Texas Instruments Corporation

Eric W Morrison

Christian V Pellon

William J Bentley, Jr

Nicholas V Pellon

A thermally compensated circuit breaker has a movable contact assembly ( ) which mounts a movable electrical contact ( ) for movement between open and closed contacts positions with a stationary electrical contact ( ). The contacts are maintained in the closed circuits position by a latching mechanism ( ) which prevents opening of the contacts through an opening contacts force provided by a spring ( ). A current carrying trip arm ( ) deflects upon sufficient I R heating to transfer motion to the latch to separate the latch ( ) from the latch receiving catch ( ) to trip the circuit breaker. The trip arm ( ) is part of a pivotably mounted actuator assembly ( ) having a movable end portion spaced from the pivot disposed adjacent a motion transfer member ( ). A calibration screw ( ) is located so that the longitudinal axis is in line with a movable end portion of the actuator assembly and the motion transfer member. In one embodiment the head of the calibration screw is captured in a slot in the free end of a calibration base ( ) attached to the trip arm so that deflection of the trip arm directly transfers motion to the motion transfer member and in another embodiment the calibration screw head is captured in a slot in the free end of the trip arm so that a bowing deflection of the trip arm causes a calibration base ( ) to which it is attached at an end thereof to rotate with the calibration base directly transferring motion to the motion transfer member.

Calibration structure for circuit breakers having bimetallic trip member

An electric circuit breaker ( ) has a toggle mechanism ( ) having two movable over center joints ( ) connected between a push-button ( ) and a movable contact mechanism ( ). When the push-button is depressed a first link rotates bringing the first movable over center joint ( ) across a center position represented by a first imaginary straight line ( ) to a stop surface ( ). A spring member ( ) provides a bias which acts on the second movable over center joint ( ) normally maintaining the second movable joint against the stop surface so that with the two movable over center joints biased against the stop surface the movable contact mechanism is moved to a closed contact position when the push-button is depressed. An overload responsive member transfers motion to the second movable over center joint ( ) upon the occurrence of a selected overload and moves the second over center joint across a center position represented by a second imaginary straight line ( ) allowing the contacts opening spring ( ) to move the movable contact mechanism to the open contacts position providing a trip free operation. The circuit breaker can be formed for a single phase or it can be formed for multiphase operation in which additional ganged phases have no toggle mechanism but do have separate ambient temperature compensated trip arms and overload responsive members which operate through the single toggle mechanism.

Growing community of inventors

Woonsocket, RI, United States of America

Eric W Morrison