Abstract: A change of state circuit breaker contact material provides a low contact resistance at a low closing force by reducing current density through a pair of circuit breaker contacts. The use of a meltable metal alloy within the contact structure forces the current through a wider area of conduction whenever the temperature increases to melt correspondingly larger quantities of the metal alloy. The reduced contact hardness results in a substantial decrease in the force required to hold the contacts together, thereby allowing the contacts to open more quickly.

Abstract: A current limiting circuit breaker utilizes a first pair of contacts for carrying continuous current and controlled by an operating mechanism. A second pair of contacts is arranged on a pair of movable contact arms ahead of an arc chute for rapid repulsion under high current fault conditions.

Abstract: Improved encapsulating compositions for inductive devices are provided. The composition has a polybutadiene base and contains an initiator, an inhibitor and a co-agent for improving the curing of the composition under the influence of the initiator.Certain compositions are usable at higher temperatures than prior polybutadiene base encapsulating compounds based on a conditioning of the composition during cure at or near the projected use temperature. When combined with high temperature conductor insulation coatings, such as polyimides, a high temperature encapsulating system is achieved.Certain compositions are usable to provide a soft cure encapsulation from which an encapsulated inductive device may be liberated without damage to the device. For such compositions, soft curable polybutadienes are employed and particularly those having high trans and cis components.

Abstract: Digital implementation of the overcurrent determination and time delay before tripping in a static circuit breaker trip unit allows the trip unit circuit to be manufactured in a single chip configuration. The signal after A/D conversion is compared within a magnitude comparator to determine pickup. A pulse stream proportional to the square of the overcurrent signal is developed by multiplying the outputs of two magnitude comparators which compare the A/D level with a continuous binary count. The time delay determination is obtained by means of 3 cascade connected divide by two counters with their outputs connected to a data selector, or by a rate-limiter circuit which uses a fixed frequency to gate a pulse stream proportional to the overcurrent level squared.

Abstract: A molded case industrial circuit breaker is provided with a shortened contact separation distance upon manual operation to reduce the stresses imposed upon the breaker operating mechanism when the breaker is manually operated to open or close the contacts. A camming surface is provided on the cradle operator to provide a stop for the toggle pin both upon opening as well as upon closing the contacts. The decreased separation which occurs between the contacts upon manual operation allows a savings in the amount of contact braid material as well as reducing the size of both the fixed and movable contacts. The decreased stresses on the mechanism correspondingly allows for a reduction in the material strength and mass of the breaker flexible connectors, operating springs, and contacts.

Abstract: A fault current interrupter is provided by the parallel combination of a positive temperature coefficient resistor and a voltage dependent resistor connected across a pair of separable contacts to permit the interruption of current without the occurrence of arcing between the contacts when the contacts first become separated. The positive temperature coefficient resistor is selected to have a relatively low resistance at room temperature and a substantially higher resistance at higher temperatures. This allows the current to transfer away from the contacts through the positive temperature coefficient resistor until the voltage across the voltage dependent resistor causes the voltage dependent resistor to become conductive and thereby transfer the current away from the positive temperature coefficient resistor.

Abstract: Molded case circuit breakers having rear mounted line connectors are provided with retainer clips and plates to prevent easy removal of the breakers from electric panel box load stab connectors. The breakers can be removed for replacement however, without disassembling the entire electrical panel box.

Abstract: An electric circuit breaker having fast short circuit response along with reduced arc energy is provided by means of a current limiting contact arm arrangement. The contact arm is arranged to pivot independently of the circuit breaker operating mechanism under the influence of magnetic repulsion forces. A contact spring configuration controls the rate at which the contacts separate, thereby limiting the energy of the arc created upon contact separation.

Abstract: High speed trip facility is provided within a molded case circuit breaker used within industrial applications. The movable contact arm is pivotally arranged to open independently of the trip unit-driven operating mechanism. A "latch kicker" arrangement interfaces between the mechanism trip bar and the circuit breaker intermediate latch whereby rotation of the trip bar causes the latch kicker to immediately displace the intermediate latch from the circuit breaker cradle thereby allowing the interrupter mechanism to untoggle the mechanism and open the breaker contacts.

Abstract: An analog signal processor used within a static trip unit is provided with an A/D converter, a digital processor and an electrically alterable non-volatile memory (EAROM) for providing trimming and calibration facility to the trip unit. The EAROM provides the ability to store parameters calculated by the user during the manufacturing process of the trip unit. Key measured or environmental variables are created and a correction algorithm is generated and stored along with data. The trip unit is then capable of self-calibration by applying the correction factor to compensate for variations in the component sensitivity. In one application, the current sensing transformer is precalibrated and provided with a correction factor and a correction algorithm. In another application, the thick film resistors within the long term trip mode network, the short term trip mode network and the power supply voltage regulator are "trimmed" by means of stored correction values.

Abstract: A ground fault circuit interrupter (GFCI) yoke with integral grounding screw and simple staked ground receptacle stab arrangement provides the device grounding features. The mounting screws that are attached to the yoke by means of staples provide a wall box self-grounding feature. A push-to-test arrangement is provided by a neutral strap and test contact attached to the line receptacle stab through a current limiting resistor. Depressing a test button energizes the test circuit by electrically connecting the test contact with the neutral strap. The combination of the line and neutral receptacle stabs with the line and neutral moveable contact arms and the arrangement of the receptacle stabs in alignment with the receptacle plug-in slots allows the push-to-test and interrupter contacts to be assembled within the GFCI enclosure without additional wiring.

Abstract: The method making a dry type, air cooled transformer having a mitered magnetic core and a compression bonded coil with air ducts formed in the end portions of the coil. The coil on each of the core legs is generally rectangular in shape and comprises a plurality of layers of wound conductor with the conductor layers in the end portions of the coil being spaced apart to form a plurality of air ducts for the passage of cooling air therethrough. The conductor layers in each of the side portions of the coil are compressed and then bonded together in their compressed state by means of a heat cured adhesive coated on opposite sides of the sheets of insulation between adjacent layers. This compression bonding of the coil sides squares up the inner and outer surfaces of the coil so as to improve the coil and core space factors thereby allowing a smaller core. Conversely, compression bonding allows higher output power ratings to be achieved by packing added conductor material through the same size core window.

Abstract: A dry type, air cooled transformer having a mitered magnetic core and a compression bonded coil. The coil on each of the core legs is generally rectangular in shape and comprises a plurality of layers of wound conductor with the conductor layers in the end portions of the coil being spaced apart to form a plurality of air ducts for the passage of cooling air therethrough. The conductor layers in each of the side portions of the coil are compressed and then bonded together in their compressed state by means of a heat cured adhesive coated on opposite sides of the sheets of insulation between adjacent layers. This compression bonding of the coil sides squares up the inner and outer surfaces of the coil so as to improve the coil and core space factors thereby allowing a smaller core. Conversely, compression bonding allows higher output power ratings to be achieved by packing added conductor material through the same size core window.

Abstract: A dry type, air cooled transformer having a mitered magnetic core and a compression bonded coil. In the disclosed embodiment, the magnetic core is of the mitered, stacked lamination type. The coil on each of the core legs is generally rectangular in shape and comprises a plurality of layers of wound conductor with the conductor layers in the end portions of the coil being spaced apart to form a plurality of air ducts for the passage of cooling air therethrough. The conductor layers in each of the side portions of the coil are compressed and then bonded together in their compressed state by means of a heat cured adhesive coated on opposite sides of the sheets of insulation between adjacent layers. This compression bonding of the coil sides squares up the inner and outer surfaces of the coil so as to improve the coil and core space factors thereby allowing a smaller core.

Abstract: A dry type, air cooled transformer having a mitered magnetic core and a compression bonded coil. In the disclosed embodiment, the magnetic core comprises a plurality of stacked lamination layers wherein each layer comprises a plurality of grain-oriented laminations wherein the ends of most of the laminations are mitered thereby resulting in joints between the leg and yoke pieces oriented at an angle to the favored magnetic directions of the adjoining laminations. The coil on each of the core legs is generally rectangular in shape and comprises a plurality of layers of wound conductor with the conductor layers in the end portions of the coil being spaced apart to form a plurality of air ducts for the passage of cooling air therethrough. The conductor layers in each of the side portions of the coil are compressed and then bonded together in their compressed state by means of a heat cured adhesive coated on opposite sides of the sheets of insulation between adjacent layers.

Abstract: A compact operating mechanism for a ground fault circuit interrupter comprises a pair of main and reset slotted latches arranged under a crossarm and over a latch plate on a spring-loaded latch pin. The mechanism is reset by interference between a neck portion on the latch pin and a surface on the reset latch. The mechanism is latched by interference between the surfaces on a pair of upright posts on the latch plate and a surface on the main latch.

Abstract: A ceramic useful as an electrically insulating material is produced by calcinating wollastonite powder, admixing the calcined powder with phosphoric acid of certain P.sub.2 O.sub.5 concentration range, die-pressing the resulting mixture, and firing the resulting pressed piece. The ceramic is employed within arc circuit breakers as a substitute for asbestos liners, dividers and arc splitters.

Abstract: A current limiting circuit breaker contains a pair of electrical contacts within separate chambers arranged side-by-side and isolated by means of an insulated barrier. The contacts are electrically connected in series such that the arcs formed between the contact pairs are magnetically motivated by the sum of the current paths through both contact pairs.

Abstract: A ground fault circuit interrupter interconnect arrangement provides wireless connection with line and neutral main current terminals by insertion through an aperture in the interrupter magnetic sensor module to form a magnetic sensor plug-in subassembly. The electronics components and trip solenoid are mounted to the interrupter printed wire board. The magnetic sensor subassembly is plugged into the printed wire board for interconnection with the electronics components. This allows the interrupter to be assembled in a completely automated process.

Abstract: A vacuum interrupter comprises an end plate having a central opening through which a movable contact rod extends. A tubular metallic bellows surrounds the contact rod and includes a plurality of annular convolutions at its inner diameter. Guide structure fixed to the end plate lines its central opening and is located outside said convolutions. A sleeve of self-lubricating plastic material surrounds the contact rod and is fixed thereto. This sleeve is disposed within the guide structure and within the tubular bellows and fits closely within said convolutions so that the convolutions are capable of bearing against the sleeve to assist in guiding the rod.