The Propagation Characteristics of Solid Repair Medium in Cable Buffer Layer

In recent years, there are many buffer layer failures occurred in high voltage cables. The reason is that the buffer layer is damp and generates white powder with extremely high resistivity, which distorts the electric field and causes partial discharges. At present, the best repair method is to inject carbon black powder to restore the semi-conductivity of the buffer layer. However, in the actual repair process, optimize the implantation parameters and make it well attached to the surface of the buffer layer has become the key point defining the effectiveness of the repair. In this paper, based on COMSOL finite element simulation, the effects of injection pressure and powder particle size on the dispersibility of the conductive repair medium were explored. The result shows that the powder in the buffer layer diffuses in a spiral advance and can effectively adhere to the surface of the buffer layer. Under the premise of not damaging other cable accessories, increasing the injection pressure and reducing the powder particle size can avoid early deposition, thereby improving the distribution uniformity and improving the repair effectiveness.