Investigation on the Surface Flashover Characteristics of Epoxy Composites in C4F7N/CO2 Mixture

Abstract

Although SF6 is widely used in electrical apparatus, it has a strong greenhouse effect, so it is necessary to find alternative gases. C4F7N/CO2 mixture, as a potential substitute, has been widely concerned by researchers. The long-term working insulation performance of C4F7N, especially the surface insulation, still needs more research. In this paper, two types of spacers are used to study the surface flashover characteristics in C4F7N/CO2 mixture. It is found that the flashover voltage of the plate spacer in 10% C4F7N /90%CO2 mixture is lower than SF6. When the C4F7N content increases from 5% to 20%, the surface flashover voltage of the downsized GIL basin spacer increases and C4F7N/CO2 mixture has obvious synergistic and polar effect. If the voltage is applied for ten minutes in advance, the homo-charges increase the surface flashover voltage, while the hetero-charges reduce the surface flashover voltage to a certain extent.