Patent ID: 6636133
Filing Date: 2003-10-21
Classification: H01H

Abstract:
A circuit breaker comprising:a fixed contact; a moveable contact, which is moveable into and out of electrically conductive engagement with said fixed contact; a line terminal operatively coupling said fixed contact with a circuit to be protected by said circuit breaker; a middle terminal operatively coupling said moveable contact with said circuit to be protected, in series with said line terminal, said fixed contact and said moveable contact; a load terminal in series with said middle terminal and operatively coupling said circuit breaker to a load; and a trip mechanism responsive to at least a thermal trip element for causing the moveable contact to move out of engagement with the fixed contact in response to a given amount of thermal energy caused by current over time passing through a circuit breaker current path comprising said fixed contact, said movable contact, said line terminal, said middle terminal, said thermal trip element and said load terminal from a circuit to be protected; wherein at least one of said line terminal, said load terminal, and said middle terminal is constructed of a positive temperature coefficient material and is configured for introducing a predetermined resistance into a current path in said circuit breaker so as to limit current reaching said thermal trip element as temperature rises, so as to protect said thermal trip element from excessive thermal stress, said predetermined resistance increasing with increased temperature.