Optimization design of shielding ring for restraining surface charge accumulation

The surface of insulators in the GIL is prone to generate charges under a DC high-voltage for a long time, which has a great impact on insulation performance of the insulators. The accumulation of the surface charges is mainly related to surface normal field on insulators. Decreasing surface normal field on insulators can reduce the rate and amount of accumulation of the surface charges. By the way of setting a shielding ring on the center high-voltage electrode, the electric field distribution can be effectively improved, and the surface normal field will be smaller. In order to study the impact of shielding ring on electric field distribution, a simulation model containing GIL hermetic cavity, center electrode, shielding ring, cone-insulator, and so on, is built to yield the electric field data with the software Maxwell 2D. Finite element method is used for analysis. The simulation results show the change of surface normal field with different sizes of the shielding ring and different locations where the shielding ring is. The simulation results suggest that there is an optimal location for the shielding ring to lead to a minimum surface normal field distribution. Also, the results will give some help for the electrode design.