In this paper

one fault of 35 kV capacitor bank at certain 500 kV substation is described

the comprehensive analysis is made from such aspects as site inspection

disassembly at the factory and tests etc.The reason of the fault is found to be inter-phase short circuit and capacitor damage due to overlap of foreign matter between capacitor bank frames.As for the problem

improvement measure to prevent such similar fault is proposed

which has a definite reference value for safe operation of capacitor.