US2447652A - Circuit breaker - Google Patents

Circuit breaker Download PDF

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Publication number
US2447652A
US2447652A US463933A US46393342A US2447652A US 2447652 A US2447652 A US 2447652A US 463933 A US463933 A US 463933A US 46393342 A US46393342 A US 46393342A US 2447652 A US2447652 A US 2447652A
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United States
Prior art keywords
latch
lever
circuit breaker
breaker
circuit
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Expired - Lifetime
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US463933A
Inventor
Oliver S Jennings
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CBS Corp
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Westinghouse Electric Corp
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Priority to US463933A priority Critical patent/US2447652A/en
Priority claimed from GB183844A external-priority patent/GB574658A/en
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Publication of US2447652A publication Critical patent/US2447652A/en
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H71/00Details of the protective switches or relays covered by groups H01H73/00 - H01H83/00
    • H01H71/10Operating or release mechanisms
    • H01H71/12Automatic release mechanisms with or without manual release
    • H01H71/40Combined electrothermal and electromagnetic mechanisms
    • H01H71/405Combined electrothermal and electromagnetic mechanisms in which a bimetal forms the inductor for the electromagnetic mechanism
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H71/00Details of the protective switches or relays covered by groups H01H73/00 - H01H83/00
    • H01H71/10Operating or release mechanisms
    • H01H71/50Manual reset mechanisms which may be also used for manual release
    • H01H71/52Manual reset mechanisms which may be also used for manual release actuated by lever
    • H01H71/522Manual reset mechanisms which may be also used for manual release actuated by lever comprising a cradle-mechanism
    • H01H71/523Manual reset mechanisms which may be also used for manual release actuated by lever comprising a cradle-mechanism the contact arm being pivoted on cradle and mechanism spring acting between handle and contact arm
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H71/00Details of the protective switches or relays covered by groups H01H73/00 - H01H83/00
    • H01H71/04Means for indicating condition of the switching device
    • H01H2071/046Means for indicating condition of the switching device exclusively by position of operating part, e.g. with additional labels or marks but no other movable indicators

Definitions

  • the invention relates to circuit breakers and more particularly to automatic circuit breakers having current responsive tripping means for automatically tripping the breaker in response to predetermined overload current conditions.
  • An object or the invention is the provision 01' a circuit breaker with an improved trip device of simple construction which is operable to trip the breaker instantaneousl upon the occurrence of heavy overloads above a predetermined magnitude or on short circuits, and which is operable to trip the breaker after a time delay in response to overloads of lesser magnitude.
  • Another object of the invention is the provision of a circuit breaker with a trip device having a current responsive bimetallic trip element and a current responsive magnetic tripping means operable independently under some conditions to trip the breaker, the two being arranged in a, novel manner to at times mutually assist in ellecting tripping of the breaker.
  • Another object of the invention is the provision of a circuit breaker as described in the preceding objects, wherein the parts are so arranged that substantially no undesirable stresses are applied to the bimetal trip element by the magnetic means.
  • Another object of the invention is the provision of a circuit breaker with an improved thermalmagnetic trip device wherein the flow of current through the bimetal element energizes the magnetic tripping means so that no separate energizing coil is required for the magnetic means.
  • Another object of the invention is the provision of a circuit breaker with an improved trip device having parts novelly arranged so that only a relatively light tripping force by the electroresponsive tripping means is required to trip the breaker mechanism.
  • Another object of the invention is the provision of a circuit breaker with an improved tripping mechanism comprising a rotatable latch member having a segmental or arcuate latch portion disposed ,very close to the axis of rotation of the latch and wherein the tripping forces produced by the bimetal element and the magnetic means are applied to the latch member at points relatively distant from the axis of rotation of the latch and on opposite sides of the axis.
  • Another object of the invention is the'provision of a circuit breaker having a, rotatable latch with the latch point close to the axis of rotation of the latch, and wherein a motion amplifier is interposed between the latch and the bimetal trip element to amplify the movement of the bimetal element, the parts being arranged to obtain a large mechanical advantage in a small space.
  • Another object of the invention is the provision of a circuit breaker with an improved current energized magnetic tripping means wherein the magnetic means acts directly on the circuit breaker latch with a large mechanical advantage and yet the air gap of the magnetic means is maintained small.
  • Another object of the invention is the provision of an improved circuit breaker construction that is very simple and compact, reliable in operation and economical to manufacture.
  • Figure 1 is a. side view, partly in section, of a circuit breaker embodying the invention. with the side plate of the casing removed to show the mechanism and other part, the circuit breaker mechanism being shown in the closed circuit position,
  • Fig. 2 is a view similar to Fig. l but showing the circuit breaker the instant it has been tripped by operation of the magnetic tripping means
  • Fig. 3 is a fragmentary view illustrating the tripping of the breaker in response to operation of the bimetallic trip element
  • Fig. 4 is a detail sectional view of the magnetic means .taken substantially along the section IVIV oi Fig. l
  • i Fig. 5 is a detail sectional view of the latching means taken substantially on the line V-V of Fig. 1.
  • the circuit breaker comprises in general a casing I of molded insulating material, a pair of terminal conductors 9, and ll.mounted on the casing adjacent the opposite ends thereof, a stationary contact IS, a cooperating movable contact IS, an are extinguisher l1, operating mechanism indicated generally at IQ for opening and closing the contacts, and a trip device indicated generally at 2! cooperating with the operating mechanism for causing automatic opening operation of the contacts in response to predetermined overload conditions.
  • the casing 1 is open at one side and is provided with various recesses and surfaces for removably receiving and supporting the parts of the circuit breaker so that pp metal mounting frame or br being directly supported by the molded mate'- ylal of the casing.
  • Figs. 1, 2 and 3 but a part of which is shown in Figs. 4 and 5.
  • Figs. 4 and 5 is adapted to be removably mounted on the open side of the casingsection 1 to complete the casing and retain the parts in mounted position.
  • the side plate is secured on the casing by bolts (not shown) which extend through openings 25 in the casing and side plate.
  • the side plate is also provided with recesses and surfaces for supporting the parts of the circuit breaker;
  • the upper terminal conductor 9 is mounted in a slot provided therefor in the casing section I and the upper end of the conductor extends out- .wardly into a niche formed in this end of the casing.
  • a terminal screw is threadedly mounted in the outer end of the terminal conductor for making connection to an external circuit.
  • the are extinguishing device H comprises-a pair of U-shaped magnetic elements 21 disposed in a fiber are chute 29 partially surrounding the path of the are drawn by the movable contact .upon interruption of the circuit.
  • the operating mechanism for operating the movable contact to open and closed circuit position comprises a bifurcated switch arm ii to the inner end of which the movable contact I! is secured, a yoke-shaped releasable carrier, lever sists of a generally flat lever and is pivotally mounted within the casing 1 adjacent the side outer end thereof and projects laterally from the lever.
  • the projecting end of the stud Ii carries a roller (not shown) which is adapted to bear against and roll on the inner surface of the side plate 23 of the casing.
  • the operating lever thus hastwo spaced bearings for its pivotal movement.
  • the overcenter spring I! is disposed between the legs or the bifurcated portion of the switch arm II and is movable in the space between the spaced legs of the carrier lever 31.
  • One end of the spring is connected to an intermediate point of the switch arm 3i and the other end of the spring is hooked over a circular slot in the central portion of the stud Ii on the operating lever II for pivotally supporting the switch arm II, a
  • the releasable carrier lever "which is of conducting material has spaced legs rigidly connected by an integral cross member and joined at their lower ends by alatch element 38 which cooperates with a movable latch-of the trip device.
  • the latch element is secured between the lower ends of the legs of the carrier member by means of rivets 4
  • the legs of the carrier lever are generally V-shaped in side elevation, and the switch arm Ii is pivotally supported in the apex of the carrier. lever for movement back and forth to open and closed circuit positions in the V -shaped notches formed by the legs of the carrier.
  • the switch arm II is bifurcated to form spaced legs which are notched at their outer ends for pivotally engaging the legs .of the carrier lever 83 at the apex thereof.
  • the carrier lever a is mounted for pivotal movement by a pivot pin 43, the ends of which are supported in cylindrical bearing recesses provided therefor in the 36.
  • the spring 3 serves to retain the switch arm in pivotal engagement with the carrier lever II and the operating lever in pivotal engagement with its bearings.
  • the spring also functions to actuate the switch arm to open and closed position with a snap action upon movement of the operating lever to oil and on positions, and
  • the operating lever 35 is moved upwardly to the on" position shown in Fig. l to effect closing'of the circuit breaker.
  • the spring acts to move the switch-farm to closed circuit position with a snap action.
  • the operating lever is moved downwardly to the "o position. and as soon as the line of action of the spring 31 passes below the pivot axis 53, the spring acts to move the switch arm to-open circuit position with a snap action.
  • the switch arm In the manually opened position of the switch arm ii the switch arm bears against the lower edges of the v-shaped notches formed in the legs of the carrier lever 33, these-edges acting as open position stops upon manually opening the circuit breaker.
  • the circuit breaker is adapted to be automatically opened in response to predetermined overshown in Fig. 1 by the latch of the trip device which engages the tip of the latch element 30.
  • the manually operable operating lever 35 conload conditions by operation of the trip device II which will be hereinafter described.
  • the operation of the trip device effects release of the releasable carrier lever 33 whereupon the overcenter spring 31 moves the carrier lever in a counterclockwise or upward direction about its pivot 43, thereby shifting the pivot axis 53 of the switch arm above the line of action of the spring 31, thus causing snap acting movement of the switch arm to the open circuit position shown in Fig. 2.
  • This circuit opening movement of the switch arm will take place irrespective oi the position of the operating handle even though the operating handle were held in closed position.
  • the switch arm is trip-free of the operating lever.
  • the operating spring also acts to move the operating lever I! to an intermediate indicating position as shown in m. 2, the lever being stopped in this intermediate indicating position by the engagement of a resetting projection 55 on the operating lever with an upper edge of a releasable carrier lever 39.
  • the circuit breaker Before the breaker can be manually reclosed following a tripping operation, it is necessary to reset the releasable carrier lever 33 back to its normal latched position. This is accomplished by moving the operating lever downwardly to the of! position. During this movement the resetting projection 55 moves the carrier lever in a clockwise direction about the pivot 93 back to its normal latched position where it is reengaged by the latch of the trip device.
  • the circuit breaker may be manually closed following resetting thereof by moving the handle upwardly to the on" position in the previously described manner.
  • the trip device 2i is removably mounted in the lower part of the circuit breaker casing and comprises a rotatably mounted latch member 51 controlled by an electromagnet 59 and by a current responsive bimetal element 91, each of which is operable to move the latch member to released position.
  • the latch member comprises a generally cylindrical member 51 having flattened portions on opposite sides thereof.
  • a notch or slot 58 (Fig. 5) is cut out of thecentral portion of the latch mem-' beer for a distance slightly past the axis of rotation of the latch member, leaving an arcuate or segmental latch portion 90, the arcuate edge of which is adapted to engage and latch the releasable carrier lever 33 in the normal position shown in Fig. 1.
  • the latch member 51 is rotatably mounted by pivot studs 53 which project from the opposite ends of the latch member and engage in circular bearing recesses provided in the casing 1 and side plate 23 of the casing. The axis of rotation or turning movement 01'. the latch member 51 passes substantially through the center thereof;
  • the arcuate latch surface of the latch is concentric with and located very close to the axis of rotation of the latch member.
  • a lever 95 is secured intermediate its ends by rivets 61 to one of the flattened sides of the latch member 51, the lever 95 providing oppositely projecting lever arms on either side of the axis of rotation of the latch member.
  • the latch member is biased to the latching position shown in Fig. l by means of a spring 69 which is mounted on a stud 1
  • One end of the spring engages in an opening of an ear formed in one arm of the latch lever 69.
  • the spring is coiled about the stud 1
  • the magnetic tripping means 59 comprises a magnetic armature secured to one arm of the latch lever 65, and a cooperating U-shaped magnet or magnetic member 11 which is fixedly mounted in supporting recesses in the casing adjacent the armature 15 in a position to provide an air gap between the armature and the U-shaped magnet.
  • the armature 15 is provided with a projecting rib 19 (Fig. 4) which projects partly into the space between the legs of the magnet 11. This rib 19 provides for a relatively small air gap despite the relatively long travel movement of the armature between its unattracted and attracted position, the relatively long movement being necessary due to the fact that the latch surface or the latch is located very close to the axis of rotation of the latch member 51.
  • the stationary magnet 11 is set at a slight angle to permit the armature to move squarely against the pole faces of the magnet as the armature turns about the rotatable axis 99.
  • the magnetic means is energized in response to the current of the circuit controlled by the breaker and the construc- ⁇ ion is such that the armature will be moved to attracted position to release the latch and trip the circuit breaker instantly upon the occurrence of an overload above a predetermined magnitude, for example, in excess of eight or ten times the rated current of the breaker, and on short circuits.
  • the current responsive birnetal element ll comprises a strip of bimetallic material which is secured at its inner end to the inner end or the terminal conductor II.
  • a portion of the bimetallic strip 9! passes through the space between the leg, of the U-shaped magnet 11 so that the flow of current through the bimetal element serves to energize and produce the magnetic flux in the magnet 11 and armature 15.
  • This portion of the bimetal strip and a portion of the conductor are insulated from the magnet 11 by a layer of insulation 19.
  • extends generally parallel to the latch lever I and the outer and of the bimetallic strip is disposed opposite the end of one lever arm of the latch lever 65.
  • a flexible conductor 9! electrically connects the free outer end of the bimetallic strip 9
  • the electrical circuit through the breaker extends from the upper terminal conductor 9, through the stationary and movable contacts l3 and II, switch arm 3
  • is thus heated in response to the current of the circuit and is arranged to deflect upwardly when heated a predetermined amount to operate the latch member 51 to unlatched position to eflect tripping of the circuit breaker.
  • a motion amplifying means in the form of a cam lever 83 is provided for amplifying and transmittin the upward deflecting movement of the free end of the bimetallic strip 9
  • the cam lever 93 is of insulating material and is pivotally mounted by means of a pivot 95 supported in pivot recesses provided in the casing 1 and side plate 23.
  • the specific cam lever shown in the drawings is designed to amplify or multiply the deflecting movement of the bimetallic strip 9
  • Deflecting movement of the bimetallic strip BI is thus made'suflicient to move the latch portion 99 of the latch to released position despite the fact that the latch surface is located close to the axis of rotation of the latch, and yet the tripping force transmitted to the latch is applied through a relatively long lever arm.
  • Both the magnetic means 59 and the bimetallic trip element ll act on the latch member through relatively long lever arms so that a large mechanical advantage is obtained and yet the entire trip mechanism occupies only a small amount of space due to the novel arrangement of the parts. With this construction only a relatively light tripping force is required to operate the latch to released position to effect tripping of the breaker.
  • the current, in flowing through the bimetallic element energizes and produces the magnetic flux for. the magnetic tripping means so that no separate energizing coil or winding is required for the magnetic means.
  • the terminal conductor in is supported in a slot 81 provided therefor in the casing i, and one end of this terminal conductor extends outwardly into a niche in thelower end of the casing and receives a terminal screw for connecting this terminal of the breaker to the external circuit.
  • An adjusting screw 89 extends through the lower end of the casing l and is threadedly engaged in an opening provided therefor in the inner portion of the terminal conductor H at a point remote from the supporting slot.
  • the screw 89 thus serves as a means for adjusting the position of the bimetallic element 6!] to thereby adjust the thermal tripcharacteristic of the circuit breaker. Turning the screw 89 in one direction or the other changes the amount of deflection of the bimetallic strip 60 that is necessary to effect tripping of the circuit breaker mechanism.
  • the operation of the trip device is as follows: when an overload below the instantaneous trip value occurs in the circuit controlled by the breaker, the bimetallic element Si is heated by the overload current and when the element is heated a predetermined amount it deflects in an upward direction.
  • the deflecting movement oi the bimetallic element 8! is amplified and transmitted by the cam lever 83 to one arm of the lever '65 causing counterclockwise movement of the latch member 51 position, therebydisengaging the latch portion I from the latch on the lower end of the releasable carrier lever 33.
  • the carrier lever 33 when thus released, is actuated by' the spring 81 to.
  • the electromagnet Upon the occurrence of a heavy overload above the predetermined magnitude, for example, above eight to ten times normal rated current, and upon short circuits, the electromagnet is sufficiently energized to instantaneously move the latch member 51 to released position before the bimetallic element 6
  • the carrier lever 33 is thusv instantaneously reabout its axis 68 to released leased and causes automatic opening of the circuit breaker contacts.
  • the magnetic tripping means does not exert any force on the bimetallic trip element at any time so that there is no danger of overstressing the bimetallic trip element and damaging its calibration.
  • lever 86 of the latch may itself be made of magnetic material and a magnetic rib corresponding to the rib is secured to the inner lever arm of the magnetic lever 85 which cooperates with the fixed magnet 11, or the whole lever and rib may be formed from a. single piece of magnetic material.
  • operating mechanism including a spring biased member releasable to cause automatic opening operation of said contacts, a rotatably mounted latch member for normally engaging and releasably restraining said releasable member, said latch having a lever arm projecting therefrom, an electromagnet for moving said latch to released position in response to predetermined overload conditions-comprising a magnetic armature member carried by the lever arm of the latch, a cooperating magnetic member mounted adjacent the armature member, and an energizing conductor passing between said magnetic members, one of said magnetic members being U-shaped and the other having a projecting portion which at least partially extends into the space between the legs of the U-shaped member in the normal unattracted position of the armature member.
  • a circuit breaker having relatively movable contacts, operating mechanism therefor ineluding a spring biased member releasable to cause automatic opening operation of said contacts, a latch for releasably engaging and restraining said releasable member,' electromagnetic means energized in response to the current of the circuit for moving said latch to released position in response to predetermined overload current conditions comprising a U-shaped member of magnetic material having substantially'square ends on the legs of .the U forming magnetic pole surfaces, and an armature having spaced surfaces for attraction toward said pole surfaces and having a portion between said spaced surfaces projecting at least partially into the space between the ends of the U and providing a shorter air gap than between the square ends of the U and said spaced surfaces when the armature is in its normal unattracted position.
  • operating mechanism therefor including a member releasable to cause automatic opening operation of said contacts, a rotatably mounted latch member having a latch surface relatively close to the axis of rotation of said latch member for releasably engaging and restraining said releasable member, a pair of lever:
  • electroload current in the circuit for moving said latch member to released position in response to predetermined overload conditions comprising a magnetizable armature member on one of said lever arms and a cooperative magnetizable member mounted adjacent said armature for attracting said armature, a bimetal element heated in response to overload currents in the circuit operative to deflect when heated a predetermined amount to move the other lever arm of said latch and thereby move said latch to released position, said bimetal element having its free end disposed opposite said last mentioned lever arm, and a pivoted motion amplifying member having an end extending between the free ends of said bimetal element and of said last-mentioned lever arm, said motion amplifying member engaging said last-mentioned lever arm at a point remote from the pivot of the motion amplifying member and being engaged by said bimetal element nearer to said pivot for amplifying and transmitting the deflecting movement of the free end of said bimetal element to said lever arm for actuating said latch member.
  • operating mechanism therefor including a member releasable to cause automatic opening operation of said contacts, a rotatably mounted latch member for releasably engaging and normally restraining the releasable member, a lever arm projecting from said latch member, a bimetal element heated in response to the current of the circuit and operative to defleet when heated a predetermined amount by overload current to move said latch member to released position and thereby release said releasable member, said bimetal element having its free end disposed opposite the free end of said lever arm, and a member pivoted adjacent one end at a fixed point and having its other end extending between said free ends of the bimetal element and the lever arm and engaged by the bimetal element near the pivot of the member and having its end remote from its pivot engaging said lever arm for amplifying and transmitting the deflecting movement of the free end of said bimetal element to said lever arm.
  • a circuit breaker having relatively movable contacts, operating mechanism therefor including a member releasable to cause automatic openingoperation of said contacts, a rotatably mounted latch member having a latch surface relatively close to the axis of rotation of the latch member for releasably engaging and normally restraining said releasable member, a lever arm projecting beyond said latch, a bimetal element connected in circuit with said contacts and operative to deflect when heated a predetermined amount by overload currents to move said latch member toward released position, said bimetal element having its free end disposed adjacent the free end of the lever arm, and a lever of insulating material having a fixed pivot for amplifying and transmitting the deflecting movement of the free end of said bimetal element to said lever arm of the latch, said lever of insulating material having an end which separably engages the projecting latch lever arm, and the free end of said bimetal element separably engaging said lever of insulating material at a point closer to the pivot axis of the lever
  • operating mechanism therefor including a member releasable to cause automatic opening operation of said contacts, a rotatably mounted latch member having a latch surface close to the axis of rotation of said latch member for releasably engaging and restraining said releasable member, a pair of lever arms projecting from said latchmember, electromagnetic means energized in response to overload current in the circuit for moving said latch member to released position in response to predetermined overload conditions comprising a magnetizable armature member mounted on one of said lever arms and a cooperating magnetizable member mounted adjacent said armature for attracting said armature, one of said magnetizable members being U-shaped and the other having a projection which at least partially extends into the space between the legs of the U-shaped member, a bimetal element heated in response to the overload currents in the circuit and operative to deflect and move the other lever arm of said latch and thereby move said latch toward released position and at the same time shorten

Description

1948. o. 5. JENNINGS I 2,447,652
cmcurr BREAKER Filed Oct. 30, 1942 2 Sheets-Sheet l Insu/a Insv/af/bn WITNESSES: INVENTOR O/A er \ijrm/hys, 1
Aug. 24, 1948. o. 5. JENNINGS 2,447,652
cmcun' BREAKER Filed Oct. 30, 1942 2 Sheets-Sheet 2 WITNESSES: INVEN'fOR 5/. 4 j/ Oliver 5: Jam/wh s.
{ a/MW Patented Aug. 24, 1948 CIRCUIT BREAKER Oliver 8. Jennings, Pittsburgh, Pa minor to Westinghouse Electric'Corpor-ation, East Pittsburgh, Pm, a corporation of Pennsylvania Application October 30, 1942, Serial No. 463,933
8 Claims. 1
The invention relates to circuit breakers and more particularly to automatic circuit breakers having current responsive tripping means for automatically tripping the breaker in response to predetermined overload current conditions.
An object or the invention is the provision 01' a circuit breaker with an improved trip device of simple construction which is operable to trip the breaker instantaneousl upon the occurrence of heavy overloads above a predetermined magnitude or on short circuits, and which is operable to trip the breaker after a time delay in response to overloads of lesser magnitude.
Another object of the invention is the provision of a circuit breaker with a trip device having a current responsive bimetallic trip element and a current responsive magnetic tripping means operable independently under some conditions to trip the breaker, the two being arranged in a, novel manner to at times mutually assist in ellecting tripping of the breaker.
Another object of the invention is the provision of a circuit breaker as described in the preceding objects, wherein the parts are so arranged that substantially no undesirable stresses are applied to the bimetal trip element by the magnetic means.
Another object of the invention is the provision of a circuit breaker with an improved thermalmagnetic trip device wherein the flow of current through the bimetal element energizes the magnetic tripping means so that no separate energizing coil is required for the magnetic means.
Another object of the invention is the provision of a circuit breaker with an improved trip device having parts novelly arranged so that only a relatively light tripping force by the electroresponsive tripping means is required to trip the breaker mechanism.
1 Another object of the invention is the provision of a circuit breaker with an improved tripping mechanism comprising a rotatable latch member having a segmental or arcuate latch portion disposed ,very close to the axis of rotation of the latch and wherein the tripping forces produced by the bimetal element and the magnetic means are applied to the latch member at points relatively distant from the axis of rotation of the latch and on opposite sides of the axis.
Another object of the invention is the'provision of a circuit breaker having a, rotatable latch with the latch point close to the axis of rotation of the latch, and wherein a motion amplifier is interposed between the latch and the bimetal trip element to amplify the movement of the bimetal element, the parts being arranged to obtain a large mechanical advantage in a small space.
Another object of the invention is the provision of a circuit breaker with an improved current energized magnetic tripping means wherein the magnetic means acts directly on the circuit breaker latch with a large mechanical advantage and yet the air gap of the magnetic means is maintained small.
Another object of the invention is the provision of an improved circuit breaker construction that is very simple and compact, reliable in operation and economical to manufacture.
The above and other objects and advantages of the invention, together with the construction and mode of operation thereof, will be best understood from the folowing detailed description of a preferred embodiment of the invention when read in conjunction with the accompanying drawings in which Figure 1 is a. side view, partly in section, of a circuit breaker embodying the invention. with the side plate of the casing removed to show the mechanism and other part, the circuit breaker mechanism being shown in the closed circuit position,
Fig. 2 is a view similar to Fig. l but showing the circuit breaker the instant it has been tripped by operation of the magnetic tripping means,
Fig. 3 is a fragmentary view illustrating the tripping of the breaker in response to operation of the bimetallic trip element,
Fig. 4 is a detail sectional view of the magnetic means .taken substantially along the section IVIV oi Fig. l, and i Fig. 5 is a detail sectional view of the latching means taken substantially on the line V-V of Fig. 1.
Referring to the drawings, the circuit breaker comprises in general a casing I of molded insulating material, a pair of terminal conductors 9, and ll.mounted on the casing adjacent the opposite ends thereof, a stationary contact IS, a cooperating movable contact IS, an are extinguisher l1, operating mechanism indicated generally at IQ for opening and closing the contacts, and a trip device indicated generally at 2! cooperating with the operating mechanism for causing automatic opening operation of the contacts in response to predetermined overload conditions.
The casing 1 is open at one side and is provided with various recesses and surfaces for removably receiving and supporting the parts of the circuit breaker so that pp metal mounting frame or br being directly supported by the molded mate'- ylal of the casing. A side cover plate 28, not
shown in Figs. 1, 2 and 3 but a part of which is shown in Figs. 4 and 5. is adapted to be removably mounted on the open side of the casingsection 1 to complete the casing and retain the parts in mounted position. The side plate is secured on the casing by bolts (not shown) which extend through openings 25 in the casing and side plate.
The side plate is also provided with recesses and surfaces for supporting the parts of the circuit breaker;
The construction of the upper terminal conductor 9. contacts lI-IU, arc extinguisher i1, operating mechanism It (except for the trip device), and the mounting arrangement of these parts in the casing are substantially similar to the corresponding parts of the circuit breaker required, all of the parts disclosed in my Patent No. 2,429,722, dated October 28. 1947, and assigned to the assignee of'the present invention.
The upper terminal conductor 9 is mounted in a slot provided therefor in the casing section I and the upper end of the conductor extends out- .wardly into a niche formed in this end of the casing. A terminal screw is threadedly mounted in the outer end of the terminal conductor for making connection to an external circuit. The
stationary contact if is secured to the inner end of the terminal conductor 0 within the casing. The are extinguishing device H comprises-a pair of U-shaped magnetic elements 21 disposed in a fiber are chute 29 partially surrounding the path of the are drawn by the movable contact .upon interruption of the circuit. 1 The operating mechanism for operating the movable contact to open and closed circuit position. comprises a bifurcated switch arm ii to the inner end of which the movable contact I! is secured, a yoke-shaped releasable carrier, lever sists of a generally flat lever and is pivotally mounted within the casing 1 adjacent the side outer end thereof and projects laterally from the lever. The projecting end of the stud Ii carries a roller (not shown) which is adapted to bear against and roll on the inner surface of the side plate 23 of the casing. The operating lever thus hastwo spaced bearings for its pivotal movement.
The overcenter spring I! is disposed between the legs or the bifurcated portion of the switch arm II and is movable in the space between the spaced legs of the carrier lever 31. One end of the spring is connected to an intermediate point of the switch arm 3i and the other end of the spring is hooked over a circular slot in the central portion of the stud Ii on the operating lever II for pivotally supporting the switch arm II, a
manually operable operating lever 38. and an vovercenter operating spring 31 which is connected in tension between the switch arm 3! and v a part of the operating lever 85;
The releasable carrier lever "which is of conducting material has spaced legs rigidly connected by an integral cross member and joined at their lower ends by alatch element 38 which cooperates with a movable latch-of the trip device. The latch element is secured between the lower ends of the legs of the carrier member by means of rivets 4|. The legs of the carrier lever are generally V-shaped in side elevation, and the switch arm Ii is pivotally supported in the apex of the carrier. lever for movement back and forth to open and closed circuit positions in the V -shaped notches formed by the legs of the carrier. The switch arm II is bifurcated to form spaced legs which are notched at their outer ends for pivotally engaging the legs .of the carrier lever 83 at the apex thereof. The carrier lever a is mounted for pivotal movement by a pivot pin 43, the ends of which are supported in cylindrical bearing recesses provided therefor in the 36. The spring 3 serves to retain the switch arm in pivotal engagement with the carrier lever II and the operating lever in pivotal engagement with its bearings. The spring also functions to actuate the switch arm to open and closed position with a snap action upon movement of the operating lever to oil and on positions, and
provides the'required contact pressure in the closed circuit position of the breaker.
The operating lever 35 is moved upwardly to the on" position shown in Fig. l to effect closing'of the circuit breaker. As soon as the line of action of the spring I! is moved above the pivot .axis n of the switch arm II the spring acts to move the switch-farm to closed circuit position with a snap action. To manually open the contacts of the circult breaker the operating lever is moved downwardly to the "o position. and as soon as the line of action of the spring 31 passes below the pivot axis 53, the spring acts to move the switch arm to-open circuit position with a snap action. In the manually opened position of the switch arm ii the switch arm bears against the lower edges of the v-shaped notches formed in the legs of the carrier lever 33, these-edges acting as open position stops upon manually opening the circuit breaker.
The circuit breaker is adapted to be automatically opened in response to predetermined overshown in Fig. 1 by the latch of the trip device which engages the tip of the latch element 30. The manually operable operating lever 35 conload conditions by operation of the trip device II which will be hereinafter described. The operation of the trip device effects release of the releasable carrier lever 33 whereupon the overcenter spring 31 moves the carrier lever in a counterclockwise or upward direction about its pivot 43, thereby shifting the pivot axis 53 of the switch arm above the line of action of the spring 31, thus causing snap acting movement of the switch arm to the open circuit position shown in Fig. 2. This circuit opening movement of the switch arm will take place irrespective oi the position of the operating handle even though the operating handle were held in closed position. Thus the switch arm is trip-free of the operating lever. During automatic opening operation of the circuit breaker, the operating spring. also acts to move the operating lever I! to an intermediate indicating position as shown in m. 2, the lever being stopped in this intermediate indicating position by the engagement of a resetting projection 55 on the operating lever with an upper edge of a releasable carrier lever 39.
Before the breaker can be manually reclosed following a tripping operation, it is necessary to reset the releasable carrier lever 33 back to its normal latched position. This is accomplished by moving the operating lever downwardly to the of! position. During this movement the resetting projection 55 moves the carrier lever in a clockwise direction about the pivot 93 back to its normal latched position where it is reengaged by the latch of the trip device. The circuit breaker may be manually closed following resetting thereof by moving the handle upwardly to the on" position in the previously described manner.
The trip device 2i is removably mounted in the lower part of the circuit breaker casing and comprises a rotatably mounted latch member 51 controlled by an electromagnet 59 and by a current responsive bimetal element 91, each of which is operable to move the latch member to released position.
The latch member comprises a generally cylindrical member 51 having flattened portions on opposite sides thereof. A notch or slot 58 (Fig. 5) is cut out of thecentral portion of the latch mem-' beer for a distance slightly past the axis of rotation of the latch member, leaving an arcuate or segmental latch portion 90, the arcuate edge of which is adapted to engage and latch the releasable carrier lever 33 in the normal position shown in Fig. 1. The latch member 51 is rotatably mounted by pivot studs 53 which project from the opposite ends of the latch member and engage in circular bearing recesses provided in the casing 1 and side plate 23 of the casing. The axis of rotation or turning movement 01'. the latch member 51 passes substantially through the center thereof;
By this construction the arcuate latch surface of the latch is concentric with and located very close to the axis of rotation of the latch member. A lever 95 is secured intermediate its ends by rivets 61 to one of the flattened sides of the latch member 51, the lever 95 providing oppositely projecting lever arms on either side of the axis of rotation of the latch member. The latch member is biased to the latching position shown in Fig. l by means of a spring 69 which is mounted on a stud 1| secured in the side wall of the casing 1. One end of the spring engages in an opening of an ear formed in one arm of the latch lever 69. The spring is coiled about the stud 1| and the other end of the spring is settable. in any one of a plurality of openings 13 formed in the side wall of the casing 1. These openings 13 provide means for adjusting the force 01' the spring to adjust the instantaneous trip setting of the circuit breaker.
The magnetic tripping means 59 comprises a magnetic armature secured to one arm of the latch lever 65, and a cooperating U-shaped magnet or magnetic member 11 which is fixedly mounted in supporting recesses in the casing adjacent the armature 15 in a position to provide an air gap between the armature and the U-shaped magnet. The armature 15 is provided with a projecting rib 19 (Fig. 4) which projects partly into the space between the legs of the magnet 11. This rib 19 provides for a relatively small air gap despite the relatively long travel movement of the armature between its unattracted and attracted position, the relatively long movement being necessary due to the fact that the latch surface or the latch is located very close to the axis of rotation of the latch member 51. The
stationary magnet 11 is set at a slight angle to permit the armature to move squarely against the pole faces of the magnet as the armature turns about the rotatable axis 99. The magnetic means is energized in response to the current of the circuit controlled by the breaker and the construc- \ion is such that the armature will be moved to attracted position to release the latch and trip the circuit breaker instantly upon the occurrence of an overload above a predetermined magnitude, for example, in excess of eight or ten times the rated current of the breaker, and on short circuits.
The current responsive birnetal element ll comprises a strip of bimetallic material which is secured at its inner end to the inner end or the terminal conductor II. A portion of the bimetallic strip 9! passes through the space between the leg, of the U-shaped magnet 11 so that the flow of current through the bimetal element serves to energize and produce the magnetic flux in the magnet 11 and armature 15. This portion of the bimetal strip and a portion of the conductor are insulated from the magnet 11 by a layer of insulation 19. The bimetallic strip 9| extends generally parallel to the latch lever I and the outer and of the bimetallic strip is disposed opposite the end of one lever arm of the latch lever 65. A flexible conductor 9! electrically connects the free outer end of the bimetallic strip 9| to the releasable carrier lever 33 which is, in turn, electrically connected to the movable contact ll of the circuit breaker.
The electrical circuit through the breaker extends from the upper terminal conductor 9, through the stationary and movable contacts l3 and II, switch arm 3| which is of conducting material, through a portion of the releasable carrier lever 33, flexible conductor 8| and through the bimetallic strip St to the lower terminal conductor II. The bimetallic strip 6| is thus heated in response to the current of the circuit and is arranged to deflect upwardly when heated a predetermined amount to operate the latch member 51 to unlatched position to eflect tripping of the circuit breaker.
A motion amplifying means in the form of a cam lever 83 is provided for amplifying and transmittin the upward deflecting movement of the free end of the bimetallic strip 9| to the outwardly extending lever arm of the latch lever 65. The cam lever 93 is of insulating material and is pivotally mounted by means of a pivot 95 supported in pivot recesses provided in the casing 1 and side plate 23. The specific cam lever shown in the drawings is designed to amplify or multiply the deflecting movement of the bimetallic strip 9| by two at the point where the movement is transmitted to the lever arm of the latch member 51. It will be understood, of course, that more or less amplification of the deflecting movement may be obtained by changing the shape and design of the cam lever 83. Deflecting movement of the bimetallic strip BI is thus made'suflicient to move the latch portion 99 of the latch to released position despite the fact that the latch surface is located close to the axis of rotation of the latch, and yet the tripping force transmitted to the latch is applied through a relatively long lever arm. Both the magnetic means 59 and the bimetallic trip element ll act on the latch member through relatively long lever arms so that a large mechanical advantage is obtained and yet the entire trip mechanism occupies only a small amount of space due to the novel arrangement of the parts. With this construction only a relatively light tripping force is required to operate the latch to released position to effect tripping of the breaker. The current, in flowing through the bimetallic element, energizes and produces the magnetic flux for. the magnetic tripping means so that no separate energizing coil or winding is required for the magnetic means.
The terminal conductor in is supported in a slot 81 provided therefor in the casing i, and one end of this terminal conductor extends outwardly into a niche in thelower end of the casing and receives a terminal screw for connecting this terminal of the breaker to the external circuit. An adjusting screw 89 extends through the lower end of the casing l and is threadedly engaged in an opening provided therefor in the inner portion of the terminal conductor H at a point remote from the supporting slot. The screw 89 thus serves as a means for adjusting the position of the bimetallic element 6!] to thereby adjust the thermal tripcharacteristic of the circuit breaker. Turning the screw 89 in one direction or the other changes the amount of deflection of the bimetallic strip 60 that is necessary to effect tripping of the circuit breaker mechanism.
The operation of the trip device is as follows: when an overload below the instantaneous trip value occurs in the circuit controlled by the breaker, the bimetallic element Si is heated by the overload current and when the element is heated a predetermined amount it deflects in an upward direction. The deflecting movement oi the bimetallic element 8! is amplified and transmitted by the cam lever 83 to one arm of the lever '65 causing counterclockwise movement of the latch member 51 position, therebydisengaging the latch portion I from the latch on the lower end of the releasable carrier lever 33. The carrier lever 33, when thus released, is actuated by' the spring 81 to.
cause automatic opening of the circuit breaker contacts in the manner previously described. During the movement of the latch member 51 to its released position the armature i is moved toward the pole faces of the U-shaped magnet 11, and, as the armature approaches the attracted position, the pull of the magnet becomes stronger and assists in moving the latch member 51 to released position. The electromagnet thus aids the bimetal in tripping the circuit breaker, and it will be apparent that the aiding force of the magnetic means becomes stronger as the magnitude of the overload increases. This means that the circuit breaker will be tripped more quickly as the magnitude of the overload increases so that a faster tripping characteristic is obtained in the range of moderate to heavy overloads than would be provided by a bimetallic trip element acting alone. I
Upon the occurrence of a heavy overload above the predetermined magnitude, for example, above eight to ten times normal rated current, and upon short circuits, the electromagnet is sufficiently energized to instantaneously move the latch member 51 to released position before the bimetallic element 6| becomes substantially heated- In this instance the armature "is quickly moved to attracted position, rotating the latch to released position independently of the. bimetal element 6 i. The carrier lever 33 is thusv instantaneously reabout its axis 68 to released leased and causes automatic opening of the circuit breaker contacts.
With the construction shown, the magnetic tripping means does not exert any force on the bimetallic trip element at any time so that there is no danger of overstressing the bimetallic trip element and damaging its calibration.
It will be understood of course that the lever 86 of the latch may itself be made of magnetic material and a magnetic rib corresponding to the rib is secured to the inner lever arm of the magnetic lever 85 which cooperates with the fixed magnet 11, or the whole lever and rib may be formed from a. single piece of magnetic material.
While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details and arrangement of parts may be made without departing from some of the essential features of the invention. It is desired therefore that the language of the appended claims be given the broadest reasonable interpretation permissible with the prior art.
I claim as my invention:
1. In a circuit breaker having relatively movable contacts, operating mechanism therefor including a spring biased member releasable to cause automatic opening operation of said contacts, a rotatably mounted latch member for normally engaging and releasably restraining said releasable member, said latch having a lever arm projecting therefrom, an electromagnet for moving said latch to released position in response to predetermined overload conditions-comprising a magnetic armature member carried by the lever arm of the latch, a cooperating magnetic member mounted adjacent the armature member, and an energizing conductor passing between said magnetic members, one of said magnetic members being U-shaped and the other having a projecting portion which at least partially extends into the space between the legs of the U-shaped member in the normal unattracted position of the armature member. g
. 2. In a circuit breaker having relatively movable contacts, operating mechanism therefor ineluding a spring biased member releasable to cause automatic opening operation of said contacts, a latch for releasably engaging and restraining said releasable member,' electromagnetic means energized in response to the current of the circuit for moving said latch to released position in response to predetermined overload current conditions comprising a U-shaped member of magnetic material having substantially'square ends on the legs of .the U forming magnetic pole surfaces, and an armature having spaced surfaces for attraction toward said pole surfaces and having a portion between said spaced surfaces projecting at least partially into the space between the ends of the U and providing a shorter air gap than between the square ends of the U and said spaced surfaces when the armature is in its normal unattracted position.
' 3. In a circuit breaker having relatively movable contacts, operating mechanism therefor including a member releasable to cause automatic opening operation of said contacts, a rotatably mounted latch member having a latch surface relatively close to the axis of rotation of said latch member for releasably engaging and restraining said releasable member, a pair of lever:
arms projecting from said latch member, electroload current in the circuit for moving said latch member to released position in response to predetermined overload conditions comprising a magnetizable armature member on one of said lever arms and a cooperative magnetizable member mounted adjacent said armature for attracting said armature, a bimetal element heated in response to overload currents in the circuit operative to deflect when heated a predetermined amount to move the other lever arm of said latch and thereby move said latch to released position, said bimetal element having its free end disposed opposite said last mentioned lever arm, and a pivoted motion amplifying member having an end extending between the free ends of said bimetal element and of said last-mentioned lever arm, said motion amplifying member engaging said last-mentioned lever arm at a point remote from the pivot of the motion amplifying member and being engaged by said bimetal element nearer to said pivot for amplifying and transmitting the deflecting movement of the free end of said bimetal element to said lever arm for actuating said latch member.
4. In a circuit breaker having relatively movable contacts, operating mechanism therefor including a member releasable to cause automatic opening operation of said contacts, a rotatably mounted latch member for releasably engaging and normally restraining the releasable member, a lever arm projecting from said latch member, a bimetal element heated in response to the current of the circuit and operative to defleet when heated a predetermined amount by overload current to move said latch member to released position and thereby release said releasable member, said bimetal element having its free end disposed opposite the free end of said lever arm, and a member pivoted adjacent one end at a fixed point and having its other end extending between said free ends of the bimetal element and the lever arm and engaged by the bimetal element near the pivot of the member and having its end remote from its pivot engaging said lever arm for amplifying and transmitting the deflecting movement of the free end of said bimetal element to said lever arm.
5. A circuit breaker having relatively movable contacts, operating mechanism therefor including a member releasable to cause automatic openingoperation of said contacts, a rotatably mounted latch member having a latch surface relatively close to the axis of rotation of the latch member for releasably engaging and normally restraining said releasable member, a lever arm projecting beyond said latch, a bimetal element connected in circuit with said contacts and operative to deflect when heated a predetermined amount by overload currents to move said latch member toward released position, said bimetal element having its free end disposed adjacent the free end of the lever arm, and a lever of insulating material having a fixed pivot for amplifying and transmitting the deflecting movement of the free end of said bimetal element to said lever arm of the latch, said lever of insulating material having an end which separably engages the projecting latch lever arm, and the free end of said bimetal element separably engaging said lever of insulating material at a point closer to the pivot axis of the lever of insulating material than the end thereof.
6. In a circuit breaker having relatively movable contacts, operating mechanism therefor including a member releasable to cause automatic opening operation of said contacts, a rotatably mounted latch member having a latch surface close to the axis of rotation of said latch member for releasably engaging and restraining said releasable member, a pair of lever arms projecting from said latchmember, electromagnetic means energized in response to overload current in the circuit for moving said latch member to released position in response to predetermined overload conditions comprising a magnetizable armature member mounted on one of said lever arms and a cooperating magnetizable member mounted adjacent said armature for attracting said armature, one of said magnetizable members being U-shaped and the other having a projection which at least partially extends into the space between the legs of the U-shaped member, a bimetal element heated in response to the overload currents in the circuit and operative to deflect and move the other lever arm of said latch and thereby move said latch toward released position and at the same time shorten the air gap between said armature member and said magnetizable member, and a pivoted lever of insulating material for amplifying and transmitting the heat deflecting movement of said bimetal element to said other lever arm of the latch, said latch being movable to released position by said electromagnetic means independently of said bimetal element and without moving said bimetal'element.
OLIVER s. JENNINGS.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 535,069 McElroy et al Mar. 5, 1895 570,419 Wurts Oct. 27, 1896 677,353 Hewlett July 2, 1901 689,836 Wheeler Dec. 24, 1901 2,027,238 Lindstrom Jan. 7, 1936 2,035,743 Frank et al Mar. 31, 1936 2,043,306 Sandin June 9, 1936 2,046,701 Sanden July 7, 1936 2,048,114 Gano et a1. July 21, 1936 2,353,756 Price July 18, 1944 FOREIGN PATENTS Number Country Date 95,895 Sweden June 6, 1939
US463933A 1942-10-30 1942-10-30 Circuit breaker Expired - Lifetime US2447652A (en)

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US2551397A (en) * 1948-12-04 1951-05-01 Trumbull Electric Mfg Co Electric circuit breaker
US2573307A (en) * 1949-05-03 1951-10-30 Gen Electric Calibration of electric circuit breakers
US2629796A (en) * 1949-06-18 1953-02-24 Gen Electric Thermal trip mechanism for circuit breakers
US2639347A (en) * 1948-12-04 1953-05-19 Gen Electric Electric circuit breaker
US2658973A (en) * 1949-09-29 1953-11-10 Gen Electric Electric circuit breaker
US2660637A (en) * 1949-11-18 1953-11-24 Gen Electric Circuit breaker
US2677025A (en) * 1952-05-02 1954-04-27 Westinghouse Electric Corp Circuit breaker
US2689893A (en) * 1952-12-16 1954-09-21 Ite Circuit Breaker Ltd Thermal magnetic trip device
US2776349A (en) * 1954-10-20 1957-01-01 Gen Electric Magnetic thermal trip
US2824191A (en) * 1953-02-05 1958-02-18 Fed Electric Prod Co Circuit breakers
US3421123A (en) * 1967-06-19 1969-01-07 Gen Electric Electric circuit breaker with magnetic tripping means
US20130207755A1 (en) * 2012-02-13 2013-08-15 Stephan Lehmann Hinged armature bearing for magnetic tripping device

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US2035743A (en) * 1934-03-29 1936-03-31 Bulldog Electric Prod Co Circuit breaker
US2043306A (en) * 1932-10-29 1936-06-09 Westinghouse Electric & Mfg Co Circuit interrupter
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US2551397A (en) * 1948-12-04 1951-05-01 Trumbull Electric Mfg Co Electric circuit breaker
US2639347A (en) * 1948-12-04 1953-05-19 Gen Electric Electric circuit breaker
US2573307A (en) * 1949-05-03 1951-10-30 Gen Electric Calibration of electric circuit breakers
US2629796A (en) * 1949-06-18 1953-02-24 Gen Electric Thermal trip mechanism for circuit breakers
US2658973A (en) * 1949-09-29 1953-11-10 Gen Electric Electric circuit breaker
US2660637A (en) * 1949-11-18 1953-11-24 Gen Electric Circuit breaker
US2677025A (en) * 1952-05-02 1954-04-27 Westinghouse Electric Corp Circuit breaker
US2689893A (en) * 1952-12-16 1954-09-21 Ite Circuit Breaker Ltd Thermal magnetic trip device
US2824191A (en) * 1953-02-05 1958-02-18 Fed Electric Prod Co Circuit breakers
US2776349A (en) * 1954-10-20 1957-01-01 Gen Electric Magnetic thermal trip
US3421123A (en) * 1967-06-19 1969-01-07 Gen Electric Electric circuit breaker with magnetic tripping means
US20130207755A1 (en) * 2012-02-13 2013-08-15 Stephan Lehmann Hinged armature bearing for magnetic tripping device
US9007154B2 (en) * 2012-02-13 2015-04-14 Siemens Aktiengesellschaft Hinged armature bearing for magnetic tripping device

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