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 SF₆ in GIS is an effective method to diagnose the PDs caused by insulation defects. It is significant to clarify the decomposition characteristics of SF₆ under PDs, which is common in GIS. In this paper the discharge energy/charge and SF₆ decomposition 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 SF₆ decomposition under PDs was also discussed. The results show that the yields of SOF₂, SO₂F₂ and SO₂ tend 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, SO₂F₂ and SO₂ are affected by the humidity (250 μL/L - 2500 μL/L) observably.