Texas Instruments Corporation

Michael J Lavado

Peter G Berg

Nathaniel Wicks

A circuit breaker (,) is shown having a movable electrical contact (,) adapted to move into and out of engagement with a stationary electrical contact (,). A current carrying thermostatic trip member (,) has a portion movable in response to changes in temperature with a motion transfer member (,) transferring the motion to latch/catch mechanism (,). The catch portion (,) comprises a generally U-shaped adjustment element (,) formed of thermostatic material whose legs are fixed to the base (,) of a catch member (,) which in turn is pivotably mounted in the casing of the circuit breaker. The bight (,) of the adjustment element is free to move in response to temperature changes relative to the catch member. Overcurrent will cause the thermostatic trip member to transfer motion to the bight of the adjustment element causing the adjustment element and catch member to pivot and release a latch to thereby open the circuit breaker. According to a first embodiment, the thermostatic adjustment element (,) is oriented relative to the thermostatic trip member such that the two components move in opposite directions upon a change in temperature making the circuit breaker sensitive to changes in ambient temperature. A modified embodiment includes a stop member (,) to limit movement of the adjustment member in one direction to make the circuit breaker sensitive to ambient temperatures over one range of temperature and less sensitive over a second range of temperature. Another embodiment shows the adjustment element (,&prime;) separated at its bight (,) with each leg (,) formed of selected material to provide various combinations of selected ambient sensitivity response to the circuit breaker.

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Chepachet, RI, United States of America

Michael J Lavado