Huadian Technology ›› 2017, Vol. 39 ›› Issue (4): 4-7.

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Features and mechanism of interturn short circuit fault by energizing noload transformer

  

  1. Nanjing SAC Automation Company Limited, Nanjing 211151, China
  • Online:2017-04-25 Published:2017-05-23

Abstract:

When interturn short circuit fault by energizing noload transformer occurs, the threephase current differential protection is blocked by blocking criteria, and it causes the singlephase interturn short circuit fault could not be rapidly removed, which threats the safe operation of transformer. Through establishing the equivalent model of interturn short circuit fault, this paper deduced the analytical expression of magnetic flux of exciting windings and analyzed the influences of system impedance and number of faulted turns on fault features. It concluded that the larger system impedance and number of faulted turns, the more difficult the inrush current occurs. Using the PSCAD software, the correctness of the conclusion was verified, and it provided a theoretical basis for the selection of blocking criteria and blocking schemes of differential protection.

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