Relationship between Phase Resolved Partial Discharge Pattern and Deformation Behavior of Cavity in Silicone Gel for Encapsulation of Power Modules

Abstract

In power modules, silicone gel is widely used for encapsulation. It is well known that partial discharges (PDs) such as surface discharge at the gel-substrate interface give rise to growth of cavities in gel. This paper reveals the relationship between the deformation behavior of cavity and PRPD (Phase-Resolved-Partial-Discharge) pattern in silicone gel. It turns out that a single trunk of tree tends to emit light with occurrence of single positive partial discharge pulse, while multiple trunks emit light with negative PD pulse. The results also show that PDs which have relatively large magnitude expand or shrink voids at the cavity tip.