Development of Pisol Insulators for UHVDC GIL Systems

Pisol insulators are the core components of GIL (Gas Insulated Line) equipment. Under direct current voltage, insulators are subjected to the action of unipolar direct current electric fields for extended periods, leading to the accumulation of a significant amount of charge on their surface. This accumulation can cause local field distortion at the solid-gas interface, which is highly susceptible to surface flashover along the insulator, thereby reducing the insulation level of the equipment. This study draws on the relevant achievements in the research of direct current insulators, and through the rational control of the surface field strength and the improvement of the resistivity of the insulating material, the accumulation of surface charge is suppressed. Simulation methods are used to guide the structural optimization design, and the insulator has been cast and subjected to dielectric and mechanical property tests under alternating and direct current stress, verifying the correctness of the design. This research has laid a solid foundation for the development of subsequent industrial products.