| 摘要 |
<p>[Problem] To obtain a circuit breaker equipped with a thermomotive electromagnetic tripping device having a small size and capable of increasing the temperature of a bimetal during a tripping operation by overcurrent. [Solution] The circuit breaker comprises: an opening and closing mechanism unit (7) for driving to open and close the contact points of a movable contact (6) and a fixed contact (5) used for opening and closing three-phase electric paths; an electromagnetic tripping device for driving a trip bar when overcurrent flows through the electric paths to trip the opening and closing mechanism unit (7); and thermomotive tripping devices (11) for driving the trip bar (14) by using bimetals (12) bending when the overcurrent flows through the electric paths to trip the opening and closing mechanism unit (7). In the circuit breaker, the thermomotive tripping devices (11) are provided at three poles provided adjacent to each other and corresponding to the three-phase electric paths, and among the bimetals (12)of the thermomotive tripping devices (11) at the respective poles, the plate thickness of at least one bimetal is differentiated from those of the other bimetals.</p> |
