Abstract: An adjustable thermal trip mechanism for a circuit breaker is provided which can improve the reliability of over-current tripping by minimizing an influence upon thermal tripping even if an assembly error such as skewing or twisting occurs during assembly of bimetallic strips. The adjustable thermal trip mechanism for the circuit breaker comprises: a crossbar that is rotatable and has at least one power receiving portion for receiving rotary power; a bimetallic strip that can bend towards the power receiving portion when an over current occurs on the circuit; and an adjustment screw installed to face the power receiving portion, wherein the power receiving portion comprises a plurality of planar portions which are at different distances from the adjustment screw.

Abstract: A circuit breaker including an adjustable instantaneous trip level. Adjustable instantaneous trip level can be applied to a one-pole and/or two-pole circuit breakers including a thermal and magnetic mechanism, including AFCI, CAFCI, and/or GFCI constructions. The circuit breaker includes a magnet position adjustment mechanism allowing an operator to adjust the instantaneous trip level to a desired setting, such as between about 5 to 10 times the handle rating. The design also allows for alternate magnets to be used for either an increased or decreased instantaneous settings as desired. In two-pole circuit breakers, the instantaneous trip level can be set independently for each mechanism pole. Multi-pole circuit breakers and methods of adjusting instantaneous trip level are provided, as are other aspects.

Abstract: A trip device support frame for a circuit breaker is provided. The trip device support frame includes a calibration tab that is a cantilever member. As a cantilever member, the calibration tab may be moved, i.e. deformed at a proximal end of the tab, so as to adjust the position of the calibration tab relative to the other portions of the trip device support frame. The calibration tab extends upwardly and the distal end thereof is disposed adjacent a top member of a circuit breaker housing assembly. The circuit breaker housing assembly, and more specifically a housing assembly top member, includes a calibration slot. In this configuration, the calibration tab distal end may be engaged by a calibration tool from the upper side of the circuit breaker rather than a lateral side.

Abstract: An improved calibration machine for calibrating a thermal trip apparatus of a circuit interrupter employs a tool having an elongated shank and a pair of engagement elements. The engagement elements are engageable with a support that carried a bimetal element. The engagement elements can deform the support in opposite directions to either increase or decrease the thermal trip setting of the thermal trip apparatus. If the support is over-deformed in one direction, it can be deformed in an opposite direction to enable a circuit interrupter whose thermal trip apparatus has been deformed beyond a desired target thermal calibration setting to be deformed in an opposite direction to reach the desired target thermal calibration setting.

Abstract: A thermal overload relay includes a main bimetal for detection of an overload current, a shifter associated with the main bimetal, a release lever working according to a displacement of the shifter, a contact reversing mechanism for changing-over contacts by reversing action caused by rotation of the release lever, and a manipulation structure for manipulating the release lever and the contact reversing mechanism. The manipulation structure includes a reset bar for returning the contact reversing mechanism to an initial state. The reset bar is arranged to change-over between a manual reset state in which the reset bar can be pushed-in and an automatic reset state in which the reset bar is pushed-in and turned from the manual reset state and held in that state.

Abstract: A thermal overload relay has a case, a main bimetal bending upon detection of an overload current, a release lever rotatably supported by an adjusting link and rotating according to a shifter displaced in response to the bending of the main bimetals, and a contact reversing mechanism for change-over contacts responsive to a rotation of the release lever. The main bimetal, release lever and contact reversing mechanism are disposed in the case. The contact reversing mechanism has a movable plate, and a reversing spring stretched between the other side of the movable plate and a spring support. The other end of the movable plate and the spring support is positioned opposite a support point. The release lever has a release lever supporting part, a reversing spring pushing part, a cam contact part, and a displacement input part, in which the release lever supporting part is pivoted on the adjusting link.

Abstract: A fast acting switching mechanism for a circuit breaker includes a drive rod articulated to a drive module and supporting at an end thereof a contact bridge having at opposite ends thereof respective moveable contacts for switchably engaging a pair of fixed contacts of the circuit breaker. A contact spring unit is operatively coupled to the drive module for applying closing pressure in the order of 200 Kg; and a latch latches the drive rod in an open or closed position after operation of the circuit breaker and prevents rebounds. The contact bridge includes a pair of side conductors supporting on upper edges thereof an armature having an exposed upper surface that supports the moveable contacts at opposite ends of the armature; and a reinforcing element inserted between the side conductors.

Abstract: A thermal overload relay includes main bimetals which bend upon detection of an overload current; a release lever displaced via movement of a shifter moved in response to the bending of the main bimetals; and a contact reversing mechanism for changing-over contacts responsive to a rotation of the release lever. The main bimetals, the release lever and the contact reversing mechanism are all disposed in a case. The contact reversing mechanism includes a pivotable movable plate; a reversing spring reversing the movable plate by coupling with a rotated release lever; and an interlock plate rotating around a support shaft together with the movable plate. Each contact has a normally opened contact piece and a normally closed contact piece and is disposed respectively in the vicinity of a front surface and in the vicinity of a back surface of the interlock plate.

Abstract: A thermal overload relay is provided with an external case, and an adjustment dial with a cam inserted into an adjustment dial insertion hole provided in the external case for adjusting a settling current. A press-fitting section is provided at one of the adjustment dial and the adjustment dial insertion hole, and a locking section is provided at the other of the adjustment dial and the adjustment dial insertion hole. The press-fitting section is press-fit and retained in the locking section.

Abstract: A circuit breaker test system includes a circuit breaker under test having a deformable frame with an elongated slot, an elongated deformable portion adjacent the elongated slot and a movable portion adjacent the deformable portion, and a thermal trip assembly coupled to the movable portion. A calibration device includes a forked tool straddling the deformable portion. The trip assembly has a first thermal response. The calibration device rotates the tool in a first rotational direction and responsively deforms the deformable portion and moves the movable portion in a first direction, in order to calibrate the trip assembly for a second different thermal response. The calibration device rotates the tool in an opposite second rotational direction and responsively deforms the deformable portion and moves the movable portion in an opposite second direction, in order to re-calibrate the trip assembly for a third thermal response between the first and second thermal responses.

Abstract: A method for adjusting a trip sensitivity in a thermal overload protection apparatus, including setting an adjusting reference point; measuring a normal position of bimetals; measuring a moving distance at a time of trip operation of a trip latch mechanism; deciding an assembling position of a shifter mechanism based on the measured moving distance at the time of trip operation of the trip latch mechanism, information on a trip distance between a pre-determined shifter mechanism and the trip latch mechanism and information on a size of the shifter mechanism; conducting a predetermined overcurrent to the thermal overload protection apparatus; measuring a conducting time of the overcurrent until a trip event; calculating a difference between the conducting time measured in the measuring step and a predetermined trip time by converting a rotation angle; and marking a graduation of a set trip operation current by the rotation angle calculated in the calculating step.

Abstract: A thermal overload trip apparatus capable of minimizing inferiority caused by variations during manufacturing of an adjusting means and simply adjusting sensitivity by duplicating the means for adjusting a sensitivity to a trip operation current, comprising: a trip mechanism driven to a trip position by a driving force from a shifter mechanism on occurrence of an overload in a circuit; a release lever mechanism for driving the trip mechanism to the trip position by pressing it when there is the driving force from the shifter mechanism or for releasing the trip mechanism when there is no driving force, on occurrence of the overload in the circuit; an adjusting lever for operating the release lever mechanism to be horizontally moved by rotation; an adjusting knob having an upper surface having a setting groove and a lower portion having a cam portion; and a means independently adjusting the sensitivity to the trip operation current regardless of manipulation of the adjusting knob.

Abstract: A circuit breaker test system includes a circuit breaker under test having a deformable frame with an elongated slot, an elongated deformable portion adjacent the elongated slot and a movable portion adjacent the deformable portion, and a thermal trip assembly coupled to the movable portion. A calibration device includes a forked tool straddling the deformable portion. The trip assembly has a first thermal response. The calibration device rotates the tool in a first rotational direction and responsively deforms the deformable portion and moves the movable portion in a first direction, in order to calibrate the trip assembly for a second different thermal response. The calibration device rotates the tool in an opposite second rotational direction and responsively deforms the deformable portion and moves the movable portion in an opposite second direction, in order to re-calibrate the trip assembly for a third thermal response between the first and second thermal responses.

Abstract: An adjusting device is for a thermal trip of a switchgear. It includes a bimetal, which is held in a fixed manner on a bimetal support, whose free end is located at a distance from a tripping lever, and which increasingly acts upon this tripping lever in a tripping direction as a result of thermal deformation. A distance can be adjusted by deforming the bimetal support. The adjusting device is particularly suited for use in circuit-breakers or the like.

Abstract: A trip system for a circuit breaker includes a current sensor and a stop surface, the current sensor having a contact surface, a first end that is supported, and a second end with a degree of freedom. The current sensor, arranged for receiving an electric current, undergoes a first deflection in response to a first current and a second deflection in response to a second current, the first deflection resulting in clearance between the contact surface and the stop surface, and the second deflection resulting in contact between the contact surface and the stop surface.

Abstract: A heater element for use in a circuit breaker whose initial shape can be varied to achieve various trip ratings for different circuit breakers. The material composition of the heater element and the bimetal strip indirectly heated by the heater element are kept the same. The electrical resistance presented to current passed through the heater element is varied by varying the shape of the heater element. The shape of one heater element relative to another heater element varies according to one geometric parameter. The geometric parameter may be surface geometry, thickness, or cross-sectional area.

Abstract: The circuit breaker current/time characteristic value at which the bimetal in a thermal trip assembly actuates a trip mechanism is adjusted by an adjustable coupler that includes first and second pivoted members separately rotatable about a common pivot axis. Deflection of the bimetal by an overload current causes rotation of the first pivoted member, which is coupled by a coupling member extending parallel to the common axis into the second pivoted member which rotates to actuate the trip mechanism. A positioner moves the coupling member toward and away from the common pivot axis to adjust the amount of deflection of the bimetal needed to actuate the trip mechanism.

Abstract: A pair of spring mounted masses have sufficient inertia to remain stationary in response to a shock force applied to the housing of a trip assembly in a circuit breaker to block movement of the trip bar and thereby prevent a nuisance trip.

Abstract: A thermal overload open-phase tripping device includes in a case bimetals corresponding to different phases; a differential shifter mechanism composed of a push shifter and a pull shifter, linked to operating ends of the bimetals, and an interlocking plate; and a compensating bimetal for transmitting output from the shifter mechanism to an opening and closing mechanism section of a breaker main body. The push and pull shifters are slidably supported to extend over interphase partition walls in the case, and a case cover is placed and held over the push and pull shifters. Rib-shaped projections projecting from an inner surface of the case cover and facing the top surfaces of the shifters are provided as shifter position guides to constrain inclination of the shifters moving in accordance with bending displacement of the bimetals to hold the shifters horizontally.

Abstract: A molded case circuit breaker that includes a double headed calibration screw. The calibration screw has a first and second end with identical convex tip surfaces and screw driver engagement surfaces. The convex tip surface is suitable for engaging a bi-metal thermal overload element. The screw driver engagement surface is suitable for applying a screw driver to adjust the calibration screw position in order to adjust the deflection of the bimetal and calibrate the thermal overload protection. At least one calibration screw planar surface allows for improved sealant injection to permanently fix the screw position and associated calibration setting following adjustment.

Abstract: The invention relates to a low voltage switchgear with a bimetallic actuator, especially to a motor safety switch. The aim of the invention is to improve such a low voltage switchgear so that the fabrication and assembly tolerances are widely compensated for. To this end, the two-part (21, 22) housing (2) of the switchgear (1) is provided with an opening (23), that is closed with a protective cover (24). By way of said opening (23), the bimetallic component (51) and the jack system are accessible for the purpose of measurement and a bridge system (52) of the bimetallic actuator (5) that is calibrated on the basis of the measured values can be mounted therethrough.

Abstract: A thermal overload relay includes an inversion operation mechanism that is driven by a releasing lever to open or close a contact. The inversion operation mechanism includes a movable plate supported at one end so as to be inverted, and a tension spring for driving the movable plate for inversion. The releasing lever presses a middle of a wire of the tension spring to drive the movable plate for inversion. A projection is formed in the middle of the wire of the tension spring to contact with the releasing lever. Thus, a stable inversion operation can be made regardless of the positioning of an adjustment dial.

Abstract: A molded circuit breaker cover for providing access to a calibration screw of a thermal trip unit is disclosed. The cover includes an exterior surface having an opening disposed therein and a locator extending from an underside of the cover. The locator includes a channel surface defining a channel continuous with the opening wherein the locator captures the calibration screw and aligns the calibration screw with the opening. Locator significantly increase the calibration yield of multi-pole circuit breakers by decreasing misalignment of the calibration screws during assembly of the circuit breaker.

Abstract: An adjustable thermal-magnetic trip unit for a molded case circuit breaker 10 is disclosed, with the circuit breaker 10 including a housing 12 having an operating mechanism 40 including an intermediate latch 52, a line terminal 18, a load terminal 16 and a cover 20. The adjustable thermal-magnetic trip unit includes a magnetic yoke 66 mounted in the housing 12, and a bimetal member mounted in the magnetic yoke 66, with the bimetal member having a fixed end and a movable end. The fixed end is coupled to a load bus 61 of the load terminal 16, and the movable end is coupled to a movable contact of the operating mechanism 40. The trip unit 610 also includes a horizontal trip bar rotatably mounted in the housing 12, with the trip bar 54 having an actuating arm gapped from the movable end of the bimetal member and with the actuating arm aligned to selectively engage the movable end of the bimetal member.

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 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 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: 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: A molded case circuit breaker includes a generally "Z" shaped intermediate latch structure which has upper and lower substantially planar sections that are each bent at an angle with respect to a center pivot section. The upper portion of the intermediate latch includes one or two latch surfaces. One of these latch surfaces engages the cradle of the operating mechanism of the circuit breaker, to latch the operating mechanism when the circuit breaker is closed. The other latch surface engages a trip bar or an intermediate latch bar, which is rotated by the trip unit when an overcurrent condition occurs. The lower portion of the intermediate latch structure also includes a latch surface which may engage a trip bar. This latch surface is sloped such that when the latch surface of the trip bar is moved along this sloped latch surface, the trip bar rotates.

Abstract: The trip device comprises a magnetic circuit having a first and second fixed parts, a movable element and an adjustment device. The adjustment device comprises a shunt and an air gap arranged between the first and second fixed parts branched off with respect to the mobile element. The tripping threshold of the trip device is modified by varying the air gap distance between the shunt and the second fixed part. In a circuit breaker, the mobile element acts on an opening mechanism and an adjustment part acts on the adjustment device making the air gap distance vary. A sensor associated to the magnetic circuit supplies a measurement signal to a processing unit.

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: An adjustment device including a rotary knob for driving a positioning stud cooperating with a ramp of an oeprating component, and a ring equipped with means for selecting the angular position of an end-of-travel stop, designed to limit the rotational movement of the knob to determine a maximum tripping threshold. The ring is covered by a cover plate having an opening for access to the head of the fine tripping threshold adjustment knob. The diameter of the second opening is smaller than the external diameter of the ring to inhibit any modification of the position of the end-of-travel stop after the cover plate has been fitted.

Abstract: A molded case circuit breaker having a thermal-magnetic trip unit is provided with a mechanical rating plug to allow a number of circuit breakers of different ampere ratings to be used within a common-sized enclosure. Multiple mechanical rating plugs are stored at the place of distribution to adapt the common enclosure to a specific ampere rating at a substantial savings in time, labor and materials.

Abstract: A thermal setting process of the bimetal strip consists in securing an adjusting pin to the trip bar by means of laser welding when the bimetal strip reaches a first preset temperature, and then checking tripping at a second temperature with or without action on a positioning screw of the bar.

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: Apparatus for adjusting the calibration of a thermal trip unit which is to be used in conjunction with an electrical circuit breaker. A rotatable knob is provided which adjusts the trip unit to between one hundred percent of the rating of the circuit breaker and some value which is less than one hundred percent. An adjustable stop screw is provided to engage the rotatable knob when the knob is rotated to adjust the calibration of the trip unit to the desired value which is less than one hundred percent of the rating of the breaker. The adjustable stop screw thereby limits travel of the adjustable knob between only one hundred percent of the rating of the circuit breaker and the desired value which is less than one hundred percent.

Abstract: A one piece member rests against a cam surface at a first end and against an adjustable pivot at a second end, biased thereagainst by an integral cantilever spring of said member, the distal end of which is interlocked in a deflected position to a hook formed in a housing. One end of a bimetal strip is riveted to the second end of the one piece member, the position of the other end of the bimetal strip being determined by manual adjustment of the pivot and the cam.

Abstract: An improved magnetic armature for magnetically activated circuit breakers. The armature being configured to provide a consistent engagement length between the armature and the contact operating mechanism of a circuit breaker. The armature also being configured to reduce the air gap distance between the armature and the magnetic yoke of a circuit breaker.

Abstract: A device is provided for adjusting the relative position of two parts of the same piece by deforming an intermediate zone connecting these two parts together, by means of a conical screw, and having a tapped bore in which said screw may be screwed, and a cut out which extends from a first edge of the piece to said bore, wherein said intermediate zone further includes at least a second cut out opening into said bore, opposite said first cut out which defines with a second edge of the piece a deformable zone, forming a hinge, offset with respect to said bore.

Abstract: A molded case circuit breaker bimetal trip unit arrangement substantially reduces the variation in trip characteristics between circuit breakers employing the improved bimetal. The number of circuit breakers failing the in-line calibration test is correspondingly substantially reduced.

Abstract: A device is provided for adjusting the thermal current of a bimetallic strip thermal tripping device and a protection switch including such a device, said adjustment device including a graduated wheel accessible from outside the switch box and having inner toothing; a flange centered on the wheel, with a member meshing with the toothing of the wheel, and formed with an excentric groove; a tumbler rotated through a finger engaged in the groove of the flange; a hook mounted for pivoting about a pin fixed with respect to the case; and a lever mounted for pivoting by means of a pin on the hook and connected to the tumbler by a stud, the lever being positionable with respect to the bimetallic strip at a given distance depending on the value of the thermal tripping current.

Abstract: The invention relates to a multiple moving contact assembly for a miniature circuit breaker with high ratings and a thermomagnetic trip release. The moving contact part of the circuit breaker includes two independent contact arms connected in parallel and mounted on a transverse spindle of the cradle. The arms are connected to a magnetic circuit of the electromagnetic trip release by two braids situated in symmetrical lateral areas. The contact parts bear on a single stationary contact pad so as to create two contact points enabling the temperature rise to be reduced. The electromagnetic top release has a coil including a tail arranged as an adjustable support device of a bimetallic strip, through whose foot the current flows thicknesswise.

Abstract: A circuit breaker having means for varying the thermal rating characterized by a circuit breaker mechanism including a releasable cradle for automatically tripping contacts to an open position in response to overload current conditions. A trip bar movable in response to movement of a bimetal element and the tie bar including a movably mounted member having an inclined surface for adjusting the spacing between the bimetal element and the movable member.

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 selectable rating plug allows a standard molded case circuit breaker design to be used over a wide range of ampere ratings. The rating plug is used to control the thermal load on the thermally responsive trip element within the breaker. Movement of the thermally responsive element articulates the breaker trip mechanism in response to predetermined overload conditions to interrupt circuit current.

Abstract: A bimetal operated latch subassembly (600) for an electrical device such as an overload/switch device which is a self-contained unit that can be mounted into operative position relative to the trippable member (012) of the electrical device. A bimetal assembly (660) and a pair of terminals (604,621) electrically connected thereto are mounted on a main insulating base (601). A vibration and shockproof latch assembly (610) is preassembled on a stainless steel sub-base (611) which is then secured by a single screw (605) to the main base (601) at the same time coupling the bimetal assembly (660) to the latch (610) in operative relationship. The latch (610) is rendered shockproof by providing a spring-biased linear slider (650) that latches to a transversely pivoted latch lever (613). The latch friction that must be overcome by the bimetal (608) is reduced to a minimum by providing the latch lever (613) with an adjustable bias (614,615) that almost balances the tripping force (Y) of the trippable member (012 ).

Abstract: An overcurrent relay comprises a housing having an external portion, an overcurrent responsive mechanism, disposed within the housing, for opening or closing a pair of contacts in response to an overcurrent, an adjusting screw device for adjusting the operating current of the overcurrent responsive mechanism, the adjusting screw device being rotatably supported by the housing and having serrations on the periphery thereof, and an engaging member mounted on the external portion of the housing for engaging with a serration of the adjusting screw device for preventing an unintentional rotation of the adjusting screw device.

Abstract: A thermal overload relay of the type which uses a shifter to transmit thermal bending of the main bimetallic element to one end of the temperature compensating bimetallic element which is connected to a release lever which controls the closing of the relay and which includes an adjusting link which has an eccentric stem whose degree of rotation controls the setting of the release lever. As a calibration control to correct for unintended manufacturing variations and aging effects, the adjusting link supports an adjustment pin with an eccentric stem which abuts the eccentric stem of the adjusting dial to provide further control of the setting of the release lever.

Abstract: A molded case circuit breaker includes a new and improved calibration adjusting means for a bimetal in a trip mechanism. The trip mechanism also includes a bimetal having a portion movable in response to predetermined overload conditions, an intermediate control lever for adjusting the spatial disposition of the movable portion of the bimetal with respect to a trip bar of the trip mechanism and a rotatable adjustment means for adjusting the spatial disposition of the intermediate control lever in the circuit breaker. By rotating the adjustment means, the distance between the movable portion of the bimetal and the trip bar can be precisely adjusted via the intermediate control lever. The intermediate control lever is coupled to a relatively stationary portion of the bimetal thereby enabling such adjustment without applying undue stress to the movable portion of the bimetal.

Abstract: A circuit breaker characterized by a pair of separable contacts, trip means operable automatically in response to overload current conditions to open the contacts which means include a rotatable trip bar biased in an untripped position, and interlock means including a manually operable button for rotating the trip bar to a tripped position when the button is pushed and for rotating a cam into tripped and untripped positions when the button is rotated.