Controlling D-C arcs

A method of controlling d-c power arcs is presented, with the emphasis on eliminating retrogressive motion of the arc. Stills from motion pictures of power arc interruptions in a normal atmosphere present the fundamental nature of arc retrogression. The various characteristics of an arc which cause such motion are detailed, and countered by simple design principles. Control of the arc reduces erosion of the metal parts, gives better protection to the circuit, and reduces total arcing time.