US3711748A - Electric plug-on circuit breaker with means for assuring tripping of the breaker before unplugging - Google Patents

Electric plug-on circuit breaker with means for assuring tripping of the breaker before unplugging Download PDF

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Publication number
US3711748A
US3711748A US00141201A US3711748DA US3711748A US 3711748 A US3711748 A US 3711748A US 00141201 A US00141201 A US 00141201A US 3711748D A US3711748D A US 3711748DA US 3711748 A US3711748 A US 3711748A
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United States
Prior art keywords
circuit breaker
trip
push
pin
movable
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Expired - Lifetime
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US00141201A
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English (en)
Inventor
R Dietz
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Schneider Electric USA Inc
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Square D Co
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02B—BOARDS, SUBSTATIONS OR SWITCHING ARRANGEMENTS FOR THE SUPPLY OR DISTRIBUTION OF ELECTRIC POWER
    • H02B1/00—Frameworks, boards, panels, desks, casings; Details of substations or switching arrangements
    • H02B1/015—Boards, panels, desks; Parts thereof or accessories therefor
    • H02B1/04—Mounting thereon of switches or of other devices in general, the switch or device having, or being without, casing
    • H02B1/056—Mounting on plugboards

Definitions

  • the breaker has a safety device comprising a settable element spring biased so that when released it moves References Cied to an operative position wherein it drives the pin to the pin operating position, and an element, arranged UNITED STATES PATENTS in fixed position along said path, which cooperates 3,480,890 11/1969 Layton ..335/23 with the settable element and holds it in an inopera- 3,l10,778 11/1963 Edmunds...
  • This invention relates to molded case electric circuit breakers which have plug-on jaws at the line end which, in a connected position of the circuit breaker, are plugged onto a plurality of flat bus bars stacked with their faces parallel to a support or mounting pin, and having a push-to-test device accessible through a hole in the casing by a tool for tripping the circuit breaker, combined with a safety trip device so arranged so to trip the circuit breaker, in event the breaker is not turned off, prior to the disengagement of the jaws from the bus bars upon movement of the breaker to a disconnected position, and at all times when the circuit breaker is in other than connected position.
  • the electric circuit breaker shown herein for purposes of illustration is of the basic type disclosed in U.S. Pat., to James H. Leonard et al., No. 3,341,791, of Sept. ll, 1967, entitled Electric Circuit Breaker with Improved Operating Mechanism. It is modified so that it can be plugged onto stacked bus bars, such as disclosed in U.S. Fat. to G. N. Jorgensen et al., Re. No. 26,737, of Dec. 9, i969, entitled Electrical Panelboard, and may be mounted on a support or mounting pan as disclosed in U.S. Pat. No. 3,346,777, of Oct. 10, 1967, entitled Electric Circuit Breaker and Mounting Means Therefor.
  • the circuit breaker of the present invention employs a push-to-test device having a pin accessible by a tool for tripping the circuit breaker, broadly as disclosed in U.S. Pat. to B. W. Layton et al., No. 3,480,890, of Nov. 25, 1969, entitled Molded-Case Circuit Breaker with Manual Tripping Means Externally Accessible Only By A Tool.
  • such a circuit breaker is normally set, and turned OFF and ON while set, by an exterior operating handle.
  • the circuit breaker is latched in set position by latches which are releasable, respectively, by such means as electromagnetic mechanisms responsive to fault currents, or to sudden severe overloads, or to both, or by thermal mechanisms responsive to heat produced by long continued, but less severe, overloads.
  • latches which are releasable, respectively, by such means as electromagnetic mechanisms responsive to fault currents, or to sudden severe overloads, or to both, or by thermal mechanisms responsive to heat produced by long continued, but less severe, overloads.
  • electromagnetic and thermal mechanisms are connected to a single or common rockable trip bar.
  • the bar is spring biased to rotate about its axis in one direction to latching position, but, when rotated in the opposite direction by the one of the electromagnetic or the thermal mechanisms, releases the latches so that the breaker mechanism is tripped and itsmovable contacts are moved to open position.
  • the latches and mechanisms employed are themselves well known in the art and their specific structural features form no part of the present invention.
  • the important features derived from the prior art and used in the combination of the present invention are (a) a trip bar which is rockable in one direction to unlatch a circuit breaker mechanism which thereupon trips the circuit breaker; (b) a push-to-test trip pin which can be operated from the exterior of the case by a suitable tool to rock the trip bar into a position to unlatch the mechanism for tripping; (c) plug-on jaws and associated bus bars arranged to be engaged edgewise by the jaws; and (d) a safety device, broadly such as disclosed in French U.S. Pat. No. 1,183,823, of Feb. 2, 1959, but arranged so that it assures that the circuit breaker is tripped before it is disconnected from the bus bars and before it is connected to the bars.
  • the present invention is directed primarily to the foregoing features combined with each other and with an additional feature which causes the push-to-test pin to be operated by the safety device so as to trip the circuit breaker prior to unplugging of the plug-on jaws from the bus bars, and to hold the push-to-test pin in tripping position while the circuit breaker is disconnected from its mounting pan.
  • FIG. 1 is a perspective view of an electrical panel board and a plurality of circuit breakers of the present invention mounted thereon, certain parts being omitted for clearness in illustration;
  • FIG. 2 is a perspective view of part of a circuit breaker of the present invention, part of the case of the circuit breaker and other mechanism being omitted, to show the relation of the push-to-test pin and associated safety device;
  • FIG. 3 is an enlarged fragmentary sectional view taken generally along the line 33 of FIG. 1, parts thereof being shown in section for clearness in illustration, and showing the circuit breaker in the untripped position and connected to the power side ofa circuit;
  • FIG. 4 is a view similar to FIG. 3 showing the circuit breaker in tripped condition, with the exterior operating handle in the tripped position, during disconnection of the circuit breaker from the power source;
  • FIG. 5 is a view similar to FIG. 3 showing a like circuit breaker, but employing stab terminals for connecting it to load terminal conductors.
  • a plurality of circuit breakers are shown mounted on an electrical panelboard, indicated generally at 1, including a mounting pan 2 carrying a stack, indicated generally at 3, of elongated insulators and a plurality of flat bus bars.
  • the bus bars 4 are interleaved between a rear insulator 5, two intermediate insulators 6, and a front insulator 7.
  • Mounted on the mounting pan 2 are three relatively large three pole molded case circuit breakers 10 which, if desired, may be interspersed with relatively small single pole molded circuit breakers l2 and with blank fillers 13.
  • the circuit breaker 10 has a two piece case 11 of molded material which, at its line end, is connected to a shroud 16 of insulating material.
  • Terminal straps 18 are provided, one for each pole of the three pole circuit breaker.
  • the straps 18 are connected through circuit breaker contacts (not shown) to pairs of plug-in jaws 20, 21, and 22, respcctively, which are disposed at the line or power end of the circuit breaker and are adapted to be plugged onto the front edges of the bus bars 4, respectively.
  • the strap 18 is associated with a magnetic release mechanism 23 which includes a magnetic core 24 of U-shaped structure having upturned marginal flanges 25.
  • the strap 18 extends between the marginal flanges of core 25 so that currents through the strap produce flux in the core 24.
  • a common trip bar 28 is spring biased, clockwise in FIGS. 2 and 3, to rock to latching position with respect to the circuit breaker mechanisms and so remains while the circuit breaker is in the untripped condition so long as the currents through the strap 18 are within a normal operating range.
  • the bar 28 is moved counterclockwise by electromagnetic mechanism to trip the circuit breaker in response to a fault current, or a temporary surge of lesser current beyond normal through the strap 18.
  • circuit breakers latches which are operated to release by thermoresponsive mechanism which becomes heated by long sustained overload currents through the strap 18 insufficient to cause the magnetic release mechanisms to operate, and thereby rocks the bar 28 to tripping position. Rocking of the bar counterclockwise against the bias of its spring by any one of the latch operating mechanisms will trip the circuit breaker.
  • the specific latching mechanism and their operating mechanisms form no part of the invention and, accordingly, only an electromagnetic release mechanism is discussed herein specifically.
  • the electromagnetic release mechanism illustrated in FIGS. 1 4 includes an armature 30 which is in magnetically attractive relation to the flanges 25 of the core 24.
  • the armature 30 is biased, upwardly in FIG. 3', by a biasing .spring 31 which is connected to a suitable bracket 32 in the casing.
  • the spring 31 is of such force that it retains the armature 30 in raised position, as illustrated in FIG. 3, against any magnetic attraction due to flux in the core 26 caused by currents in the strap 18 within the normal operating range of the circuit breaker.
  • the armature is drawn downwardly against the force of the spring 31 by flux generated by currents in excess of the normal currents.
  • the armature 30 is carried on an upright rod 33 which, at its upper end has a cap portion 34 which extends through a hole in an arm 35 of the bracket 32 and is guided thereby for vertical reciprocation.
  • the circuit breaker is provided with a push-to-test pin 36.
  • the push-to-test pin 36 is mounted for vertical reciprocation in a bracket 37 and with its upper end reciprocable in and guided by a passage 38 in one wall of the circuit breaker case 11.
  • the pin 36 is biased upwardly to an extended position by a spring 39 interposed between a shoulder 40 and the rod and the bracket 37.
  • the upper end of the pin 36 is near the top surface of the case 11 and it is accessible through the passage 38 by a suitable tool so that it can be depressed against the force of the biasing spring 39.
  • the lower end of the pin 36 normally rests on the upper end of the cap portion 34 of the rod 33.
  • the push-to-test pin 36 is depressed, thus depressing the armature 30 the same as though it were drawn downwardly by the armature 30 and magnetic flux in the core 24, thereby causing the cap portion 34 to engage the trip bar 28 and rock it counterclockwise in FIGS. 2 and 3, against the bias of its spring, to a position for tripping the circuit breaker.
  • a suitable bracket 44 is provided on the load end of the case 11 and is adapted to be received in a suitable opening or slot 45 in the pan 2.
  • the bracket is arranged to guide the load end of the circuit breaker as the circuit breaker is moved toward the bus bars, line end foremost, and is provided with a retaining screw 46 so as to retain the circuit breaker in position after the push-on jaws have engaged the bus bars 4.
  • the rear insulator Sis provided with grooves 47, extending transversely of the bus bars.
  • Suitable ribs 48 on the rear or lower surface of the shroud 16 are received in and guided by the grooves 47.
  • the mating grooves and ribs are arranged one rib and one associated groove near each outer lateral limit of the circuit breaker case.
  • the circuit breaker In order to install the circuit breaker on the panel, it is placed in position such that the rear end of the bracket 44 can pass readily through the opening or slot 45, in which position the plug-on jaws are spaced transversely of and outer contact with their associated bus bars 4.
  • the ribs 48 are engaged at their outer ends with the outer portions of the grooves 47. With this alignment of the ribs 48 and grooves 47, the circuit breaker is pushed toward the bus bars so as to cause the plug-on jawsto engage their associated bus bars 4, and drawn away from the bus bars to disengage thejaws from the associated bus bars.
  • the safety trip mechanism comprises a push rod 50 which at its lower end extends through a hole in the rear or bottom of the case 1 1 of the circuit breaker, and is mounted within the case 11 for vertical reciprocation.
  • the rod 50 carries a transversely extending yoke 51 which has spaced arms 52 between which the push-to-test pin 36 passes.
  • a suitable E-ring or locking washer 53 is provided on the pin 36 and is adapted to be engaged and pushed downwardly by the yoke arms 52 as the rod 50 is moved downwardly, thus, in effect, pushing the push to trip pin36 downwardly so that the cap portion 34 of the magnetic armature rod 33 is pushed downwardly to tripping position-
  • the rod 50 is normally biased downwardly by a spring 55.
  • a finger 56 is mounted on, and extends upwardly from, the yoke 51 and has a shoulder 57 spaced from its upper end.
  • the spring 55 is interposed between the shoulder 57 and an inverted socket 58 in the front or top wall of the case 11.
  • the spring 55 is such strength that when the rod 50 is free to move downwardly the spring 55 can push downwardly on the lock washer 53 and drive the pin 36 downwardly against the combined forces of its spring 39 and the biasing force of the armature spring 31, thus causing the common trip bar 28 to trip the circuit breaker in the same manner as it would be tripped by the push-to-test pin.
  • the safety device assures that the circuit breaker is tripped as the rod 50 is then free and is moved downwardly and held extended by its spring 55.
  • a cam 60 is provided, and is arranged to lie in the path of the lower end of the rod 50 as the circuit breaker is moved to and from final contact position with respect to the bus bars.
  • the cam 60 is contoured so that, assuming that the push-on jaws are in contact with the bus bars, the cam holds the rod 50 in raised position against the force of the spring 55, and constrains it from operating the push-to-test pin. If the circuit breaker is moved to the left from the position shown in FIG.
  • the rod in moving the circuit breaker toward connected position, the rod remains in the position illustrated in FIG. 4, in which it has caused the circuit breaker to be tripped, until the push on jaws are connected with the bus bars 4, whereupon continued movement to the right to final connected position, the rod is again lifted by the cam 60 so that it does not drive the push-to-test pin 36 to operating position. Thereby the trip bar remains in tripping position until after the contact with the bus bars is effected. Thereafter, of course, the circuit breaker can be set in the untripped position, with the operating handle 61 thereof in the ON or OFF position, and with the various latching mechanisms holding the movable contacts in closed position.
  • FIG. 5 a similar circuit breaker is shown in the position illustrated in FIG. 3.
  • the load side contacts are carried in a separate housing 62 mounted on the front or upper face of a portion of a mounting pan 63, which corresponds to the pan 2.
  • Mounted in the housing 62 is a conductor 64 secured in place by a bolt 64a and carrying a terminal connector 65for receiving the end of an exterior load conductor.
  • the conductor 63 is provided with contact jaws 66 which are open to the left in FIG. 5.
  • the housing 62 is provided with a cover 67, having an elongated slot 68 therein.
  • a stab terminal 69 is connected to the load bar 70 of the circuit breaker, corresponding to the load bar 18 therefore described, and is connected to the housing of the breaker 70 by a suitable screw or bolt 71.
  • the stab terminal extends rearwardly or downwardly and is insertable through the slot 68 when the breaker is lowered into position on the pan and housing 62 preparatory to sliding it toward the bus bars into connected position with the bus bars 4.
  • the slot is sufficiently long so that when the breaker is lowered in place, the stab terminal passes endwise through the slot 68 and lies in a position to the left of the jaws 66 so that upon movement of the circuit breaker to the right to connected position, the stab terminal engages resiliently between the jaws 66.
  • the width of the slot 68 is such that the stab terminal, by engaging the sides thereof, acts as a forward guide in much the same manner as the bracket 44 heretofore described.
  • a suitable bracket 73 may be provided and arranged as is the bracket 62 in the co-pending application of Wilhelm T.hackenbroch, Ser. No. 2,l49, filed Jan. I2, 1970, for cooperation with a suitable rack disclosed at 60 in the application, for the purpose of prying the circuit breaker from the unconnected position to the connected position, as illustrated in FIG. 4, should the frictional resistance to such movement so require.
  • a circuit breaker and safety trip combination comprising:
  • circuit breaker including a casing
  • a trip device operative when moved to one position to trip the circuit breaker
  • a safety trip mechanism mechanically normally drivingly connected to the push-to-test device, and disconnectable therefrom, and operative, when drivingly connected, to move the push-to-test device to, and to hold the push-to-test device in, its said active position, and operative, when disconnected, to release the push-to-test device;
  • the safety trip mechanism includes:
  • biasing means normally operative for biasing the movable means from an inoperative position to an operative position wherein the movable means operates the push-to-test device to trip the circuit breaker;
  • said operator means is cooperable with the biasing means to render the biasing means inoperative while the circuit breaker is in its connected position and to release the biasing means so that it can operate as the circuit breaker is moved along said path to said disconnected position.
  • the push to test device includes a pin which is drivingly connected to a trip bar 'of the circuit breaker, and which is movable endwise in opposite directions along a given path in one of which directions it moves to a tripping position wherein it trips the trip bar;
  • said electroresponsive means include a member movable relative to the push-to-test device, by electroresponsive means when the electroresponsive means are operative, to engage and operate the trip device;
  • said push-to-test device is connected to said member for moving the member to cause it to engage and trip the trip bar.
  • said safety trip mechanism includes an operator element in fixed position on the support, and, a movable element having a portion disposed exteriorly of the casing and cooperable with, andmo'ved by, the operator element as the circuit breaker is moved and guided along its pathito effect said rendering of the safety trip mechanism operative and inoperative.

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  • Engineering & Computer Science (AREA)
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US00141201A 1971-05-07 1971-05-07 Electric plug-on circuit breaker with means for assuring tripping of the breaker before unplugging Expired - Lifetime US3711748A (en)

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US14120171A 1971-05-07 1971-05-07

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4227238A (en) * 1977-09-28 1980-10-07 Nippon Gakki Seizo Kabushiki Kaisha Mounting and electrical connection means for operation unit for electric devices
US4787588A (en) * 1986-11-28 1988-11-29 Siemens Aktiengesellschaft Arrangement for mounting a housing at a carrier, particularly for motor vehicles
FR2618615A1 (fr) * 1987-07-20 1989-01-27 Gen Electric Module adaptateur pour tableau de distribution electrique
EP0562058A1 (en) * 1991-07-18 1993-09-29 Square D Co SWITCHBOARD.
US5559662A (en) * 1994-05-20 1996-09-24 Cooper Industries Fused disconnect switch
US5880927A (en) * 1994-03-17 1999-03-09 Siemens Energy & Automation, Inc. Circuit breaker fastener
US5995362A (en) * 1996-10-18 1999-11-30 Schneider Electric Sa Support and electrical power supply device for electrical switchgear
US20110083949A1 (en) * 2009-10-08 2011-04-14 Ladislav Dostal Switching device
US9979164B2 (en) * 2015-02-09 2018-05-22 General Electric Company Electrical distribution apparatus, system, and methods of assembling same
US10164387B2 (en) 2015-02-09 2018-12-25 Abb Schweiz Ag Electrical device, electrical distribution system, and methods of assembling same

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3110778A (en) * 1960-01-07 1963-11-12 Ite Circuit Breaker Ltd Automatic trip device for plug-in circuit breaker
US3118034A (en) * 1960-09-30 1964-01-14 Wood Electric Corp Automatic circuit breaker
US3346777A (en) * 1966-12-20 1967-10-10 Square D Co Electric circuit breaker and mounting means therefor
US3440580A (en) * 1967-06-19 1969-04-22 Gen Electric Electrical protective device
US3480890A (en) * 1968-03-26 1969-11-25 Square D Co Molded-case circuit breaker with manual tripping means externally accessible only by a tool
US3526861A (en) * 1968-05-03 1970-09-01 Westinghouse Electric Corp Circuit breaker with improved trip device
US3588619A (en) * 1969-02-25 1971-06-28 Square D Co Mounting bracket for a molded-case electric circuit breaker

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3110778A (en) * 1960-01-07 1963-11-12 Ite Circuit Breaker Ltd Automatic trip device for plug-in circuit breaker
US3118034A (en) * 1960-09-30 1964-01-14 Wood Electric Corp Automatic circuit breaker
US3346777A (en) * 1966-12-20 1967-10-10 Square D Co Electric circuit breaker and mounting means therefor
US3440580A (en) * 1967-06-19 1969-04-22 Gen Electric Electrical protective device
US3480890A (en) * 1968-03-26 1969-11-25 Square D Co Molded-case circuit breaker with manual tripping means externally accessible only by a tool
US3526861A (en) * 1968-05-03 1970-09-01 Westinghouse Electric Corp Circuit breaker with improved trip device
US3588619A (en) * 1969-02-25 1971-06-28 Square D Co Mounting bracket for a molded-case electric circuit breaker

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4227238A (en) * 1977-09-28 1980-10-07 Nippon Gakki Seizo Kabushiki Kaisha Mounting and electrical connection means for operation unit for electric devices
US4787588A (en) * 1986-11-28 1988-11-29 Siemens Aktiengesellschaft Arrangement for mounting a housing at a carrier, particularly for motor vehicles
FR2618615A1 (fr) * 1987-07-20 1989-01-27 Gen Electric Module adaptateur pour tableau de distribution electrique
EP0562058A1 (en) * 1991-07-18 1993-09-29 Square D Co SWITCHBOARD.
EP0562058A4 (it) * 1991-07-18 1994-02-16 Square D Company
US5880927A (en) * 1994-03-17 1999-03-09 Siemens Energy & Automation, Inc. Circuit breaker fastener
US5559662A (en) * 1994-05-20 1996-09-24 Cooper Industries Fused disconnect switch
US5995362A (en) * 1996-10-18 1999-11-30 Schneider Electric Sa Support and electrical power supply device for electrical switchgear
US20110083949A1 (en) * 2009-10-08 2011-04-14 Ladislav Dostal Switching device
US8354603B2 (en) * 2009-10-08 2013-01-15 Siemens Aktiengesellschaft Switching device
US9979164B2 (en) * 2015-02-09 2018-05-22 General Electric Company Electrical distribution apparatus, system, and methods of assembling same
US10164387B2 (en) 2015-02-09 2018-12-25 Abb Schweiz Ag Electrical device, electrical distribution system, and methods of assembling same
US20190372282A1 (en) * 2015-02-09 2019-12-05 Abb Schweiz Ag Electrical device, electrical distribution system, and methods of assembling same
US10958023B2 (en) * 2015-02-09 2021-03-23 Abb Schweiz Ag Electrical device, electrical distribution system, and methods of assembling same

Also Published As

Publication number Publication date
AU4203072A (en) 1973-11-15
IT958809B (it) 1973-10-30
GB1382311A (en) 1975-01-29
ZA723001B (en) 1973-02-28

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