Abstract: A current-limiting electrical apparatus is provided including a housing with first and second electrical terminals contained therein. A pair of electrical contacts is disposed within the housing and electrically connected in series with the first and second terminals. A biasing means applies a biasing force to the pair of electrical contacts to bias them to a closed position. The pair of electrical contacts is configured to cause the contacts to electromagnetically repel each other and to overcome the biasing force and open when the current flowing through the contacts exceeds a predetermined value. A mechanism is provided responsive to the current flowing through the pair of electrical contacts for decreasing the biasing force as the current flowing in the electrical contacts approaches the predetermined value, to thereby decrease the predetermined value causing the electrical contacts to immediately open.

Abstract: A molded housing contains a pair of cooperating contacts arranged to be magnetically blown open and an arc chute therefor. The contacts are biased closed and there is no mechanism for manually operating or latching open the contacts. The magnetically blown-open contacts are connected in series with respective poles of a conventional circuit interrupter which also has magnetically blown open contacts but which also has manual operating means and latch means for the contact system.

Abstract: A blocking attachment to limit movement of a circuit breaker operating handle consists of a single member constructed of material having the resilient properties of sheet steel. Outwardly extending tabs at opposite ends of the attachment are inwardly movable for mounting and dismounting the attachment with respect to a circuit breaker housing. An inverter L-shaped section of the attachment defines a freeway wherein the circuit breaker handle is movable from On to Trip positions and is readily viewable to determine when automatic tripping has taken place. Handle movement is limited to the freeway so that the circuit breaker may not be opened manually while the blocking attachment is operatively mounted to the circuit breaker.

Abstract: This invention relates generally to handle locking attachments for circuit breakers and more particularly relates to handle locking attachments of the kind which receive padlocks.

Abstract: An enclosed multipole fuse disconnect switch is constructed of a single molded base, a single contact carrier, and an overcenter spring powered toggle mechanism constructed solely of a coiled compression spring and a stamped sheet metal tongue which extends through an aperture in the contact carrier. The tongue is formed integrally with a pivot shaft through which operating forces are applied to the toggle mechanism. Each pole includes a U-shaped bridging contact constructed of spring metal and floatingly mounted in an aperture of the contact carrier.One end of the pivot shaft extends into a slot in the enlarged end of a bearing rivet that extends through the sidewall of the switch enclosure and is keyed to a manual operating member at one end thereof. The latter extends through a guide slot in an arcuate bracket outside the enclosure.

Abstract: A compact molded case circuit breaker having a high interrupting capacity is provided with an arc chute constructed of stacked metal plates notched to form a passage for the movable contact as it moves between open and closed circuit position. The stationary contact is at one end of the arc chute and the arc plate at the other end of the arc chute is provided with a tab that extends outside of the arc chute. In its fully open position, the movable contact is positioned so that at least half of it is outside the arc chute, adjacent the free end of the tab on the last contact plate, and slightly spaced therefrom. The movable contact, in the terminal portion of its movement toward full open circuit position, moves generally parallel to the tab of the last arc plate. This construction assures that all of the arc plates will become active almost instantaneously at the time the movable contact reaches the tab.

Abstract: A switch which is opened and closed by successively depressing a manual operating handle is provided with one spring for separating the switch contacts and a separate spring for closing the switch contacts. Interrupting capacity is improved without increasing overall size by utilizing a J-shaped movable contact arm mounted on a pivot located a substantial distance from the movable contact. The closing spring is located adjacent to the arcing or interrupter area. A metal shield is positioned to protect the closing spring from hot arcing gases as they exit from the interrupter area. The speed of instantaneous or magnetic tripping is improved by providing the magnet coil with at least one complete current carrying loop.

Abstract: A multi-pole circuit breaker is provided with a molded insulating housing defining an internal chamber wherein the mechanical trip free contact operating mechanism is disposed, an external recess wherein an auxiliary switch unit is removably mounted, and an external cavity wherein a shunt trip assembly is removably mounted. The switch unit includes one switch operable by the mechanism as it opens and closes the circuit breaker contacts and a second switch operated by the latchable cradle of the mechanism to indicate automatic tripping. The shunt trip assembly includes an electromagnet having an operating member which engages the cradle latch to release the latter.

Abstract: A narrow molded case circuit breaker is provided with a spring powered trip free contact operating mechanism including a manual operating member and a releasable cradle which must be latched in a reset position in order to close the contacts. The cradle and operating member are connected by a reset link pivotally mounted to the operating member for moving the cradle from a released or tripped position to a latched or reset position.

Abstract: A magnetic trip means for automatically opening a circuit breaker contact upon the occurrence of predetermined fault current conditions is constructed of a stationary yoke, an armature biased away from the yoke and movable toward the yoke for tripping of the switch, an actuating coil in series with the contacts, and a sealed capsule coaxial with the coil for obtaining selected tripping characteristics. Within the sealed capsule there is a movable magnetic core biased to a normal position extending substantially outside the coil. The core is movable inside of the coil toward the armature upon the occurrence of overload current conditions with movements of the core toward the armature being retarded in a controlled manner. Control is obtained by closely spacing the outer cylindrical wall of the core and the inner cylindrical wall of the capsule, and additionally by utilizing a viscous fluid within the capsule.

Abstract: An electric switch mounted within an enclosure having a hinged cover is manually operated from outside the enclosure by a handle mechanism secured to the enclosure. The cover is provided with a single aperture near the edge thereof remote from the cover hinges, with this aperture providing clearance for the operating handle of the mechanism when the cover is closed and also providing clearance for a catch which holds the cover closed. The mechanism also includes a defeatable cover interlock to prevent opening of the cover when the switch is closed, and a defeatable switch interlock to prevent closing of the switch when the cover is open.

Abstract: An electrical switch is provided with a pivotable contact arm so constructed and positioned that when the switch is open an indicating portion of the arm is viewable from the front of the switch, and when the switch is closed the indicating portion is retracted from view. This indicating portion of the arm is located on a forwardly stepped portion of the arm and is disposed at the end of the arm remote from the separable contact region.

Abstract: A unitized combination motor starter is provided with a single insulated housing wherein a plurality of pole units are disposed in side-by-side relationship. The pole units are electrically connected in series with an electromagnetic contactor disposed within the insulated housing and located at one end of the pole units. A spring powered contact operating mechanism for the pole units is disposed on one side of the pole units. An overload sensing electromagnet coil, provided for each of the pole units, is positioned for removal and replacement after opening the front cover of the insulated housing.