Analysis of arc plasma during small capacitive current interruption in SF6 circuit breaker

This paper establishes a model for the conductivity of non-equilibrium dual temperature arc plasma during small capacitive current interruption in a SF₆ circuit breaker. Considering the contributions of electron-ion-neutral particle collision frequency and collision cross-section, we obtain the conductivity of SF₆ plasma as a function of temperature and pressure and establish a dynamic arc model for small capacity currents. Based on the model, a numerical simulation is performed on the flow field with a load of small current of 1600 A for a 126 kV SF₆ circuit breaker. Density, pressure and temperature distributions inside the circuit breaker chamber are obtained. With the electric field inside the same interrupter, dielectric recovery characteristic curves are described. In addition, the effect of arc duration on the dielectric recovery characteristics for small capacitive current is studied and the influence mechanism is discussed.