The dust inside Gas Insulated Transmission Lines (GIL) will cause partial discharge or even surface flashover of the insulators. In this paper, aluminum, silicon and aluminum oxide powder were used to simulate the metal, semiconductor and insulation dust that may be attached to insulators in GIL, respectively. The surface charge accumulation and dissipation characteristics of the samples attached by dust of different materials and particle sizes, and its surface flashover characteristics in pure SF₆ gas and C₄F₇N-CO₂ mixture gas were studied. The results showed that the metal dust-attached samples had the largest charge accumulation and the fastest charge dissipation rate. The semiconductor and insulation dust-attached samples had similar charge accumulation, but the former had faster charge dissipation rate than the latter. With the decrease of dust particle size, the AC flashover voltage of metal dust-attached samples increased, while that of semiconductor and insulation dust-attached samples decreased.

charge accumulation,charge dissipation,dust,epoxy resin,surface flashover