US3319195A - Circuit breaker trip unit assembly - Google Patents

Circuit breaker trip unit assembly Download PDF

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Publication number
US3319195A
US3319195A US465313A US46531365A US3319195A US 3319195 A US3319195 A US 3319195A US 465313 A US465313 A US 465313A US 46531365 A US46531365 A US 46531365A US 3319195 A US3319195 A US 3319195A
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armature
trip unit
assembly
actuating rod
magnet
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US465313A
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Strobel Albert
John C Brumfield
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Siemens Energy and Automation Inc
ITE Circuit Breaker Co
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ITE Circuit Breaker Co
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Assigned to SIEMENS-ALLIS, INC., A DE CORP. reassignment SIEMENS-ALLIS, INC., A DE CORP. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: GOULD, INC., A DE CORP., ITE INDUSTRIES, LIMITED, A FEDERAL CORP. OF CANADA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H71/00—Details of the protective switches or relays covered by groups H01H73/00 - H01H83/00
    • H01H71/74—Means for adjusting the conditions under which the device will function to provide protection
    • H01H71/7418—Adjusting both electrothermal and electromagnetic mechanism
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H71/00—Details of the protective switches or relays covered by groups H01H73/00 - H01H83/00
    • H01H71/10—Operating or release mechanisms
    • H01H71/12—Automatic release mechanisms with or without manual release
    • H01H71/40—Combined electrothermal and electromagnetic mechanisms

Definitions

  • Automatic circuit breakers are usually provided with a trip unit including both a magnetic trip assembly, instantaneously responsive to a severe overload condition, and a thermal trip assembly, responsive to a moderate overload condition existing for a prolonged time interval.
  • the actuation of either the instantaneous or the delayed trip unit conventionally actuates a mechanism which causes a tripper bar to be urged into rotational movement, with such rotational movement serving to unlatch the general contact operating mechanism of the circuit breaker unit.
  • the instantaneous trip assembly conventionally includes a stationary magnet member and a cooperating armature member.
  • energization of the magnet be provided in such a manner that substantially all of the circuit breaker current Will serve to establish the magnetic flux field.
  • calibration adjustments be proved for: (1) the initial position of the armature; (2) the extent of armature travel required for tripping; (3) the biasing force to be overcome by the magnetic force; and (4) variation of the open-gap position in accordance with the particular circuit parameters.
  • the satisfaction of these various requirements has necessitated cumbersome and intricate trip unit structures requiring excessive assembly time and cost.
  • the trip unit structure of our instant invention includes a generally U-shaped magnet mounted such that its body portion is horizontally located at the lower region of the overall trip unit assembly.
  • the magnet includes generally upstanding arms having horizontally located pole faces at their end extremes.
  • the cooperating armature member is horizontally located in a parallel plane above the pole faces. Normally the armature is separated from the pole faces by a predetermined gap distance, with such gap being rapidly closed upon the occurrence of a predetermined excessive overload condition.
  • the movement of the armature member is translated to the tripper bar by means of a vertically extended actuating rod secured to the armature member, with the rod having a transverse extension at one end thereof for engagement with the tripper bar upon the downward movement of the armature.
  • the upper end of the actuating rod containing the trip unit actuating extension is at an accessible region of the overall assembly, such that a calibration adjustment of the armature travel may be conveniently made after final assembly of the trip unit.
  • the mounting of the trip assembly is provided in an extremely simplified manner by means of a unique mounting bracket serving a variety of functions.
  • the mounting bracket includes a generally L-shaped portion having a vertically extending rear planar portion and a forwardly projecting top portion.
  • the forwardly projecting top portion is horizontally disposed above the armature member.
  • a sintered magnet is used having tapped openings within an enlarged cross-sectional area adjacent the pole faces. The tapped openings receive screw members for securably mounting the magnet to the mounting bracket and base support member.
  • a cold rolled steel magnet is used, having a pair of inwardly turned ear members, integral with the magnet and placed flush against the rear portion of the mounting bracket.
  • the armature member which it will be recalled, is secured to the actuating rod, has the actuating rod extending through aligned openings in the body portion of the magnet and the forwardly projecting portion of the bracket assembly.
  • a vertically disposed planar surface of the mounting bracket is located in juxtaposition with respect to a vertical edge of the armature and serves as a guide for movement thereof between its engaged and disengaged positions.
  • Upward bias of the armature towards its disengaged position is provided by a spring member about the lower portion of the actuating rod. One end of the spring member bears against the body portion of the magnet member and the other end urges the armature member upward.
  • the bias force calibration may be provided by an adjustable nut, movable along the actuating rod and interposed between the upper end of the spring member and lower surface of the armature.
  • the lower surface of the forwardly projecting bracket support portion advantageously serves as a positive stop for such upward movement, there-by facilitating the sub-assembly location of the armature member.
  • an externally accessible calibration member be provided to adjust the magnetic trip characteristics in accordance with the specific requirements of the circuit to be protected, as well as to compensate for wear of the operating components.
  • This external calibration is conveniently coupled to the magnet trip unit of our invention by the provision of an additional extension member along the actuating rod. This member is also movable along the actuating rod to provide an initial calibration adjustment during manufacture.
  • the external calibration unit is coupled to the trip unit such that the upper surface of the forwardly projecting support bracket provides a reference surface.
  • Another extremely advantageous aspect of our invention relates to the manner in which the magnetic trip assembly is associated with, and electrically connected to, the current carrying members of the circuit breaker.
  • energization of the magnetic circuit is typically provided by a current carrying strap passing therethrough such that the flux field generated thereby is coupled to the magnetic members.
  • the prior art magnetic trip assembly structures have typically necessitated a plurality of connecting points whereas the current carrying terminal strap, or elements in electrical conductivity relationship therewith, were connected to the magnetic trip assembly. This arrangement tends to promote the astablishment of a parallel current path through the magnetic trip assembly.
  • Such parallel current paths disadvantageously divert a portion of the current from its magnetizing function, thereby requiring magnetic members of increased size, complexity and cost to provide the necessary tripping forces response to the predetermined overload conditions.
  • the current flow through the magnetic trip assembly has in the past tended to cause welding of the armature to the cooperating pole faces of the magnet, thereby adversely affecting future reliability of operation.
  • These problems have in the past necessitated the additional expense and bothersome assembly procedure of including insulative members intermediate the current carrying elements of the circuit breaker and the magnetic trip assembly.
  • Our invention advantageously avoids these problems by requiring only a single point of interconnection between the magnetic trip assembly and those portions of the overall trip unit which are electrically connected to the current carrying path.
  • this single Point connection prevents the establishment of a parallel current path through the magnetic trip assembly.
  • this single Point connection also serves to secura-bly mount the thermal trip unit to our novel mounting bracket to provide a combined magnetic and thermal trip unit of increased simplicity of structure and ease of fabrication.
  • the L-shaped bracket of the instant invention serves a variety of functions which, in addition to mounting the magnetic and armature of the trip unit base, serves as a positive stop for the upward movement of the armature; guides the vertical movement of the armature during its travel; acts as a reference for the externally accessible magnet trip calibration means; and serves to mount the thermal trip in a manner avoiding a parallel current path through the magnetic trip.
  • a further object of our invention is to provide a magnetic trip unit assembly wherein the operating components thereof may be simply fabricated and assembled.
  • Another object of our invention is to provide a magnetic trip assembly for use in conjunction with a circuit breaker mechanism, which is constructed to provide increased accessibility to the various calibration adjustments thereof.
  • An additional objects of our invention is to provide a circuit breaker magnetic trip unit assembly, including a novel mounting bracket serving a variety of functions.
  • Still a further object of our invention is to provide such a trip unit assembly where the mounting bracket serves as a guide for the armature open gap position, the path of armature movement, as well as the tripping characteristic calibration adjustment means.
  • Still another object of our invention is to provide a circuit breaker magnetic trip unit assembly wherein the electrical interconnection between the current carrying members and the magnetic trip unit portion thereof is limited to a single point, thereby preventing the establishment of parallel current paths within the magnetic trip unit.
  • Still an additional object of our invention is to provide a magnetic trip unit assembly which includes a generally U-shaped magnetic member with the arms thereof projecting upward for cooperation with a horizontally disposed armature, such that actuation of the magneticcircuit moves the armature downward into engagement with the magnetic pole faces, with such downward armature movement being coupled to the circuit breaker tripper bar via an actuating rod secured to the armature member and upwardly extending therefrom.
  • FIGURE 1 is a perspective view of a three-phase molded case circuit breaker construction, which may be used in the practice of the instant invention, and wherein the cover is removed to reveal the internal mechanism thereof;
  • FIGURE 2 is a plan view of the circuit breaker unit shown in FIGURE 1, with the cover replaced and partially cut away;
  • FIGURE 3 is a longitudinal cross-sectional view taken through the center phase and along the arrows 3-3, as shown in FIGURE 2;
  • FIGURE 4 is a cross-sectional view along the lines 44 of FIGURE 1 and showing one form of the trip unit assembly, in accordance with our invention
  • FIGURE 5 is a top view of FIGURE 4 showing the trip unit assembly, and partially broken away in crosssection;
  • FIGURE 6 is a cross-sectional view along the lines 66 of FIGURE 4, looking in a direction of the arrows and showing further details of the trip unit assembly, with the magnetic trip portion thereof shown in the nontripped condition;
  • FIGURE 7 corresponds to FIGURE 6, but shows the magnetic trip unit in the actuated or tripped condition
  • FIGURE 8 is a perspective view of the trip unit assembly of FIGURES 4-7.
  • FIGURE 9 is an exploded perspective view of the magnetic trip unit in conjunction with the trip unit assembly and calibration adjustment button, and FIGURE 9A explodes the magnetic trip portion of the trip unit assembly.
  • FIGURE 10 is a perspective view of another form of trip unit assembly in accordance with our invention, which has a somewhat modified magnetic trip portion;
  • FIGURE 11 is an exploded perspective view of the modified magnetic trip portion thereof.
  • circuit breaker 10 where in our invention is incorporated is typically shown as a commercially available three-phase molded case unit.
  • the unit is assembled within a housing comprising molded base 11, separated into compartments 12, 13 and '14, respectively, for locating the operating members of each 'of the phases.
  • the adjacent compartments are separated by housing walls 15 and 16.
  • Main cover assembly 17 and end covers 18 similarly include barriers for maintaining the longitudinally extending compartments of the housing, with end shields 19 being located at the line and load ends of the circuit breaker 10.
  • the current carrying members of all three phases are identical so that for the sake of brevity only one of the sets of elements, such as the center phase as shown in FIGURE 3, will be described.
  • the current path between the line terminal strap 20 and load terminal strap 21 pro ceeds from stationary contacts 22 and 23 to movable contacts 24 and 25 carried by contact arms 26 and 27 through flexible braids 28, contact carrier strap 29 and trip unit strap 102.
  • contacts 22-24 function as arcing contacts and are properly situated to move into engagement and disengagement within the opening defined by circuit breaker arc chute assembly 31.
  • the arcing contacts 22-24 are shown parallelled by two seats of main contacts 23-25.
  • the main movable contacts 25 are each mounted to individual contact arms 27, each connected by an individual section of braid 28 to contact carrier strap 29, while cooperating stationary contacts 23 are mounted to line terminal strap 20.
  • the movable arcing contact 24 is similarly mounted to its contact arm 26, which is connected by a braid section 28 to the strap 29. Its c0- operating stationary contact 22 is also mounted to line terminal strap 20.
  • the contact arms 26-27-26 of each phase are, in turn, pivotally mounted by rod 36 to contact carrier 35.
  • the movable contact arm mounting may include individual adjusting studs 60 to establish the open gap circuit position of contacts 24-25 relative to stationary contacts 22-23 as shown in the open position of FIGURE 3; as well as a contact pressure adjustment means shown as 71; as is the subject of copending U.S. patent application Ser. No. 430,549 filed Feb. 5, 19 65, in the name of Carl E. Gryctko and entitled, Circuit Breaker Contact Mounting, now U.S. Patent No. 3,268,702..
  • Circuit breaker 10 also includes an automatic tripping mechanism and a quick make-break-toggle operating mechanism 32.
  • Operating mechanism 32 is connected to the contacts of all three phasees by means of a transverse insulating tiebar 33, with U-shaped straps 34 connecting the respective contact carriers 35 to the common tiebar 33.
  • Carrier 35 is pivotally mounted at 46- to suitable bearings in the operating mechanism frame 47.
  • Mounting frame 47 includes ears 84 which receive screw members 49 for securement to circuit breaker base embossment 50.
  • Knee 39 includes a pivotally mounted plate member 40- to which the circuit breaker operating springs, shown as a pair 41-41, are connected at one end 42-42 thereof.
  • the other ends 43-43" are located in suitable apertures with the operating handle frame 45, such that the operating springs 45-45 are in overcenter relationship with respect to toggle linkage 37-38.
  • the lower end of handle frame member 45 is pivotally mounted to bosses 83 of operating mechanism frame 47.
  • Operating handle 80 is mounted to upstanding posts 81 of frame member 45.
  • the operating mechanism 32 also includes a cradle carried lat-ch tip 51 for engagement with latching bracket extension '52 of the trip assembly 100.
  • a coupling member generally shown as 52 interconnects latching bracket extension 52 to the tripper bar 53 of the trip unit assembly so as to effect tripping disengagement of latched members 51-52 upon counter-clockwise movement of tripper bar 53.
  • Such counter-clockwise movement is effected by either the actuation of the instantaneous or magnetic trip or the time-delayed or thermal trip units contained in trip unit assembly 100.
  • the trip unit assembly 100 includes a terminal strap 102 for each of the phases.
  • Terminal straps 102 include apertures 104 at one end thereof to mate with cooperating aperture 106 of the load terminal strap 21 for electric-a1 and mechanical securement thereto.
  • the opposite end of terminal strap 102 includes aperture :108 which similarly mates with cooperating aperture 110 of the contact carrier strap 29.
  • Bolt means 112 extend through cooperating apertures 104, 106 at the load end of the circuit breaker frame, with similar bolt means 114 extending through cooperating apertures 108, 110 for mounting each of the terminal straps 102 of the trip unit assembly 100 to their respective load terminal straps 21 and contact carrier straps 29.
  • the magnetic trip assembly which is the subject of the instant invention and is generally shown as 250, includes an actuating rod 56 having a trip unit actuating extension 57 which moves down into engagement with tripper bar extension member '58.
  • the trip unit actuating extension 57 to the upper extreme of actuating rod 56 is preferably of an external knurled configuration to facilitate adjustment thereof, during the initial calibration procedure.
  • Extension 57 is also of a sufiicient diameter to extend over a substantial portion of its cooperating tripper bar bracket 58. This advantageously avoids the use of a fork-type tripping bracket and the cumbersome assembly techniques associated therewith, as is required in some prior art structures. Furthermore, this design eliminates pole-to-pole misalignment problems between armature trip rod and tripping bracket that are commonly present when fork type brackets are used.
  • the time-delayed trip unit assembly includes an elongated bimetallic member 54 which will deflect towards the left, as shown in FIGURE 3, into engagement with tripper bar adjustment screw 55 upon the occurrence of moderate overload conditions for a predetermined interval of time.
  • FIGURES 4-9 show one form thereof.
  • the magnetic trip unit assembly 250 includes a cooperating magnet member 101 and armature 103.
  • Magnet member 101 which may be of the sintered variety, has a generally U-shaped configuration which includes a body portion 105 disposed generally horizontally and mounted at the lowermost region of the overall trip unit assembly 100.
  • the ends of body portion 105 include upstanding space-separated arms 107, 109, respectively, having horizontally disposed pole faces 111, 113, respectively, at their uppermost extremes.
  • the upper portions of the arms 10-7, 109 include enlarged cross-section areas 116, 118, respectively, having tapped opening 157. These openings are in alignment with openings 159 of the mounting bracket 150, 206 of the terminal shunt bracket 204, as well as cooperating opening (not shown) of the base support 200, for receiving mounting screws 155.
  • the armature member '103 is horizontally positioned intermediate the plane of pole faces 111, 113 and the bottom surface 161 of forwardly projecting extension 154 of the mounting bracket 150. In its non-engaged condition, as shown in FIGURE 6, the armature member 103 is separated from the pole faces 111, 1 13 by an airgap separation of predetermined calibrated extent, as shown by d. Upon sufiicient magnetizing flux the armature member 103 is downwardly drawn towards cooperating pole faces 111, 113 as shown in FIGURE 7.
  • the mounting of the armature member for travel between its engaged and non-engaged positions is provided in the following manner.
  • Actuating rod member 56 which extends through cooperating aligned apertures 163 of the mounting bracket top portion, 165 of the thermal trip unit assembly and 167 of the magnetic member body portion 105, is secured to the armature member at 170.
  • a biasing spring 172 is positioned about the lower portion of actuating rod 56 with the bottom end 173 thereof bearing against the upper surface of magnetic member body portion 105 and the top end 174 bearing against a calibration adjustment nut member 175.
  • the armature member will be located with the bias spring 172 serving to urge the armature upwards to its disengaged position.
  • the rearmost edge 164 thereof is in juxtaposition to forward surface of the mounting bracket forwardly turned portion 152, as best seen in FIGURES 8 and 9. It should be noted at this point that the lower surface 161 of the forwardly projecting bracket portion 154 will be in the path of upward travel of the armature member 103 and serve as a positive step to limit such upward movement. This feature is particularly advantageous during the sub-assembly fabrication of the circuit breaker trip unit.
  • An armature gap calibration means is provided.
  • This adjustment means which is the subject of copending U.S. patent application entitled Circuit Breaker Instantaneous Trip Adjustment, Ser. No. 465,305, filed June 21, 1965, and assigned to the assignee of the instant invention, includes a mounting bracket 187 having an externally accessible calibration button 189, for rotation of cam member 191. This rotational movement causes vertical translation of calibration adjustment extension secured to the actuating rod 56 in accordance with the cam surface 193 of rotatable cam 191. Such movement of the actuating rod 56 naturally moves the armature member 103 a corresponding distance to adjust the gap separation d.
  • the armature gap calibration adjustment means includes a lower pin member 197 which rests on upper surface 162 of the mounting bracket forward projecting top portion 154. This advantageously serves as a reference plane for the gap calibration adjustment, as well as serving to position pin 197 against the calibration adjust bias force provided from within member 189.
  • trip unit actuating extension 57, the calibration adjustment extension 195 and armature bias pressure calibration nut 175 are all threadedly maintained along actuating rod 56 and are easily accessible subsequent to final assembly of the overall trip unit assembly; as shown, for example, in FIG- URE 8.
  • the extension members 57, 195 and 175 are properly secured in place along the actuating rod 56, as by solder. This is to be contrasted to the intricate adjustment structures necessitated by the prior art trip unit assemblies for calibrating these various parameters.
  • the energization for the magnetic trip unit assembly is provided by current carrying strap member 102 passing through the U-arins of magnet member 101.
  • Current carrying strap member 102 is connected to a thermal shunt 202 which in turn is thermally connected to the bimetallic :member 54, as is more fully disclosed in copend ing US. patent application entitled, Circuit Breaker Trip Assembly With Increased Compensation for Misalignmerit, Ser. No. 465,304, filed June 21, 1965 and assigned to the assignee of the instant invention.
  • the thermal trip unit includes a mounting bracket 204 which has apertures 206 in alignment with apertures 159 of the mounting bracket 150 and 157 of the magnet 101 for receiving screws 155.
  • Thermal shunt member 202 may typically be formed of copper laminates or other conductive material. Hence, this could establish a current path from the conductive strap 102 via terminal shunt member 202 and mounting bracket 204 of the time delay trip subassembly to the main mounting bracket :member 150 and magnet member 101. Should there be a current return, the possibility of such a parallel current path tends to lower the pull-in force of the magnet 101 as well as subjecting the armature and magnet to the danger of welding. Our invention absolutely avoids this by the provision of only one point of interconnection between the magnet trip unit and the current carrying members of the overall trip assembly, thereby avoiding the necessity of including insulative members in the assembly.
  • magnet member 101' is now formed of a uniform thickness of material, which may be, for example, cold rolled steel.
  • Magnet members 101 is of a general U-shaped configuration, including a central body portion 105', having upstanding arms 107', 109', with the pole faces 111, 113' at the ends thereof.
  • a pair of inwardly turned mounting ears 116, 118' are provided, having tapped openings 157, which receive mounting screws 155.
  • Mounting openings 157 are in alignment with cooperating openings 159 of the mounting bracket for securely mounting the magnet member 101' to the mounting bracket 150'.
  • Mounting bracket 150' is similarly of a generally L- shape configuration, having a generally vertically extending rear planar portion 185' and a forwardly projecting top portion 154' extending in a generally horizontal direction.
  • Rearwardly extending U-sections 152 having openings 159' which mate with screw members 212' (and cooperating openings of the thermal shunt mounting bracket, not shown) provided for securably fixing the mounting bracket to the trip unit support member 200.
  • the vertically orientated planar surface 185' of the mounting bracket is in juxtaposition to the rear edge 164' of the armature and serves to guide its vertical movement; the bottom surface 161' of the forwardly projecting portion 154' of the mounting bracket serves asa positive stop for the upward movement of the armature 103'; the
  • upper surface 162' of the mounting bracket forward extension serves as a reference for the externally accessible magnetic trip calibration means, and likewise serves to mount the thermal trip in a manner avoiding a parallel current path through the magnetic trip.
  • the instant invention provides a trip unit assembly of substantially increased simplicity of parts, ease of manufacture, increased reliability, as well as permitting increased accessibility to the variety of calibration adjustments associated therewith.
  • a circuit breaker comprising at least one pair of cooperating contacts, contact operating means for moving said contacts between an engaged and disengaged position; latch mean cooperating with said operating means for maintaining said contacts in their engaged position under normal load conditions, a trip unit including current sensing means operatively responsive to the current flow through the circuit, and including means for releasing said latch means responsive to predetermined overload conditions, said current sensing means including a magnetic trip assembly having cooperating magnet and armature members, said magnet member of a generally U- shaped configuration, including space-separated arms joined by a body portion, said body portion disposed generally horizontally, and mounted at the lower region of said trip unit, with said arms vertically extending upwardly therefrom, the uppermost ex'u'emes of said arms including pole faces disposed in a generally horizontal plane, vertically displaced upwards from said body portion, said armature member horizontally extending parallel to the plane of said pole faces, and bridging the space separation between the arms thereof, said armature member having a first position above said pole faces, and separated therefrom
  • a circuit breaker comprising at least one pair of cooperating contacts, contact operating means for moving said contacts between an engaged and disengaged position; latch means cooperating with said operating means for maintaining said contacts in their engaged position under normal load conditions, a trip unit including current sensing means operatively responsive to the current flow through the circuit, and including means for releasing said latch means responsive to predetermined overload conditions, said current sensing means including a magnetic trip assembly having cooperating magnet and armature members, said magnet member of a generally U- shaped configuration, including space-separated arms joined by a body portion, said body portion disposed generally horizontally, and mounted at the lower region of said trip unit, with said arms vertically extending upwardly therefrom, the uppermost extremes of said arms including pole faces disposed in a generally horizontal plane, vertically displaced upwards from said body portion, said armature member horizontally extending parallel to the plane of said pole faces, and bridging the space separation between the arms thereof, said armature member having a first position above said pole faces, and separated therefrom by a pre
  • a circuit breaker comprising at least one pair of cooperating contacts, contact operating means for moving said contacts between an engaged and disengaged position, latch means cooperating with said operating means for maintaining said contacts in their engaged position under normal load conditions, a trip unit including current sensing means operatively responsive to the current flow through the circuit, and including means for releasing said latch means responsive to predetermined overload conditions, said current sensing means including a magnetic trip assembly having cooperating magnet and armature members, said magnet member of a generally U-shaped configuration, including space-separated arms joined by a body portion, said body portion disposed generally horizontally, and mounted at the lower region of said trip unit, with said arms vertically extending upwardly therefrom, the uppermost extremes of said arms including pole faces disposed in a generally horizontal plane, vertically displaced upwards from said body portion, said armature member horizontally extending parallel to the plane of said pole faces, and bridging the space separation between the arms thereof, said armature member having a first position above said pole faces, and separated therefrom by a predetermined
  • said armature member includes a generally vertically extending edge in juxtaposition to a vertically extending bracket portion, said vertically extending bracket portion defining the path of movement of said armature member edge corresponding to the movement of said armature between its first and second positions, such that said last mentioned bracket portion provides a guide for the armature travel.
  • a circuit breaker comprising at least one pair of cooperating contacts, contact operating means for moving said contacts between an engaged and disengaged position, latch means cooperating with said operating means for maintaining said contacts in their engaged position under normal load conditions, a trip unit including current sensing means operatively responsive to the current fiow through the circuit, and including means for releasing said latch means responsive to predetermined overload conditions, said current sensing means including a magnetic trip assembly having cooperating magnet and armature members, said magnet member of a generally U-shaped configuration, including space-separated arms joined by a body portion, said body portion disposed generally horizontally, and mounted at the lower region of said trip unit, with said arms vertically extending upwardly therefrom, the uppermost extremes of said arms including pole faces disposed in a generally horizontal plane, vertically displaced upwards from said body portion, said armature member horizontally extending parallel to the .plane of said pole faces, and bridging the space separation between the arms thereof, said armature member having a first position above said pole faces, and
  • said armature having a second position, in contact with said pole faces, with said second position corresponding to the engaged condition of the magnetic trip assembly, magnet energizing means for moving said armature downwardly between said first and second positions corresponding to a predetermined overload condition, an actuating rod mounted to said armature, and including a first portion upwardly extending therefrom in a generally vertical direction, a trip unit actuating extension mounted to said rod for movement therewith responsive to downward movement of said armature towards its engaged condition, means operatively connecting said actuating extension to said contact operating latch means, for release of said latch means responsive to downward movement of said actuating rod, said trip unit including a mounting bracket for mounting said magnetic trip assembly, said mounting bracket including a generally vertically extending rear planar portion communicating with a forwardly projecting top portion, said top portion extending in a generally horizontal direction, parallel to and above said armature member, said magnet member including mounting

Description

y 9, 1967 A. STROBEL ETAL 3,319,195
CIRCUIT BREAKER TRIP UNIT ASSEMBLY Filed June 21, 1965 9 Sheets-Sheet 1 Q INVENTORE y 9, 1967 A. STROBEL :ETAL 3,319,195
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CIRCUIT BREAKER TRIP UNIT ASSEMBLY Filed June 21, 1965 9 Sheets-Shet s May 9, 1967 A. STROBEL ETAL 3,319,195
CIRCUIT BREAKER TRIP UNIT ASSEMBLY Filed June 21, 1965 9 Sheets-Sheet 4 INVENTORS 4165 67 $708t2 May 9, 1967 Al STROBEL ETAL 1 CIRCUIT BREAKER TRIP UNiT ASSEMBLY Filed June 21, 1965 9 Sheets-Sheet 5 y 19 7 A. STROBEL ETAL 3,319,195
CIRCUIT BREAKER TRIP UNIT ASSEMBLY I Filed June 21, 1965 1 9 Sheets-Sheet 6 INVENTORS 6785 27 f diz ay 9, 67 A. STROBEL E ETAL 3,319,195
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CIRCUIT BREAKER TRIP UNIT ASSEMBLY Filed June 21, 1965 9 SheetsSheet 9 United States Patent vania Filed June 21, 1965, Ser. No. 465,313 15 Claims. (Cl. 335-36) Our invention relates to molded case circuit breakers in general, and more particularly to an improved trip unit assembly therefor which provides increased ease of manufacture, reliability of operation and calibration adjustment.
Automatic circuit breakers are usually provided with a trip unit including both a magnetic trip assembly, instantaneously responsive to a severe overload condition, and a thermal trip assembly, responsive to a moderate overload condition existing for a prolonged time interval. The actuation of either the instantaneous or the delayed trip unit conventionally actuates a mechanism which causes a tripper bar to be urged into rotational movement, with such rotational movement serving to unlatch the general contact operating mechanism of the circuit breaker unit.
The instantaneous trip assembly conventionally includes a stationary magnet member and a cooperating armature member. In order to achieve rapid actuation responsive to a severe overload condition, it is desirable that energization of the magnet be provided in such a manner that substantially all of the circuit breaker current Will serve to establish the magnetic flux field. To insure reliable, safe and accurate operation over extended periods of use, it is also necessary that calibration adjustments be proved for: (1) the initial position of the armature; (2) the extent of armature travel required for tripping; (3) the biasing force to be overcome by the magnetic force; and (4) variation of the open-gap position in accordance with the particular circuit parameters. In the past, the satisfaction of these various requirements has necessitated cumbersome and intricate trip unit structures requiring excessive assembly time and cost.
It is a principal purpose of our invention .to provide an extremely simplified trip unit assembly which provides these various functions in an efi'lcient manner while providing increased accessibility to the various members thereof, and specifically, the calibration adjustment means.
Basically, the trip unit structure of our instant invention includes a generally U-shaped magnet mounted such that its body portion is horizontally located at the lower region of the overall trip unit assembly. The magnet includes generally upstanding arms having horizontally located pole faces at their end extremes. The cooperating armature member is horizontally located in a parallel plane above the pole faces. Normally the armature is separated from the pole faces by a predetermined gap distance, with such gap being rapidly closed upon the occurrence of a predetermined excessive overload condition. The movement of the armature member is translated to the tripper bar by means of a vertically extended actuating rod secured to the armature member, with the rod having a transverse extension at one end thereof for engagement with the tripper bar upon the downward movement of the armature. The upper end of the actuating rod containing the trip unit actuating extension is at an accessible region of the overall assembly, such that a calibration adjustment of the armature travel may be conveniently made after final assembly of the trip unit.
The mounting of the trip assembly is provided in an extremely simplified manner by means of a unique mounting bracket serving a variety of functions. The mounting bracket includes a generally L-shaped portion having a vertically extending rear planar portion and a forwardly projecting top portion. The forwardly projecting top portion is horizontally disposed above the armature member. In one form of our invention, a sintered magnet is used having tapped openings within an enlarged cross-sectional area adjacent the pole faces. The tapped openings receive screw members for securably mounting the magnet to the mounting bracket and base support member. In another form of our invention, a cold rolled steel magnet is used, having a pair of inwardly turned ear members, integral with the magnet and placed flush against the rear portion of the mounting bracket.
The armature member, which it will be recalled, is secured to the actuating rod, has the actuating rod extending through aligned openings in the body portion of the magnet and the forwardly projecting portion of the bracket assembly. A vertically disposed planar surface of the mounting bracket is located in juxtaposition with respect to a vertical edge of the armature and serves as a guide for movement thereof between its engaged and disengaged positions. Upward bias of the armature towards its disengaged position is provided by a spring member about the lower portion of the actuating rod. One end of the spring member bears against the body portion of the magnet member and the other end urges the armature member upward. The bias force calibration may be provided by an adjustable nut, movable along the actuating rod and interposed between the upper end of the spring member and lower surface of the armature. The lower surface of the forwardly projecting bracket support portion advantageously serves as a positive stop for such upward movement, there-by facilitating the sub-assembly location of the armature member.
It is also desirable that an externally accessible calibration member be provided to adjust the magnetic trip characteristics in accordance with the specific requirements of the circuit to be protected, as well as to compensate for wear of the operating components. This external calibration is conveniently coupled to the magnet trip unit of our invention by the provision of an additional extension member along the actuating rod. This member is also movable along the actuating rod to provide an initial calibration adjustment during manufacture. Advantageously, the external calibration unit is coupled to the trip unit such that the upper surface of the forwardly projecting support bracket provides a reference surface.
Another extremely advantageous aspect of our invention relates to the manner in which the magnetic trip assembly is associated with, and electrically connected to, the current carrying members of the circuit breaker. Specifically, energization of the magnetic circuit is typically provided by a current carrying strap passing therethrough such that the flux field generated thereby is coupled to the magnetic members. The prior art magnetic trip assembly structures have typically necessitated a plurality of connecting points whereas the current carrying terminal strap, or elements in electrical conductivity relationship therewith, were connected to the magnetic trip assembly. This arrangement tends to promote the astablishment of a parallel current path through the magnetic trip assembly. Such parallel current paths disadvantageously divert a portion of the current from its magnetizing function, thereby requiring magnetic members of increased size, complexity and cost to provide the necessary tripping forces response to the predetermined overload conditions. Further, the current flow through the magnetic trip assembly has in the past tended to cause welding of the armature to the cooperating pole faces of the magnet, thereby adversely affecting future reliability of operation. These problems have in the past necessitated the additional expense and bothersome assembly procedure of including insulative members intermediate the current carrying elements of the circuit breaker and the magnetic trip assembly. Our invention advantageously avoids these problems by requiring only a single point of interconnection between the magnetic trip assembly and those portions of the overall trip unit which are electrically connected to the current carrying path. The provision of such a single point connection prevents the establishment of a parallel current path through the magnetic trip assembly. Advantageously, this single Point connection also serves to secura-bly mount the thermal trip unit to our novel mounting bracket to provide a combined magnetic and thermal trip unit of increased simplicity of structure and ease of fabrication.
Thus, it is seen that the L-shaped bracket of the instant invention serves a variety of functions which, in addition to mounting the magnetic and armature of the trip unit base, serves as a positive stop for the upward movement of the armature; guides the vertical movement of the armature during its travel; acts as a reference for the externally accessible magnet trip calibration means; and serves to mount the thermal trip in a manner avoiding a parallel current path through the magnetic trip.
It is therefore a primary object of our invention to provide a simplified magnetic trip unit assembly.
A further object of our invention is to provide a magnetic trip unit assembly wherein the operating components thereof may be simply fabricated and assembled.
Another object of our invention is to provide a magnetic trip assembly for use in conjunction with a circuit breaker mechanism, which is constructed to provide increased accessibility to the various calibration adjustments thereof.
An additional objects of our invention is to provide a circuit breaker magnetic trip unit assembly, including a novel mounting bracket serving a variety of functions.
Still a further object of our invention is to provide such a trip unit assembly where the mounting bracket serves as a guide for the armature open gap position, the path of armature movement, as well as the tripping characteristic calibration adjustment means.
Still another object of our invention is to provide a circuit breaker magnetic trip unit assembly wherein the electrical interconnection between the current carrying members and the magnetic trip unit portion thereof is limited to a single point, thereby preventing the establishment of parallel current paths within the magnetic trip unit.
Still an additional object of our invention is to provide a magnetic trip unit assembly which includes a generally U-shaped magnetic member with the arms thereof projecting upward for cooperation with a horizontally disposed armature, such that actuation of the magneticcircuit moves the armature downward into engagement with the magnetic pole faces, with such downward armature movement being coupled to the circuit breaker tripper bar via an actuating rod secured to the armature member and upwardly extending therefrom.
These, as well as other objects of our invention, shall become readily apparent after reading the following description and the accompanying drawings, in which:
FIGURE 1 is a perspective view of a three-phase molded case circuit breaker construction, which may be used in the practice of the instant invention, and wherein the cover is removed to reveal the internal mechanism thereof;
FIGURE 2 is a plan view of the circuit breaker unit shown in FIGURE 1, with the cover replaced and partially cut away;
FIGURE 3 is a longitudinal cross-sectional view taken through the center phase and along the arrows 3-3, as shown in FIGURE 2;
FIGURE 4 is a cross-sectional view along the lines 44 of FIGURE 1 and showing one form of the trip unit assembly, in accordance with our invention;
FIGURE 5 is a top view of FIGURE 4 showing the trip unit assembly, and partially broken away in crosssection;
FIGURE 6 is a cross-sectional view along the lines 66 of FIGURE 4, looking in a direction of the arrows and showing further details of the trip unit assembly, with the magnetic trip portion thereof shown in the nontripped condition;
FIGURE 7 corresponds to FIGURE 6, but shows the magnetic trip unit in the actuated or tripped condition;
FIGURE 8 is a perspective view of the trip unit assembly of FIGURES 4-7; and
FIGURE 9 is an exploded perspective view of the magnetic trip unit in conjunction with the trip unit assembly and calibration adjustment button, and FIGURE 9A explodes the magnetic trip portion of the trip unit assembly.
FIGURE 10 is a perspective view of another form of trip unit assembly in accordance with our invention, which has a somewhat modified magnetic trip portion; and
FIGURE 11 is an exploded perspective view of the modified magnetic trip portion thereof.
Now referring to the figures: circuit breaker 10 where in our invention is incorporated is typically shown as a commercially available three-phase molded case unit. It should be naturally understood that the novel concepts of our invention may be incorporated in numerous other frame sizes and types, with this embodiment being merely for illustrative purposes. The unit is assembled within a housing comprising molded base 11, separated into compartments 12, 13 and '14, respectively, for locating the operating members of each 'of the phases. The adjacent compartments are separated by housing walls 15 and 16. Main cover assembly 17 and end covers 18 similarly include barriers for maintaining the longitudinally extending compartments of the housing, with end shields 19 being located at the line and load ends of the circuit breaker 10.
The current carrying members of all three phases are identical so that for the sake of brevity only one of the sets of elements, such as the center phase as shown in FIGURE 3, will be described. The current path between the line terminal strap 20 and load terminal strap 21 pro ceeds from stationary contacts 22 and 23 to movable contacts 24 and 25 carried by contact arms 26 and 27 through flexible braids 28, contact carrier strap 29 and trip unit strap 102.
Since circuit breaker 10 is of a relatively high current carrying capacity, contacts 22-24 function as arcing contacts and are properly situated to move into engagement and disengagement within the opening defined by circuit breaker arc chute assembly 31. The arcing contacts 22-24 are shown parallelled by two seats of main contacts 23-25. The main movable contacts 25 are each mounted to individual contact arms 27, each connected by an individual section of braid 28 to contact carrier strap 29, while cooperating stationary contacts 23 are mounted to line terminal strap 20. The movable arcing contact 24 is similarly mounted to its contact arm 26, which is connected by a braid section 28 to the strap 29. Its c0- operating stationary contact 22 is also mounted to line terminal strap 20. The contact arms 26-27-26 of each phase are, in turn, pivotally mounted by rod 36 to contact carrier 35.
The movable contact arm mounting may include individual adjusting studs 60 to establish the open gap circuit position of contacts 24-25 relative to stationary contacts 22-23 as shown in the open position of FIGURE 3; as well as a contact pressure adjustment means shown as 71; as is the subject of copending U.S. patent application Ser. No. 430,549 filed Feb. 5, 19 65, in the name of Carl E. Gryctko and entitled, Circuit Breaker Contact Mounting, now U.S. Patent No. 3,268,702..
Circuit breaker 10 also includes an automatic tripping mechanism and a quick make-break-toggle operating mechanism 32. Operating mechanism 32 is connected to the contacts of all three phasees by means of a transverse insulating tiebar 33, with U-shaped straps 34 connecting the respective contact carriers 35 to the common tiebar 33. Carrier 35 is pivotally mounted at 46- to suitable bearings in the operating mechanism frame 47. Mounting frame 47 includes ears 84 which receive screw members 49 for securement to circuit breaker base embossment 50.
The center phase carrier 35 is connected at its pivot rod 36 to the lower of the operating mechanism toggle linkage 37-38, with the toggle links joined at knee 39. Knee 39 includes a pivotally mounted plate member 40- to which the circuit breaker operating springs, shown as a pair 41-41, are connected at one end 42-42 thereof. The other ends 43-43" are located in suitable apertures with the operating handle frame 45, such that the operating springs 45-45 are in overcenter relationship with respect to toggle linkage 37-38. The lower end of handle frame member 45 is pivotally mounted to bosses 83 of operating mechanism frame 47. Operating handle 80 is mounted to upstanding posts 81 of frame member 45.
The operating mechanism 32 also includes a cradle carried lat-ch tip 51 for engagement with latching bracket extension '52 of the trip assembly 100. A coupling member generally shown as 52 interconnects latching bracket extension 52 to the tripper bar 53 of the trip unit assembly so as to effect tripping disengagement of latched members 51-52 upon counter-clockwise movement of tripper bar 53. Such counter-clockwise movement is effected by either the actuation of the instantaneous or magnetic trip or the time-delayed or thermal trip units contained in trip unit assembly 100.
The trip unit assembly 100 includes a terminal strap 102 for each of the phases. Terminal straps 102 include apertures 104 at one end thereof to mate with cooperating aperture 106 of the load terminal strap 21 for electric-a1 and mechanical securement thereto. The opposite end of terminal strap 102 includes aperture :108 which similarly mates with cooperating aperture 110 of the contact carrier strap 29. Bolt means 112 extend through cooperating apertures 104, 106 at the load end of the circuit breaker frame, with similar bolt means 114 extending through cooperating apertures 108, 110 for mounting each of the terminal straps 102 of the trip unit assembly 100 to their respective load terminal straps 21 and contact carrier straps 29.
The magnetic trip assembly, which is the subject of the instant invention and is generally shown as 250, includes an actuating rod 56 having a trip unit actuating extension 57 which moves down into engagement with tripper bar extension member '58. The trip unit actuating extension 57 to the upper extreme of actuating rod 56 is preferably of an external knurled configuration to facilitate adjustment thereof, during the initial calibration procedure. Extension 57 is also of a sufiicient diameter to extend over a substantial portion of its cooperating tripper bar bracket 58. This advantageously avoids the use of a fork-type tripping bracket and the cumbersome assembly techniques associated therewith, as is required in some prior art structures. Furthermore, this design eliminates pole-to-pole misalignment problems between armature trip rod and tripping bracket that are commonly present when fork type brackets are used.
The time-delayed trip unit assembly includes an elongated bimetallic member 54 which will deflect towards the left, as shown in FIGURE 3, into engagement with tripper bar adjustment screw 55 upon the occurrence of moderate overload conditions for a predetermined interval of time.
With respect to the specific details of the magnetic trip unit assembly of the instant invention, reference is first made to FIGURES 4-9, which show one form thereof.
The magnetic trip unit assembly 250 includes a cooperating magnet member 101 and armature 103. Magnet member 101, which may be of the sintered variety, has a generally U-shaped configuration which includes a body portion 105 disposed generally horizontally and mounted at the lowermost region of the overall trip unit assembly 100. The ends of body portion 105 include upstanding space-separated arms 107, 109, respectively, having horizontally disposed pole faces 111, 113, respectively, at their uppermost extremes. The upper portions of the arms 10-7, 109 include enlarged cross-section areas 116, 118, respectively, having tapped opening 157. These openings are in alignment with openings 159 of the mounting bracket 150, 206 of the terminal shunt bracket 204, as well as cooperating opening (not shown) of the base support 200, for receiving mounting screws 155.
The armature member '103 is horizontally positioned intermediate the plane of pole faces 111, 113 and the bottom surface 161 of forwardly projecting extension 154 of the mounting bracket 150. In its non-engaged condition, as shown in FIGURE 6, the armature member 103 is separated from the pole faces 111, 1 13 by an airgap separation of predetermined calibrated extent, as shown by d. Upon sufiicient magnetizing flux the armature member 103 is downwardly drawn towards cooperating pole faces 111, 113 as shown in FIGURE 7.
The mounting of the armature member for travel between its engaged and non-engaged positions is provided in the following manner. Actuating rod member 56, which extends through cooperating aligned apertures 163 of the mounting bracket top portion, 165 of the thermal trip unit assembly and 167 of the magnetic member body portion 105, is secured to the armature member at 170. A biasing spring 172 is positioned about the lower portion of actuating rod 56 with the bottom end 173 thereof bearing against the upper surface of magnetic member body portion 105 and the top end 174 bearing against a calibration adjustment nut member 175. Thus, the armature member will be located with the bias spring 172 serving to urge the armature upwards to its disengaged position. To guide the movement of armature 103 between its engaged and disengaged conditions, the rearmost edge 164 thereof is in juxtaposition to forward surface of the mounting bracket forwardly turned portion 152, as best seen in FIGURES 8 and 9. It should be noted at this point that the lower surface 161 of the forwardly projecting bracket portion 154 will be in the path of upward travel of the armature member 103 and serve as a positive step to limit such upward movement. This feature is particularly advantageous during the sub-assembly fabrication of the circuit breaker trip unit.
An armature gap calibration means, generally shown as 185, is provided. This adjustment means which is the subject of copending U.S. patent application entitled Circuit Breaker Instantaneous Trip Adjustment, Ser. No. 465,305, filed June 21, 1965, and assigned to the assignee of the instant invention, includes a mounting bracket 187 having an externally accessible calibration button 189, for rotation of cam member 191. This rotational movement causes vertical translation of calibration adjustment extension secured to the actuating rod 56 in accordance with the cam surface 193 of rotatable cam 191. Such movement of the actuating rod 56 naturally moves the armature member 103 a corresponding distance to adjust the gap separation d. The armature gap calibration adjustment means includes a lower pin member 197 which rests on upper surface 162 of the mounting bracket forward projecting top portion 154. This advantageously serves as a reference plane for the gap calibration adjustment, as well as serving to position pin 197 against the calibration adjust bias force provided from within member 189.
It should he noted at this point that the trip unit actuating extension 57, the calibration adjustment extension 195 and armature bias pressure calibration nut 175 are all threadedly maintained along actuating rod 56 and are easily accessible subsequent to final assembly of the overall trip unit assembly; as shown, for example, in FIG- URE 8. After these calibrated adjustments are made, the extension members 57, 195 and 175 are properly secured in place along the actuating rod 56, as by solder. This is to be contrasted to the intricate adjustment structures necessitated by the prior art trip unit assemblies for calibrating these various parameters.
The energization for the magnetic trip unit assembly is provided by current carrying strap member 102 passing through the U-arins of magnet member 101. Current carrying strap member 102 is connected to a thermal shunt 202 which in turn is thermally connected to the bimetallic :member 54, as is more fully disclosed in copend ing US. patent application entitled, Circuit Breaker Trip Assembly With Increased Compensation for Misalignmerit, Ser. No. 465,304, filed June 21, 1965 and assigned to the assignee of the instant invention. The thermal trip unit includes a mounting bracket 204 which has apertures 206 in alignment with apertures 159 of the mounting bracket 150 and 157 of the magnet 101 for receiving screws 155. The combined magnetic and thermal trip unit assemblies of each of the phases are mounted to a base support member 200 of the overall trip unit assembly, as by mounting screws 212, which mate with apertures 210. Thermal shunt member 202 may typically be formed of copper laminates or other conductive material. Hence, this could establish a current path from the conductive strap 102 via terminal shunt member 202 and mounting bracket 204 of the time delay trip subassembly to the main mounting bracket :member 150 and magnet member 101. Should there be a current return, the possibility of such a parallel current path tends to lower the pull-in force of the magnet 101 as well as subjecting the armature and magnet to the danger of welding. Our invention absolutely avoids this by the provision of only one point of interconnection between the magnet trip unit and the current carrying members of the overall trip assembly, thereby avoiding the necessity of including insulative members in the assembly.
Reference is now made to FIGS. 1'0 and 11 which sh w another form of our invention having a slightly modified magnetic trip assembly. To simplify the comparison with the embodiment described above, components of like designations are indicated by the same numerals and those components having a corresponding function are indicated by prime numerals. It is noted that magnet member 101' is now formed of a uniform thickness of material, which may be, for example, cold rolled steel. Magnet members 101 is of a general U-shaped configuration, including a central body portion 105', having upstanding arms 107', 109', with the pole faces 111, 113' at the ends thereof. A pair of inwardly turned mounting ears 116, 118' are provided, having tapped openings 157, which receive mounting screws 155. Mounting openings 157 are in alignment with cooperating openings 159 of the mounting bracket for securely mounting the magnet member 101' to the mounting bracket 150'.
Mounting bracket 150' is similarly of a generally L- shape configuration, having a generally vertically extending rear planar portion 185' and a forwardly projecting top portion 154' extending in a generally horizontal direction. Rearwardly extending U-sections 152 having openings 159' which mate with screw members 212' (and cooperating openings of the thermal shunt mounting bracket, not shown) provided for securably fixing the mounting bracket to the trip unit support member 200.
It will be noted that in this embodiment of our invention the vertically orientated planar surface 185' of the mounting bracket is in juxtaposition to the rear edge 164' of the armature and serves to guide its vertical movement; the bottom surface 161' of the forwardly projecting portion 154' of the mounting bracket serves asa positive stop for the upward movement of the armature 103'; the
8 upper surface 162' of the mounting bracket forward extension serves as a reference for the externally accessible magnetic trip calibration means, and likewise serves to mount the thermal trip in a manner avoiding a parallel current path through the magnetic trip.
It is accordingly seen that the instant invention provides a trip unit assembly of substantially increased simplicity of parts, ease of manufacture, increased reliability, as well as permitting increased accessibility to the variety of calibration adjustments associated therewith.
Although there have been described preferred embodiments of our novel invention, many variations and modifications will now be apparent to those skilled in the art. Therefore, this invention is to be limited, not by the specific disclosure herein, but only by the appended claims.
The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:
1. A circuit breaker comprising at least one pair of cooperating contacts, contact operating means for moving said contacts between an engaged and disengaged position; latch mean cooperating with said operating means for maintaining said contacts in their engaged position under normal load conditions, a trip unit including current sensing means operatively responsive to the current flow through the circuit, and including means for releasing said latch means responsive to predetermined overload conditions, said current sensing means including a magnetic trip assembly having cooperating magnet and armature members, said magnet member of a generally U- shaped configuration, including space-separated arms joined by a body portion, said body portion disposed generally horizontally, and mounted at the lower region of said trip unit, with said arms vertically extending upwardly therefrom, the uppermost ex'u'emes of said arms including pole faces disposed in a generally horizontal plane, vertically displaced upwards from said body portion, said armature member horizontally extending parallel to the plane of said pole faces, and bridging the space separation between the arms thereof, said armature member having a first position above said pole faces, and separated therefrom by a predetermined gap with said first position corresponding to the disengaged condition of the magnetic trip assembly, said armature having a second position, in contact with said pole faces, with said second position corresponding to the engaged condition of the magnetic trip assembly, magnet energizing means for moving said armature downwardly between said first and second positions corresponding to a predetermined overload condition, an actuating rod mounted to said armature, and including a first portion upwardly extending therefrom in a generally vertical direction, a trip unit actuating extension mounted to said rod for movement therewith responsive to downward movement of said armature towards its engaged condition, means operatively connecting said actuating extension to said contact operating latch means, for release of said latch means responsive to downward movement of said actuating rod, including means for upwardly biasing said armature towards its first position, said actuating rod including a second portion downwardly extending towards said magnet body portion, said biasing means including an elongated spring about said actuating rod second portion, a first end of said spring bearing against a surface of said magnet body portion, and a second end of said spring bearing against a pressure adjustment extension mounted to said actuating rod.
2. A circuit breaker comprising at least one pair of cooperating contacts, contact operating means for moving said contacts between an engaged and disengaged position; latch means cooperating with said operating means for maintaining said contacts in their engaged position under normal load conditions, a trip unit including current sensing means operatively responsive to the current flow through the circuit, and including means for releasing said latch means responsive to predetermined overload conditions, said current sensing means including a magnetic trip assembly having cooperating magnet and armature members, said magnet member of a generally U- shaped configuration, including space-separated arms joined by a body portion, said body portion disposed generally horizontally, and mounted at the lower region of said trip unit, with said arms vertically extending upwardly therefrom, the uppermost extremes of said arms including pole faces disposed in a generally horizontal plane, vertically displaced upwards from said body portion, said armature member horizontally extending parallel to the plane of said pole faces, and bridging the space separation between the arms thereof, said armature member having a first position above said pole faces, and separated therefrom by a predetermined gap with said first position corresponding to the disengaged condition of the magnetic trip assembly, said armature having a second position, in Contact with said pole faces, with said second position corresponding to the engaged condition of the magnetic trip assembly, magnet energizing means for moving said armature downwardly between said first and second positions corresponding to a predetermined overload condition, an actuating rod, means rigidly connecting said actuating rod to said armature, said actuating rod including a first portion upwardly extending therefrom in a generally vertical direction, a trip unit actuating extension mounted to said rod for movement therewith responsive to downward movement of said armature towards its engaged condition, means operatively connecting said actuating extension to said contact operating latch means, for release of said latch means responsive to downward movement of said actuating rod, including means for adjusting said predetermined gap separation including a gap adjustment extension mounted to said actuating rod, and vertically displaceable by an externally accessible member such that said armature is vertically adjustable relative to said pole faces,
3. A circuit breaker as set forth in claim 1, means for adjusting said predetermined gap separation including a gap adjustment extension mounted to said actuating rod,
and vertically displaceable by an externally accessible member, such that said armature is vertically adjustable relative to said pole faces.
4. A circuit breaker as set forth in claim 3, wherein at least a portion of the length of said actuating rod is externally threaded, at least one of said extensions formed of a member having an internal thread for mating engagement with said rod threaded portion, .said member vertically movable along said rod for calibrated adjustment of its respective function.
5. A circuit breaker as set forth in claim 3, wherein said actuating rod includes externally threaded portions, each of said extensions including an internally threaded member, such that said extensions are vertically movable along said rod threaded portions for calibrated adjustment of the trip unit release, armature bias force and open gap separation.
6. A circuit breaker as set forth in claim 5, wherein said trip unit includes a support member, mounting means for mounting said magnetic trip assembly to said support member of said trip unit, said mounting means constructed to provide accessibility to said calibrated adjustment, whereby said magnetic trip assembly may be readily calibrated when mounted to said trip assembly support member.
7. A circuit breaker comprising at least one pair of cooperating contacts, contact operating means for moving said contacts between an engaged and disengaged position, latch means cooperating with said operating means for maintaining said contacts in their engaged position under normal load conditions, a trip unit including current sensing means operatively responsive to the current flow through the circuit, and including means for releasing said latch means responsive to predetermined overload conditions, said current sensing means including a magnetic trip assembly having cooperating magnet and armature members, said magnet member of a generally U-shaped configuration, including space-separated arms joined by a body portion, said body portion disposed generally horizontally, and mounted at the lower region of said trip unit, with said arms vertically extending upwardly therefrom, the uppermost extremes of said arms including pole faces disposed in a generally horizontal plane, vertically displaced upwards from said body portion, said armature member horizontally extending parallel to the plane of said pole faces, and bridging the space separation between the arms thereof, said armature member having a first position above said pole faces, and separated therefrom by a predetermined gap, with said first position corresponding to the disengaged condition of the magnetic trip assembly, said armature having a second position, in contact with said pole faces, with said second position corresponding to the engaged condition of the magnetic trip assembly, magnet energizing means for moving said armature downwardly between said first and second positions corresponding to a predetermined overload condition, an actuating rod mounted to said armature, and including a first portion upwardly extending therefrom in a generally vertical direction, a trip unit actuating extension mounted to said rod for movement therewith responsive to downward movement of said armature towards its engaged condition, means operatively connecting said actuating extension to said contact operating latch means, for release of said latch means responsive to downward movement of said actuating rod, said trip unit including, a mounting bracket for mounting said magnetic trip assembly, said mounting bracket including a generally Vertically extending rear planar portion communicating with a forwardly projecting top portion, said top portion extending in a generally horizontal direction, parallel to and above said armature member, said magnet member including mounting regions integrally formed therein, securing means for securably mounting said mounting regions to said mounting bracket rear portion,
8. A circuit breaker as set forth in claim 7, further including means for upwardly biasing said armature towards its first position, said actuating rod including a second portion downwardly extending towards said magnet body portion, said biasing means including an elongated spring about said actuating rod second portion, a first end of said spring bearing against a surface of said magnet body portion, and a second end of said spring bearing against a pressure adjustment extension mounted to said actuating rod, said forwardly projecting top portion having an upper and lower surface, said lower surface in the upward path of travel of said armature, and serving as a positive stop means for the upward movement of said armature memher.
9. A circuit breaker as set forth in claim 7, wherein said forwardly projecting top portion has an upper and lower surface, said lower surface is in the upward path of travel of said armature and serves as a positive stop means for the upward movement of said armature member.
10. A circuit breaker as set forth in claim 7, wherein said forwardly projecting top portion has an upper and lower surface, and further including means for adjusting said predetermined gap separation including a gap adjusted extension mounted to said actuating rod, and vertically displaceable by an externally accessible member, such that said armature is vertically adjustable relative to said pole faces, said gap separation adjustment means including a member in engagement with said top surface, such that said top surface provides a support guide for said adjustment means.
11. A circuit breaker as set forth in claim 7, further including means for upwardly biasing said armature towards its first position, said actuating rod including a second portion downwardly extending towards said magnet body portion, said biasing means including an elongated spring about said actuating rod second portion, a first end of said spring bearing against a surface of said magnet body portion, and a second end of said spring bearing against a pressure adjustment extension mounted to said actuating rod, means for adjusting said predetermined gap separation, including a gap adjustment extension mounted to said actuating rod, and vertically displaceable by an externally accessible member, such that said armature is vertically adjustable relative to said pole faces, said forwardly projecting top portion having an upper and lower surface, said lower surface in the upward path of travel of said armature, and serving as a positive stop means for the upward movement of said armature member, said gap separation adjustment means including a member in engagement with said top surface, such that said top surface provides a support guide for said adjustment means.
12. A circuit breaker as set forth in claim 7, wherein said armature member includes a generally vertically extending edge in juxtaposition to a vertically extending bracket portion, said vertically extending bracket portion defining the path of movement of said armature member edge corresponding to the movement of said armature between its first and second positions, such that said last mentioned bracket portion provides a guide for the armature travel.
13. A circuit breaker as set forth in claim 11, wherein said armature member includes a generally vertically extending edge in juxtaposition to a vertically extending bracket portion, said vertically extending bracket portion defining the path of movement of said armature member edge corresponding to the movement of said armature between its first and second positions, such that said last mentioned bracket portion provides a guide for the armature travel.
14. A circuit breaker comprising at least one pair of cooperating contacts, contact operating means for moving said contacts between an engaged and disengaged position, latch means cooperating with said operating means for maintaining said contacts in their engaged position under normal load conditions, a trip unit including current sensing means operatively responsive to the current fiow through the circuit, and including means for releasing said latch means responsive to predetermined overload conditions, said current sensing means including a magnetic trip assembly having cooperating magnet and armature members, said magnet member of a generally U-shaped configuration, including space-separated arms joined by a body portion, said body portion disposed generally horizontally, and mounted at the lower region of said trip unit, with said arms vertically extending upwardly therefrom, the uppermost extremes of said arms including pole faces disposed in a generally horizontal plane, vertically displaced upwards from said body portion, said armature member horizontally extending parallel to the .plane of said pole faces, and bridging the space separation between the arms thereof, said armature member having a first position above said pole faces, and
separated therefrom by a predetermined gap, with said first position corresponding to the disengaged condition of the magnetic trip assembly, said armature having a second position, in contact with said pole faces, with said second position corresponding to the engaged condition of the magnetic trip assembly, magnet energizing means for moving said armature downwardly between said first and second positions corresponding to a predetermined overload condition, an actuating rod mounted to said armature, and including a first portion upwardly extending therefrom in a generally vertical direction, a trip unit actuating extension mounted to said rod for movement therewith responsive to downward movement of said armature towards its engaged condition, means operatively connecting said actuating extension to said contact operating latch means, for release of said latch means responsive to downward movement of said actuating rod, said trip unit including a mounting bracket for mounting said magnetic trip assembly, said mounting bracket including a generally vertically extending rear planar portion communicating with a forwardly projecting top portion, said top portion extending in a generally horizontal direction, parallel to and above said armature member, said magnet member including mounting regions integrally formed therein, securing means for securably mounting to said mounting regions to said mounting bracket rear portion, said magnet energizing means being a current carrying terminal strap passing through the U-arms of said magnet member, a thermal shunt meansconnected to said terminal strap at a first end thereof, and connected to said mounting bracket at a second end thereof, said terminal shunt providing the sole connection between the current carrying terminal strap and the magnetic trip assembly, whereby a parallel current path in the trip unit assembly is avoided.
15. A circuit breaker as set forth in claim 14, further including a thermally actuated tripping element mounted to said second end of said thermal shunt, an intermediate bracket member secured to said thermally actuated element and thermal shunt at a central portion thereof, and mounted to said mounting bracket at end extremes thereof, such that said thermal trip element is mounted to said mounting bracket.
References Cited by the Examiner UNITED STATES PATENTS 2,294,838 9/1942 Dorfman 200-88 3,097,277 7/1963 Wingard 20088 3,206,576 9/1965 Michetti 200- References Cited by the Applicant UNITED STATES PATENTS 2,047,739 7/1936 Lingal.
BERNARD A, GILHEANY, Primary Examiner.
H. E. SPRINGBORN, Assistant Examiner.

Claims (1)

  1. 2. A CIRCUIT BREAKER COMPRISING AT LEAST ONE PAIR OF COOPERATING CONTACTS, CONTACT OPERATING MEANS FOR MOVING SAID CONTACTS BETWEEN AN ENGAGED AND DISENGAGED POSITION; LATCH MEANS COOPERATING WITH SAID OPERATING MEANS FOR MAINTAINING SAID CONTACTS IN THEIR ENGAGED POSITION UNDER NORMAL LOAD CONDITIONS, A TRIP UNIT INCLUDING CURRENT SENSING MEANS OPERATIVELY RESPONSIVE TO THE CURRENT FLOW THROUGH THE CIRCUIT, AND INCLUDING MEANS FOR RELEASING SAID LATCH MEANS RESPONSIVE TO PREDETERMINED OVERLOAD CONDITIONS, SAID CURRENT SENSING MEANS INCLUDING A MAGNETIC TRIP ASSEMBLY HAVING COOPERATING MAGNET AND ARMATURE MEMBERS, SAID MAGNET MEMBER OF A GENERALLY USHAPED CONFIGURATION, INCLUDING SPACE-SEPARATED ARMS JOINED BY A BODY PORTION, SAID BODY PORTION DISPOSED GENERALLY HORIZONTALLY, AND MOUNTED AT THE LOWER REGION OF SAID TRIP UNIT, WITH SAID ARMS VERTICALLY EXTENDING UPWARDLY THEREFROM, THE UPPERMOST EXTREMES OF SAID ARMS INCLUDING POLE FACES DISPOSED IN A GENERALLY HORIZONTAL PLANE, VERTICALLY DISPLACED UPWARD FROM SAID BODY PORTION, SAID ARMATURE MEMBER HORIZONTALLY EXTENDING PARALLEL TO THE PLANE OF SAID POLE FACES, AND BRIDGING THE SPACE SEPARATION BETWEEN THE ARMS THEREOF, SAID ARMATURE MEMBER HAVING A FIRST POSITION ABOVE SAID POLE FACES, AND SEPARATED THEREFROM BY A PREDETERMINED GAP WITH SAID FIRST POSITION CORRESPONDING TO THE DISENGAGED CONDITION OF THE MAGNETIC TRIP ASSEMBLY, SAID ARMATURE HAVING A SECOND POSITION, IN CONTACT WITH SAID POLE FACES, WITH SAID SECOND POSITION CORRESPONDING TO THE ENGAGED CONDITION OF THE MAGNETIC TRIP ASSEMBLY, MAGNET ENERGIZING MEANS FOR MOVING SAID ARMATURE DOWNWARDLY BETWEEN SAID FIRST AND SECOND POSITIONS CORRESPONDING TO A PREDETERMINED OVERLOAD CONDITION, AN ACTUATING ROD, MEANS RIGIDLY CONNECTING SAID ACTUATING ROD TO SAID ARMATURE, SAID ACTUATING ROD INCLUDING A FIRST PORTION UPWARDLY EXTENDING THEREFROM IN A GENERALLY VERTICAL DIRECTION, A TRIP UNIT ACTUATING EXTENSION MOUNTED TO SAID ROD FOR MOVEMENT THEREWITH RESPONSIVE TO DOWNWARD MOVEMENT OF SAID ARMATURE TOWARDS ITS ENGAGED CONDITION, MEANS OPERATIVELY CONNECTING SAID ACTUATING EXTENSION TO SAID CONTACT OPERATING LATCH MEANS, FOR RELEASE OF SAID LATCH MEANS RESPONSIVE TO DOWNWARD MOVEMENT OF SAID ACTUATING ROD, INCLUDING MEANS FOR ADJUSTING SAID PREDETERMINED GAP SEPARATION INCLUDING A GAP ADJUSTMENT EXTENSION MOUNTED TO SAID ACTUATING ROD, AND VERTICALLY DISPLACEABLE BY AN EXTERNALLY ACCESSIBLE MEMBER SUCH THAT SAID ARMATURE IS VERTICALLY ADJUSTABLE RELATIVE TO SAID POLE FACES.
US465313A 1965-06-21 1965-06-21 Circuit breaker trip unit assembly Expired - Lifetime US3319195A (en)

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3521179A (en) * 1968-04-02 1970-07-21 Weston Instruments Inc Amplifier with source voltage control
US3538475A (en) * 1966-12-20 1970-11-03 Westinghouse Electric Corp Circuit breaker with current limiting fuse means
US5844188A (en) * 1996-12-19 1998-12-01 Siemens Energy & Automation, Inc. Circuit breaker with improved trip mechanism
US5866996A (en) * 1996-12-19 1999-02-02 Siemens Energy & Automation, Inc. Contact arm with internal in-line spring
US5894260A (en) * 1996-12-19 1999-04-13 Siemens Energy & Automation, Inc. Thermal sensing bi-metal trip actuator for a circuit breaker
US6087914A (en) * 1996-12-19 2000-07-11 Siemens Energy & Automation, Inc. Circuit breaker combination thermal and magnetic trip actuator
WO2013133786A1 (en) * 2012-03-05 2013-09-12 Siemens Aktiengesellschaft Methods and apparatus for an improved magnetic armature selective tripping device of a circuit breaker
WO2013133787A1 (en) * 2012-03-05 2013-09-12 Siemens Aktiengesellschaft Methods and apparatus for calibrating a thermomagnetic trip unit of a circuit breaker
EP2911177A1 (en) * 2014-02-25 2015-08-26 Siemens Aktiengesellschaft Magnetic trip device of a thermal magnetic circuit breaker having a stabilizer element
EP2911178A1 (en) * 2014-02-25 2015-08-26 Siemens Aktiengesellschaft Magnetic trip device of a thermal magnetic circuit breaker having an adjustment element

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2047739A (en) * 1932-03-23 1936-07-14 Westinghouse Electric & Mfg Co Circuit interrupter
US2294838A (en) * 1941-05-15 1942-09-01 Westinghouse Electric & Mfg Co Circuit breaker
US3097277A (en) * 1961-04-07 1963-07-09 Fed Pacific Electric Co Latch-trip circuit breakers
US3206576A (en) * 1962-11-07 1965-09-14 Ite Circuit Breaker Ltd Air gap and tripping operation adjustment means for a circuit breaker

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2047739A (en) * 1932-03-23 1936-07-14 Westinghouse Electric & Mfg Co Circuit interrupter
US2294838A (en) * 1941-05-15 1942-09-01 Westinghouse Electric & Mfg Co Circuit breaker
US3097277A (en) * 1961-04-07 1963-07-09 Fed Pacific Electric Co Latch-trip circuit breakers
US3206576A (en) * 1962-11-07 1965-09-14 Ite Circuit Breaker Ltd Air gap and tripping operation adjustment means for a circuit breaker

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3538475A (en) * 1966-12-20 1970-11-03 Westinghouse Electric Corp Circuit breaker with current limiting fuse means
US3521179A (en) * 1968-04-02 1970-07-21 Weston Instruments Inc Amplifier with source voltage control
US5844188A (en) * 1996-12-19 1998-12-01 Siemens Energy & Automation, Inc. Circuit breaker with improved trip mechanism
US5866996A (en) * 1996-12-19 1999-02-02 Siemens Energy & Automation, Inc. Contact arm with internal in-line spring
US5894260A (en) * 1996-12-19 1999-04-13 Siemens Energy & Automation, Inc. Thermal sensing bi-metal trip actuator for a circuit breaker
US6087914A (en) * 1996-12-19 2000-07-11 Siemens Energy & Automation, Inc. Circuit breaker combination thermal and magnetic trip actuator
CN104160466A (en) * 2012-03-05 2014-11-19 西门子公司 Methods and apparatus for an improved magnetic armature selective tripping device of a circuit breaker
WO2013133787A1 (en) * 2012-03-05 2013-09-12 Siemens Aktiengesellschaft Methods and apparatus for calibrating a thermomagnetic trip unit of a circuit breaker
WO2013133786A1 (en) * 2012-03-05 2013-09-12 Siemens Aktiengesellschaft Methods and apparatus for an improved magnetic armature selective tripping device of a circuit breaker
US9396899B2 (en) 2012-03-05 2016-07-19 Siemens Aktiengesellschaft Methods and apparatus for calibrating a thermomagnetic trip unit of a circuit breaker
CN104160466B (en) * 2012-03-05 2017-05-31 西门子公司 For the method and apparatus of breaker improvement type armature keeper selective trip unit
US9672995B2 (en) 2012-03-05 2017-06-06 Siemens Aktiengesellschaft Methods and apparatus for an improved magnetic armature selective tripping device of a circuit breaker
EP2911177A1 (en) * 2014-02-25 2015-08-26 Siemens Aktiengesellschaft Magnetic trip device of a thermal magnetic circuit breaker having a stabilizer element
EP2911178A1 (en) * 2014-02-25 2015-08-26 Siemens Aktiengesellschaft Magnetic trip device of a thermal magnetic circuit breaker having an adjustment element
US20150243466A1 (en) * 2014-02-25 2015-08-27 Siemens Aktiengesellschaft Magnetic trip device of a thermal magnetic circuit breaker having a stabilizer element
US9425015B2 (en) * 2014-02-25 2016-08-23 Siemens Aktiengesellschaft Magnetic trip device of a thermal magnetic circuit breaker having a stabilizer element
US9431202B2 (en) 2014-02-25 2016-08-30 Siemens Aktiengesellschaft Magnetic trip device of a thermal magnetic circuit breaker having an adjustment element

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