Patent ID: 8717127
Filing Date: 2014-05-06
Classification: H01H

Abstract:
1. A circuit breaker, comprising: a molded case constructed of a case main body and a cover placed on an upper portion of the case main body, and housing: a first movable contact having a first movable contact point disposed at a leading end thereof; a contact portion pivotally supporting the first movable contact through an insulating holder; a second movable contact having a second movable contact point disposed at a leading end thereof to contact with the first movable contact point, and connected to a power source side terminal block through a lead; a switching mechanism to switch the first movable contact; a load side terminal block connected to the first movable contact; an overcurrent tripping device connected to the load side terminal block; an arc extinguishing chamber to extinguish an arc generated between the first movable contact point and the second movable contact point; and a latch mechanism having a latch operating together with a second movable contact, which opens in response to an electromagnetic repulsive force of a short circuit current, and holding the second movable contact in a predetermined open position through the latch, which pivots by an increase of an internal pressure of the arc extinguishing chamber due to the generation of the arc, wherein the case main body comprises a bottom case forming a bottom portion of the circuit breaker, and an intermediate case mounted on an upper portion of the bottom case and having a dividing wall blocking a space between the intermediate case and the bottom case, the power source side terminal block and the second movable contact are fitted inside the bottom case, the first movable contact, the load side terminal block, the overcurrent tripping device, the holder, the contact portion, and the arc extinguishing chamber are fitted inside the intermediate case; the latch mechanism further comprises a side plate pivotally supporting a contact spring urging the second movable contact toward the first movable contact and the latch through shafts, and a gas pressure base covering the side plate, the latch mechanism and the power source side terminal block connected to the second movable contact through the lead are formed into a unit, and the unit, a magnetic yoke enclosing the second movable contact point of the second movable contact from left and right so that side portions thereof extend upright in an opening movement direction of the second movable contact, and a magnetic yoke cover covering the left and right side portions of the magnetic yoke from inner and outer sides, are fitted inside the bottom case.