US3155805A - Multipole circuit breaker with novel contact arm construction - Google Patents

Description

Nov. 3, 1964 G. w. KIESEL ETAL 3,155,805

M'U'LTIPOLE CIRCUIT BREAKER WITH NOVEL CONTACT ARM CONSTRUCTION Original Filed April 15. 1960 3 Sheets-Sheet 1 INVENTORS GEORGE W K/EsEL, Ems/av M. WEGH 6M1 C 4 TTORNE' 1964 a. w. KIESEL ETAL 3,155,805

MULTIPOLE CIRCUIT BREAKER WITH NOVEL CONTACT ARM CONSTRUCTION Original Filed April 15, 1960 3 Sheets-Sheet 2 INVENTORS Gama: W. KIESEL,

EMERY M. was

WMJK A TTORNEY 1964 s. w. KIESEL ETAL 3,155,805

MULTIPOLE CIRCUIT BREAKER WITH NOVEL CONTACT ARM CONSTRUCTION Original Filed April 15. 1960 3 Sheets-Sheet 3 INVENTORS GEORGE W. K/Esn, MRY P7. Was/4 KMJ C 4 TT'ORNEY United States Patent 3,155,805 MULTIPOLE CIRCUIT BREAKER WITH NOVEL CONTACT ARM CONSTRUCTION George W. Kiesel, Unionville, and Emery M. Wegh,

Terryville, Conn, assignors to General Electric Comparry, a corporation of New York Original application Apr. 15, 1960, Ser. No. 22,483. Divided and this application Dec. 20, 1962, Ser. No.

4 Claims. (Cl. 200-166) Our invention relates to electric circuit breakers and particularly to plug-in type multipole electric circuit breakers adapted for use in panel assemblies, such, for example, as in the panel assembly shown in Patent No. 2,738,446, W. I. Fleming, March 13, 1956, assigned to the same assignee as the present invention.

This application is a division of copending application Serial Number 22,483, filed April 15, 1960, and assigned to the same assignee as the present invention.

Electric circuit breakers of the type referred to herein are characterized by their extreme compactness. Such compactness is achieved in large measure by a particular arrangement of the basic component portions of the electric circuit breaker. Such electric circuit breakers, for example, comprise three primary component portions: (a) a pair of separable contacts and associated arc-cooling and extinguishing means for each circuit or pole; (b) operating mechanism for operating the contacts both manually and automatically upon the occurrence of overload conditions, and (c) current-responsive means for detecting the existence of such overload conditions and for initiating an actuation of the operating mechanism in response thereto. These components, in conventional circuit breakers, are ordinarily arranged within a molded enclosing case in a row, with the current-responsive means at one end of the casing, the operating mechanism next, and the contacts and are extinguishing means at the opposite end. In the compact type of circuit breaker referred to herein, however, the overall length of the circuit breaker is significantly shortened by raisingv the opcrating mechanism and positioning the contacts and are extinguishing structure below the operating mechanism,

so that these two components are in stacked relation.

As an incident of this arrangement, as the movable contact moves toward and away from the stationary contact, the contact arm supporting the movable contact It is another object of the invention to provide a circuit breaker of the type described in which the size and strength of the contact arm proper, as well as of the contact pressure spring are increased without an increase in the size of the circuit breaker.

In accordance with the invention in one form, a circuit breaker is provided including a. pivotally supported contact operating member formed of sheet metal stock bent into a U or channel-shape, with a bent-over lug at one end of the bight of the U. A contact arm is pivotally I carried by the ope-rating member and has a portion bent at right angles to the main position adjacent the bight of the U. A tension spring is arranged between the bentover lug and the contact arm extension, biasing the extension against the bight as a stop. The spring is thereby positioned out of the path of hot arc gases emanating from the contacts.

In the drawings,

FIGURE 1 is a side elevation view, partially in section, of an electric circuit breaker embodying the inven tion;

FIGURE 2 is a sectional plan view taken generally on the line 2-2 of FIGURE 1;

FIGURE 3 is an exploded elevation view partially in section of the circuit breaker of FIGURE 1;

FIGURE 4 is a partially exploded elevation sectional view of the circuit breaker of FIGURE 1 showing the mechanism and current-responsive means in mounted condition;

FIGURE 5 is a sectional plan view of the circuit breaker taken generally on the line 5-5 of FIGURE 4;

FIGURE 6 is a fragmentary elevation view of the circuit breaker of FIGURE 1 showing the mechanism in the olf position;

FIGURE 7 is a fragmentary elevation view of the circuit breaker of FIGURE 1, showing the parts in the tripped position;

FIGURE 8 is an elevation view of an assembly of plugin type circuit breakers according to the prior art, and

FIGURE 9 is an elevation view similar to FIGURE 8, showing an assembly utilizing an electric circuit breaker of the present invention.

(1) Insulating Casing Construction Referring first to FIGURES l-S, the invention is shown as embodied in a two-pole electric circuit breaker comprising an insulating casing of molded material including a central body portion 10 (see FIGURES 3 and 5), a top cover portion 11 and a bottom cover portion 12. As indicated particularly in FIGURES 2 and 5, the central portion 10 includes a longitudinal extending integral vertical barrier portion 13 and a shorter similar barrier portion 14 spaced apart therefrom to leave a space 15 for a cross or common trip bar to be described.

The longitudinal barriers 13 and 14 serve to essentially divide the inner space of the insulating easing into two elongated generally rectangular chambers 16 and 17. Each of the chambers 16 and'17 contains a pair of con t acts comprising a stationary contact 18 and a movable contact 19 (only one pair of contacts shown). In addition, each of the chambers 16 and 17 contains a trip device current-responsive means indicated generally at 20 and to be described more fully hereinafter. In addition, the chamber 17 contains an operating mechanism serving to operate the movable contacts of both chambers manually and automatically in a manner to be described.

The central insulating casing portion 10 further includes an integral transversely extending horizontal bar'- rier 22 (see FIGURES 4 and 5) in each of the chambers 16 and 17 and extending slightly more than one half the lengthwise distance of such chamber. Each of the bar riers 22 has a portion thereof notched or cut away as at 23 to permit movement of the contact arm in a manner to be described.

The central casing portion 10 further includes trans versely extending vertical barrier portions 24, 25, 26 which are in alignment and spaced apart to provide passages 27 and 28 for flexible conductors leading to the movable switch members (to be described). i

It will therefore be observed that in effect, the generally rectangular space within the-central insulating portion 10 is subdivided into two elongated chambers 16 and 17 by the longitudinal barriers 13 and 14, and that each of such chambers 16 and 17 is further subdivided. The horizontally extending transverse barriers 22 divide the forward portion of each of the chambers 16 and 17 into two substantially equal upper and lower portions.

- Patented Nov. 3, 1964 The transversely extending vertical barriers 24, 25, 26 serve to subdivide the lower portion of each of the chambers 16 and 17 into a forward and a rearward compartment. Thus in effect, each of the chambers 16 and 17 is divided into three portions: an upper and lower forward portion and a rearward portion. In addition, horizontally extending transverse barriers 29, are provided, for a purpose to be described. All of the components of the circuit breaker according to the invention are supported on and substantially contained within the central insulating member 10. The cover portions 11 and 12 serve to enclose and shield such parts.

(2) Terminals and Current Path The details of the construction of the parts will be set forth in connection with the pole chamber 17. Referring to FIGURES 1 and 2, a load terminal or connector 32 is supported on the barrier 39, and is retained thereon by the down-turned lip of terminal strap 33. The terminal strap 33 extends through the connector 32 and through an aperture 34 in the end wall 10a of the casing portion 10, extends upwardly along the inner surface of the end wall, and is rigidly afiixed to the end wall by means of the screw 35.

It will be observed that the connector 32 when in position blocks access to the screw 35. For this reason, the assembly of these parts is accomplished as follows: The terminal strap 33 is assembled by inerting it through the open top of the casing portion 10 and projecting the end thereof through the aperture 34. The terminal strap 33 as initially assembled is bent so that the projecting end thereof extends in the position shown in dotted lines in FIGURE 1. The screw 35 is then inserted and tightened. The connector 32 is thereafter slid onto the end of the strap 33 to the position shown. Following this, the end of the terminal strap 33 is bent down to its solid line position, trapping the terminal member 32 in place. This may be done by turning the clamping screw 36 down to its lowest position, or by other suitable means.

A reverse-bent elongated bimetallic strip 37 is rigidly attached to the terminal strap 33 by suitable means such as by welding. The bimetallic strip 37 has its free end portion 38 bent at right angles to its major intermediate portion. A flexible electrical connector 39 is connected to the end 38 of the bimetallic strip by suitable means such as by welding or brazing and has its other end similarly connected to the switch arm 40 carrying the movable contact 19. The movable contact 19 is adapted to contact the stationary contact 18, which is carried by the bent-over lug portion 41 of the generally U-shaped contact jaw assembly 42. In order to increase contact pressure of the socket 42, a resilient spring clip member 43 is placed over the outside of the socket member 42. The central casing portion 10 and the bottom cover portion 12 are provided with contiguous openings 21 forming corner slots in the casing to permit the insertion of contact blades in a manner to be described. The current path through this pole of the circuit breaker may therefore be traced as follows: from line terminal strap 33 to bimetallic strip 37, to flexible conductor 39, to switch arm 40, to movable contact 19, to stationary contact 18, to line socket 42.

(3) Operating Mechanism and Contact Arms In order to move the switch arm and movable contact 19 between open and closed circuit positions, an operating mechanism is provided, comprising a pair of opposed side frames 45 spaced apart by spacer pins 46 and 47. The side frames 45 are each provided with downwardly extending mounting lugs 48 which project through openings in the horizontal barrier portions 22. The lugs 48 are riveted or headed over against retaining plates 49 to securely mount the side frames 45 on the barrier 22. A generally U-shaped contact operating member 50 is pivotally supported on the spacer pin 47 and carries a contact cross-arm of insulating material 51. The switch arm 46 is pivotally supported on the pivot pin 52 carried by the operating member 59 and has a projecting end portion 53 connected by tension spring 54 to a projecting lug 55 of the operator 50. The spring 54 serves to resiliently urge the contact arm 40 for rotational movement in a counterclockwise direction about its pivot 52 and, in the closed position as shown in FIGURE 1, it urges the movable contact 19 into engagement with the stationary contact 18.

It will be observed that the spring 54 is removed from the path of hot arc gases which may be generated by the separating contacts 18 and 19. Also, because of the space available at the location of the spring 54, a larger and stronger spring may be used than if the contact arm 40 itself were to be made resilient.

(4) Latching and Tripping Mechanism It will also be observed that the insulating barrier 10B extends between the spring 54 and the contacts 13 and 19, shielding the spring 54 from direct contact by the are gases.

For the purpose of operating the operating member 50 about its pivot point 47 between open and closed circuit positions, a pair of toggle links 56 and 57 are provided. The link 56 is pivotally connected to the pivot pin 52, while the link 57 is pivotally connected at 58 to a normally stationary releasable member 59 pivotally supported between the plates 45 on spacer pin 60. The toggle links 56 and 57 are interconnected by a pin 61.

When the toggle links 56, 57 are in the extended position as shown in FIGURE 1, the contact operating member 50 is held in the closed position as shown. When the toggle links are moved to collapsed position, as shown for example in FIGURE 6, the contact operating member 56 is moved to the left or off position.

For the purpose of operating the toggle links, a manually operable member is provided including an insulating handle member 62 and a generally U-shaped metallic hanle support member 63 which straddles the frame members 45 and is pivotally supported upon lugs 63 struck out from the sides of the frames 45. A pair of elongated tension springs 64 are supported between a pin 65 carried by the handle support member 63 and the knee pin 61 of the toggle links.

As the manually operable member 62 is moved from on to o position and vice versa, the upper end of the spring 64 is moved to one side or the other of the line of centers of the toggle knee and the relatively stationary pivot 58, thereby collapsing and straightening the toggle links.

For the purpose of releasably restraining the releasable member 59, a latch assembly is provided comprising a latch member 66 pivotally supported between the side frames 45 by projections 67. The latch 66 has an aperture 68 therein which is adapted to receive a latch projection 69 carried by the releasable member 59. The latch member 66 carries a transversely extending insulating trip bar 70 which extends into both of the chambers 16 and 17. The latch assembly, including the latch member 66 and the trip bar 70 is biased in a clockwise direction by tension spring 71 which is connected to the frame spacer pin 46.

When the trip bar 70 is moved to the right as shown in FIGURE 1, so as to rotate the latch member 66 in counterclockwise direction about its pivot point 67, the latch member 66 is withdrawn from the latch projection 69 of the releasable member 59. Upon release of the projection 69, the tension spring 64 acting through the toggle links 56 and 57, moves the releasable member to the fully tripped position as shown in FIGURE 7, causing automatic opening of the contacts and movement of the manually operable member to a mid or trip indicating position. The releasable member 59 may be re-engaged with the latch member 66 by moving the handle member 62 to the fully counterclockwise position coinciding with the off position as shown in FIGURE 6.

For the purpose of moving the trip bar to cause release of the releasable member in the manner described, upon the occurrence of predetermined conditions in the circuit, current-responsive means is provided. The current-responsive means includes the bimetallic strip 37 previously described. In addition, magnetic tripping means is provided including a magnetic field piece 73 which is rigidly attached to the bimetallic strip 37 by suitable means such as by welding. A magnetic armature member 74 is provided which is pivotally held in notches 75 in the side walls of the casing. The armature 74 comprises a generally flat plate of magnetic material. The armature 74 is loosely connected to the bimetatllic strip 37 by means of a generally J-shaped wire clip 76 carried by the armature 74 and extending around in front of the magnetic field piece 73. The wire clip 76 is preferably constructed of non-magnetic material. The armature 74 is biased away from the bimetallic strip 37 by means of a compression spring 78 extending between the bent-over portion 38 of the bimetallic strip and a lug portion 79 of the armature 74. The armature 74 is further provided with an elongated calibrating screw 80 which is threadedly engaged therein and is adapted to contact the insulating tripbar 70 in a manner to be described. The insulating casing comprising the center portion and the bottom cover 12 are each formed to provide an aperture affording access to the calibrating screw 80. After assembly of the circuit breaker and calibration thereof, the aperture referred to is closed by suitable means, such as by an insulating closure 81. Passage of excess current through the bimetallic strip 37 causes the strip to deflect to the right as viewed in FIGURE 1. Such deflection causes the armature member 74 to follow because of the connection by the wire clip 76. This in turn moves the calibrating screw 80, which engages the trip bar 70, rotating the trip bar to cause tripping. Upon the occurrence of an extremely high overload condition, a magnetic attraction is set up between the magnetic field piece 73 and the armature 74, moving the armature 74 to the right as viewed toward the bimetallic strip 37. This causes the calibrating screw 80 to engage the trip bar 70 in a similar manner to cause tripping.

While the construction has been described in detail for the parts supported in the pole 17, it will be understood that corresponding parts, with the exception of the operating mechanism, are supported in the pole space 16. Thus the contact cross-arm 51 is extended into the pole space 16 and a second contact operator 50 is supported thereon, being clamped thereto by means of the retaining plate 83. The plate 83 has a ing 83' struck out and projecting into a recess in the cross-arm 51 to position the assembly laterally on the cross-arm. A switch arm and movable contact (not shown) are carried by the contact operator 50 in a manner similar to arm 40 and contact 19.

For the purpose of aiding in the extinction of electric arcs drawn by the movable contact, an arc extinguishing assembly is provided comprising a generally U-shaped fiber supporting wall 84, see FIGURE 4, having a series of generally U-shaped plates of magnetic material 85 supported therein. An insulating barrier plate 86 is slid into notches 87 in the pole space 16 and serves to limit movement of the switch arm 40 in the contact opening direction in this pole space.

It will be observed by reference to FIGURE '3 that virtually all of the parts of the circuit breaker are supported on the central insulating section 10. Thus the line terminal strap 33 and its associated parts comprising the terminal connector 32 and the bimetallic strip 37 are mounted on the end wall 10A. The armature member 74 is supported in notches in the insulating casing being held spaces is supported upon the barriers 22 of the section 10. The are extinguishing assemblies and line contact assemblies comprising the arc extinguishing members 84 and 05 and the plug-in line contact 42 are supported on the base portion 12 and contained within the chamber formed by the lower portion of the central section 10. The manner of assembly of the parts is clearly shown in the exploded FIGURE 3 of the drawings. Thus as indicated, the main operating mechanism and the line terminal strap and bimetallic strip are assembled from the top of the section 10, while the armature member 74 and the arc extinguishing assembly and line contact assembly are assembled from the bottom. Once these parts are assembled, the top and bottom covers are then put in place and the assembly held together by suitable rivets or bolts extending through the openings 86. This casing construction provides very effective mechanical reinforcement for the side walls of the center section 10, greatly contributing to its strength. In addition, the construction effectively isolates the arcing chamber from the remaining portion of the pole chambers.

In addition to the above advantages, this type of assem bly has the important advantage that it is possible to mount all of the parts in their final positions, to calibrate, adjust, and examine the entire mechanism after it is in its finally mounted position, before adding the top and bottom covers. This is an important advantage in the manufacture of such devices.

(5) Plug-In Terminal Construction In accordance with another aspect of the invention, an electric circuit breaker is provided of the plug-in type which is suitable for use in protecting higher rated circuits than customarily used in such plug-in panel assemblies. In accordance with this aspect of the invention, the circuit breaker is provided with an enlarged line contact socket which is adapted to cover the entire contact blade of such a panel assembly. This prevents the mounting of a second circuit breaker on such contact blade and therefore avoids overloading of such a contact blade. In FIGURE 8 there is shown an endwise elevation View of a panel assembly utilizing circuit breakers according to the prior art, such for example as shown in our prior abovementioned patent. Such a panel assembly comprises a supporting base or pan having an insulating base 101 supported therein by suitable means, not shown. The insulating base 101 serves to support a plurality of bus bars 102 for connection to a source of electric power. The bus bars 102 are also provided with a plurality of branch connecting straps, not shown, terminating in upstanding contact blades 103 aligned centrally of the support. The supporting pan 100 further includes outwardly directed flanges 104 provided with inturned retaining lugs or tangs 105. The circuit breakers 106 are mounted on this supporting base by hooking one end portion thereof under the retaining lugs 105, pivoting the circuit breaker about the lugs 105 and plugging them into contact with the central contact blade 103. The supporting assembly and the circuit breakers are dimensioned so that each contact blade 103 is adapted to receive two circuit breakers 106 in endwise aligned relation. It will be apparent that the contact blade 103 and its associated branch strap must carry the total current required by the two circuit breakers 106. Since such panel assemblies ordinarily are designed to utilize circuit breakers rated from 15-70 amperes, such branch connecting straps may not have suflicient capacity to feed two circuit breakers each rated higher than 70 amperes. In accordance with the invention, the circuit breaker is provided with a casing of increased length and a contact socket is provided which utilizes the entire blade 103, making it impossible to mount another circuit breaker on the same contact blade. In addition to assuring that such contact blade will not be overloaded, this construction provides increased contact area for the 100 ampere circuit breaker.

.While the invention has been described as embodied in a two-pole circuit breaker, it will be appreciated that the inventionis equally applicable to a three-pole circuit breaker, in which case an insulating casing is provided having three pole chambers and having a contact crossarm 51 and trip bar 70 extended across all three such pole chambers.

While the invention has been shown in one specific embodiment, it will be readily apparent that many modifications thereof may be made without departing from the spirit of the invention. It is therefore intended by the appended claims to cover all such modifications as fall within the true spirit and scope of the invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. An electric circuit breaker comprising:

(a) a pivotally supported contact operator having two opposed side portions and an intermediate bight portion,

(b) means supporting said contact operator for pivotal movement about a pivotal axis through said side portions,

(c) a relatively movable contact arm pivotally supported on a pivot pin extending through said side portions,

(d) said contact arm having a first portion extending from said pivot pin and carrying a movable contact thereon and a second portion extending from said pivot pin at an angle tosaid first portion, and

(e) a tension spring between said second portion of said contact arm and said bight portion of said contact operator biasing said switch arm for rotation about its pivotal support and into engagement with said bight portion of said contact operation as a stop.

2. An electric circuit breaker comprising:

(a) a contact operator of sheet metal comprising a bight portion and upwardly bent opposed side portions,

(b) said bight portion having an outwardly bent lug portion at one end thereof extending in a direction opposite from said side portions,

(c) said contact operator being pivotally supported on a pivot pin extending transversely between said opposed side portions,

(d) a movable contact member pivotally supported on a pivot pin extending transversely between said side portions and spaced away from said contact operator pivot pin,

(e) said movable contact member comprising an elongated contact arm having a first portion projecting from said pivot pin and carrying a movable contact at the end thereof and a second portion extending from said pivot pin at an angle to said first portion, and

(f) a tension spring extending between said second portion of said contact arm and said lug bent from said contact operator and biasing said contact arm for rotation about its pivotal support.

3. An electric circuit breaker compirsing:

(a) a contact operator'of sheet metal having a bight portion and upwardly bent opposed side portions extending substantially at right angles to the plane of said bight portion,

(b) said bight portion having an integral lug at one end thereof extending substantially at right angles to the plane of said bight portion in a direction opposite from said side portions,

(0) means pivotally supporting said contact operator for movement about a first axis extending transversely of said side portions at one end thereof.

(d) a movable contact arm pivotally supported for movement about a second axis extending transversely of said side portions at the other end thereof,

(a) said. movable contact arm having a first portion extending in a first direction from said second axis and carrying a movable contact adjacent the end thereof,

(1) said movable arm having a second portion extending from said second axis in a direction substantially at right angles to that of said first portion,

(g) a tension spring extending between said second portion of said contact arm and said integral lug of said bight portion of said contact operator, said tension spring biasing said contact arm for rotation about said second axis,

(11) said bight portion of said contact operator serving as a stop to limit rotational movement of said contact arm when said contact arm is in contact-disengaged condition.

4. An electric circuit breaker comprising:

(a) an insulating casing,

(b) at least one relatively stationary contact supported in said insulating casing,

(c) at least one relatively movable contact supported for movement into and out of engagement with said relatively stationary contact,

(d) an elongated contact arm carrying said relatively movable contact adjacent one end thereof,

(e) a contact operating member of flat sheet metal having a bight portion and a pair of upstanding parallel side portions extending substantially at right angles to the plane of said bight portion,

(1) a spring anchor lug projecting from said bight portion at one end thereof,

(g) means pivotally supporting said contact arm at an intermediate point thereof on said contact operating member,

(h) spring means interconnecting the other end of said contact arm and said lug portion of said contact operating member,

(1') means pivotally supporting said contact operating member in said casing,

(j) means for operating said contact operating member about said pivotal support to operate said movable contact into and out of engagement with said stationary contact, and

(k) an insulating barrier carried by said casing intermediate said spring means and said relatively stationary contact, whereby to shield said spring means from impingement by are gases.

References Cited in the file of this patent UNITED STATES PATENTS 2,788,421 Jones Apr. 9, 1957

Claims (1)

1. AN ELECTRIC CIRCUIT BREAKER COMPRISING: (A) A PIVOTALLY SUPPORTED CONTACT OPERATOR HAVING TWO OPPOSED SIDE PORTIONS AND AN INTERMEDIATE BIGHT PORTION, (B) MEANS SUPPORTING SAID CONTACT OPERATOR FOR PIVOTAL MOVEMENT ABOUT A PIVOTAL AXIS THROUGH SAID SIDE PORTIONS, (C) A RELATIVELY MOVABLE CONTACT ARM PIVOTALLY SUPPORTED ON A PIVOT PIN EXTENDING THROUGH SAID SIDE PORTIONS, (D) SAID CONTACT ARM HAVING A FIRST PORTION EXTENDING FROM SAID PIVOT PIN AND CARRYING A MOVABLE CONTACT THEREON AND A SECOND PORTION EXTENDING FROM SAID PIVOT PIN AT AN ANGLE TO SAID FIRST PORTION, AND (E) A TENSION SPRING BETWEEN SAID SECOND PORTION OF SAID CONTACT ARM AND SAID BIGHT PORTION OF SAID CONTACT OPERATOR BIASING SAID SWITCH ARM FOR ROTATION ABOUT ITS PIVOTAL SUPPORT AND INTO ENGAGEMENT WITH SAID BIGHT PORTION OF SAID CONTACT OPERATION AS A STOP.

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