Influence of Different External Magnetic Field Applied Time on the Dynamic Voltage Distribution of Double-break Vacuum Gaps in Series

External magnetic field configurations have an important effect on the dynamic voltage distribution of vacuum circuit breakers (VCBs) in series, but few works pay attention to it so far. The objective of this paper is to study the dynamic voltage distribution of VCBs with different external magnetic field (EMF) applied time. The simulation model of integrated vacuum chamber was built up. The capacitances of each break and stray capacitance were calculated. The test platform was set up based on integrated vacuum chamber. The dynamic voltage distributions of VCBs with different EMFs applied time were studied and analyzed. The test results prove that, the unbalanced coefficient of dynamic voltage distribution is improved with EMFs. Under the experimental conditions, the unbalanced coefficient is reduced by 12.6% at most. And better dynamic voltage distribution results can be obtained by applying magnetic field of low-voltage break closer to current zero point. The works in this paper provide references for magnetic field regulation and optimization design of the series vacuum switch of multi-break VCBs.