SF6 Alternative Gas Lightning Impulse Insulation Breakdown Characteristic in Medium Voltage

Sulfur hexafluoride (SF6), a greenhouse gas, is used as an insulating medium for power equipment due to its excellent insulating properties. However, as global warming and climate change become a global concern, the development of products that minimize the environmental impact is increasing, and SF6 replacement gas is being studied as an environmentally friendly alternative. Currently, there are N2, CO2, and fluorine mixed gas as substitute gas of SF6 in medium voltage classes, and research on insulation characteristic for substitute gas is actively proceeding. In this paper, we present the results of a comparative study of breakdown voltage of C5F10O/CO2 and SF6 gases under lightning impulse voltage in a sphere-to-plate electrodes arrangement. The equivalencies between breakdown voltage of SF6 and those of SF6 replacement gases with respect to pressure and percentage of SF6 and C5F10O/CO2 are presented and discussed.