Voltage-current characteristics of breaking arc at constant opening speed in the air

Voltage-Current (VI) characteristics of breaking arc between electrical contacts have been investigated for several contact materials (Au, Ag, Cu, Pt, and Ni). The purpose of this paper is to investigate the VI-characteristics and minimum arc voltages of the breaking arcs that occur between slowly opening (1.0 cm/s) contacts, and compare these results with those of Holm. Experimental circuit is resistive, which has 5-Ω circuit resistance. Experiments were carried out in the air at atmospheric pressure for supply voltages 30, 42, and 54V. The time evolutions of arc voltage, arc current and gap length were measured simultaneously. The VI-characteristics and minimum arc voltages were obtained from those measured values. The results showed that minimum arc voltages for each contact material (Au, Ag, Cu, Pt, and Ni) agreed with those of Holm. On the other hand, VI-characteristics of Au, Ag, Cu, and Pt contacts agreed with those of Holm, but VI-characteristics of Ni electrical contacts disagreed with those of Holm. The difference for VI-characteristics between Ni electrical contacts and the others was because of lower electric field of the arc column for the case of nickel electrical contacts.