Modeling and Simulation of the Dynamic Characteristics of Vacuum Arc in DC Interruption Based on Artificial Current Zero When the Current is Close to Zero

During the rapid current falling phase of DC breaking, due to the current drops quickly, resulting in a strong eddy current effect, which makes that the variation of the axial magnetic field (AMF) produced by AMF contact obviously lags behind that of current. Therefore, when the current approaches zero, the strength of AMF in the electrode gap is still strong. According to previous research, when the current density of high-current vacuum arc is less than 500 A/cm2 or the strength of the AMF is greater than 10 mT/kA, the vacuum arc (VA) is a multi -cathode vacuum arc. This article aims to study the dynamic properties of VA in DC breaking process based on artificial current zero when the current approaches zero. The dynamic characteristics of single-cathode spot jet are simulated by 2D transient MHD model. The simulation results indicate that the ion density, axial current density, ion pressure, ion temperature and electron temperature of plasma decrease with the decrease of arc current, and the diffusion degree of arc shape decreases with the decrease of current.