Contact Arm Assembly For Switchgear Circuit Breaker Having Improved Cooling Fins And Contact Fingers To Maximize Heat Rejection

A method of providing a heat rejecting contact arm assembly for a switch gear circuit breaker, the method comprising the steps of:

• providing a contact arm having a shaft with a longitudinal axis, the shaft having first and second ends;
• a substantially constant outside diameter D;
• a plurality of annular rings extending from the outside diameter of the shaft, the rings being spaced along the longitudinal axis to define cooling fins, diameters of the rings gradually decreasing from the first end to generally the center of the shaft, and then gradually increasing to the second end of the shaft;
• and a groove in the periphery of the shaft,
• assembling the contact arm in a bushing structure such that the center of the shaft is disposed generally at an inlet end of the bushing structure, and
• providing a contact finger having a body and a ball member extending from the body, the ball member being received in the groove so that the contact finger makes contact with the contact arm.