Towards the surface flashover in DC GIL/GIS: the electric field distribution and the surface charge accumulation

Under DC voltage, the interface charge of the spacer in gas-insulated metal-enclosed transmission lines (GIL) and gas-insulated metal-enclosed switchgear (GIS) is prone to accumulate, and the charge is an important factor to induce surface flashover. On different spacers, the distribution of the electric field can be varied and affect the flashover greatly. This paper concentrates on the surface flashover induced by solid-gas interface charge accumulation in DC GIL/GIS. The electric field distribution of the real insulator and the electrode structure commonly used in research are analyzed and summarized into two distribution forms: the tangential-component dominant type and the hybrid type. According to the electric field distribution forms, how the density distribution and electric field distortion of interface charge influence the flashover voltage of spacer is reviewed, and the influence of metal particles on charge and surface flashover is reviewed as well. Efforts to understand the mechanism of the surface flashover have alse been tracked.