Simulation of Dynamic Characteristics in the Interruption Process of a 126kV Single-Pressure SF6 Circuit Breaker

To address the challenges posed by the complex airflow, electrical, and thermal fields in the interrupting arc of high-voltage SF6 circuit breaker, this study simulates the dynamic process of short-circuit current interruption in a 126 kV single-pressure circuit breaker using a multi-physics coupling approach. A multi-field coupling model was developed, incorporating plasma thermal equilibrium equations, Navier-Stokes equations for fluid dynamics, the Laplace equation for the electric field, and moving mesh techniques. The simulation results show that the maximum arc temperature in the arcing stage is 18,000 K. During the arc quenching stage, the cold SF6 air flow velocity reaches 250 m/s, which effectively reduces the arc temperature to below 3,000 K through strong convection and heat conduction, ensuring that the arc is reliably extinguished. The synergistic mechanism between the compressed air characteristics of the interrupter and the arc energy dissipation is verified, which provides important data support for the design of circuit breakers.