Experimental Study on Surface Charge Accumulation and Dissipation of HVDC GIS/GIL Post Insulator

Gas insulated metal enclosed switchgear(GIS) and transmission line(GIL) have basically the same post insulators which are used for gas chamber isolation and conductor support. They are the weak links in the electrical insulation and mechanical strength of GIS/GIL equipment. Studying the law of charge accumulation and dissipation of GIS/GIL post insulators in DC electric field, especially the charge accumulation behavior when there are tiny defects on the surface of insulator or electrode, is the premise of reducing surface flashover and nearfield gas breakdown, and also is the key to developing HVDC product technology. A set of post insulator surface charge measurement system is established. The electrostatic probe can measure the potential distribution of the entire surface of the insulator only by the accumulated charge. The accumulation and dissipation laws of the surface charge of insulators with different gas (SF6, N2, CO2), different voltages (+200kV-+450kV) and gas pressure (latm and 4atm absolute values) are studied. And the surface potential distribution law of the insulator before and after the gas discharge occurred in the measurement system is compared. The results of this paper provide more comprehensive experimental data for the actual operating behavior characteristics of the post epoxy resin insulator, which has certain reference value for guiding the design of HVDC GIS/GIL gas-solid insulation structure.