Mechanism of Electric Field Control at the Interface of Central Conductor and Insulation Basin of UHV GIS Spacer

UHV GIS spacer is an important component in gas-insulated enclosed switchgear (GIS), and its reliability plays a vital role in the safe and stable operation of power system. Due to the differences of the electrical properties between the central conductor and basin insulation material, the interface formed by the two materials becomes the electric field strength concentration region of the spacer. During the process of operation, the ablation damage arising from the interface occurs, which is caused by partial discharge at the interface. Therefore, it is necessary to study the electric field strength concentration effect at the interface of the spacer. And the electric field strength at the interface was taken as the research object in this paper. The reason why the electric field strength at the interface of the spacer is so concentrated was analyzed by finite element simulation. The method of coating interfacial material was used to suppress the interfacial electric field concentration effect after discussion. Then the model of the spacer that coated with interfacial material was established, and the relationship between the electric field strength on both sides of the interfacial coating materials and the parameters relating to the coating material was derived. Combined with the established model and simulation, the variation of the maximum electric field strength on both sides of the interfacial layer with the dielectric parameters and the coating thickness was analyzed when there are no defects and small defects such as small burrs and bumps at the interface. The simulation results verified the validity of the established model.