Experimental investigation on the hysteresis characteristic of vacuum arc voltage during the current commutation

During the current-sharing process of vacuum multi-breakers in parallel, the arc voltage drives the current transfer, which causes current commutation among the branch currents. For this special current variation condition, this paper built an experimental platform, which can effectively simulate a current commutation process of vacuum multi-breakers in parallel. Firstly, the volt-ampere characteristics of the vacuum arc in the process of current commutation were analyzed in detail through the arcing experiments. It was found that there was a hysteresis characteristic in the arc voltage, especially in the decreasing current commutation. Next, the influence of peak current, the moment of current commutation, and the depth of current commutation on the hysteresis characteristic of arc voltage were studied, and it was pointed out that when the current in the current commutation was closer to the current zero region, the hysteresis characteristics of the arc voltage were more significant when the current rose back. Furthermore, the arc morphology of the vacuum arc was simultaneously photographed by a high-speed camera, and the evolution of the arc morphology during the current commutation process was investigated. The microscopic physical mechanism causing the hysteresis characteristics of arc voltage was briefly discussed. Finally, the influence of arc voltage hysteresis characteristic on parallel current-sharing was analyzed, and the future improvement direction was proposed. The research of this paper will lay the foundation for revealing the complex current-sharing mechanism of vacuum multi-breakers in parallel.