Voltage-Dependent Multi-Stage Consecutive Self-Healing in Metallized Polypropylene Film Capacitors

Metallized polypropylene film capacitors (MPPFCs) are pivotal components utilized across a spectrum of applications, including electromagnetic ejection, aerospace, and DC power transmission. Understanding the self-healing (SH) mechanism of MPPFCs is challenging, necessitating a comprehensive grasp of the physicochemical processes involved in SH, alongside a deep understanding of the impact of MPPFCs’ multilayer winding structure on SH. In this paper, we present an analysis of the voltage-dependent characteristics of the SH mode of MPPFCs under DC voltage. We substantiated our findings through experimentation and proposed a voltage-dependent multi-stage consecutive self-healing (CSH) model based on MPPFCs’ SH behavior at varying voltage levels. Our investigation reveals that as the SH voltage increases, the SH mode transitions from single SH to multi-stage CSH. In the CSH mode, sub-SH events are temporally and physically coupled through arc plasma and energy transfer, with notably stronger coupling between the first two sub-SHs observed in the three-stage CSH compared to the two-stage CSH. This heightened coupling leads to more breakdown layers with a significant increase in SH time, SH energy, and electrode removal area, albeit accompanied by a substantial decrease in insulation resistance. This paper offers direct evidence that multi-stage CSH is identified as the dominant mechanism driving insulation resistance decay and structural damage under high voltage. This understanding serves as a crucial basis for condition monitoring and structural optimization of MPPFCs.