Abstract
The combination of two solid dielectrics increases the risk of partial discharge (PD) activity in microscopic cavities at the solid-solid dielectric interfaces, facilitating interface tracking failures. The main purpose of this study is to propose a novel methodology to monitor PD activities in the microvoids at solid-solid interfaces that are likely to trigger a complete interfacial failure. To scrutinize the principal mechanisms governing the interfacial breakdown, initiation, development, and propagation of discharge streamers at solid-solid interfaces were monitored using a sensitive digital camera attached to a high-voltage (HV) test setup. The captured images showed that the surface roughness and contact pressure affect the length of the vented air-filled channels at the interface. In the case of rougher surfaces, the discharged cavities formed continuous, connected discharge channels that were wider and longer than those in the case of smoother surfaces. In some cases, only microcavities were discharged and were isolated between the contact spots.