Abstract: A circuit breaker may be plugged into a breaker compartment in a panelboard without making a connection to a power bus of the panel board. A tool may be inserted into the breaker compartment to operate movable contacts that connect, or disconnect, the circuit breaker from the power bus without de-energizing the power line network. Inserting the tool into the breaker compartment first causes a trip actuator to trip the circuit breaker.

Abstract: Disclosed is a gap adjusting method which easily adjusts a gap between a bimetal and a crossbar by using a gap adjusting block and an adjusting screw in a trip mechanism of a molded case circuit breaker without a separate additional device. The gap adjusting method in the trip mechanism of the molded case circuit breaker includes setting a reference gap between a crossbar and a bimetal, measuring a total resistance of the trip mechanism and a trip stroke of a switching mechanism to set a compensation gap, placing a gap adjusting block on a position separated from a crossbar by a gap based on the sum of the reference gap and the compensation gap, rotating an adjusting screw assembled with the bimetal to contact the adjusting screw with the gap adjusting block, and adhering the adjusting screw to the bimetal.

Abstract: Methods, apparatus, and systems are provided for calibrating a thermomagnetic trip unit in a circuit breaker base assembly. An apparatus for calibrating a trip unit includes a calibration nut, an extended armature guide pin having a threaded portion, a spring disposed on the calibration nut and coiled around the extended armature guide pin, and an armature disposed on the spring and adapted to be held by an electromagnet. The calibration nut is threaded on the threaded portion of the extended armature guide pin and adapted to translate up or down depending on rotation of the extended armature guide pin to compress or decompress the spring against the armature. The extended armature guide pin includes a slotted end that is accessible when the apparatus is installed in the circuit breaker base assembly. The calibration nut is also accessible when the apparatus is installed in the circuit breaker base assembly.

Abstract: An electromagnetic relay including an electromagnet, a movable contact actuated by the electromagnet, and a fixed contact disposed opposite to the movable contact and capable of contacting and separating from the movable contact. The electromagnetic relay further includes a backstop for stopping movement of the movable contact in a direction separating from the fixed contact, and a backstop positioner for setting the backstop at a position for defining a predetermined contact gap between the fixed contact and the movable contact. In a state where movement of the movable contact is stopped by the backstop, different-sized contact gaps are defined between the fixed contact and the movable contact, depending on the position of the backstop set by the backstop positioner.

Abstract: Methods, apparatus, and systems are provided for calibrating a thermomagnetic trip unit in a circuit breaker base assembly. The invention provides a calibration nut, an extended armature guide pin having a threaded portion, a spring disposed on the calibration nut and coiled around the extended armature guide pin, and an armature disposed on the spring and adapted to be held by an electromagnet. The calibration nut is threaded on the threaded portion of the extended armature guide pin and adapted to translate up or down depending on rotation of the extended armature guide pin to compress or decompress the spring against the armature. The extended armature guide pin includes a slotted end that is accessible when the apparatus is installed in the circuit breaker base assembly. The calibration nut is also accessible when the apparatus is installed in the circuit breaker base assembly. Numerous additional aspects are disclosed.

Abstract: Methods, apparatus, and systems are provided for a selectivity device for a circuit breaker. The invention includes a modular assembly adapted to be coupled to a load conductor assembly. The modular assembly includes a tripping plunger including a cam surface adapted to interact with a breaker tripping mechanism; an armature coupled to the tripping plunger; a yoke adapted to generate a magnetic field in response to an electric current in the load conductor assembly and disposed to apply a magnetic force proportionate to the electric current on the armature; and a spring assembly adapted to counter-balance the magnetic force up to a predefined tripping current in the load conductor assembly. Numerous additional aspects are disclosed.

Abstract: A circuit breaker is disclosed, wherein the circuit breaker according to an exemplary embodiment of the present disclosure includes a permanent magnet rotatably hinged to a yoke, and wherein the permanent magnet is changed in magnetic path direction thereof by rotation to set up a sensitivity current, whereby a defect ratio of product is minimized.

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 divided armature for the trip mechanism of a circuit breaker especially useful for low trip current breakers allows for two independent adjustments: first of the magnetic air gap between the yoke and the armature and second of the clearance between the trip bar and the back plate of the armature. The divided armature allows the force of a return spring of the trip mechanism to be unchanged while adjusting the magnetic air gap to set the trip current point.

Abstract: A shunt separator is provided for an electrical switching apparatus including a housing, separable contacts enclosed within the housing, an operating assembly including a trip bar, and a trip assembly. The trip assembly cooperates with the trip bar to trip open the separable contacts in response to a fault condition. The trip assembly includes a number of shunts. The shunt separator includes a molded projection, which extends outwardly from the housing of the electrical switching apparatus. The molded projection at least partially surrounds a portion of the trip bar, thereby separating the number of shunts from the trip bar.

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 divided armature for the trip mechanism of a circuit breaker especially useful for low trip current breakers allows for two independent adjustments: first of the magnetic air gap between the yoke and the armature and second of the clearance between the trip bar and the back plate of the armature. The divided armature allows the force of a return spring of the trip mechanism to be unchanged while adjusting the magnetic air gap to set the trip current point.

Abstract: A user adjustment assembly for translating user-adjustable dial settings to tripping levels of an electronic trip unit includes a potentiometer and an adjustment button. The potentiometer is positioned inside a cover of the trip unit and includes a potentiometer button. The adjustment button is coupled to the potentiometer for mechanically adjusting it and includes an insulation disc for increasing resistance to electrostatic discharge, preventing contaminants from entering the printed wire assembly components, and preventing application of downward force to the potentiometer button. The insulation disc has a bottom surface that is dimensioned to be larger than the potentiometer button. The adjustment button includes one or more stops that trigger a fail safe operation mode where the tripping levels are automatically adjusted to higher or predetermined protective levels when the adjustment button is moved to those stop positions. Switch calibration is obviated and the simplified design reduces overall cost.

Abstract: A divided armature for the trip mechanism of a circuit breaker especially useful for low trip current breakers allows for two independent adjustments: first of the magnetic air gap between the yoke and the armature and second of the clearance between the trip bar and the back plate of the armature. The divided armature allows the force of a return spring of the trip mechanism to be unchanged while adjusting the magnetic air gap to set the trip current point.

Abstract: Certain exemplary embodiments comprise a device comprising: a trip mechanism adapted to engage an operating mechanism of an alternating current circuit breaker, said trip mechanism comprising: a bi-metal element arranged lengthwise into a first end zone, a central zone, and a second end zone, a load bus coupled to said first zone, said second end zone adapted to engage an armature latch that is adapted to trip on operating mechanism of the circuit breaker; and an electromagnetic element coupled to the load bus.

Abstract: The invention relates to a trip assembly for use in an electro-mechanical device, such as a circuit breaker. The trip assembly is used for interrupting the flow of current upon the detection of excess current in a circuit breaker and comprises a trip bar, a stationary armature bracket, a movable armature, and a spring. The movable armature includes a first end coupled to a base portion of the armature bracket, and a trip-actuating surface being disposed proximate a trip finger of the trip bar. The spring is directly coupled at its respective ends to a spring-support portion of the armature bracket and to a spring tab of the movable armature.

Abstract: Resettable circuit interrupting devices, such as GFCI devices, that include a reset lockout mechanism, an independent trip mechanism and reverse wiring protection. A conical reset plunger is notched to force a successful test before reset.

Abstract: A trip unit for a circuit breaker having a current carrying conductor that electrically communicates with a cable or a bus bar. The trip unit includes a current carrying strap, a magnet core, an armature and a magnetic barrier. The current carrying strap is adapted to be in electrical communication with the current carrying conductor. The magnet core is disposed at the current carrying strap. The armature is pivotally disposed in magnetic communication with the magnet core. The magnetic barrier is disposed to shield the armature from a magnetic flux generated in the current carrying conductor.

Abstract: A trip system for a circuit breaker having a calibration system is disclosed. The calibration system includes a retainer, a tripping member responsive to an electric current, an actuator retained by the retainer, a spring adjuster adjustably engaged with the actuator and the tripping member, and a bias spring disposed for biasing the actuator in a first direction. Movement of the spring adjuster absent movement of the actuator and the tripping member results in a change in the bias spring force and no change in the position of the tripping member, and movement of the tripping member absent movement of the spring adjuster results in a change in the position of the tripping member and no change in the bias spring force.

Abstract: An electromagnetic relay with adjustable tripping threshold for a low-voltage circuit breaker, comprising a magnetic circuit that has a fixed part,, which comprises a fixed element made of ferromagnetic material, a core, and at least one winding coil, and a moving part, which has a moving plate made of ferromagnetic material and arranged so as to face at least partially the fixed element with the coil interposed between the moving plate and the fixed element, the moving plate being functionally connected to means for adjusting the tripping threshold; its particularity consisting of the fact that the moving plate and/or the fixed element have a contoured body that allows, by acting on the adjustment means, to set the tripping threshold by simultaneously varying the gap between the moving plate and the fixed element and the magnetic coupling between the moving plate and the core.

Abstract: The magnetic trip device of a circuit breaker has a magnetic pole in which a magnetic field is generated by load current, and an armature assembly that includes: a bracket supported for pivotal movement relative to the magnetic pole; a spring biasing the bracket to a position spaced from the magnetic pole; an armature hinged on the bracket; and an adjusting screw for adjusting a gap between the armature and the magnetic pole for calibrating the trip device without affecting the spring bias, which can be separately and independently adjusted to select the load current at which the magnetic trip is initiated.

Abstract: An adjustable magnetic trip unit for a circuit breaker includes a torsion spring which applies a bias force to the plunger of a trip solenoid. The torsion spring is mounted on a driven bevel gear and wound by an adjustment knob coupled to a driving bevel gear to adjust the current at which the solenoid is activated. An indexer having peripheral flats which engage a seat in the circuit breaker housing provides a plurality of discrete positions of the adjustment knob. Depressing the adjustment knob against a second spring unseats the indexer for rotation of the adjustment knob between settings. In addition, a slide with an inclined surface bearing against the plunger and coupled to the driven bevel gear, provides simultaneous adjustment of plunger gap with adjustment of the torsion spring force to increase the range of adjustment.

Abstract: A release unit for a circuit breaker is equipped with a magnet yoke and an armature collaborating with it for actuating a release device, in which case a nonmagnetic weight element that increases the inertia of the armature is applied to the armature.

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 generates a tripping operation. The automatic trip assembly includes a magnetic yoke, an armature, and a plurality of abutment members. The magnetic yoke has pivot supports providing for a rotatable disposition of a head portion of the armature. The assembly also includes a biasing member having a first portion and a second portion, the first portion abutted against a selected one of the plurality of abutment members, the second portion abutted against the armature and applying a force to the armature in a direction to normally rotationally displace a bottom portion of the armature away from the magnetic yoke, wherein selecting a different one of the plurality of abutment members to be the selected one causes the force to vary.

Abstract: The present invention provides an armature assembly for adjusting the magnetic calibration of a tripping mechanism in a circuit breaker includes a bracket having a channel defined by a pair of legs and a bight with opposing sides. A first tab and a second tab are fixedly connected to opposing sides of the bight. The first and second tabs are positioned parallel to one another and perpendicular to the opposing sides of the bight. The first and second tabs have a respective first and second hole that are threaded. A first pin rotatably connects to the tripping mechanism within the interior of the circuit breaker. The first pin is affixed across the legs of the channel. An adjustment screw has an elongated body with a top portion on one end and at the opposing end a bottom portion. The adjustment screw has a plurality of screw threads defining an exterior side wall of the elongated body along the bottom portion. The plurality of screw threads configured to releasably engage the threaded fastener component.

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 adjusting ring includes a surface which is matched to the pitch of the winding wire. This adjusting ring is used in a device having a coil winding. As such, the coil winding can be positioned in its axial direction.

Abstract: A flux transfer shunt trip actuator has an elongated seat member extending between the legs of a U-shaped magnetically permeable frame member. A plunger is magnetically latched against the seat formed by the seat member in a retracted position by permanent magnets positioned adjacent the seat. The field generated by permanent magnets produces a latching force which exceeds a bias force generated by a helical compression spring extending along the elongated seat member and biasing the plunger toward an actuated position spaced from the seat. A coil surrounding the elongated seat member and the spring, generates an electromagnetic field when energized which bucks the permanent magnet field so that the plunger is driven to the actuated position by the spring. Preload on the spring is adjusted by an adjusting member positioned along a threaded shaft coaxial with the spring and extending from the bight of the U-shaped frame in the opposite direction from the pair of legs of the frame.

Abstract: A circuit breaker having a trip unit includes a lock out assembly positioned adjacent the trip unit for controlling access thereto. The lock out assembly includes a base member, a cover member and a slide member received therebetween. The slide member is moveable between various positions for controlling access to settings for the various operating parameters of the circuit breaker as provided by the trip unit.

Abstract: The trip bar is sub-divided into a first actuating part associated to the trip rod of the actuator and a second actuating part operating in conjunction with the indicating device. A mechanical coupling link is arranged between the two actuating parts being adjustable between a coupled position and a disengaged position. An operating lever performs locking of the second actuating part in the active position to keep the fault information on the indicating device, whereas the first actuating part returns automatically to the inactive position when said mechanical link is in the disengaged position.

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: 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 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: 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 circuit breaker with improved magnetic trip assembly includes electrical contacts operable between a closed position in which a circuit is completed and an open position in which the circuit is interrupted, 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. The circuit breaker further includes a magnetic trip assembly comprising a stationary magnetic structure, a movable armature which is attracted to the stationary magnetic structure by an abnormal current through the conductor to rotate the trip bar to the trip position and a plate means mounted to the movable armature and disposed between the armature and the stationary magnetic structure. The plate means adjusts the amount of abnormal current required to attract the movable armature to the stationary magnetic structure and in turn rotate the trip bar.

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. The rating plug interacts with a thermal-magnetic trip unit to set the circuit breaker ampere rating.

Abstract: An overcurrent tripping device which is included in a circuit breaker is constituted by a pre-assembly unit of a holder with a conductor, a fixed core for generating a magnetic attraction force responding to an overcurrent, and a bimetal warping responding to the temperature rise of the conductor, and an operation arm rotatably borne on the holder and having a moving core which is to be attracted to the fixed core by the magnetic attraction force.

Abstract: A compact circuit breaker containing an electronic trip unit employs an actuator-accessory unit to articulate the circuit breaker operating mechanism and separate the circuit breaker contacts to interrupt current within a protected circuit. A tolerance compensating spring is attached to the actuator-accessory unit trip armature to precisely set the separation gap between the tip of the armature and the actuator-accessory trip actuator arm.

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 has a magnetic trip assembly which can be adjusted to trip the breaker for low level overcurrents in the range of five to ten times rated current. The magnet trip includes for each pole of the breaker a helical torsion spring having one torsion arm which biases an armature against an adjusting bar to form a gap between the armature and a stationary magnetic structure in which magnetic flux strong enough to attract the armature and trip the breaker is induced by overcurrent. A second torsion arm of the spring has a first portion which bears against and slides along a pivot member carried by the adjusting bar to adjust the bias force applied to the armature by a given amount per unit travel of the adjusting bar over a low trip current portion of the range of travel of the adjusting bar.

Abstract: A molded case circuit breaker is provided with a magnetic trip device which allow for a relatively wide range of adjustment. The magnetic trip device allows the magnetic air gap to be varied as well as the spring force on the plunger. Additionally, the magnetic trip device allows the force required to rotate the trip bar to be varied. By providing a means for adjust the force required to rotate the trip bar, the adjustment range of the magnetic trip device can be substantially enhanced. The molded case circuit breaker includes at least one pair of separable main contacts. The separable main contacts are mounted on upper and lower contact arms. The lower contact arm may be rigidly mounted to a line side conductor, while the upper contact arm is pivotally mounted to a load side conductor. The upper contact arm is mechanically coupled to an operating mechanism. A pivotally mounted trip bar is operatively coupled to the operating mechanism.

Abstract: A trip interlock assembly trips a circuit breaker any time the circuit breaker is removed from its panel mounting. The trip assembly is adapted to be disposed about a load side terminal and cooperate with the circuit breaker tripping device. In one embodiment, the trip assembly includes a housing and a spring-loaded actuation arm, disposed generally perpendicular to the circuit panel surface. The actuation arm is formed with a cam surface which cooperates with a trip pin adapted to actuate said circuit breaker tripping device. The trip pin acts as a cam follower and rides along the cam surface formed in the actuation arm. When the actuation arm is in an inward position the trip pin is in a normal position. However, when the circuit breaker is removed from the panel, the actuation arm under the influence of a biasing spring moves outwardly. This causes the cam surface on the actuation arm to actuate the trip pin to trip the circuit breaker.

Abstract: A multiphase circuit breaker has a magnetic trip assembly which includes an adjusting bar slidable longitudinally to simultaneously adjust the bias applied by individual torsion springs to the rotatable armature of the magnetic trip assembly for each pole over a range of trip currents from a high setting to a low setting. Adjusting screws carried by the adjusting bar provide for adjustment of the gap between the armature and stationary magnetic structure independently at the high and low settings separately for each pole. An additional set of adjusting screws can be inserted in the adjusting bar to provide a single adjustment of the gap over the full range of spring bias settings.

Abstract: A circuit breaker is disclosed having a movable magnetic core provided in the magnetic trip assembly thereof adapted to lower the current levels at which the magnetic trip mechanism will operate. The magnetic trip assembly also includes a pivotally connected armature, a current carrying conductor, a fixed magnetic yoke and a latchable operating mechanism. A primary air gap exists between the armature and the fixed yoke. The movable core is designed to move into an extended position which reduces the primary air gap which in turn increases magnetic flux coupling which allows the magnetic force required for the armature to pivotally rotate to unlatch the operating mechanism and thereby trip the circuit breaker to be generated at a lower current level. This reduction in current is the desired effect of the new design.

Abstract: The tripping adjustment range of a magnetic trip device with a plunger core is increased by providing, in the movable plunger core, a groove whose edges define polar surfaces bounding air-gaps with the edges of the yoke in such a way as to generate in the minimum adjustment position a force which is added to the attractive force of the movable core by the stationary core, and inversely a force in the maximum adjustment position which is subtracted from the attractive force of movable plunger core. The trip device excitation coil is offset with respect to the yoke to increase the adjustment range, and a return device with adjustable stop and decreasing return force as the movable core approaches the stationary core, contributes to increasing this tripping threshold adjustment range.

Abstract: A compact current limiting circuit breaker with an electronic trip unit arranged within the circuit breaker cover and current transformers in the circuit breaker case incorporates reinforcement ribs in the cover to provide added strength. The cover also includes line terminal plugs that removably attach to the cover for preventing inadvertent access to the circuit breaker line terminals when the circuit breaker is energized. Protrusions formed on the bottom surface of the circuit breaker cover under the trip unit provide further strength while cooperating with flexible pads on the top of the current transformers to automatically compensate for manufacturing tolerances.

Abstract: A combined arc gas controller-line terminal plug is used within molded case circuit breaker covers to direct the flow of arc gases that occur during intense overcurrent circuit interruption. The plugs simultaneously prevent access to the line terminal lugs while controlling the egress of the arc gases. Moreover, the plugs are removable for connection with and disconnection from an associated electrical power distribution system.

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: In a circuit breaker having electromagnetic tripping device (55), thermal tripping device (56,57), and adjusting device (59-64), the adjusting device (59-64) is disposed above the thermal tripping device (56,57) in perpendicular direction to power source side-load side direction, and the adjusting device (59-64) has an arm (69) for transmitting adjusting actions from an adjusting dial (24) to a movable iron core (55a) of the electromagnetic tripping device (55), and such constitution enables to shorten a configuration in the power source side-load side direction, and enables to compensate loose-assembly or deformations of the adjusting device (59-64), and thereby initial setting for the adjusting device (59-64) becomes correct.