Decomposition characteristics of SF₆ under partial discharges with point-to-plane electrode defect

Field experience shows that the long-term existence of the partial discharge (PD) in gas-insulated switchgear (GIS) will gradually erode the insulation and ultimately cause disastrous insulation breakdown. The decomposition compound analysis of SF6in GIS is an effective method to diagnose the PDs caused by insulation defects. It is significant to clarify the decomposition characteristics of SF6under PDs, which is common in GIS. In this paper the discharge energy/charge and SF6decomposition under PDs with point-to-plane electrode defect were investigated under different factors such as needle curvature, applied voltage, gas pressure and moisture content (adsorbent). And the feature extraction of SF6decomposition under PDs was also discussed. The results show that the yields of SOF2, SO2F2and SO2tend to increase approximately linearly with the accumulation of PD energy. In addition, the needle curvature and applied voltage have a great influence on the discharge energy/charge and the yield of SOF2/SO2F2. Also, the adsorbents composed of KDHF-03 or F-03 have a certain effect on the discharge energy. Besides, the discharge energy and charge tend to decrease with the increased moisture content, and the yields of SOF2, SO2F2and SO2are affected by the humidity (250 μL/L - 2500 μL/L) observably.