Plasma arc interactions with electric circuit: Variability of arc V-I characteristic

The main goal of this letter is the investigation of the interaction of generated plasma arc in SF6 circuit breakers with electric circuits. According to the electric circuit theory, when there is a nonlinear element in the circuit such as an arc, the intersection of the nonlinear V-I curve of the arc and the circuit V-I curve can be used to find the circuit operating point. In this letter the correctness of this approach for finding the system operating point is interrogated, by using a multi-physic model, including the Navier-Stokes equations and standard K - epsilon turbulent model for modeling the dynamic of the SF6 gas, heat equation for calculation of the SF6 gas temperature, Maxwell equations for electromagnetic fields modeling, gas state equation for taking into account the temperature dependency of SF6 gas properties, and Kirchhoffs voltage and current laws equations. Numerical studies have been performed during the closing operation of a puffer-type 72.5 kV SF6 circuit breaker.