The fault reason of capacitor is found through the inspection and test of the tripping

fault recordwave analysis and EMTP/ATP simulation calculation of 21 C capacitor bank of certain a 110 k V substationas follows:The first reason is that B5 capacitor has the defect of weak insulation before closing operation and

in case of closing operation

the insulation breakdown occurs;the second one is that the fuse of B5 capacitorhas the defect of weak contact before closing operation and

in case of closing operation

the gap dischargesoccurs inside the fuse and therefore the B5 capacitor occurs breakdown due to the action of high frequencydischarge current.The EMTP/ATP simulation calculation is introduced so to provide new method for theanalysis of the similar fault of capacitor

accumulate experience

which has a definite engineering practicalsignificance.