Arc Runners

Arc runners are metallic or conductive elements strategically positioned within an arc chute assembly of circuit breakers or switches. Their primary function is to attract, split, and guide the electrical arc formed during contact separation away from the main contacts, directing it into the arc chute's quenching chamber where it is cooled, elongated, and extinguished through deionization and cooling mechanisms. This prevents contact erosion, maintains dielectric strength, and ensures safe interruption of fault currents.

Arc runners operate on electromagnetic and thermal principles. When an arc forms between separating contacts, the high current creates a magnetic field. The arc runners, being conductive and positioned to create a lower impedance path, attract the arc due to electromagnetic forces (Lorentz force). The arc then travels along the runners into the arc chute, where it is split into smaller arcs, cooled by heat dissipation and deionizing plates, and extinguished as current approaches zero.