HVDC cable accessories made of ethylene-vinyl acetate copolymer (EVA) by incorporation of specific fillers have to face the problem of space charge accumulation. The effects of doping contents on the space charge behaviors of EVA/ZnO composite are not completely clear. EVA composites are prepared with the fraction of 0, 1, 5 and 10 wt%, respectively, with which 5 wt% nano-sized plus 5 wt% micro-sized ZnO-doped samples are chosen for comparison. 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 homocharge injection occurs in cathode instead of anode when ZnO nanoparticles are introduced and 5 wt% nanoparticle doping performs well in suppressing space charge injection. The electric field in the 5 wt% nanoparticle-doped EVA distributes more uniformly under the high electric stress than that of others. During the depolarization procedure, the total remnant charges of 10 wt% doped samples are the least in the final. The above results are well explained by the DC conduction, apparent mobility and trap distribution characteristics.
Part of the book: Nanocomposites