Abstract: A molded case circuit breaker of the type using electrodynamic repulsion to separate the circuit breaker contacts under intense overcurrent conditions also includes an arc chute arrangement for cooling and quenching the arc that occurs during such contact separation. A plastic cover insert added to the interior of the circuit breaker cover multi-functionally retains the arc chute within the circuit breaker case while providing clearance for the circuit breaker operating handle shutter. A resilient pad on the top surface of the cover insert receives the circuit breaker operating handle skirt upon contact separation and dampens the energy imparted to the operating handle and to the circuit breaker cover.

Abstract: An interlock arrangement is provided between adjoining circuit breaker compartments by the addition of a contact arm operated interlock to circuit breakers which contain trip arm operated interlocks. The contact arm interlock comprises a paddle mounted on the rear surface of each of the adjoining breakers for sensing the condition of the contacts in one breaker and for interreacting with the trip arm interlock mechanism to trip the breaker when an attempt is made to close the first breaker contacts while the adjoining breaker contacts are closed. A stop lever mounted in the first breaker compartment interconnects with a similar lever mounted in the compartment of the adjoining breaker to prevent the first breaker contacts from being closed while the adjoining breaker contacts are closed. The compartment interlock arrangement finds utility when one of the interconnected circuit breakers connects with a utility power source and the other circuit breaker connects with an auxiliary generator.

Abstract: An arc motivating assembly positioned on both sides of a pair of circuit breaker contacts is coated with electrical insulating material arranged in alternate layers of two different compositions. The first is selected to have good electrical insulation and high arc resistance, and the second is selected for vaporizing and generating gases to assist in arc blow out and extinction.

Abstract: A switchgear unit contains interlocked circuit breaker and fuse compartments. The interlock prevents the fuses from being withdrawn from their power stabs until the circuit breaker is withdrawn from its power stabs first. A mechanical linkage arrangement causes an interference between the racking tool and the fuse compartment racking shaft until the breaker is withdrawn from the breaker compartment power stabs.

Abstract: A current limiter unit employs both a magnetic repulsion field and a gas pressure force to direct arcs to within the high voltage region of an arc chute. The unit confines the evolved gas pressure in all directions except in the direction of the arc plates. Venting the opposite end of the arc chute rapidly motivates the arc through the arc plates and out of the unit. Venting the sides of the arc chute reduces the back pressure produced by arc gases as well as the pressure exerted upon the heated breaker casing. The combination of magnetic and directed gas repulsion substantilly reduces the I.sup.2 t value of the unit. A parallel positive temperature coefficient impedance can be connected across the arc to reduce the arc current to a low enough value so that the arc becomes extinguished within a predetermined period of time.

Abstract: A thermal magnetic circuit interrupter with instantaneous short circuit current response utilizes a hook-shaped contact arm pivotally mounted on the operating mechanism at the end of the contact arm most distant from the contact. A saddle-type torsion spring proximate the pivot end of the contact arm provides adequate contact pressure while allowing the contact to immediately respond to magnetic forces generated under short circuit conditions. The immediate separation of the contacts reduces the current let-through the operating mechanisms while the tripping mechanism operates to trip the breaker.

Abstract: An electric circuit breaker includes an insulated latch and cradle mechanism to prevent deleterious arc formation between their points of separation when the circuit breaker contacts are opened under short circuit conditions. One embodiment employs an insulated latch mounted on the breaker armature.

Abstract: A movable contact arm for circuit breakers allows the contact opening characteristics to be determined over an entire range of breaker ratings. The contact arm is provided with a camming surface with the contact closure spring arranged as a cam follower. Under short circuit conditions, the contact repulsion force is sufficient to overcome the bias provided by the contact closure spring and to drive the cam follower along the camming surface so that the resulting spring torque rapidly changes from a high initial torque on the contact arm to zero torque in a very short period of time. The contact arm is linked with the contact operating mechanism to open upon current overload in response to the trip mechanism.

Abstract: A secondary disconnect plug is arranged on the sidewall of a circuit breaker compartment for mating with a complimentary receptacle attached to the sidewall of a track-mounted circuit breaker for allowing auxiliary electrical functions to be maintained when the circuit breaker is partially withdrawn from the compartment to a test position. The disconnect plug is floatingly attached to the compartment sidewall and contains a centering and aligning mechanism to provide a wide range of tolerance when the circuit breaker is moved in and out of the compartment.

Abstract: A zone selective interlock module is interposed between a pair of upstream and downstream static trip circuit breakers for controlling the short-time and ground fault zone selective interlock functions of the breakers. When a signal is received from a downstream static trip breaker, the module transmits a low-level interlock signal to a static trip breaker upstream. The interlock signal, in turn, activates the programmer circuit of the upstream breaker causing a shift in the upstream programmer time delay characteristics. The module also provides an energy storage feature to ensure the integrity of the interlock function in the event that the control power is lost upon the occurrence of a fault.

Abstract: An adapter assembly is provided for use with circuit breakers having automatic charge and employing undervoltage release accessory. The adapter is inserted between the undervoltage release tripping mechanism and the circuit breaker operating mechanism to prevent the circuit breaker from tripping from a charged position when the circuit breaker contacts are open. The adapter assembly interferes with the undervoltage tripping lever when the circuit breaker contacts are open to prevent the undervoltage release tripping mechanism from tripping the breaker under conditions of undervoltage or power outage, thus providing a true stored energy device regardless of undervoltage conditions.

Abstract: A shield unit for interchangeable fit within circuit breaker compartments of various manufacture contains a split linkage arrangement of two pivotally connected arms, a return spring and a connecting spring to operate a shield linkage mechanism. The shield assembly comprises two moveable shields brought into a closed configuration when a circuit breaker is removed from the breaker compartment and into an open configuration when the circuit breaker is inserted within the breaker compartment. The interposition of the moveable shields between the power stabs within the breaker compartment and the breaker plugs prevents inadvertent contact by an operator when the circuit breaker unit is disconnected from the stabs. A balanced arrangement of shield linkage mechanisms on both sides of the shield unit prevents manual operation by an operator in any attempt to bypass the shield unit.

Abstract: A rapid arc extinguishing assembly includes an arc chute comprising a large number of essentially parallel deionizing plates each in form of thin magnetically permeable, electrically conductive plates bent in U-shape, with the curve of the U facing the circuit breaker contacts and the arms thereof insulated from each other by a thin insulation sheet. To promote arc extinction by the arc chute and accelerated breaker contact separation, the breaker contacts are flanked by a magnetic assembly comprising opposed columns of parallel, spaced ferromagnetic plates embedded in an insulating material. The columns may be magnetically coupled by a yoke to create a closed slot in which the breaker movable contact travels.

Abstract: Polyolefin compounds containing nitrile polysiloxane fluid which have improved electrical properties, and electrical conductors insulated therewith.

Abstract: A compact and symmetrically arranged construction for electrical current indicating meters of small size. The meter construction comprises a concentrically pivoted coil which encircles a rounded magnetic fluxplate.

Abstract: A compact and symmetrically arranged construction for electrical current indicating meters of small size. The novel construction for a meter comprises combinations of magnet components including the matching of a permanent magnet with a flux conducting non-permanent magnetic body.

Abstract: Insulation penetrating contact of a single piece electrical blade and contact is achieved in a connector of dead front construction by providing a single piece three link insulating housing adapted to fold up in valise fashion about the single piece blade and contact and about a wire extending into the housing. Electrical contact is made as the housing is closed and fastened in close form by forcing a bladed surface of the electrical contact into a channel in which the wire to be contacted is disposed.

Abstract: A compact and symmetrically arranged construction for electrical current indicating meters of small size. The novel construction for a meter comprises a unitary frame member combined with concentrically arranged components.

Abstract: The present invention relates to an electrical measuring instrument of the D'Arsonval type and more specifically to an improved low cost and small suspension system for the bobbin or armature assembly of such an instrument. Such improved suspension system includes the combination of a small light weight bobbin having thin gauge, surface insulated conductor wound on a light weight bobbin frame. Thin conducting strips are mounted to the frame above and below and these thin plates are provided with pins extending above and below respectively into jeweled pin pockets. Each pin is inserted at its blunt end through a strip in which it later resides by incorporating the pin in a punch, mounting the strip over an opening in a die beneath the punch and aligning the blunt end of the pin with the opening in the die.