Study on the Dynamic Process and Extinguishing Criterion of Metallized Film Self-Healing Arc

Owing to the property of self-healing, metalized film capacitors can be reliably used under high electric field. However, self-healing is at the expense of capacitance loss. Therefore, it is of great significance to study the mechanism and characteristics of self-healing to improve the life and reliability of metallized film capacitors. In this paper, a metallized film self-healing arc observation platform was established. DC voltage with increasing amplitude was applied to the double-layer overlapped metallized film by the high voltage source until the film was broken down. The morphological change of the self-healing arc was observed by the high-speed camera. The change process of the arc can be divided into three stages: arc expansion stage, stable combustion stage and arc extinction stage. When the power density reached the power density threshold, the arc began to extinguish. The self-healing characteristics of the metallized film with pressures of 20 kPa, 100 kPa, 200 kPa, 500 kPa and 1 Mpa were studied. The power density threshold is affected by the interlayer pressure significantly. The power density threshold increases with increasing pressure. The increase of the power density threshold leads to the decrease of self-healing duration, self-healing energy and self-healing area under high pressure.