Abstract: An arc-extinguishing processed resin article is disclosed that exhibits an excellent arc-extinguishing behavior, heat resistance, pressure resistance, and molding processability, and a circuit breaker that uses this arc-extinguishing processed resin article are provided. The circuit breaker includes a stationary contactor that has a stationary contact point, a movable contactor that has a movable contact point contacting the stationary contactor and that carries out a switching operation with the stationary contactor, and an arc-extinguishing device that extinguishes the arc generated when the stationary contactor and movable contactor engage in a switching operation. The circuit breaker uses, as the arc-extinguishing device, an arc-extinguishing processed resin article obtained by molding a resin composition containing (A) polyolefin resin that has the hydroxyl group substituted for a portion of the hydrogen atoms in the methylene chain and that contains 0.2 to 0.

Abstract: A circuit breaker for a double-break mechanism includes a current interrupting section having a contact mechanism. The contact mechanism includes first and second fixed contactors arranged in parallel and having fixed contacts, and a bridging movable contactor having an arm with movable contacts opposing the fixed contacts. A magnetic plate may be interposed in a middle region between two pairs of the fixed and movable contacts extending along a path of switching movement of the movable contactor. Partition walls formed of organic polymer material may be provided to stand along the path of the movable contactor. The partition walls sandwich each pair of the fixed contact and the movable contact to form a narrow gap arc extinguishing space between the partition walls.

Abstract: A circuit breaker for a double-break mechanism includes a current interrupting section having a contact mechanism. The contact mechanism includes first and second fixed contactors arranged in parallel and having fixed contacts, and a bridging movable contactor having an arm with movable contacts opposing the fixed contacts. A magnetic plate may be interposed in a middle region between two pairs of the fixed and movable contacts extending along a path of switching movement of the movable contactor. Partition walls formed of organic polymer material may be provided to stand along the path of the movable contactor. The partition walls sandwich each pair of the fixed contact and the movable contact to form a narrow gap arc extinguishing space between the partition walls.

Abstract: A current-interrupting section of a molded case circuit breaker includes fixed contact shoes and a rotary bridge-type contact shoe held in a contact shoe holder. A pair of pressure springs is assembled in the contact shoe holder to press the rotary contact shoe to the fixed contact shoes. The pressure spring is torsion coil springs and have U-shaped offset arm portion drawn out from the center of the coil. A pair of the torsion coil springs is arranged above and under the rotary contact shoe. Furthermore, legs of the torsion coil springs at ends are hooked to sidewalls of the contact shoe holder. The offset arm portions at the center of the torsion coil springs engage the rotary contact shoe at positions symmetrical with respect to the rotational center of the rotary contact shoe.

Abstract: A current-interrupting section of a molded case circuit breaker includes fixed contact shoes and a rotary bridge-type contact shoe held in a contact shoe holder. A pair of pressure springs is assembled in the contact shoe holder to press the rotary contact shoe to the fixed contact shoes. The pressure spring is torsion coil springs and have U-shaped offset arm portion drawn out from the center of the coil. A pair of the torsion coil springs is arranged above and under the rotary contact shoe. Furthermore, legs of the torsion coil springs at ends are hooked to sidewalls of the contact shoe holder. The offset arm portions at the center of the torsion coil springs engage the rotary contact shoe at positions symmetrical with respect to the rotational center of the rotary contact shoe.