Abstract: This circuit breaker comprises closing-assist means for opposing the contact-repulsion forces developed when a high current flows through the circuit breaker. This closing-assist means comprises spaced segments of high permeability material fixed to opposite sides of the usual movable contact rod and projecting laterally therefrom. Two stationary bridging members of high permeability material are located at opposite sides of said contact rod, and each extends between said segments when the contacts are engaged. The segments are located in proximity to but slightly spaced from the bridging members when the contacts are engaged so that said bridging members and said segments define a high permeability path around the contact rod containing short gaps between said segments and said bridging members.

Abstract: This trip device comprises a permanent magnet of cobalt-rare earth material and a plunger which is normally held in a withdrawn position by the permanent magnet. A tripping coil surrounds the plunger and, upon energization, develops tripping flux that opposes the holding flux from the permanent magnet, thereby to effect release of the plunger. In a position between the tripping coil and the permanent magnet, flux-diverting structure of highly permeable magnetic material is provided for shunting a portion of the tripping flux through a shunt path bypassing the permanent magnet. This shunt path contains a relatively large non-magnetic gap for limiting the tripping flux through the shunt path sufficiently to cause 30 percent or more of the tripping flux to pass through the permanent magnet in a direction opposite to the direction of the holding flux.