Research on Nonlinear EPDM for ±525kV HVDC Cable Accessories

High voltage direct current (HVDC) cable accessories are usually the weak link in the cable system for the electric field distribution is often extremely uneven, and it has a range of adverse effects in design and manufacture. In this paper, Ethylene-propylene-diene terpolymer (EPDM) was developed for ±525 kV HVDC cable accessories, and the conductivity, XLPE/EPDM interface charge behavior and breakdown strength were tested respectively. The electric field distribution of cable accessories was calculated by COMSOL analysis software. It is shown that the conductivity of EPDM is nonlinear with electric field, and it is possible to achieve the uniformity of electric field distribution by using a composite material with nonlinear conductive properties. Furthermore, the interfacial charge characteristics of XLPE/EPDM depend on the conductivity of EPDM. As a consequence, the research will make a potential application for ±525 kV HVDC cable accessories.