Particle-in-cell/Monte Carlo collision simulation on gap breakdown characteristics of under the conditions of hot-electrode and high-temperature gas medium in low-voltage circuit breaker chamber

The gas composition inside the low-voltage circuit breaker (LVCB) chamber and the residual plasma in the post-arc stage affect the breakdown process, which in turn affects the breaking capacity of LVCBs. In this paper, the back-arc breakdown and post-arc re-breakdown phenomena occurring inside the LVCB chamber are categorized as the breakdown in the case of high-temperature gas gap of hot electrodes, for which a particle-in-cell/Monte Carlo collision simulation model has been established, which takes into account the effects of high-temperature gas components, cathode electron thermal emission, electron collision ionization, and other effects, and simulation studies have been conducted. The simulation results show that the gap breakdown is mainly caused by the high-temperature hot free background gas and the cathode thermal electron emission. A plasma sheath layer is formed at the cathode during the breakdown process, and the electric field strength in the sheath layer is higher than that in other regions. With the development of the streamer to the cathode, the thickness of the sheath layer becomes narrower and the electric field strength increases, and finally, a discharge plasma channel is formed in the gap.