Influence of contact materials and opening velocity on various characteristics of DC high voltage arc

In this study, we use a apparatus that can be opened at constant speed. The voltage is set to DC 200, 300, and 500 V. The closed contact current is set to constant at 10 A at each voltage. The opening velocity is varied in the range of 1 to 200 mm/s. The contact material is Pd and Pt with low thermal conductivity. The arc duration is obtained from the voltage· current waveforms of the arc discharge, and the arc energy is obtained from the electric power waveform. In addition, arc length and contacts gap length at the time of arc extinction is obtained from the video analysis of the arc discharge light. As a result, it became clear that the arc duration and the arc energy are inversely proportional to the opening speed. These results were similar to that of Ag, W, Ni, and Cu, and the difference due to the contact material was small. The arc length immediately before the arc extinguishment became a constant value determined by the source voltage independent of the contact material and opening velocity. The value was about 30 mm at 200 V, about 60 mm at 300 V and about 110 mm at 500 V.