Characteristics of PD Decomposition of SF6/N2 Gas Mixture Under Metal Protrusion Defects

SF6 gas has many disadvantages such as extremely high greenhouse effect and easy to liquefy in low temperature environment. Using SF6/N2 gas mixture to replace pure SF6 gas can improve the liquefaction temperature and environmental characteristics of pure SF6 gas. In this paper, the needle-plate electrode is used to simulate the metal protrusion defects and carry out the 96 h partial discharge (PD) decomposition experiment of 50% SF6/50% N2 gas mixture. The results show that the content of five characteristic components, SO2F2, SOF2, SO2, NO2 and NF3, all increase with the increase of discharge time and external applied voltage, and the content of SOF2 is always higher than SO2F2 at the same external applied voltage, and the effective gas production rate of SO2F2 and SOF2 basically shows a linear growth trend with the increase of magnitude of PD, SO2F2 and SOF2 can be used as the characteristic products to characterize the severity of defective metal protrusions in SF6/N2 gas mixture insulated equipment.