Sparkover Characteristics in CF3I Gas and CF3I/N2 Gas Mixture under Non-uniform Field Gaps

Abstract

A steep-front square pulse voltage generator, which has a rise time of 16ns, a dumping factor less than 2.5% after 10μs duration and a peak value of 200kV, is successfully used to survey the V-t characteristics in nanosecond range. The V-t characteristics of CF3I, SF6, CF3I/N2 and SF6/N2 gas mixtures under non-uniform field gaps by using the steep-front square pulse voltage. When the field utilization factor are measured less than 0.38, the sparkover voltage of CF3I is lower than that of SF6. On the contrary, when the field utilization factor is more than 0.38, the sparkover voltage of CF3I is higher than that of SF6. The corona inception voltage calculated by using Schumann's criteria and compared with measured one. The V-t characteristics for a uniform field gap in CF3I/N2 gas mixture containing N2 gas of 40% are equivalent to those in pure SF6 gas. The synergism for appears when CF3I gas is mixed with N2 gas.