The fault of shunt capacitor for certain 500 kV substation was happened after auto switching through AVC.In order to find out the specific cause of the fault and avoid recurrence of similar failure

the comprehensive analysis and inference on the fault process and cause are carried out by the analysts from such aspects as parameters validation

harmonics

protection action

overvoltage and disassembly at the manufacture.Throughout analysis

such factors as parameters

harmonics

protection

overvoltage are eliminated in turn.Finally

it is thought that the fault is the three-phase short-circuit fault of the complete set of capacitors due to internal insulation fault of individual capacitor after operation.The introduction in this paper can provide a certain reference for the fault analysis of similar shunt capacitors.