Effect of Plasma Surface Step Gradient Silicon Deposition on Flashover Properties of Epoxy Resin

Abstract

The basin insulator in gas insulated transmission line is suffered from the non-uniform electric field for a long time. The surface charge accumulation caused by local high field intensity will further distort the external electric field, which will trigger to the partial discharge and even the flashover along the surface. The conventional uniform modification method is difficult to take into account the insulation requirements of different field strength areas, and it is difficult to achieve the best effect on the overall insulation performance. In this paper, atmospheric pressure plasma jet technology are used to realize step plasma gradient silicon deposition on the surface alumina/epoxy resin surface. The results show that the material surface is covered with different thickness of silicon oxide film by step gradient plasma silicon deposition, which can construct step gradient distribution of surface roughness, surface conductivity and trap level. This method can control the charge dissipation rate of different surface areas, and increase the flashover voltage up to 31.1% at most, which is significantly higher than that of unmodified and uniformly modified materials. The analysis shows that, on the one hand, the surface conductivity with gradient distribution can effectively reduce the maximum electric field strength of needle electrodes and reduce the electric field distortion. On the other hand, when the surface charge dissipation in high field intensity region is accelerated and the surface charge dissipation rate is properly controlled, the advantages of plasma silicon deposition can be exerted and the adverse effects can be reduced, and the flashover performance of the material along the surface can be improved to the maximum extent.