Interfacial Insulation Degradation Characteristics Between Epoxy Resin and Silicone Rubber Under Different Interface Pressures

In this paper, an equivalent experimental platform for interfacial insulation degradation testing with controllable pressure is established. The growth process of discharge tracking, and the characteristics of partial discharge and dielectric breakdown under different interface pressures are explored. The results indicate that compared to high pressure of 0.3 MPa, the inception voltage under 0.05 MPa is reduced by
$30{\rm{\% }}$
and the growth rate of tracking is increased by 5 times. With the reduction of interface pressure, interfacial breakdown strength is decreased and the characteristics of partial discharge transition from internal discharge to a coexistence of surface and internal discharges. Besides, under lower pressure, the discharge tracking mainly occurs on the surface of silicone rubber, while under higher pressure, it shifts to epoxy resin. This research provides a theoretical basis for the insulation state evaluation of dry-type cable termination for gas insulated switchgear (GIS) under different interface pressures.