Electrical contact arm assembly for a circuit breaker

Abstract

A contact arm assembly is provided having an electrical contact for making and breaking an electrical current, a contact arm for supporting the electrical contact, and a bond surface on the contact arm that is conditioned for improving the bond between the electrical contact and contact arm. Also provided is an electrical circuit breaker that utilizes the improved contact arm assembly. The bond surface of the contact arm is provided with pyramid-shaped serrations that serve to more uniformly distribute the electrical current during brazing, provide multiple areas of localized current constriction during brazing, and provide collector pockets for accumulating the molten braze alloy during brazing. The uniform distribution of electrical current during brazing serves to generate a uniform temperature gradient across the braze area for uniform melting of braze alloy. The multiple areas of localized current constriction during brazing serves to temporarily elevate the temperature of the braze joint during brazing by localizing the heat generation proximate the braze alloy, thereby effectively reducing annealing of the contact arm. The collector pockets for accumulating the molten braze alloy during brazing effectively eliminates the overflow of braze alloy onto the edges of the contact and contact arm. A contact arm assembly having uniform melting of braze alloy, reduced annealing of the contact arm, and reduced overflow of braze alloy onto the edges of the contact and contact arm results in an improved bond of contact to contact arm.