Switching Surge Sparkover Characteristics of Air Gaps and Insulator Strings Under Nonstandard Conditions

This paper describes the results of sparkover tests made with switching surge voltages superposed on 50-Hz voltage, standard deviations of sparkover voltage of a pair of sphere and air gaps, sparkover characteristics of 11- by 6.75-inch suspension insulators, the influence of electrode size on switching surge sparkover voltage, and the humidity correction factor for switching surge voltages of an air gap. The tests were conducted at the Shiobara Laboratory; a 10 000-kV, 750-kJ surge generator was used.