Chemical kinetic modeling and experimental study of SF6 decomposition byproducts in 50 Hz ac point-plane corona discharges

Corona (partial) discharges are generated in electrical equipment before faults occur due to insulation defects. The SF6-decomposition byproducts induced by the partial discharge are closely related to the insulation state of electrical equipment, so understanding the decomposition mechanisms of the byproducts is very important. In order to analyze the chemical processes and the generation mechanisms of the products of decomposition, two coupled 0D chemical kinetic models were developed and an experiment platform was established to verify the simulation results. The measured and predicted concentrations of SOF2, SO2F2 and SO2 were compared and found to have a reasonable agreement. The time-dependent generation mechanisms of SOF4 and HF were also predicted by the simulation model. The influence of moisture and oxygen impurities was examined; their presence increased the concentration of most of the decomposition products, with moisture generally having a stronger effect; the main exception is SOF4, whose production is predicted to be inhibited by the presence of moisture. Finally, the dominant pathways involving these five species in the plasma region and the gas region were analyzed to determine the dominant chemical processes for the generation and loss of these decomposition products.