Abstract: A current-limiting device includes a current-limiting material, such as a molded thermoset material, and first and second electrodes structured for carrying current through the current-limiting material. The first electrode electrically engages a first portion of the current-limiting material, and the second electrode electrically engages a second portion of the current-limiting material. A mechanism provides a non-uniform pressure distribution between one or both of the first and second electrodes and the current-limiting material.

Abstract: A circuit interrupter including an operating mechanism and separable main contacts interconnected with load and line terminals has an interface region between the top and bottom portions of the completed housing thereof, which may be of reduced cross section relative to the remainder of the side walls of the circuit interrupter for being moved or pushed outwardly under the pressure of expanding gas during a circuit interruption operation. To more easily clear or separate abutment surfaces by near lateral movement thereof to provide a small opening for pressurized gas to escape the elasticity of the side wall is utilized for this purpose. Provided that the elasticity limit is not exceeded, the wall will return to its original position sealing the internal portions of the circuit interrupter from the exterior once the gas pressure has dropped below a predetermined level.

Abstract: A circuit breaker system with a shunt trip device is taught in which the shunt trip device occupies a miniature circuit breaker case and utilizes features of the miniature circuit breaker case except that it is provided with a coil and two-piece armature which initiates the shunt tripping operation when properly energized to thus open the separable main contacts of side-by-side mounted circuit breakers having the same intermediate axial member. A back plate is provided for the two-piece joined armature member in the central region of the toroid, solenoid or coil to assist the snug fit of the two-piece core within the central opening of the bobbin of the solenoid and to provide a low reluctance bypass for the magnetic flux crossing the gap formed by the end abutments of the two-pieces of the magnetic core.

Abstract: A circuit breaker has a shock absorber to prevent nuisance tripping which results from shock generated during ON to OFF operation of the circuit breaker. The shock is primarily caused by a snap action which occurs within the operating mechanism of the circuit breaker when the handle is moved from the ON to OFF position. The snap action results from the circuit breaker employing, as part of the operating mechanism, a toggle mechanism within an over center tension spring as a means for imparting motion in the operating mechanism. By strategically positioning the shock absorber for engagement with the operating mechanism when the circuit breaker is in the OFF position, the shock may be effectively absorbed thereby preventing the undesirable nuisance tripping.

Abstract: A support plate for a circuit breaker has a longitudinal slot centrally located in the support plate, a free end with a tab for affixing an elongated bimetal of a trip assembly, a longitudinal edge opposite to the free end and terminating in proximity to a latch ledge of a cradle of an operating mechanism, opposed lobes each having a transverse edge, and an opening in each of the transverse edges. The support plate extends partially along a planar wall of a base of a housing for the circuit breaker. Molded pins in the base of the housing of the circuit breaker enter the openings in the transverse edges of the support plate for securing the support plate to the base. These molded pins extend outwardly to space the support plate away from the cradle of the operating mechanism. Bent over tabs are provided in one of the lobes for abutting a cover of the circuit breaker to maintain the fixed position of the support plate in the housing base.

Abstract: In a circuit breaker having a thermal-magnetic trip, the voltage across the bimetal is used to sense load currents. This voltage signal representative of current through the bimetal can be used as an input to an arcing fault detector. The signal is converted to a bandwidth limited di/dt signal. If the magnitude of the di/dt signal exceeds a threshold indicative of the onset of an arc a predetermined number of times within a given interval, the circuit breaker is tripped. The voltage across the bimetal can also be used in other devices requiring a measure of load current such as, for example, a meter or an overcurrent alarm.

Abstract: A case for a circuit breaker provides a base and a cover, both having an inner surface ribbing system and an inner surface coring system. The ribbing systems form an inner cavity retaining a circuit breaker mechanism and an outer aperture area for receiving a handle for manual operation of the mechanism. The handle is supported in the arcuate areas of the coring systems near the aperture area. A barrier member is located adjacent to the arcuate area in the base, and a barrier member is located adjacent to the arcuate area in the cover. When the base and the cover are assembled the two barrier members are spaced away from the handle and overlap the handle in the arcuate areas to separate the outer aperture area containing the handle from the inner cavity containing the circuit breaker mechanism and still allow the handle to extend freely down into the inner cavity for its connection to and operation of the circuit breaker mechanism. The width or thickness of the barrier member in the base is about 0.

Abstract: A molded case for a miniature circuit breaker provides a base and a cover whose outer mating peripheral walls, which form and enclose a cavity for housing a circuit breaker mechanism, have approximately equal widths, except for the projected handle area. In this handle area, the width of the peripheral wall of the base is increased and contains an aperture for receiving the handle, and the width of the peripheral wall of the cover is decreased to receive the increased aperture area of the base. This arrangement provides for full handle support in the base for ease of assembly; high ribbing for maximum strength for short circuits; and a minimum overall thickness of about 0.500 inches.

Abstract: A bolt-on, duplex circuit breaker having an external, integrally formed key member designed with a truncated pyramidal shape. The pyramidal shape is used to discourage tampering aimed at its removal. A panelboard into which bolt-on, duplex circuit breakers are mounted having mounting rails onto which the circuit breakers are disposed. The mounting rails have cooperating, key member accepting notches that act in conjunction with the key member integrally formed upon the circuit breaker for limiting the number of bolt-on, duplex circuit breakers that are insertable within the panelboard.

Abstract: A multipole circuit breaker, for example, a three pole circuit breaker, can detect a condition when less than all of the phases are open circuited to trip the circuit breaker. This reduces the tripping time and hence risk of damage to the electrical load. The circuit breaker includes a thermal trip unit and a phase sensitivity assembly that is interlocked with the bimetals included with the thermal unit. The phase sensitivity assembly includes one or more levers, responsive to the deflection of a bimetal corresponding to the open circuited phase resulting from cooling action of a bimetal relative to the other bimetals. The relative displacement of the cooling bimetal is used to either trip or reduce the tripping time of the circuit breaker.

Abstract: A mounting tab plate for a panelboard has been designed, so that two such plates can be used in pairs on each pole for gang-mounting of multipole circuit breakers, the plates being fixed on the panelboard on opposite sides by a screw after insertion of the tab in a corresponding groove of the housing of the circuit breaker.

Abstract: A circuit breaker with a thermal trip has a calibration opening in the electrically insulating housing through which a tool may be inserted and rotated to distort a support plate on which a bimetal is mounted to calibrate the thermal trip after the circuit breaker has been fully assembled and enclosed within the insulating housing. A tamper indicating seal in the form of a destructible film secured over the calibration opening by an adhesive having an adhesive strength exceeding the tensile strength of the destructible film provides a visual indication of any subsequent attempts to tamper with the calibration setting.

Abstract: A circuit breaker having a trip mechanism comprising a primary armature which is attracted toward a bimetal by magnetic flux produced by a predetermined overcurrent flowing through the bimetal to unlatch an operating mechanism and open electrical contacts, includes a pivoted supplemental armature which is also attracted toward the bimetal by the overcurrent and which bears against and urges the primary armature toward the bimetal to thereby reduce the predetermined overcurrent at which the breaker opens the electrical contacts. The supplemental armature comprises a flat strip of magnetically permeable material which is bent at one end to form a hook which merely drops into a recess in the breaker housing. Integral flanges on the strip form a magnetic yoke which concentrates the magnetic flux to increase the sensitivity of the magnetic trip function.

Abstract: A circuit breaker structure having a faster trip unit characterized by a circuit breaker operator and a trip unit comprising a coil, a core, and an armature, and a hold-back bracket extending from and retaining the armature in a spaced position from the core so as to cause the magnetic field lines to flow through the bracket and the armature.

Abstract: A circuit breaker for use in remote load energy management systems and characterized by an insulating housing including opposite side walls, end walls and edge walls with a circuit breaker structure contained therein; a manual operator including a handle extending through an edge wall for actuating the structure between open and closed circuit conditions; an electromagnetic within the housing and including an armature for opening the circuit which armature is movable in an axis substantially perpendicular to the edge walls.

Abstract: A circuit breaker structure having a faster trip unit characterized by a circuit breaker operator and a trip unit comprising a coil, a core, and an armature, a flux concentrating plate spaced from and on the side of the armature opposite the core and for concentrating the magnetic field between the core and the armature, and a hold-back bracket having extending from and retaining the armature in a spaced position from the core so as to cause the magnetic field lines to flow through the bracket and the armature.

Abstract: A circuit interrupter responsive to abnormal currents in conductors of an electrical distribution system characterized by a circuit breaker mechanism for opening and closing separable contacts and which mechanism comprises a releasable member operable between latched and unlatched positions, trip means comprising a bimetal element and a trip bar movable to unlatch the circuit breaker mechanism and biased in the latched position, the trip bar having a surface facing and spaced from the bimetal element which surface is slanted at an oblique angle to the longitudinal axis of the trip bar, and manually adjustable knob connected to the trip bar for sliding the trip bar longitudinally to vary the space between the bimetal element and the trip bar surface in accordance with a desired thermal rating.

Abstract: A circuit breaker structure having an adjustable magnetic trip unit characterized by an insulating housing containing a circuit breaker mechanism having separable contacts and containing a trip unit comprising a magnetic device responsive to overload current conditions for separating the contacts, the magnetic device having an armature and a calibrating screw for calibrating an air gap between the armature and an associated magnet, the trip unit also including a cam for varying the tension of the spring and the cam having spaced indexing indentations and an associated ball in the frame for rolling engagement with the cam surface and for seating in any indentation to provide positive settings of the spring tension.

Abstract: A circuit breaker apparatus characterized by a molded case forming a plurality of intercommunicating compartments with a circuit breaker structure within a compartment, arc-quenching means in an adjacent compartment, a line terminal in a next adjacent compartment and electrically insulating shield means between the line terminal and the arc-quenching compartment.

Abstract: A molded case circuit breaker apparatus is taught with an operating mechanism which is triggered in response to the movement of a trip bar. The trip bar in turn is responsive to current flowing in the main terminals of the circuit breaker apparatus. The trip bar is responsive to electrothermal conditions as a gradual overload increases. It is also responsive to a short circuit condition due to a magnetic reaction between an armature and an electromagnet. The armature is flexibly attached to the trip bar for flexible movement in one direction and non-flexible movement in the other direction so that a short circuit may be accommodated by a relatively small air gap by non-flexible movement of the armature and the trip bar to cause a tripping operation.