Abstract: A circuit breaker includes an elongated movable contact having a contact at one end thereof for flowing a current therethrough and the other end rotatably supported with a holder, and a protection cover made of an insulating material for covering and protecting a movable contact from short circuit and discharge. The protection cover is made of only the insulating material, covers the movable contact, and has elasticity to tightly hold the movable contact.

Abstract: A circuit breaker has a molded case with a main case, a middle cover and a top cover being dividable from one another. The main case contains contactor sections, each including a stationary contactor and a movable contactor for a pole corresponding to each phase in a polyphase circuit, an arc-extinguishing device, an overcurrent tripping device actuating a tripping mechanism by detecting an overcurrent, and a zero-phase current transformer detecting a leak current. The middle cover has a partitioned recess for containing a switching mechanism and the tripping mechanism. Interpole partitions, surrounding the contactor section and the arc-extinguishing device, and a screen-like intermediate partition, isolating the contactor sections from the overcurrent tripping device, are formed with the middle cover laid on the main case. A wall with gas outlets for an arc gas is provided on the back of the arc-extinguishing devices.

Abstract: A circuit breaker has a molded case with a main case, a middle cover and a top cover being dividable from one another. The main case contains contactor sections, each including a stationary contactor and a movable contactor for a pole corresponding to each phase in a polyphase circuit, an arc-extinguishing device, an overcurrent tripping device actuating a tripping mechanism by detecting an overcurrent, and a zero-phase current transformer detecting a leak current. The middle cover has a partitioned recess for containing a switching mechanism and the tripping mechanism. Interpole partitions, surrounding the contactor section and the arc-extinguishing device, and a screen-like intermediate partition, isolating the contactor sections from the overcurrent tripping device, are formed with the middle cover laid on the main case. A wall with gas outlets for an arc gas is provided on the back of the arc-extinguishing devices.

Abstract: A circuit breaker includes an elongated movable contact having a contact at one end thereof for flowing a current therethrough and the other end rotatably supported with a holder, and a protection cover made of an insulating material for covering and protecting a movable contact from short circuit and discharge. The protection cover is made of only the insulating material, covers the movable contact, and has elasticity to tightly hold the movable contact.

Abstract: A contactor device of a repulsion-type circuit breaker includes a first movable contactor with a first movable contact to be driven by an open-close mechanism; a fixed contactor; a second movable contactor having second and third movable contacts; a first contact spring for urging the first movable contactor toward the second movable contactor; and a second contact spring for urging the second movable contactor toward the first movable contactor and the fixed contactor. The first movable contactor, fixed contactor, and second movable contactor are arranged such that when an over-current flows, an electromagnetic repulsive force is generated so that the first and second movable contactors are rotated against the first and second contact springs to open between the first movable contact and the second movable contact and between the fixed contact and the third movable contact before the open-close mechanism opens the first movable contact.

Abstract: A contactor device of a repulsion-type circuit breaker includes a first movable contactor with a first movable contact to be driven by an open-close mechanism; a fixed contactor; a second movable contactor having second and third movable contacts; a first contact spring for urging the first movable contactor toward the second movable contactor; and a second contact spring for urging the second movable contactor toward the first movable contactor and the fixed contactor. The first movable contactor, fixed contactor, and second movable contactor are arranged such that when an over-current flows, an electromagnetic repulsive force is generated so that the first and second movable contactors are rotated against the first and second contact springs to open between the first movable contact and the second movable contact and between the fixed contact and the third movable contact before the open-close mechanism opens the first movable contact.

Abstract: A circuit breaker includes a movable contact, a fixed contact, a switching device, a switching operation handle, and an over-current tripping device. The switching device has a switching lever connected to the handle, a toggle linkage having an upper link and a lower link for connecting to the movable contact, a tripping mechanism for activating the toggle linkage in response to over-current, and an operation spring tightly stretched between the switching lever and the toggle linkage. A locking member is provided in the switching device for interconnecting the toggle linkage and the switching lever and for restricting a movement range of the switching lever according to an operational position of the toggle linkage. When main-circuit contact points are stuck, the locking member restricts the movement of the switching lever and prevents the handle from moving to the OFF position.

Abstract: A circuit breaker includes a fixed contact; a movable contact disposed in a rotary-type contact holder; a switching device; an operation handle; and an over-current tripping device. The operation handle is operated to open and close main-circuit contact points through the switching device. The switching device includes a handle lever connected to the operation handle; a toggle linkage having an upper toggle link and a lower toggle link; a switching spring placed between the handle lever and an arm connecting point of the toggle linkage; and a side plate for holding the components. The circuit breaker further includes a device for preventing the operation handle from moving to an off position when the contact points are stuck together. The device includes first stoppers formed on a cross bar of the contact holder and the handle lever facing the cross bar, and a second stopper formed on the side plate.

Abstract: A circuit breaker includes a fixed contact; a movable contact disposed in a rotary-type contact holder; a switching device; an operation handle; and an over-current tripping device. The operation handle is operated to open and close main-circuit contact points through the switching device. The switching device includes a handle lever connected to the operation handle; a toggle linkage having an upper toggle link and a lower toggle link; a switching spring placed between the handle lever and an arm connecting point of the toggle linkage; and a side plate for holding the components. The circuit breaker further includes a device for preventing the operation handle from moving to an off position when the contact points are stuck together. The device includes first stoppers formed on a cross bar of the contact holder and the handle lever facing the cross bar, and a second stopper formed on the side plate.

Abstract: A circuit breaker includes a movable contact, a fixed contact, a switching device, a switching operation handle, and an over-current tripping device. The switching device has a switching lever connected to the handle, a toggle linkage having an upper link and a lower link for connecting to the movable contact, a tripping mechanism for activating the toggle linkage in response to over-current, and an operation spring tightly stretched between the switching lever and the toggle linkage. A locking member is provided in the switching device for interconnecting the toggle linkage and the switching lever and for restricting a movement range of the switching lever according to an operational position of the toggle linkage. When main-circuit contact points are stuck, the locking member restricts the movement of the switching lever and prevents the handle from moving to the OFF position.