Aiming at the problem that the on-line monitoring data of lightning arresters in a 500 kV substation are abnormal and the subsequent power outage pre-test data exceed the regulations

the causes of defects are systematically analyzed through various means such as tracking on-line monitoring data

carrying out on-site power outage pre-test

implementing factory disassembly test and tracing the operating conditions of equipment. The results show that the direct cause of data exception is the superimposed impact of multiple lightning strikes. The huge energy generated by lightning strikes leads to thermal collapse and breakdown of zinc oxide resistors on phase A of the lightning arresters

which in turn leads to a chain reaction of surface flashover of adjacent resistor chips.