In this paper

the parameters and internal electrical structure of one faulty power capacitor is introduced through disassembly and study.It is found through disassembly that the impregnated oil of the power capacitor has become black completely due to contamination of discharging products.In all 56 capacitor elements

breakdown has been found in 17 which result in the thorough short circuit between terminals of the capacitors and the remaining 39 are at good condition.The AC and DC withstand voltage test are carried out for the well capacitors elements together with the disassembly result

the fault reason of the capacitors is analyzed and some constructive suggestions are made.