Characteristics and Control of High Current Vacuum Arc Deflection Under the Impact of Lateral Magnetic Field

In high-voltage switchgear, the external busbars and conductive rods of a handcart-type vacuum circuit breaker form a “U” shaped loop. During the interruption of short-circuit currents, an asymmetric external lateral magnetic field is generated in the arc region of the arc chamber, leading to arc deflection and electrode erosion. These results in localized high temperatures on the electrode surface, ultimately reducing the circuit breaker’s breaking capacity and service life. This study establishes a high-current vacuum arc magnetohydrodynamic model considering the structure of the arc chamber, and investigates the lateral magnetic field distribution in the arc chamber and its impact on plasma transport characteristics. The distribution results show that, under the influence of the lateral magnetic field generated by the external busbars, the lateral magnetic field in the arc region is severely asymmetric. This asymmetry leads to a shift in the distribution of typical plasma parameters of high-current vacuum arcs, resulting in localized increases in anode temperature, which is detrimental to the interruption of vacuum circuit breakers. To eliminate the impact of the external lateral magnetic field and considering the stainless steel shielding hood structure of the actual vacuum arc zone, this study constructs shielding hoods with intermediate layers made of iron and silicon steel respectively to shield the external lateral magnetic field. Results indicate that both types of intermediate layer shielding hoods have a certain shielding effect on the lateral magnetic field. The findings of this study provide important reference for eliminating external lateral magnetic fields in the arc region.