Numerical Study of Large Contact Diameter and Gap High Current Vacuum Arc

As the voltage level of the vacuum interrupter increases to 252 kV (245 kV), the contact diameter and gap will increase significantly. Based on the 2-D vacuum arc (VA) MHD model, this work explores the characteristics of large contact diameter (150 mm) and gap (70 mm) VA plasma. The simulation obtained the arc column plasma parameters distribution with different contact diameters, contact gap, cathode side current density distribution, breaking current size, and axial magnetic field (AMF). The simulation results show that the VA shrinks to a high degree when there is no AMF. As the AMF increases, the particle temperature and current density gradually change from a central agglomeration distribution to an annular distribution on the anode side. The control effect of the AMF on the VA weakens. Reducing the breaking current and the contact gap will make the axial current density distribution more uniform and the particle temperature lower. The reduction of the contact diameter is not conducive to breaking large diameter and large spacing VAs. The research results can provide an in-depth understanding of the switching characteristics of higher voltage vacuum circuit breakers and provide an essential theoretical basis for developing 252 kV vacuum circuit breakers.