Characteristics of Break Arcs Driven by External Magnetic Field in a DC42V Resistive Circuit

Break arcs occurring between electrical contacts are driven by the external magnetic field. Break arcs are observed using a high-speed camera. The external magnetic field is applied with a permanent magnet. The distance between the electrical contacts and the magnet is varied. Experimental circuit is DC 42 V-10 A resistive circuit. Material of electrical contacts is pure silver. The opening speed of electrical contacts is varied as 5, 10 and 20 mm/s. Following results are shown. The arc duration decreases with decrease of the distance between the electrical contacts and the magnet. When the magnetic-flux density applied by the external magnet is lower than a certain value at the center axis of the electrical contacts, the effect of the magnetic field to drive the break arc becomes ineffective to shorten the arc duration. The result is explained with a relationship between the motion of break arc and the distribution of the external magnetic field.