Characterization of the switching arc in hydrogen under different pressure conditions

The characteristics of filling gas and its resulting arcing behavior is a major factor influencing the current-limiting and switching performance of gas-filled direct current (DC) switches. The use of hydrogen (H2) or mixtures containing H2 as dielectric gas has shown increased breaking performance in compact DC switches. However, arcs in such gases, especially in pure H2 show a complex fluctuating dynamics, especially at higher filling pressures and by simultaneous use of magnetic blown-off. This paper conducts an electrical and optical study of the rapid and unstable arc behavior in H2 at pressures of 1 and 6 bar using a model switch with arc runners. The results remark the significant impact of filling pressure on the arc voltage and the coupled current limiting performance. Moreover, the arc dynamics become more unstable and faster, and the arc shape becomes strongly distorted. Compared to atmospheric pressure, the rate of increase in arc voltage and arc length are noticeably higher.