Research on Partial Discharge and Self-Healing Characteristics for Metallized Film of Capacitors

In this paper, an experimental system is established to characterize the partial discharge (PD) and self-healing (SF) properties of the metallized film based on the actual structure of metallized film capacitors. Compared with the PD signal waveforms of the polypropylene film, internal discharge, surface discharge and SF discharge signal waveforms of the metallized film were investigated and distinguished. Meanwhile, the phase resolved partial discharge spectrum of the metallized film also reflects a variety of discharge types. Through studying the microscopic morphology of metallized films, SF and surface discharge will cause the loss of metal electrodes on the films. The interaction between them will cause the phenomenon of “margin degradation”, which will accelerate the decrease of capacitance, and lead to the deterioration of capacitor performance until the failure. This paper aims to investigate the PD and SF characteristics of the metallized film and provide a theoretical basis for exploring the capacitance loss mechanism with monitoring the operational status of capacitors.