AC flashover characteristics of insulators under haze–fog environment

The occurrence of large-scale haze–fog weather in some developing countries brings a new threat to the safe operation of outdoor insulation. In order to study the effect of the haze–fog on the flashover performance of insulators and the flashover mechanism, kieselguhr, calcium sulphate (CaSO­ 4) and ammonium sulphate ((NH4)2SO4) in different particle sizes were mixed with ultrasonic fog to simulate the haze–fog environment and quantitative ac flashover experiments on the standard suspension porcelain insulator were carried out. The test results indicate that the flashover voltage is related with the pollution degree, particle component, particle size and fog-water conductivity, and may decrease by more than 20% under haze–fog environment. The effect of salt aerosols on flashover voltage is determined by the solubility and larger than that of non-soluble mineral aerosols or organic carbon aerosols. The flashover voltage increases with the increase of the particle size, but decreases with the increase of fog-water conductivity. The flashover of insulator under haze–fog condition is a special kind of pollution flashover in essence.