Surface charge behaviors of SiR/SiC composites with nonlinear conductivity

High temperature vulcanized (HTV) silicone rubber (SiR) is widely used as HVDC cable accessory insulation considering its outstanding electrical properties along with elasticity and thermal resistance. However surface charge caused by corona would accumulate on SiR surface and distort the local field which in consequence led to accessory premature discharge and insulation failure. This paper tried to modify the surface charge behaviors of HTV SiR composites by incorporating silicon carbide (SiC) particles with different filler size and crystal morphology The influences of SiC filler size and crystal morphology on the dc conductivity and surface charge behavior of HTV SiR composites were studied. The results indicated that, for the α-SiC particles filled composites, with the increase of the filler size from 0.45 μm to 5.0 μm, the fleld-dependent conductivity and surface potential decay (SPD) is enhanced, due to an increase of shallow trap density and a decrease of deep trap density. Compared with α-SiC particles, the β-SiC whiskers could provide a larger nonlinear conductivity, resulting in an acceleration of surface charge dissipation.