Circuit breaker includng improved undervoltage trip means

Claim 1

A circuit breaker comprising relatively movable contact means, operating means releasable to effect opening of said contact means, a trip shaft disposed in a first position to latch said operating means and movable to a second tripping position to release said operating means, an undervoltage trip device comprising an electromagnet including a magnetic member movable from a first position to a second position in response to a predetermined loss of voltage, a latching member operatively connected to said magnetic member, said latching member being maintained in a first position when said magnetic member in a first position and being rotatably supported to move to a second position when said magnetic member moves to its second position, first means for biasing said latching member and said magnetic member to their second positions, respectively, upon said loss of voltage, an actuating member releasably latched in a first position by said latching member when said latching member is in its first position and movable to a second tripping position when said latching member moves to its second position to release said actuating member, second means for biasing said actuating member to its second position when said latching member releases said actuating member, an extending member disposed on saiD trip shaft and engaged by said actuating member during the movement of said actuating member from its first position to its second position to actuate said trip shaft to said second tripping position to release said operating means, the torque exerted on said latching means in its first position through said actuating member by second biasing means being substantially negligible.