Influence of oxygen on solid carbon formation during arcing of eco-friendly SF<sub>6</sub>-alternative gases
Boya Zhang, Sunsiqin Wang, Li Chen, Xingwen Li, Nian Tang
Abstract
Abstract During the arc breaking process of high-voltage circuit breakers, the eco-friendly SF 6 -alternative gases will inevitably decompose and generate various decomposition products. In some cases, this will contain solid by-products such as solid carbon, which will have a deterioration effect on the electrical insulation performance of the equipment. It has been found that adding a proper amount of O 2 can effectively inhibit the formation of solid carbon. In this paper, based on the improved Gibbs free energy minimization method, a calculation model considering the solid decomposition products was established, and the arc plasma composition of CO 2 /O 2 mixtures with the new eco-friendly gases, such as C 4 F 7 N, C 5 F 10 O, HFO-1234ze(E) and HFO-1336mzz(E), in local thermodynamic equilibrium state was calculated. The change of decomposition products with the initial O 2 ratio is studied, and the criterion expression of inhibiting solid carbon formation is obtained. We also applied the method to the calculation of other SF 6 -alternative gases containing sulfur atoms such as NSF 3 and CF 3 SO 2 F. Finally, we showed that solid carbon can be inhibited when a proper molecule formula is satisfied. This work may provide new ideas for further exploring the potential of SF 6- alternative gases.