Characteristics of Break Arcs Magnetically Blown-Out with Simplified Shape in a 200V-500VDC/10A Resistive Circuit

摘要

Silver electrical contacts were separated at constant opening speed in a 500VDC resistive circuit. Break arcs were extinguished by magnetic blowing-out with transverse magnetic field of a permanent magnet. Circuit current when contacts were closed was 10A. Supply voltage was varied between 200-500V. The electrical contacts and the magnet were arranged to simplify horizontal shape of the break arcs. Magnetic flux density of the transverse magnetic field was in the range of 20-140mT. Images of the break arcs were taken simultaneously from two directions that were the horizontal and vertical directions using two high speed cameras. The shape of the break arcs and arc length L just before arc extinction were analyzed from the images. As a result, both the cathode and anode spots were able to be observed under all experimental conditions, and the shape of the break arcs were relatively simple except when the magnetic flux density was 20mT and the supply voltage E was 400V and more. The arc length just before arc extinction increased with increasing the supply voltage and decreased with increasing the magnetic flux density.