| 摘要 |
PROBLEM TO BE SOLVED: To improve the installation structure of a contact pressure spring so as to improve the current limiting effect by reducing the loading force for slowing down the contact opening speed, when the movable contactor makes contact-opening action after receiving electromagnetic repulsion by excess current. SOLUTION: The circuit breaker holds a movable contactor 4 and a double torsion spring ( contact pressure spring) 7 at a contactor holder 5, and a movable contact 5 is made to open the contact by utilizing the driving force of the electromagnetic repulsion F working between the fixed contactor 2 and the movable contactor 4 when excess current i flows, and the offset arm 7b drawn from the coil center of the contact pressure spring 7 is spring-energized in the contact closing direction by being bridged over the rear face of the movable contactor. A taper face 4c having a slope descending frontward on the rear face of the movable contactor is formed, and the tip of the offset arm 7b is pressed on this taper face 4c and energized, thereby, by reducing the bending angleαof the double torsion spring accompanying the contact opening action of the movable contactor, spring resistance for slowing down the contact opening speed is reduced. COPYRIGHT: (C)2004,JPO
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