Abstract: A two-pole miniature circuit breaker is configured for calibration of both pole mechanisms with the circuit breaker fully assembled. The identical pole mechanisms are mounted in the same orientation in parallel outer compartments of a molded housing with the metal support frame of one pole against the outer housing wall and the frame of the other spaced from the associated outer wall. A coupler couples the two-pole mechanisms together for simultaneous opening of both poles when either pole is tripped has an actuating member on each end which engages the trip device of the associated pole. The actuating member, at least of the pole with the metal frame spaced from the housing outer wall, is configured to provide direct access for a calibration tool inserted through a calibration opening in the housing to engage a calibration slot in the metal frame.

Abstract: A thermal-magnetic trip unit, suitable for use in a circuit breaker, for eliminating the requirement for latching surfaces while still providing the additional force and motion required to trip the breaker during a short circuit or an overcurrent trip event. The trip unit comprises a link that is biased based on the position of a trip bar. A spring biases the link in a first direction when the trip unit is in a reset condition and biases the link in a second direction when the trip bar is rotated about a pivot point. A trip unit further including an improved indication-of-trip system comprising a two-piece trip bar mechanism and flag system is described to discriminate between overcurrent and short circuit faults. In this embodiment of the invention, visual confirmation of the cause of the trip is provided.

Abstract: An arc fault circuit breaker (10) conducting an electric current to a protected load is presented. The circuit breaker (10) has a first (mechanical) compartment (24) and a second (electrical) compartment (62). A bimetal resistor (50) is disposed within the first compartment (24) and conducts the current therethrough. The bimetal resistor (50) has a stud (56) extending into the second compartment (62). A single sense line (60) is electrically connected to the bimetal resistor (50) and routed into the second compartment (62). The sense line (60) and said stud (56) conduct a voltage signal indicative of arcing of the current. A circuit board (84) is disposed within the second compartment (62) and is connected to the sense line (60) and stud (56) within the second compartment (62) to process the voltage signal. The circuit board (84) has a first conductive path (104) electrically connected to the stud (56), and a second conductive path (106) electrically connected to the sense line (60).

Abstract: The circuit breaker (10) of the present invention is a molded case circuit breaker and includes a molded case (12) having a main cover (20), a first terminal (16) and a second terminal (16) mounted inside the case (12) with a stationary contact (44) electrically coupled to the first terminal (18) and a movable contact (42) electrically coupled to the second terminal (16). The movable contact (42) is coupled to an operating mechanism (40) which has a pivoting member (13) moveable between an ON position, an OFF position and a TRIPPED position. An intermediate latching mechanism (52) also is mounted in the housing (12) and is coupled to the operating mechanism (40). The intermediate latching mechanism (52) is selectively operated by a trip unit (60) which comprises a magnetic short circuit release and a thermal overload release.

Abstract: A circuit interrupter including a housing, separable main contacts disposed in the housing, and an operating mechanism disposed in the housing and interconnected with the contacts. A trip mechanism is disposed in the housing and includes a rotatable trip bar assembly that, when selectively rotated, generates a tripping operation that causes the contacts to open. The trip mechanism further includes an automatic trip assembly for selectively rotating the trip bar assembly upon a predetermined current threshold. The automatic trip assembly includes a magnetic yoke having two arms with a pivot support on the top of each. Each of the pivot supports includes a pivot surface, and one of the pivot supports includes a rear retaining protrusion adjacent its pivot surface. The other of the pivot supports includes a front retaining member adjacent its pivot surface.

Abstract: A thermal-magnetic trip unit, suitable for use in a circuit breaker, for eliminating the requirement for latching surfaces while still providing the additional force and motion required to trip the breaker during a short circuit or an overcurrent trip event. The trip unit comprises a link that is biased based on the position of a trip bar. A spring biases the link in a first direction when the trip unit is in a reset condition and biases the link in a second direction when the trip bar is rotated about a pivot point. A trip unit further including an improved indication-of-trip system comprising a two-piece trip bar mechanism and flag system is described to discriminate between overcurrent and short circuit faults. In this embodiment of the invention, visual confirmation of the cause of the trip is provided.

Abstract: A thermal trip unit within a multi-pole circuit breaker includes a bimetal element having an off-set end to provide cam function during the calibration of the bimetal element. A calibration screw is threadingly engaged within the bimetal element and is adjusted at various calibration levels by means of a step motor driver element.

Abstract: A shunt (heater strap) (36) for a bimetallic strip (34) is presented. The shunt (36) has a section of reduced thickness (70) for the generation of a localized hot spot. The bimetallic strip (34) is attached to the shunt (36) at the reduced thickness section (70).

Abstract: A circuit interrupter including a housing, separable main contacts disposed in the housing, and an operating mechanism disposed in the housing and interconnected with the contacts. A trip mechanism is disposed in the housing and has an automatic trip assembly that selectively generates a tripping operation to cause the operating mechanism to open the contacts upon a predetermined current threshold. The automatic trip assembly includes a magnetic yoke, an armature, and an electrical terminal. The magnetic yoke has pivot supports on which are positioned pivot arms of a head portion of the armature. A clamp member applies a clamping force to the head portion of the armature in a direction to normally rotationally displace a bottom portion of the armature away from the yoke and the terminal.

Abstract: A molded case circuit breaker and includes a molded case (12) having a main cover (20), a first terminal (16) and a second terminal (16) mounted inside the case (12) with a stationary contact (44) electrically coupled to the first terminal (18) and a movable contact (42) electrically coupled to the second terminal (16). The movable contact (42) is coupled to an operating mechanism (40) which has a pivoting member (13) moveable between an ON position, an OFF position and a TRIPPED position. An intermediate latching mechanism (52) also is mounted in the housing (12) and is coupled to the operating mechanism (40). The intermediate latching mechanism (52) is selectively operated by a trip unit (60) which comprises a magnetic short circuit release and a thermal overload release.

Abstract: A circuit breaker includes an upper rail mounting device defined by a line terminal having a pair of spaced-apart jaws. A bimetal is adjusted by means of a calibration screw. An aperture is provided in an upper sidewall portion of a base of the circuit breaker for access to the calibration screw by a calibration device. The aperture is positioned so that the calibration device must pass through the jaws of the upper rail mounting device. This ensures that the calibration screw can only be operated when the circuit breaker is disconnected from an electrical supply.

Abstract: An overcurrent release device for protection switching devices, in particular automatic line circuit breakers or motor protective switches, with electromagnetic and thermoelectric release, includes a thermoconducting tubular supporting body onto which a coil is wound and which has a striking end and an opposite widened receiving end for bearing contact and radial support of a bimetal snap-action disk with a central bore, a core having a bore defined therein, an armature movable in the supporting body between its striking end and the core, and a slide extending through the bore in the snap-action disk and through the bore in the core in a direction towards the armature. The slide is provided for thermoelectric disengagement by means of the snap-action disk via a thickened portion and for electromagnetic disengagement by means of the armature via a slide actuator. In the operative state, the spacing between the armature and the core corresponds at maximum to the snapping travel of the snap-action disk.

Abstract: In an exemplary embodiment of the invention, a calibration arrangement and process for use in a circuit protective device are presented. An exemplary calibration assembly for use in the calibration process of the present invention includes a split clamp arm having a first opening for receiving and holding a calibration pin and a second opening for receiving an actuator key. A portion of the split clamp arm is divided into a first arm and a second arm by a channel which extends from a first end of the split clamp arm through the first opening and communicates with the second opening. The split clamp arm is opened by inserting the actuator key through the second opening and because of the preferred oblong or rectangular shape of the second opening of the split clamp arm, rotation of the actuator key therein forces the members forming the first opening of the split clamp arm apart from one another.

Abstract: This concerns a four pole molded case circuit breaker having separable main contacts and an operating mechanism utilized to cause the separable main contacts to open and close. A trip unit is provided to actuate the operating mechanism in desirable circumstances. The circuit breaker in this case has four-poles, one of which is a neutral pole. The circuit breaker trip unit has rotatable trip bars therein, one of which is associated with the three-line terminals and one of which is associated with the neutral terminal. If the line terminal trip bar is actuated to move because of a fault to overload in one of the line terminals, only the line terminals will open because the neutral trip bar will not be moved. However, if the neutral trip bar is moved because of a predescribed neutral current value in the neutral conductor all of the contacts including the neutral contact will be opened because of the interlocking arrangement between the neutral trip bar and the line trip bar.

Abstract: A trip mechanism (140), including two trip actuators, namely a bi-metal trip actuator (144) and a magnetic trip actuator (142), that act on a plunger (160). A plunger guide (162) guides motion of the plunger along a straight line path of travel. Each trip actuator is capable of moving the plunger independently of the other trip actuator to cause the circuit breaker to trip in response to detection of either a thermal fault or a magnetic fault.

Abstract: A trip device of a main circuit breaker is provided which causes only a branch circuit breaker to be set into a tripped state when an abnormal current occurs at a load of the branch circuit breaker while keeping a closed state of the main circuit breaker. The trip device of the circuit breaker has a structure including a trip latch mechanism for opening switching contacts, a stationary core, a movable core which is attracted to the stationary core to release the latch mechanism of a trip lever, an operating pin for interrupting movement of the movable core while the movable core is attracted, an operating spring charged with force when the movable core is attracted, and an inertia roller holding the operating pin, kicked when the operating spring discharges the force, and moved to a position which does not interrupt movement of the movable core. Accordingly, this structure allows a selective tripping system to be implemented simply with small size and low cost.

Abstract: An overcurrent circuit breaker arranged inside an approximately cube-shaped, two-part insulating housing, having a chassis section and a locking section. Located between the parallel side walls of the housing sections is a switchgear with a contact bridge, the movement of which is guided parallel to the side walls and which extends in essentially longitudinal direction at a right angle to the side walls and while in the on position between two fixed contacts that are fastened inside the housing and are positioned on both sides of the movement plane for the switchgear. The fixed contacts are flat pieces akin to a knife blade and fit against the side walls and, respectively, form a contact point with their narrow, knifeblade type edges facing the contact bridge. With their rear sides opposite the contact points, the fixed contacts fit against a flank wall of housing. As a result of this, the fixed contacts are positioned in an especially space-saving manner in the corners of housing.

Abstract: A mid-trip stop circuit breaker, having a handle, adapted for displacement about an axis of rotation between a first position and a second position, the handle being linked to a member whose position corresponds to a rotation position of the handle, a spring urging the handle toward the second position; a stop surface, displaceably supported in relation to the axis of rotation, the stop surface being selectively disposed along a path of the member at a middle position of a transition path from the first position to the second position, and being adapted to engage the member and counter a force of the spring, to retain the handle in the middle position of the transition path, such that a sufficient manual force applied to the handle when retained at the middle position of the transition path will displace the stop surface, allowing the handle to achieve the second position, while in an absence of the sufficient manual force and under influence of the spring alone, the stop surface impedes displacement of the h

Abstract: A circuit breaker for interrupting the flow of electric current in a line includes a switch connected in series with the line, the switch having an open position and a closed position. At least one positive temperature coefficient resistivity element (PTC element) is connected in series with the line. A first magnetic coil is positioned around a yoke, for example, an iron core, and connected in parallel with the PTC element and a second magnetic coil is positioned around the yoke and connected in series with the line and the switch. A voltage limiting device, such as a metal oxide varistor, is connected in parallel with the at least one PTC element. An armature is pivotally mounted in relation to the yoke wherein the yoke and the armature form a magnetic circuit with the first magnetic coil and the second magnetic coil.

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: An overcurrent trip (1) for circuit breakers or motor safety switches has a very short reaction time. The short reaction time is achieved by connecting a bimetal snap-action disk (8) to the heating device (7) in such a way that its central region is always in contact with the heating device (7), irrespective of creeping movement. This heating device (7) is formed by a ferromagnetic core (5) on which the magnet winding (12) is directly fitted, without a further yoke, which magnetic winding simultaneously serves as the heating winding. The bimetal snap-action disk (8) is held on this heating device (7) with the aid of the electromagnetically actuated rod (21), while a plunger (43) which coaxially surrounds the electromagnetically actuated rod is moved by the bimetal snap-action disk (8).

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 method and apparatus for interrupting the flow of electrical current in a multiphase circuit path between at least one source and at least one load including a circuit breaker having an electro-mechanical assembly and a blade carrier corresponding to each phase of the multiphase circuit path and a phase barrier between each blade carrier. The blade carriers are interconnected, preferably, with a crossbar wherein, when one or more phases of the circuit path are interrupted, opening one or more of the blade carriers, the crossbar moves all of the blade carriers to open positions. The phase barrier is positioned circumferentially around the crossbar between each blade carrier and includes a thermoplastic material. The electro-mechanical assembly is housed within a circuit breaker enclosure having an insulating base wall and cover wall. The phase barrier has a main body planar surface perpendicular to the blade carriers and extending from the base wall to the cover wall.

Abstract: A solenoid type magnetic trip assembly for a molded case circuit breaker includes an armature biased against an adjustable stop by a tension spring to set the initial gap for the magnetic trip, so that the spring bias remains constant for the full range of the initial gap. The armature includes an elongated magnetically permeable member mounted by a frame to slide longitudinally along a pair of guide rails. The frame defines a trip surface axially aligned with the elongated magnetically permeable member which engages a trip arm on a trip bar to trip the circuit breaker in response to a predetermined level of overcurrent. A bimetal providing a thermal trip function is cantilevered from a support spaced from the trip bar by the armature, but has a terminal portion at the free end projecting toward the trip bar and through which the elongated magnetically permeable member of the armature extends.

Abstract: A modular thermal magnetic trip unit includes the bimetal, magnet, armature and latch in a one-piece assembly. A latch opening is formed in a bottom part of the magnet on a side opposite the bimetal for receiving and retaining the tip of the cradle. The motion of the inodular assembly is accelerated by the combined thermal and magnetic forces acting in unison.

Abstract: An improved circuit interrupter having a solenoid in series with the line and load terminals with an armature operable to activate a trip mechanism within the circuit breaker upon experiencing current levels indicative of short circuit conditions. The traditional solenoid coil is replaced with a free form conductor stamped in a serpentine pattern with adjacent legs deformed slightly in opposite directions to permit an electromagnetic material to be disposed therebetween. Current is directed through the conductor progressively back and forth through the serpentine pattern and creates a magnetic field in the electromagnetic material which is sufficient to activate an armature when current levels approximate short circuit conditions.

Abstract: A thermal and magnetic trip unit for a multi-pole circuit breaker includes a thermal structure having a bimetallic element and one or more heater elements. Each of the heater elements and a portion of the bimetallic element is generally "U" shaped defining a conductive path which extends from one leg of the U to the other leg. The heater elements and bimetallic element may be configured in parallel to reduce the level of current flowing through the bimetallic element and thus increase the current level at which the bimetallic element will trip the breaker. Alternatively, the heater elements may be configured in series with the bimetallic element, by inserting electrical insulators between the bimetallic element and each of the heater elements and connecting the various "U" shaped elements using a connecting bus which connects the second leg of one element to the first leg of the next element.

Abstract: A residential circuit breaker electromagnetic trip unit facilitates the assembly of the trip unit components by use of a pair of braid connectors for connection between the trip unit magnet and the circuit breaker contact arm. The trip unit bimetal is directly welded to the trip unit magnet and the braid connectors for reduction in material and labor costs. The contact arm and the magnet are shaped to present a parallel path connection between the contact arm and the magnet for close fit tolerance. The front surface of the magnet is configured to prevent magnetic adhesion between the magnet and the trip unit armature under intense short circuit overcurrent conditions.

Abstract: A reverse deflection prevention arrangement is provided for use in a circuit breaker for preventing a bimetal from bending in a direction opposite its normal thermal deflection. The reverse deflection prevention arrangement includes a tab portion extending from a yoke and a corresponding block member disposed on the inside surface of a circuit breaker cover. The tab portion engages the block member when the bimetal is forced to deflect in the direction opposite its normal deflection. An alternate embodiment of the reverse deflection prevention arrangement includes a reinforcement member secured to one end of the bimetal. The reinforcement member strengthens and supports the bimetal so that it is prevented from bending in the direction opposite its normal thermal deflection.

Abstract: A remotely controllable circuit breaker device for interrupting current in a circuit path between a source and a load includes local and remote monitoring capabilities and a gear mechanism for reliable remote control of the interruption mechanism. The device includes a first contact and a second contact cooperatively arranged in the circuit path so as to provide current from the source to the load. At least one of the contacts is disposed on a contact carrier which is movable for interrupting the current provided to the load. The gear mechanism includes a motor with a rotatable shaft which responds to open and closed control signals generated from a remote location, and a gear, rotatably responsive to the rotatable shaft, for controlling the contact carrier so that the circuit path is interrupted and established, respectively. The gear mechanism controls the contact carrier using a coupling arrangement, which has a first part coupled to the contact carrier and a second part coupled to the gear.

Abstract: A compact current limiting circuit breaker utilizes a polymer current limiter, an arc rail and an arc gap for effective overcurrent protection. Upon the occurrence of contact separation an arc is drawn between the circuit breaker contacts and driven toward an arc rail. Commutation of the arc from the stationary contact to the arc rail effectively changes the current path to incorporate the polymer current limiter which rapidly suppresses the overcurrent. Circuit isolation is achieved by extinction of the arc within the arc gap between the movable contact and the arc rail.

Abstract: A selective magnetic trip unit comprises a fixed magnetic armature located facing a movable magnetic armature and a damping device with a blade mounted on the movable magnetic armature. The damping device is designed to be in an inactive state up to an intermediate non-tripping position when the movable magnetic armature is attracted by polar parts of the fixed magnetic armature during a first travel, switching to the active state resulting from a deformation of the damping device during a second travel of the movable armature between the intermediate position and the final attraction position causing tripping of the circuit breaker.

Abstract: A solenoid type magnetic trip assembly for a molded case circuit breaker includes an armature biased against an adjustable stop by a tension spring to set the initial gap for the magnetic trip, so that the spring bias remains constant for the full range of the initial gap. The armature includes an elongated armature element mounted by a frame to slide longitudinally along a pair of guide rails. The frame defines a trip surface axially aligned with the elongated armature element which engages a trip arm on a trip bar to trip the circuit breaker in response to a predetermined level of overcurrent. A bimetal providing a thermal trip function is cantilevered from a support spaced from the trip bar by the armature, but has a terminal portion at the free end projecting toward the trip bar and through which the elongated armature element of the armature extends.

Abstract: A circuit breaker device for interrupting current in a circuit path between a source and a load. The device includes a first contact and a second contact cooperatively arranged in the circuit path so as to provide current from the source to the load. At least one of the contacts is disposed on a contact carrier which is movable for interrupting the current provided to the load. A contact status indication arrangement is provided for indicating the status of the contacts. The contact status indication arrangement includes a trip flag, a status insert, a clear plastic lens, a flag guide, and a status flag. The trip flag, status insert and status flag are viewable through the lens, which is disposed in an aperture in the circuit breaker housing. Only one status indicator is viewable through the lens at any one time, each indicating a different circuit breaker status.

Abstract: The stray inductance created by the loop formed by voltage sensing conductors connected to opposite ends of the bimetal in a miniature circuit breaker for determining load current is reduced by joining a voltage sense bar to the free end of the bimetal. The voltage sense bar extends beside the bimetal toward the fixed end of the bimetal where an insulated wire connected to the free end of the sense bar forms a twisted pair with an insulated wire secured to the fixed end of the bimetal.

Abstract: A molded-case multicircuit breaker which suffers insufficient contact pressure at no poles and which is free from damage. The molded-case multicircuit breaker having at least two circuits comprises a handle which performs on-off operation of the circuits simultaneously, a first finger having a movable contact for a first circuit, and another finger having a movable contact for a circuit other than the first circuit, wherein the first finger is designed to be switched on and off directly by the handle, and the finger for a circuit other than the first circuit is electrically insulated from the first finger and is attached resiliently to the first finger. The second finger may be pivotally attached or spring loaded to the first finger.

Abstract: A circuit breaker device for interrupting current in a circuit path between a source and a load includes a first contact and a second contact cooperatively arranged in the circuit path so as to provide current from a source to a load. A trip mechanism assembly, which includes an armature, a bimetal and a yoke, is provided for interrupting the current. The armature includes an aperture in which a latch point is provided to engage a latching surface of a trip lever for latching the trip lever thereon. The amount of current that is required to cause the trip mechanism to interrupt the circuit path is determined by the amount of overlap between the latching surface and the latch point. This overlap is adjusted by bending a calibration plate by tightening a calibration screw which extends through an aperture in a circuit breaker housing and a slotted aperture in the calibration plate. A substantially square shaped nut secures the calibration screw tightly against the housing.

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 solenoid type magnetic trip assembly for a molded case circuit breaker includes an armature biased against an adjustable stop by a tension spring to set the initial gap for the magnetic trip, so that the spring bias remains constant for the full range of the initial gap. The armature includes an elongated magnetically permeable member mounted by a frame to slide longitudinally along a pair of guide rails. The frame defines a trip surface axially aligned with the elongated magnetically permeable member which engages a trip arm on a trip bar to trip the circuit breaker in response to a predetermined level of overcurrent. A bimetal providing a thermal trip function is cantilevered from a support spaced from the trip bar by the armature, but has a terminal portion at the free end projecting toward the trip bar and through which the elongated magnetically permeable member of the armature extends.

Abstract: An earth leakage breaker has a case, a handle protruding from the case, a cradle for determining stable positions of the handle, and a movable finger including a movable contact at a bottom portion of the movable finger. The movable finger is pivotally jointed to the handle at a protrusion provided on a lower side of the handle. An extension spring spans between the cradle and the movable finger, and a top-end swinging trigger plate is provided for engaging the cradle. The trigger plate has a fulcrum at a bottom portion thereof, and a test button and a leak trip solenoid are adjacently arranged at a top portion of the case, with the leak trip solenoid having a trip piece engaged with a contact portion formed on a top portion of the trigger plate for effecting circuit breaking due to a leak.

Abstract: A circuit breaker (1) with a trip assembly (5) provided by an armature (7) carried on a yoke (6). The circuit breaker (1) trips in the event of a fault condition moving the yoke (6) and integrally formed flag section (8) so that an indicating flag section is visible through a window (15).

Abstract: Molded case circuit breaker accessories using slightly modified circuit breaker cases are described. Several of the accessories utilize a microswitch to provide remote indication of an auxiliary function. One modification of the circuit breaker case includes upstanding posts to capture and position the microswitch while a further modification utilizes the magnetic trip unit adjustment screw and a support plate.

Abstract: A magnetic flux concentrator trip unit for molded case circuit breakers in the form of a flux concentrator magnet arranged round the load strap at one end of the circuit breaker is positioned in magnetic proximity to an armature. Current transport through the load strap generates attractive magnetic forces to articulate the circuit breaker operating mechanism when the current exceeds a threshold value.

Abstract: A switch including a breaker, the size and cost of which can be reduced is provided, the switch including a breaker having a structure such that a mechanical switch for turning an electric circuit on/off includes a breaker for interrupting the electric circuit. Moveable contacts arranged to approach and move apart from fixed contacts are elastically urged in a direction where the moveable contacts move apart from the fixed contacts. When the breaker is set, the moveable contacts are located apart from the fixed contacts in such a manner that a short distance is maintained. By switching the mechanical switch on, a solenoid is operated to bring the moveable contacts into contact with the fixed contacts. When the breaker is operated, the elastic urging force is suspended to move the moveable contacts apart from the fixed contacts for a distance longer than a distance for which the moveable contacts are located apart from the fixed contacts when the mechanical switch is switched off.

Abstract: In a molded case circuit breaker with an interchangeable thermalmagnetic trip unit, the C-shaped heater transformer core is permanently held in place in the casing by a load bus strap with the gap in the core facing the trip unit. When the interchangeable trip unit is inserted into the molded casing, a magnetically permeable member mounted in the trip unit is aligned in the gap in the heater transformer core. The bimetal of the trip unit is fixed at one end to an electrically conductive sleeve surrounding the magnetically permeable member and forming the secondary of the heater transformer. The length of the magnetically permeable member is selected to establish the current conditions at which the bimetal trips the circuit breaker.

Abstract: A circuit breaker includes a housing having an opening; separable contacts disposed within the housing and moveable between a closed position and an open position; an operating mechanism having a trip position where the separable contacts are tripped open for moving the separable contacts between the closed and open positions; a trip mechanism cooperating with the operating mechanism for tripping the operating mechanism to the trip position; an electromagnetic mechanism cooperating with the trip mechanism for sensing a current flowing between the separable contacts and engaging the trip mechanism with an armature in response to a predetermined current flowing between the separable contacts; and a manual push-to-trip mechanism operatively associated with the opening of the housing and cooperating with the electromagnetic mechanism for engaging the armature thereof, in order to engage the trip mechanism, trip the operating mechanism to the trip position, and trip open the separable contacts.

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: A modular trip unit for automatically tripping a switch of a circuit breaker when the circuit breaker is being removed from its panel mounting when the circuit breaker has not been manually overridden. The modular trip unit is an integral part of the circuit breaker and includes a trip interlock assembly integrally mounted in the modular trip unit. The trip interlock assembly comprises a spring biased slider extending through and out of the housing of the trip unit, and an actuator in engagement with the slider. The actuator engages a first cam surface of a trip bar and a catching member of a latching assembly is engaged by a lip member on a second cam surface of the trip bar. When the circuit breaker is being mounted on the panel mounting, the slider is forced inwardly thereby compressing a spring associated with the slider, and the slider causes the actuator to rotate in a first direction.

Abstract: A circuit breaker comprises high-duty arc-quenching means 23 and a latching mechanism 19, which is adapted to be electromagnetically and thermoelectrically unlatched by means of a snap-action bimetal disk 52 to open contacting means 21 in response to an overload. The snap-action bimetal disk 52 is held in a carrying body 32, which has a high thermal conductivity and which carries an electromagnetic exciter coil 33 and contains an associated plunger 42. For tripping in response to an overload, the plunger 42 is adapted to be actuated either electromagnetically and/or by the snap-action bimetal disk 52. The movable contact 21 will remain open when the latching mechanism 19 has been unlatched. In response to a movement of the plunger 42 out of its make position, the latching mechanism 19 is unlatched by a first arm of a two-armed lever 37, which is made of lucite and is pivoted to the carrying body 42. The contacting means 21 are adapted to be struck open by the second arm 41 of the lever 37.

Abstract: A circuit breaker having electrical contacts operable between a closed position in which a circuit is completed through the conductor and an open position in which the circuit through the conductor is interrupted. The circuit breaker includes a latchable operating mechanism operable to open the electrical contacts when unlatched and a trip bar rotatable from a biased position to a trip position to unlatch the operating mechanism. A magnetic trip assembly is provided including a frame, a stationary magnetic structure mounted to the frame and a movable armature which is attracted to the stationary magnetic structure by abnormal current through the conductor to rotate the trip bar to a trip position. The movable armature includes a nib extending angularly therefrom, the nib defining a detent. The armature is pivotably mounted to the stationary magnetic frame by a pin.