Breakdown voltage characteristics in the SF6/N2 gas mixtures for DS/ES compartment of a 245kV gas insulated switchgear

The SF₆ gas insulated switchgear (GIS) is the electric power equipment for transmission and distribution line which reduced the size of the electric power equipments by installing in a sealed tank. Since the size of the GIS is about 1/10 of the air insulated switchgear, high quality insulation gas should be used. However this gas is a source of global warming and its production cost is very high because of expensive insulation material. Therefore, it is necessary either to develop a new relative gas: air and N₂ gas or to reduce SF₆ gas. The development of N₂ mixture gas is needed when we consider safety and economic feasibility. In this study, a full scaled gas chamber for DS/ES compartment was designed and evaluated the breakdown voltage characteristics. In the mixing ratio of SF₆/N₂=50/50, insulation performance tests for DS/ES compartment for 245kV GIS were also conducted. By comparing and analyzing SF₆ gas and SF₆/N₂ mixture gas, the results will be actually used as the standard reference of insulation design for eco-friendly 245kV GIS.