US3171932A - Multipole electric circuit breaker with common tripping means - Google Patents

Description

March 2, 1965 N. R. BEAUDOIN 3,171,932

MULTIPOLE ELECTRIC CIRCUIT BREAKER WITH COMMON TRIPPING MEANS Filed May 20, 1963 2 Sheets-Sheet 1 OFF TR/PPED INVENTOR.

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March 2, 1965 N. R. BEAUDOIN MULTIPOLEJ ELECTRIC CIRCUIT BREAKER WITH COMMON TRIPPING MEANS 2 Sheets-Sheet 2 Filed May 20, 1965 INVENTOR. NORMAN RIB/E4 UDO/N, By W 7 ATTORNEY.

United States Patent M 3,171,932 MULTIPOLE ELECTRIC CIRiIUIT BREAKER WITH COMMON TRIPPING MEANS Norman R. Beaudoin, Southington, Conm, assignor to General Electric Company, a corporation of New York Filed May 20, 1963, Ser. No. 281,593 3 Claims. (ill. 200116) My invention relates to multipole electric circuit breakers, and particularly to interlocked tripping means for current responsively tripped circuit breakers having individual overload tripping elements associated with each pole of the breaker, ie. with each pair of cooperating contact members. This invention is an improvement upon that described and claimed in application S.N. 268,738, filed March 28, 1963, by D. B. Powell and assigned to the same assignee as the present invention.

The invention is especially well adapted for use with small manually operable, current responsively tripped air circuit breakers of the single pole type commonly mounted in multiple arrays for the control of branch lighting and power loads, such as in residential and commercial service entrance load centers, industrial distribution panelboards and the like. Such panelboard circuit breakers are commonly made up with one or more single pole breakers in a single casing and may be utilized separately as single pole branch breakers or in ganged pairs as double pole breakers. When two such circuit breakers are electrically connected for double pole use in a single branch circuit, it is desirable to ensure that both breakers in any one circuit trip in response to actuation of the trip element of either of them. This is true whether or not the manually operating elements of the two breakers are coupled for simultaneous actuation.

As shown in Patent 2,779,881, Thomas, single pole circuit breakers of the foregoing type have been coupled for simultaneous tripping of two breakers which are disposed in side-by-side relation. The interlocking element there disclosed is positioned exteriorly of and between side recessed circuit breaker casings. Ganged breakers of this design thus require special casings the expense of which increases the cost of full line manufacture. Moreover, the lateral casing recess requires an individual breaker design of appreciable thickness module.

In order to simplify and speed the installation of service entrance equipment and reduce cost there has been an increasing use of multiple assemblies consisting of several complete single pole circuit breakers mounted in a single integral casing. It is desirable that such breakers be of a design to provide for either individual or ganged operation with minimum use of special parts. Also, the trend to increasing numbers of branch circuits to meet growing residential and commercial power loads has led to panelboard circuit breaker designs of smaller physical size. Primarily it is desirable to decrease appreciably the thickness dimension of such breakers to permit more circuits in a panelboard of predetermined length. While the thickness module of commercially available circuit break ers of the type shown in the Thomas patent is commonly about one inch, it is now a growing practice to design for one half inch thickness. A circuit breaker of such narrow dimension requires a mechanism of simplified and narrow design and leaves very little space for any lateral interconnection between breakers.

Accordingly it is a general object of my invention to provide improved means for optionally interconnecting the separate operating mechanisms of several single pole electric circuit breakers with a minimum number of special parts.

It is a more particular object of my invention to provide means interior of the casing for interconnecting the operat- 3,171,932 Patented lVlar. 2, 1965 ing mechanisms of a pair of circuit breakers disposed in end-to-end or tandem relation in integral or separate casings of extremely narrow proportion relative to requisite mechanical strength and electrical clearance.

It is a specific object of my invention to provide means interior of the casing for interconnecting the trip elements of a pair of electric circuit breakers assembled in end-toend relation in a single unitary casing and having manually operable wedge type operatnig mechanisms laterally releasable upon current overload.

In carrying out my invention in one preferred embodiment, I provide within a single narrow casing of suitable molded plastic insulating material, a pair of substantially identical single pole electric circuit breakers disposed in essentially co-planar end-to-end or tandem relation. Each circuit breaker includes a pair of separable contacts, a moveable current responsive trip member and manually operable wedging means therebetween. Individual latch members responsive to the current through the respective pairs of contacts normally restrain the trip members against movement but when released permit the trip members against movement but when released permit the trip members to laterally relieve and release the wedge.

To ensure that overload tripping of any one such endto-end pair of breakers effects like tripping operation of the other, I provide a single flat interlocking bar interiorly of the casing which is positioned to be engaged and moved longitudinally by a part or" the manual operating mechanism of either breaker in its trip operation. The driving part of each operating mechanism is one which moves through a distinctive path in automatic trip operation only. The interlocking bar is provided with portions disposed to engage and unlatch the current responsive trip element of either breaker which is itself not released by the overload current. Preferably the manual operating handles of the two breakers are also coupled together and the operating mechanisms are of the trip-free type. By this arrangement the manual handle of either breaker which is separately tripped by o-vercurrent is held by the other breaker in its on position until the second breaker is tripped by the interlock bar. Such handle interconnection ensures reliable operation of the trip interlock even with breaker mechanisms of the automatic reset type.

Further objects and advantages of my invention will be apparent to those skilled in the art from the following detailed specification taken in conjunction with the ac companying drawings in which:

FIG. 1 is a side elevational view of a pair of single pole electric circuit breakers embodying my invention, the breakers being shown in their open circuit position I with a side of the casing removed;

FlG. '2 is a side elevational view similar to FIG. 1 showing the same circuit breakers in their circuit closing positions;

FIG. 3 is a side elevational view similar to FIGS. 1

' and 2 showing the same circuit breakers in their automatically tripped positions but with the manual handles held against movement, i.e. the trip free position; and

FIG. 4 is a fragmentary transverse cross sectional view of one of the circuit breaker mechanism taken along the 1 line 44 of FIG. 2.

described and claimed in a co-pending patent application SN. 248,293 filed on January 2, 1963, by Klein and Powell and assigned to the same assignee as the instant application.

As illustrated in the drawings, my multipole circuit breaker consists of two individual single pole circuit breaker mechanisms mounted in end-t'o-end relation in a single narrow and elongated casing 10. In the drawing one side of the casing has been removed to expose the operating mechanism. In the lower central portion of the casing it) there are located a pair of line terminal clips 11 and 11a adapted to be disposed in clamping reiation on a pair of side-by-side flat busbars B. Through a pivoted contact arm 12 of one circuit breaker 13 the line terminal clip 11 is connected to a first load terminal 14 disposed at one end of the casing 1UP and serving as a fixed switch contact member. Similarly the line terminal clip 11a, serving in this case as the fixed contact member of the other circuit breaker 13a, is connected through a pivoted contact arm 12a of that circuit breaker to a second load terminal member 14a at the opposite end of the casing It). The contact arms 12 and 12a are each biased to open circuit position by separate springs 4-0 and actuated to closed position by individual manually operable, current responsively tripped mechanisms of identical structure to like parts of which the same reference numerals will be applied.

Each operating mechanism for manually and automatically moving the separate circuit breaker contact arms 12 and 12:: between their open circuit and closed circuit positions comprises a releasable tripping member 15, shown as a fiat plate of insulating material loosely pivotally mounted upon a pivot pin 16 and having at its edge adjacent the contact arm 12 a cam surface 1'7. The cam surface 17 is formed in two parts providing therebetween an apex point 17a with which a cam follower cooperates with an overcenter locking action to be more fully described hereinafter. The releasable tripping member is normally restrained against tripping movement by means of a thermostatic latch member 18 which is preferably of the type described and claimed in the foregoing application S.N. 248,293.

The lateral edge of the contact arm 12 adjacent the normally fixed cam surface 17 constitutes a cooperating cam surface 19 of essentially linear configuration and is disposed to converge toward the sam surface 17 in the open circuit position of the parts as illustrated at FIG. 1. For manual closing and opening operation there is provided a movable wedging roller 20 rotatably mounted upon a pivot pin 21 at the free end of a swinging link 22. The link 22 is pivotally mounted eccentrically upon a rotary handle member 23 carried by the fixed pivot 16. The handle member 23 is provided with a radial arm 24 which extends through the upper end wall of the easing 10 to serve as a handle lever. The link 22 is swingably mounted upon an internal arm of the handle 23 by means of a pin 25. The upper portion of the handle member 23 is provided with an arcuate rim 26, one end of which serves as an abutment or shoulder to engage the releasable tripping member 15 when released and return it to latched position. The two manual handles 24 are coupled together by a link 27 which is partially enclosed by an upper shroud portion We of the switch housing. Both handles are biased to off or circuit opening position by a spring 28 interposed between a housing abutment 10b and a shoulder 27a on the link 27. As described in the foregoing application S.N. 242,424, this operating mechanism is both trip free and automatically resetting.

As previously stated, each of the individual circuit breaker mechanisms mounted in the single casing 10 includes a releasable trip member 15 is pivotally mounted upon the pivot 16 and normally restrained against tripping movement by a current responsive latching member 18. In order to couple the tripping members for simultaneous operation in the event of overload release of only one of the trip member 15, I provide an elongated interlock bar 30 mounted for rectilinear sliding movement in the casing 10 and having abutment portions 31, 31a disposed adjacent the two thermal latches 18 to engage and move these latches to releasing position. The interlock bar is slidably mounted upon a fixed pin 30:: and engages at its upper edge the spaced apart pivot pins 16. Adjacent the circuit breaker 13a the interlock bar 3% is apertured at 32 and the cam roller pin 21 of the breaker 13a passes through the aperture. One edge surface 32a of aperture 32 is positioned to be engaged by the pin 21 in its tripping movement when the associated trip member 15 is released by the thermal latch 18. A similar edge surface 32b of rod 30 is positioned in like manner with respect to the roller 20 of circuit breaker 13. Either pin 21 when released in trip opera tion to strike the surface 3211 or 32b (directly or through the roller 20 as the case may be) acts to drive the rod 34} to latch-releasing position (to the right as shown in the drawing). The rod 30 is freely mounted, i.e. unbiased as to position, and is moved back to a normal position of non-interference with the latches by action of the roller pin 21 (on the breaker 13a) in resetting to its off or open position. In such resetting action the pin 21 engages the edge surface 33 of aperture 32.

While it will be evident to those skilled in the art that any desired type of current responsive latch member may be utilized to restrain tripping movement of the trip members 1d, I have shown a thermally responsive latch member in the form of a generally U-shaped bimetallic strip loosely pivotally mounted at its bight and biased to latching position by means of a spring 35. As more fully described in the foregoing patent application SN. 248,293, the U-shaped bimetallic latch member 18 is arranged when heated by a predetermined excessive current to increase appreciably the divergence of its two legs and remove its latching leg from engagement with the trip member 15. This is accomplished by the free leg of the bimetal first engaging an abutment portion 36 of the trip member 15 whereupon it acts as a prop so that further thermal divergence causes unlatching movement of the latching leg. Each bimetallic latch member 18 is rendered current responsive by passing therethrough the current traversing the associated contact arm 12 or 12a. For this purpose one leg of each bimetallic latch 18 is connected by means of a flexible connector 37 to the associated contact arm 12 or 12a and the other leg of each bimetal is connected through a flexible connector 38 to the other terminal of its associated circuit breaker.

At FIG. 4 I have shown a cross sectional view of one of the circuit breakers of FIGS. 1, 2 and 3 to illustrate that, if desired, the principal operating parts may be made in dual or divided form with the interlock bar 35 centrally located in the casing. As shown in that view, each trip member 15 is comprised of two identical plates one on each side of the bar 30. Outside the two plates 15 and also mounted on the handle pivot 16 is the divided or two-part handle member 23, the paired parts being connected by a pin 42:: through the side-by-side handle levers 24. The roller pin 21 is carried by a pair of spaced parallel links 22, and the contact arm 12 is also made up of a pair of spaced apart and connected metal arms.

It will now be evident that in manual operation when the connected handle levers 24 are moved from the position of FIG. 1 to the position of FIG. 2, the swingab le actuating links 22 are moved downwardly and the wedging rollers 20 forced between the cam surfaces 17 and 19, respectively, of the releasable tripping members 15 and the respective movable contact arms 12 and 12a. The rollers 20 move overcenter on the apex points 17a of the normally fixed cam surfaces 17 and lock the movable contact arms 12 and 12a in closed circuit position against the bias of the contact springs 40, as shown at FIG. 2. In this position the force of each spring 40 upon the associated contact arms 12 (or 12a) is transmitted through the wedging roller or cam follower 20 to the releasable tripping member 15 by pressure against the normally fixed cam surface 17. This pressure from the contact bias spring serves, in the circuit closing position of the mechanism, to bias the releasable tripping member 15 for counterclockwise movement (as shown in the drawings) to a released or tripping position. Normally the releasable trip members 15 are restrained against such tripping movement by the current responsive latch members 18 so that in manual opening or closing operation the trip member 15 is stationary. It will be evident that manual circuit opening movement for each of the breakers is the reverse of that described above for closing in that clockwise movement of the handle levers 24 raises the swingable links 22 and removes the rollers 20 from locked wedging position between the fixed cam surfaces 17 and the contact arm surfaces 19.

Assuming now that both of the circuit breakers 13 and 13a are in their circuit closing positions as shown at FIG. 2 and are being held manually in that position, the operation upon overload release will be as follows. First let it be further supposed that only one pole of the dual circuit breaker mechanism is affected by excessive overload current and that only one of the bimetallic latch members 18 moves to unlatching position by the thermal action previously described. When that thermal latch is released, for example in the circuit breaker 13, the associated trip member 15 moves (counterclockwise as shown in the drawing) about its pivot 16 under the influence of the contact spring 40 acting through the contact arm 12 and the wedging roller 20. Such movement permits the contact arm 12 to move to open circuit position and releases the swingable link 22 and roller 2t) for upward movement out of wedging position under the influence of the handle spring 28. The handles 24 however are momentarily held in on position by the unreleased circuit breaker mechanism 13a even if not manually held on as has been assumed. The release link 22 of circuit breaker 13 is therefore contained to swing counter-clockwise about its pivot 25 (i.e. to trip free position, as shown at FIG. 3), so that its roller pin 21 engages the edge surface 32b of rod and drives that rod to the right. In moving to the right the rod 30 (at its abutment 31a) engages the thermal latch 18 of circuit breaker 13a and releases the trip member 15 of that breaker. When the second trip member 15 moves to trip-free position as shown at FIG. 3, both circuit breakers are open. If the handles 24 (assumed held on) are now released their annular rims 26 engage the upper edges of the trip members 15 and return these members 15 to their normal latched positions awaiting return of the latch members 18.

In resetting automatically to off position under the influence of handle spring 28 the link 22 of circuit breaker 13a is raised and moved in a clockwise direction from the position of FIG. 3 to that of FIG. l. In this movement the roller pin 21 of that breaker engages the edge 33 of aperture 32 in the rod 30 and moves the rod 30 to the left to a position (FIGS. 1 and 2) of non-interference with the latches 18.

It will noW be evident to those skilled in the art that in the event overload current simultaneously affects both of the thermal latch members 18 but does so in different degree, due either to different current values or slightly unequal overload settings, the first circuit breaker mechanism to trip will actuate the interlock bar 30 to mechanically force simultaneous tripping of the other breaker.

While I have illustrated the individual circuit breaker mechanisms within the common casing 10 as having coupled manual operating handles 24 (as shown at FIGS. 1, 2 and 3), it will of course be understood by those skilled in the art that these handles may be independently operable if desired. If the handles are independent, a thermally released trip member 15 does not ordinarily move fully to its trip-free position before it is engaged and reset by the handle rim 26. The member 15 moves only enough to release the roller 20, so that counterclockwise swinging movement of the link 22 will be quite limited. Very close tolerance is then required to obtain adequate movement of rod 30.

It will also be understood by those skilled in the art that while my invention has particular application to released wedge circuit breaker mechanisms disposed in endto-end tandem relation, the particular type of operating mechanism is not significant except insofar as it must include some manually operable part movable in automatic tripping operation through a path not transversed in manual operation. If an automatic reset mechanism is used, it is desirable to have it also trip-free in operation and to couple the manual handles together to ensure reliable operation of the trip interlock.

While I have illustrated only a preferred embodiment of my invention by way of illustration, many modifications will occur to those skilled in the art, and I therefore wish to have it understood that I intend in the appended claims to cover all such modifications as fall Within the true spirit and scope of my invention.

I claim:

1. A pair of electric circuit breakers each including a pair of separable contacts and an individual actuating mechanism therefore having a manually operable handle biased to open circuit position, means mounting said actuating mechanisms in end-to-end substantially coplanar relation, each said mechanism including a wedging member movable through a predetermined path in manual operation and a releasable trip member restraining said wedging member against lateral movement, individual latch means each responsive to excessive current through its associated separable contacts to release the respective wedge member for lateral contact opening movement, a rectilinearly slidable interlocking member having means engageable by each said wedging means in lateral movement and movable thereby to a latch-disengaging position, said interlocking member having portions disposed to engage and move each said latch means to releasing position, whereby current responsive release of either said wedging member effects movement of said interlocking member to release the other said wedging member thereby to open both said circuit breakers substantially simultaneously.

2. A pair of electric circuit breakers each including a pair of separable contacts and a pivotally mounted movable contact arm biased to open circuit position, individual circuit breaker actuating mechanisms each including a manually operable wedging member and a releasable trip member, said trip members restraining said wedging members respectively against lateral movement, separate latch means responsive respectively to excessive current through the associated contact-s to release said trip members, common handle means biased to contact opening position and connected to actuate said wedging members, said handle means biasing said trip member-s when released to latching position, and a rectilinearly slidable interlocking member having means engageable by each said wedging member upon lateral movement thereof to move said interlocking member to a latch-disengaging position, said interlocking member having portions disposed to engage and move each said latch means to releasing position, whereby current responsive unlatching of either said trip member effects movement of said interlocking member to unlatch the other said trip member thereby to open both said circuit breakers substantially simultaneously.

3. A multipole circuit breaker comprising a thin elongated flat casing, a pair of individual circuit breaker mechanisms mounted within said casing in end-to-end substantially co-planar relation and each comprising a pair of separable contacts including a flat blade-like movable contact arm biased to open circuit position, each said circuit breaker mechanism including also a m'ovably mounted fiat trip member having an aperture therein and a cam surface on one edge thereof, manually operable wedge means movable between said contact arm and said cam surface for manually opening and closing said contacts, said manually operable means including common handle means biased to off position and arranged to engage and automatically return said trip members to latching position, separate latch means restraining said trip members against circuit-opening movement and responsive respectively to excessive current through the associated Contact to release said trip members, said trip members when released laterally relieving said wedge means, and a flat elongated interlocking bar mounted for rectilinear slid- &

ing'movement within said casing and including means disposed for driving engagement by either of sai d wedge means when laterallyrelieved, said interlocking barhaving portions disposed to engageand mechanically release each said latch means.

References Cited by the Examiner UNITED STATES PATENTS BERNARD A. 'GILHEAN Y, Primary Examiner.

Claims (1)

1. A PAIR OF ELECTRIC CIRCUIT BREAKERS EACH INCLUDING A PAIR OF SEPARABLE CONTACTS AND AN INDIVIDUAL ACTUATING MECHANISM THEREFORE HAVING A MANUALLY OPERABLE HANDLE BIASED TO OPEN CIRCUIT POSITION, MEANS MOUNTING SAID ACTUATING MECHANISMS IN END-TO-END SUBSTANTIALLY COPLANAR RELATION, EACH SAID MECHANISM INCLUDING A WEDGING MEMBER MOVABLE THROUGH A PREDETERMINED PATH IN MANUAL OPERATION AND A RELEASABLE TRIP MEMBER RESTRAINING SAID WEDGING MEMBER AGAINST LATERAL MOVEMENT, INDIVIDUAL LATCH MEANS EACH RESPONSIVE TO EXCESSIVE CURRENT THROUGH ITS ASSOCIATED SEPARABLE CONTACTS TO RELEASE THE RESPECTIVE WEDGE MEMBER FOR LATERAL CONTACT OPENING MOVEMENT, A RECTILINEARLY SLIDABLE INTERLOCKING MEMBER HAVING MEANS ENGAGEABLE BY EACH SAID WEDGING MEANS IN LATERAL MOVEMENT AND MOVABLE THEREBY TO A LATCH-DISENGAGING POSITION, SAID INTERLOCKING MEMER HAVING PORTIONS DISPOSED TO ENGAGE AND MOVE EACH SAID LATCH MEANS TO RELEASING POSITION, WHEREBY CURRENT RESPONSIVE RELEASE OF EITHER SAID WEDGING MEMBER EFFECTS MOVEMENT OF SAID INTERLOCKING MEMBER TO RELEASE THE OTHER SAID WEDGING MEMBER THEREBY TO OPEN BOTH SAID CIRCUIT BREAKERS SUBSTANTIALLY SIMULTANEOUSLY.

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