An Experimental Study of the Influence of a Uniform External Magnetic Field on Electric Arcs in Low Voltage DC Switching

The effect of magnetic field on low voltage electric arcs is investigated experimentally in a dc switch apparatus with a controlled contact opening velocity (10–500 mm/sec). The switch comprises <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{AgSnO}_{2}$</tex> contacts and parallel copper runners. The applied voltage is up to 55 V, and the applied current up to 45 A. A uniform magnetic field (0 mT-40 mT) is applied. In addition, an oscilloscope was employed to measure the arc voltage and current, and a high-speed camera was used to record the arcing event at a rate of 10,000 frames per second. The images were analyzed to measure the arc's length and diameter and estimate its column conductivity. The results show that arc conductance and conductivity reduce significantly when a magnetic field is applied.