Although the self-healing metallized film capacitor recovers insulation automatically in case of partial breakdown

yet self-healing failure due to sustaining discharge can still lead to occurrence of failure caused by sustained discharge still leads to catastrophic fault. For exploring self-healing failure process

HVDC voltage is applied on the capacitor element

the voltage and current at the breakdown point is measured indirectly by the shunt capacitor so to analyze the development process of the self-healing failure and deduce the impedance feature of its breakdown point. It is shown by the test result that the self-healing failure is the bigger self-healing process as a lead

the frequent self-healing process with sustaining time of several ms is existed before complete breakdown of the element

and the peak of these self-healing current decreases with decreasing voltage. During the breakdown period of element

with the sustaining discharge

the equivalent resistance of the breakdown point is reduced gradually and the minimum resistance is basically close to complete short circuit. The study of the self-healing failure process provides reference for the fuse protection and safe film design.