Switching Surge Flashover Characteristics of Extremely Long Air Gaps

The purpose of this paper is to estimate the limit of the possible transmission line voltage and to clarify the mechanism of discharge in the air. Tests were performed on the switching surge flashover of long air gaps under dry conditions. The flashover voltages of the switching surge with the duration of wave front 180 ?s were obtained up to 13 meters for rod-plane gaps for positive polarity. The tests were performed at the Shiobara Outdoor Laboratory.