Characteristics of the Concentration Ratio of SO₂F₂ to SOF₂ as the Decomposition Products of SF₆ Under Corona Discharge

Partial discharge (PD) is triggered by insulation defects in a gas-insulated switchgear (GIS), leading to the decomposition of SF6gas. The decomposition products of SF6can be used to detect and recognize PD, but feature parameters must first be established. The main stable components of SF6decomposition products are SO2F2and SOF2. Their concentration ratio c(SO2F2)/c(SOF2) is used as a feature parameter in PD recognition. However, the physical significance and characteristics of c(SO2F2)/c(SOF2) have not yet been studied. In this paper, an experimental platform was constructed to simulate SF6decomposition under PD in a GIS. The concentration data of SO2F2and SOF2under different discharge energies, moisture contents, and oxygen contents were obtained. The data show that c(SO2F2)/c(SOF2) increases with increased discharge energy and decreases with increased moisture as well as oxygen contents. These phenomena are explained by the discharge decomposition mechanism of SF6. The results further indicate that c(SO2F2)/c(SOF2) can be used as a feature parameter for determining the discharge energy with which it has a positive relationship. To improve PD recognition, the effects of moisture and oxygen contents must be considered when using c(SO2F2)/c(SOF2) as a feature parameter.