Re-strike phenomenon occurs while the direct current circuit breakers (DCCB) interrupts the fault current, which causes theinterruption time extension and serious damage to the DCCB. However, the reason of the re-strike frequency increment remainsunsolved when the external magnetic field applied. In this paper, a three-dimensional electromagnetic thermal fluid simulationprogram is developed to analyze the occurrence conditions of re-strike phenomenon when different external magnetic field densitiesapplied. Based on the quantitative analyses of simulation results, the electric field density between the re-strike point and the arccolumn right before the re-strike phenomenon occurrence decreases along with the external magnetic field density increase.Because the gas temperature of the re-strike point area becomes higher and leads to the electrical breakdown occur at a lowerelectric field density. As a result, it was elucidated that the re-strike phenomenon occurrence not only affect by the electric fielddensity between the re-strike point and the arc column, but also the gas temperature of the re-strike point area.
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