Formation Characteristics of SF6 Decomposition under Partial Discharge Induced by Metal Protrusions with Varying Degrees of Severity

Due to its excellent insulating and arc-suppression properties, sulfur hexafluoride (SF₆) is widely used in gas-insulated switchgear. In the presence of partial discharge, SF₆ decomposes into various by-products according to discharge scenarios. These by-products are often used to detect and identify partial discharge. In this article, formation characteristics of SF₆ decomposition under partial discharge induced by metal protrusions with varying degrees of severity are investigated. The varying degrees of severity of partial discharge were assessed by partial discharge applied voltage and partial discharge inception voltage. Partial discharge applied voltage and partial discharge inception voltage are related to magnitude of partial discharge and varying degrees of the non-uniform electric field distribution distortion, respectively. The results show that the production rates of SO₂F₂ and SOF₂+SO₂ decrease with increasing partial discharge inception voltage, while increasing proportionally to partial discharge applied voltage. The ratio of SO₂F₂ to (SOF₂+SO₂) exhibits a similar trend. As partial discharge applied voltage increases, the production rates of CO₂ and CF₄ increase, but the ratio of CO₂ to CF₄ decreases. Based on the experiments, the formation mechanisms of SF₆ decomposition by-products under varying degrees of severity of partial discharge are analyzed.