Effect of the thickness and the relative permittivity of epoxy resin coating on the hemispherical tip electrode to the first flashover voltage in pressurized dry air

SF6 gas has high dielectric strength and current interrupting ability, so it has been widely used in electric power apparatus such as Gas Insulated Switchgear (GIS), gas circuit breaker and so on. However, since the global warming potential of SF6 gas is 22,800 times higher than that of CO2, dry air is going to be used as insulation medium for GIS. However, since the dielectric strength of dry air is 1/3 of that of SF6, very high gas pressure is necessary to fulfil the insulation requirement by dry air. Therefore, pure dry air insulation technique is not a realistic way of high voltage insulation in GIS. Instead, the composite insulation system which combines relatively high gas pressure dry air and solid insulating material becomes an important technology. In this investigation, we setup…