconditions specified in the standard. The instrument transformers may have diflerent perlormance during an in-scrvictinternal arc fault. Refer to Annex D for morc information regarding the interprctation of internal arc protection. Thcperformance does not apply to any internal pressure relief device (e.g., rupture disc) provided with the transformer
3.4 prescribed extinction voltage: The lowest required line-to-ground voltage for the transformer at whichthe partial discharge is determined if the reference intensity is met when the voltage applied to thetransformer is gradually decreased without interruption from the power frequency withstand voltage or prestress voltage value during the partial discharge test.
NOTE–The reference partial discharge intensity for the transformers covered in this standard is 10 pC
3.5 rated voltage factor: A multiplier applied to the rated (primary) voltage to derive the maximum voltageat which a transformer must comply with the relevant thermal requirements for a specified time and with therelevant accuracy requirements.
NOTE-Refer to Annex F for additional information
4. General
For performance and safety, the instrument transformers shall comply with IEEE Std C57.13-1993supplemented with the requirements provided in this clause, If any conflicts or inconsistencies exist betweenIEEE Std C57.13-1993 and this standard, the clauses in this standard shall take precedance.
4.1Insulation requirements
4.1.1 Voltage ratings, dielectric test levels, and prescribed extinction voltages
The voltage ratings, dielectric test levels, and prescribed extinction voltages for instrument transformers aregiven in Table l.
IEEE C57.13.5-2003 pdf download
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