II — Various factors aid extinction of arcs

EXPERIMENTS to determine the influence of such parameters as electrode material, current strength, and arc length on the characteristics of the more common type of stationary arcs with molten electrodes, have given results not previously expected. Simplified calculations made by Slepian a few years ago based on the theory that ions are lost from the arc space only by direct ion recombination, predicted a manner of recovery of dielectric strength substantially the same as that actually revealed by experiments made on cold electrode arcs at about the same time. The rate of recovery of voltage across the arc space following a current zero was controlled by shunting the arc with resistance, and the maximum allowable rate of rise of voltage was determined from the maximum value of shunting resistance at which the arc would just be extinguished after one-half cycle.