Fundamental characteristics of arc extinction by magnetic blow-out at DC voltages (<500V) II

As various DC power supply systems such as photovoltaic power generation, fuel cell and others have become gradually popular, DC current interruption is one of the key technologies for reliability and safety of DC switching devices. In a previous paper a model switch is developed with magnetic blow-out of three levels, and gap length and arc length at arc extinction are obtained by a high-speed camera in range of current less than 4 A and voltage lower than 500V. The gap length and arc length at extinction are much shorter than those without magnetic blow-out.In this paper the interrupted current is expanded to 30A and source voltage is 100, 300 and 500V. The results are compared with previous ones and the followings can be made clear. The gap width at arc extinction is almost independent of interrupted current and source voltage. Those gap width is 0.8, 0.3 and 0.2 mm for magnetic flux densities 19, 53 and 157mT, respectively, and in accordance with the previous values. On the other hand, the arc length becomes longer with interrupted current / source voltage. The maximum length reaches about 60 mm at 500V and 30A for19mT. In addition the change of arc length with time is discussed and the process is found to consist of slow rising and rapid rising intervals.