Impulse Voltage Breakdown Characteristics of Teranry Gas Mixtures in A Coaxial Cylinder Gap

Impulse breakdown characteristics for ternary gas mixtures were studied using a coaxial cylinder geometry. The experimental mental pressure ranged from 100 to 600 kPa. The mixtures comprised SF6 with an additive C-C4F8 and various proportions of "buffer" gases including N2, C02, CO, and dry air. For 50% flashover voltages, mixtures containing CO exhibited highest dielectric strength for pressures up to 500 kPa. The studies also showed that for a coaxial cylinder geometry the breakdown strength is not affected significantly by increasing the amount of the additive gas C-C4F8 but is determined by the total percentage of the electronegative gas component.