Response time and maximum overvoltage of spark gaps in compressed SF 6 for steeply rising pulses

Abstract

First results on the time response of a spark gap in compressed SF 6 upon a steeply rising voltage pulse and on the maximum overvoltage reached across the gap are reported. The method of analysing voltage pulses of 10 to 60 kV and rise times in the nanosecond region and below is described. At overvoltage slopes of around 2.5 to 3.5 ns −1 the minimum predischarge time (statistical plus formative time lags) varied between 0.20 and 0.5 ns for gap widths between about 0.1 and 0.5 mm. Maximum overvoltages did not exceed 2.5 times the breakdown voltage. The results are discussed in terms of measurements at constant overvoltages.