Due to the issues of multi-layer insulation coordination, the interface of cable accessories is prone to surface discharge and breakdown, which are the weakest link in the power cable system. The discharge model of composite dielectric interface is established. This article investigates the variation of breakdown voltage at the interface of XLPE/SiR double-layer dielectric under different interfacial roughness and pressures. The results indicate that the higher the interfacial roughness, the lower the interfacial breakdown voltage; the higher the interfacial pressure, the higher the interfacial breakdown voltage. In addition, considering the model, the quantitative relationships between breakdown voltage and roughness and pressure are established respectively. Finally, the interfacial breakdown mechanism is explained.

Cable accessory; Composite dielectric; Interfacial breakdown; Multiphysics Fields