Compressed Gas Insulation in the Million-Volt Range: A Comparison or SF6 with N2 and CO2

Maximum voltage which can be insulated between a sphere and a plane has been measured as a function of gas pressure and gap. It is found to be approximately three times higher in SF6 than in N2+C02, up to pressures of roughly 9 atm (atmosphere). For higher pressures the relative superiority of SF6 over N2+C02 diminishes. Gradients of more than 100 Mv (million volts) per m (meter) were insulated on a 19-mm (millimeter)-diameter electrode in 20 atm of SF6.