Study on the Distribution Characteristics of Actual Magnetic Field in Vacuum Interrupter

The external bus and conductive rod of a vacuum circuit breaker form a “U” shaped circuit, which generates an external transverse magnetic field in the arc area of the arc extinguishing chamber, resulting in severe asymmetry of the transverse magnetic field in the arc area, reducing the breaking capacity and service life of the circuit breaker. In the paper, we use Maxwell to establish a transverse magnetic field model for single-phase short circuit arc region. The analysis revealed that transverse magnetic field in the arc region is severely asymmetric under the effect of the transverse magnetic field generated by the external bus. So as to eliminate the effect of external transverse magnetic field, this paper has constructed stainless steel and iron shield shields to shield the external transverse magnetic field. The results show that both stainless steel and iron shields can shield against transverse magnetic fields, but the effect of iron shields with high magnetic permeability is more obvious. The research results of this paper provide important basis and reference for eliminating the external transverse magnetic field in the arc region, improving the breaking capacity and service life of circuit breakers.