Breakdown characteristics of N2 containing 0.125% of SF 6

AC breakdown strengths of N₂, SF₆ and a mixture of N₂+SF₆ containing 0.125% of SF₆ in nonuniform field were experimentally studied. The electrode gap spacing and the relative gas pressure were varied within the range of 5-25 mm and of 100-500 kPa respectively. The experimental results have shown that the addition of SF₆ to N₂ causes a significant increase the AC breakdown voltage with respect to N₂ . Even at about pressures of 250 kPa and 25 mm gap spacing breakdown voltages of the mixture were obtained 74% higher than that of pure N₂. But above 400 kPa and 25 mm gap spacing the breakdown voltage is 10% lower than that of pure N₂