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For vacuum circuit breakers, the anode will change to active mode when the current is high enough. The vapor produced by the anode will become another important source of plasma. In this paper, a three-dimensional (3D) magnetohydrodynamic model considering anode vapor and multiple components is developed to study the vacuum circuit breakers with cup-shaped CuCr contact. The characteristics of arc under the actual magnetic field with different anode temperature distribution and different cathode utilization are simulated. Moreover, the ionization and recombination processes between different kinds of components are considered. The simulation results show that the arc current concentrates toward the center. The current value is high between electrodes slots under the actual magnetic field, which significantly affects the arc characteristics. At the same time, higher anode temperatures will produce more neutral atom vapor area (NAVA). Current is concentrated outside NAVA due to the low conductivity of NAVA. As NAVA expands, the constriction of current on the outside is more severe. The simulation results in this paper are consistent with the experimental results.
Wang et al. (Fri,) studied this question.