Decomposition Process of SF6 with Residual O2 under Over-Thermal Fault

Partial over-thermal fault may occur in gas insulated equipment during operation due to poor contact or overload. SF6 gas insulating medium is stable under normal conditions, while it begins to decompose into sulfur fluorides when the temperature exceeds 300 degree Celsius. Especially when moisture and oxygen exist in the chamber, the decomposition products further react with them to form stable products such as SO2, SO2F2, SOF2, CO2, COF2, SOF4, HF and so on, the reaction processes of which are irreversible. However, the mechanism of O2 on the decomposition of SF6 and the formation of the products is still unclear. The paper focuses on the reaction processes involving oxygen and analyses the role O2 plays in the decomposition of SF6.