Fault Analysis of 500 kV Circuit Breaker Failure Protection Malfunction and Tripping

This paper introduces a main transformer tripping fault caused by the GIS discharge of the voltage transformer. According to the three-phase voltage and current changes of the main transformer and the protection action when the fault occurs, the possible causes of the fault are inferred from the test test of the equipment within the differential protection range, and then through the voltage transformer Dismantling inspection and analysis, it is determined that the cause of the fault is improper welding of the primary winding, resulting in inter-turn discharge, and finally put forward reasonable suggestions for this fault to ensure the safe and stable operation of the voltage transformer.