Characteristics of Break Arcs Driven by Transverse Magnetic Field in a DC High-Voltage Resistive Circuit

Abstract

Break arcs are generated between pure silver electrical contacts in a DC high-voltage resistive circuit. The break arc is driven by the external magnetic field of a permanent magnet from horizontal direction of contacts. Electrical contacts are separated at constant opening speed at 75 mm/s. The maximum supply voltage is 300 V. The maximum circuit current when electrical contacts are closed is 20 A. The maximum output power of the supply is limited to 6.0 kW. The gap between the contacts and the magnet is defined as x. The gap is varied from 2.5 mm to 10.0 mm to change the magnetic flux density that affects the break arc. The break arc is observed with a high-speed camera. The effect of the magnetic field on the arc duration was examined. As a result, break arcs are successfully extinguished by the transverse magnetic field when the gap x is 2.5 mm. Then the length of the break arc just before lengthening of the break arc L and the Lorentz force that affects the break arc F are examined. The length L was almost constant for each gap x and independent of the circuit current I and the Lorentz force F. The break arc is driven by the magnetic field when the arc length reached a certain length that was determined by the strength of the magnetic flux density.