Introduction and Test Analysis of the Disconnector and Earthing Switches of SF6/N2 Mixed Gas in GIS

Sulfur hexafluoride (SF₆) gas is widely used in high-voltage and ultra high-voltage electrical equipment because of its excellent insulation and arc-extinguishing performance and stable chemical properties. SF₆ is an inert gas with significant greenhouse effect. If SF₆/N₂ mixed gas is used in GIS, the usage of SF₆ can be significantly reduced and the harm of greenhouse gases can be reduced. Therefore, many manufacturers carry out the key technology research and engineering promotion of SF₆/N₂ mixed gas in GIS application. At present, SF₆/N₂ mixed gas has been applied in insulated bus of GIS in China, and it operates well in power system. On this basis, China has carried out the design and research of low content SF₆/N₂ mixed gas for disconnector and earthing switches in GIS. At the same time, many manufacturers have carried out tests in lab to verify the low content SF₆/N₂ mixed gas for disconnector and earthing switches in GIS, including insulation test, induced current switching test and short-circuit making test, and so on. In this paper, the related requirements of SF₆/N₂ mixed gas of disconnector and earthing switches in GIS are briefly introduced. Combined with low content SF₆/N₂ mixed gas of disconnector and earthing switches in several GIS, the induced current switching test and short-circuit making test are analyzed. The test situation of this kind of product in the test is summarized, and the existing problems in the induced current switching test are emphatically analyzed. It is of great significance to the follow-up development of this kind of product.