Patent ID: 6255925
Filing Date: 2001-07-03
Classification: H01H

Abstract:
An adjustable thermal-magnetic trip unit for a molded case circuit breaker, with the circuit breaker including a housing having an operating mechanism including an intermediate latch, a line terminal, a load terminal and a cover, the adjustable thermal-magnetic trip unit comprising:a magnetic yoke mounted in the housing;a bimetal member mounted in the magnetic yoke, with the bimetal member having a fixed end and a movable end, with the fixed end coupled to a load bus of the load terminal and the movable end coupled to a movable contact of the operating mechanism;a trip bar extending along a horizontal axis and rotatably mounted in the housing, with the trip bar having an actuating arm positioned with a gap from the movable end of the bimetal member and with the actuating arm aligned to selectively engage the movable end of the bimetal member;a latch pawl mounted on the trip bar, with the latch pawl having an inclined latching surface aligned with and engaging an inclined latch surface of the intermediate latch; and,an adjustment knob associated with the trip bar, with the adjustment knob having an eccentric pin aligned with a slot in the trip bar, wherein the rotation of the adjustment knob imparts a lateral position motion to the trip bar along the horizontal axis thereby moving the latch pawl along the inclined latching surface to change the gap between the actuating arm and the movable end of the bimetal member.