Behavior of insulators under dew and fog

Abstract The sparkover characteristics of insulators subjected from 20 to 80 min to 50 Hz voltage under simulated conditions of dew and fog are described. Results obtained with different materials are discussed. A test procedure for the purpose of reducing the duration of test is proposed. It consists of the superposition of a surge voltage of slow-rising front on the rated 50 Hz voltage applied to the insulator.