The arcing and post-arc breakdown characteristics of SF6 generator circuit breaker based on magnetohydrodynamic model

The structure of the arc chamber in a generator circuit breaker (GCB) influences the movement characteristics of the arc plasma, which in turn affects the breaking capacity of the GCB. Different arc chamber structures are proposed in this paper. Combined with the principles of fluid dynamics, the arcing characteristics in the different arc chambers are obtained by using magneto-hydro-dynamics (MHD) simulation. To further enhance the dissipation of arc energy, a self-blasting GCB structure with pistons is proposed. The results show that the "funnel" structure can accelerate the gas flow during the arcing and arc extinguishing stages, promoting convection between cold and hot gases. The "funnel" structure results in the smallest arc radius at current zero-crossing, and the probability of post-arc thermal breakdown is the lowest. The thermal breaking capacity of the "rectangular" and "trumpet" structures is 82.38% and 42.73% of that with "funnel" structure, respectively. Comparing the structures with and without pistons, the temperature at the end of the center rod in the self-blasting with pistons decreased by a maximum of 36.43%. The arc energy dissipation of self-blasting GCB is the fastest, which helps to improve the breaking capacity of the GCB. This study can provide a reference for improving the breaking characteristics of GCBs and the reliability of the power system.