SF6 arc plasma simulation and breakdown performance prediction using computational fluid dynamics and arc modeling

In SF6 self-blast interrupters, which are being developed as the next-generation switching mechanism, the arc burns within insulating nozzles with an ablation of the nozzle material and leads to an incoming gas flow for the pressure chamber with a pressure-rise during the high-current phase. Close to current zero, the arc can be cooled down and quenched completely by the reverse gas flow from the chamber to the arcing zone according to the pressure gradient between them. Therefore, the interruption of fault currents is dependent on the thermal decay of arcs during the current-zero phase by the blowing-off force, which is generated by the pressure-rise of the chamber during the high-current phase. In this study, we calculated SF6 arc plasmas caused by fault current interruption inside a SF6 self-blast interrupter using a computational fluid dynamics (CFD) technique and investigated the thermal interruption performance with thermal decay near current zero as well as the switching mechanism of the interrupter with an ablation of the nozzle material.