Modeling and Simulation of Vacuum Arc Plasma Transport Properties Under the Influence of Anode Melting Pool

With advancements in vacuum technology, the application range of vacuum circuit breakers has increased to high-voltage applications. When a vacuum circuit breaker breaks a high current, the vacuum arc type changes from diffusion to agglomeration. The energy transported from the arc column to the anode increases as the arc current and anode temperature increase to surpass the melting point of the anode material. Under extreme circumstances, an anode melting pool is formed; this influences the properties of the vacuum arc plasma between the electrodes and inhibits the strength recovery of the insulating medium, which increases the likelihood of breaking failure. Taking the arc region of an electrode with a diameter of 30 mm and a spacing of 10 mm as the basic simulation object, we developed a 2-D magnetohydrodynamic (MHD) model to simulate the properties of a high-current vacuum arc after anode melting pool formation. By changing the anode boundary conditions, different ablation conditions of the anode surface after the arc are analyzed, demonstrating that the pressure distribution of vacuum arc plasma is independent of the anode melting pool depth, diameter, and distance. The maximum pressure increases with an increase in the arc current. The maximum temperature of the vacuum arc plasma is positively correlated with the arc current, depth, and diameter of the melting pool and distance between the electrodes; however, it is independent of the presence of a melting pool on the cathode surface. When the edge of the melting pool produces bumps, the maximum temperature decreases and greater protrusion heights produce further temperature drops. These research results provide the theoretical basis for the improvement and development of vacuum circuit breakers.