Abstract: A contact structure of a switching device having a pivoted movable contact arm for reducing contact chatter, i.e., bounce, at the instant of closing or separation is given. Such chatter is mainly caused by clearances existing around pivots of the movable contact arm and operating mechanisms. A contact spring for applying a contact pressure when the switch is closed is provided between a portion of the movable contact arm at the other side of a contact in relation to the pivot of the movable contact and a stationary portion of the switching device. Also, a stopper is provided on a contact arm support member engagable with the contact arm at a side of the contact. With structure the movable contact arm and operating mechanisms are perfectly biased by the contact spring always in one direction and prevents free movement of the movable contact arm.

Abstract: It is the main object of this invention to provide a circuit breaker in which the movable contacts have sufficient opening force and opening distance, and in which the breaking time is short. In order to attain the object, the circuit breaker of this invention is provided with a dead center link mechanism comprising a movable contact link which is rotatably supported by the arms of a cross bar which is operated so as to be capable of opening-closing the circuit and tripping by means of a trip-free mechanism, and a toggle spring which is bridged between the cross bar and the movable contact link. When a large current such as a short-circuit current flows, a movable steel plate attracted by an electromagnet for instantaneously tripping hits a rod for supporting the movable contacts which is connected to the movable contact link, whereby the dead center link mechanism makes the movable contacts open at high speed from the fixed contacts.

Abstract: The contact structure and the arc extinguisher means of a circuit interrupter are enclosed in an insulating housing of each pole and the operating mechanism is isolated from the contact structure and located outside of the housing. The housing for each pole forms an arc extinguisher amper with a detachably attached cover containing an arc extinguisher, and a contact chamber containing a contact structure in each pole. An interconnecting rod, located between the contact structure and the operating mechanism has a flange or barrier for covering an opening in the housing through which the rod extends. Upon contact separation, the electric arc increases the internal pressure within the housing, thereby rapidly effecting arc extinction. The dielectric strength between the contact structure and the operating mechanism is also greatly increased in comparison with conventional designs.

Abstract: The disclosed circuit interrupter comprises a magnetic core structure including a magnetic core and magnetic yokes defining an annular magnetic gap around the core, and a primary and a secondary coil wound on the core to form a current transformer. The movable contact arm is disposed in the magnetic gap to be magnetically driven to the open position, and a magnetic armature of an instantaneous trip means is disposed adjacent to the magnetic yokes so that it is magnetically actuated upon a short-circuit current. A bimetallic element of a thermally responsive trip means is electrically connected to the secondary coil of the transformer. The magnetic yokes include extended portions which serve as magnetic means for driving an electric arc established between the separated contacts into an arc extinguisher which is also disposed between the magnetic yokes.