Dc Voltage Breakdown of SF6-Air and SF6-CO2 Mixtures in Rod-Plane Gaps

dc breakdown and corona inception voltages are reported for SF6-air and SF6-CO2 mixtures in positive and negative rod-plane gaps. These voltages are compared with values obtained for SF6-N2 mixtures. The results show that the breakdown voltages of SF6-air mixtures exhibit corona stabilization over a pressure range which depends upon SF6 content of these mixtures, and is higher than the corresponding values for SF6-N2 and SF6-CO2 mixtures. Moreover, a simple method to estimate the corona-stabilized breakdown voltages of SF6-gas mixtures is discussed. It is shown that at low pressures, this method gives estimated voltages which are generally in reasonable agreement with the experimental measurements of several authors.