Space charge accumulation characteristics in ethylene-vinyl acetate copolymer filled with ZnO nanoparticles

The performance of cable accessories, as an essential part of the HVDC networks, is a great concern to the reliability of the system. Cable accessories made of ethylene-vinyl acetate copolymer (EVA) by incorporation of specific fillers have to face the problem of space charge accumulation and become more unpredictable considering the complex conditions. The effects of doping contents on the space charge behaviors of EVA/ZnO nanocomposite are not completely clear, which needs further investigation. In this paper, EVA composites were prepared by incorporating ZnO nanoparticles into EVA matrix with fraction of 0, 1, 5 and 10 wt% respectively. The dependence of the dielectric properties on the doping contents was measured. PEA method was applied to research the space charge behaviors of EVA composites under −25 kV/mm. Obtained results show that the particles in EVA composite are in homodisperse. The permittivity is increased by ZnO doping and the dissipation factor of EVA composites with 1 and 5 wt% nanoparticles is lower at the lower frequencies. The homocharges injection occurs in cathode instead of anode when ZnO nanoparticles are introduced and 5 wt% nanoparticles doping performs well in suppressing space charge injection. The electric field in the 5 wt% nanoparticles doped EVA distributes more uniformly under the high electric stress than that of others. During the depolarization procedure, the total remnants charges of 10 wt% doped samples are less than that of others in the final.