Effect of breaking speed on plasma distribution characteristics during the arc extinction process

Abstract

During the tripping of a direct current (DC) vacuum circuit breaker, a plasma arc is generated between the contacts. Different tripping speeds alter the plasma diffusion space between the contacts, affecting the plasma’s longitudinal and axial diffusion rates. Under identical commutation gap conditions, tripping speed also influences the arc duration, thereby affecting the generation and persistence of the plasma. Consequently, this leads to differences in the plasma energy dissipation rate during the arc extinction phase and the residual plasma quantity after arc extinction. To investigate the effect of tripping speed on the vacuum arc extinction process, a 10 kV DC vacuum circuit breaker was selected as the research subject. A three-dimensional transient magnetohydrodynamic simulation model was established to analyze the influence of tripping speed on arc characteristics and the distribution patterns of temperature, pressure, and velocity fields, followed by experimental verification. The results show that, for a given arc burning duration, increasing the opening speed promotes axial elongation of the arc column and enhances convective transport within the plasma. This leads to accelerated arc quenching, improved arc controllability, and enhanced diffusion of high-temperature plasma. Correspondingly, the temperature, pressure, and velocity fields evolve toward configurations that are more favorable for arc extinction. Therefore, increasing the opening velocity enhances the spatial diffusion and energy dissipation of the plasma, thereby significantly improving the interrupting performance of the circuit breaker.