US3466578A - Circuit breaker contact separation initiator - Google Patents

Description

. P 9, 1969 J. c. BRUMFIELD 3,466,578

CIRCUIT BREAKER CONTACT SEPARATION INITIATOR Filed June 26, 1967 3 Sheets-Sheet 1 v 1 IN VEN TOR. JON/V C BRO/141 7620 M MM Se t. 9, 1969 J. c. BRUMFIELD 3,465,573

CIRCUIT BREAKER CONTACT SEPARATION INITIATOR 3 Sheets-Sheet 2 Filed June 26, 1967 m. Rm 3 M f h C x m J W m n uk m Sept; 9, 1969 J. c. BRUMFIELD 3,466,578

CIRCUIT BREAKER CONTACT SEPARATION INITIATOR United States Patent M 3,466,578 CIRCUIT BREAKER CONTACT SEPARATION INITIATOR John C. Brumfield, Philadelphia, Pa., assignor, by mesne assignments, to I-T-E Imperial Corporation, Philadelphia, Pa., a corporation of Delaware Filed June 26, 1967, Ser. No. 648,557 Int. Cl. H01h 71/16, 9/20 US. Cl. 335-172 6 Claims ABSTRACT OF THE DISCLOSURE This invention relates to an electric circuit breaker contact separation initiator and more particularly to a structure secured to the tripper of the circuit breaker which engages the movable contact or its support arm to initiate separation of the movable contact from the stationary contact.

In recent years considerable effort has been expended in the electrical industry to reduce the size of circuit protective equipment. For example, in the area of small air circuit breakers of the type with which the instant invention is intended to cooperate, the industry has seen acceptance of one-half inch wide circuit breakers as a substitute for the long accepted one inch wide breaker. Further evidence of the present emphasis on reduction in size and simplicity in design is evidenced by United States patent application Ser. No. 587,709 filed Oct. 19, 1966, now Patent No. 3,377,574, entitled Circuit Breaker Resetting and Closing Mechanism, and assigned to the assignee of the instant invention, where there has been described in great detail a novel circuit breaker which has achieved utmost simplicity in design and maximum reduction in overall size.

Simultaneously with the development of smaller and more simplified circuit breakers, and related thereto, engineers have re-examined the operating characteristics of small circuit breakers and looked for ways in which their operation might be simplified.

Circuit breakers with which the present invention are employed have a stationary contact and a movable contact, which is normally in engagement with the stationary contact and which is supported by an arm. The circuit breaker has a tripper, comprising a cradle, which is pivotably mounted at one end thereof, and at the other end thereof it is supported by a latch. The cradle is normally biased to pivot in a manner to trip apart the circuit breaker contacts. The latch supports the cradle against the force exerted upon the cradle by biasing means.

Circuit breakers of the prior art make use of a toggle consisting of the circuit breaker operating handle, the movable contact of the breaker or the contact support arm, and a pivot point between these two elements. An over-center spring is provided for causing the toggle to collapse either in a direction which secures the movable contact against a stationary contact or in the opposite direction which snaps the movable contact away from the stationary one. No separate contact separation initia- 3,466,578 Patented Sept. 9, 1969 tor is provided other than the toggle and overcenter spring themselves.

In small circuit breakers, it is necessary to have all movement of the components take place within a rather confined space. To minimize the movement necessary to initiate separation of the contacts, the present invention provides a contact separation initiator which initiates contact separation before the normal action of the toggle and over-center spring would initiate separation.

The cradle portion of the tripper has thereto connected the contact separation initiator of the present invention. The initiator is so positioned on the cradle, that once the latch releases the cradle and the cradle begins to pivot, the initiator engages the movable contact support arm and moves the movable contact away from the stationary contact thereby initiating contact separation.

In the prior art, initiators are known which are pivotally connected to the cradle. However, such initiators are complicated structures, require molding of circuit breaker casings to close tolerances and take up extra space in crowded casings. See US. Patent No. 2,996,589, entitled Pivoted Birnetal, issued to Felix Myers, and assigned to the assignee of the present invention.

In the embodiment shown in detail herein, the initiator is comprised of a projection fixedly attached to the cradle. The initiator is positioned to strike the movable contact support arm after the cradle has begun to pivot once it is released by the latch. The initiator need not be fixedly connected to the cradle so long as it is so connected with the cradle that it is brought into engagement with the support arm of the movable contact once the cradle has begun to pivot upon its being released by the latch.

The present invention is being illustrated in detail in conjunction with a circuit breaker shown in aforementioned application Ser. No. 587,709, new Patent No. 3,377,574, in which embodiment the movable contact support arm pivots on a pivot point on the cradle and the over-center spring is connected between the movable contact support arm and the operating handle of the circuit breaker. The present invention may be employed in conjunction with any other type of circuit breaker employing a tripper, supported by a latch type device, which tripper pivots when the latch type device releases its support of the tripper. For instance, the present invention might be mounted on the cradle of a circuit breaker shown in US. Patent No. 2,996,589 issued on Aug. 15, 1961, to Felix Myers, entitled Pivoted Bimetal and assigned to the assignee of the instant invention. This latter patent illustrates a circuit breaker wherein the movable contact support arm pivots not on the cradle but on the operating handle and the overcenter spring is connected between the movable contact support arm and the cradle, rather than between the movable contact support arm and the operating han le.

It is an object of the present invention to provide a circuit breaker contact separation initiator which initiates the separation of the contacts after minimum movement of the circuit breaker tripper.

It is another object of the invention to provide a circuit breaker contact separation initiator adaptable for use in a circuit breaker having limited interior space.

It is another object of the present invention to provide a circuit breaker contact separation initiator for use in conjunction with .a circuit breaker employing a pivotable tripper.

Other objects and a fuller understanding of the instant invention may be had by referring to the following description and drawings, in which:

FIGURE 1 is an exploded perspective View of the internal components of a circuit breaker constructed in accordance with the teachings of the instant invention,

and including the circuit breaker contact separation initiator of the instant invention;

FIGURE 2 is a plan view, with the cover removed, of the circuit breaker of FIGURE 1, with the circuit breaker mechanism thereof in the closed or on position;

FIGURE 3 is a plan view of the circuit breaker of FIGURE 2 showing the components thereof shortly after the tripping mechanism has tripped the circuit breaker; and

FIGURE 4 is a plan view of the circuit breaker of FIGURE 2 in the fully tripped position.

Referring to FIGURE 1, there is shown the internal mechanism of a circuit breaker constructed in accordance with the principles of the instant invention. It is reemphasized that although the circuit breaker contact opening initiator 43 of the instant invention will be specifically described with respect to the internal mechanism 10 shown in aforementioned application Ser. No. 587,709, now patent No. 3,377,574, such disclosure is intended in no way to limit the application of the instant invention.

Similarly, it is to be understood that although the instant invention will be described with respect to a circuit breaker for the protection of a single phase of current, the instant invention can be readily employed in a multiphase circuit breaker -by positioning an initiator on the tripper in every phase of a multi-phase circut breaker.

* The circuit breaker mechanism 10 includes the common mounting plate 11, which is integrally provided with the following parts: an upstanding cradle-pivoting tab 12; an upstanding relatch mechanism pivoting tab 13; an upstanding tripper mechanism pivoting tab 14 and an upstanding spring retaining tab 15. In addition the plate 11 includes an elongated slot 16; a generally centrally located operating handle pivoting aperture 17; and an arcuate slot 18 which receives an upstanding tab portion 23 of the operating handle 20, as hereinafter described.

The operating handle '20 of the circuit breaker includes an upstanding knob receiving tab 21 at one end thereof, and a pair of upstanding tabs 22 and 23 at the opposite end thereof. Tab 22 is provided with an open-ended slot 24 which fits over a pivot portion 25 of the mounting plate aperture 17 whereby the operating handle 20 may experience rotation in a plane parallel to the plane of the mounting plate 11 about the point 25. The second tab 23 of the operating handle 20 is freely received within the arcuate slot 18 and extends forward of the mounting plate 11 when the operating handle 20 is placed behind the mounting plate 11, with the open-ended slot 24 riding on the point 25.

Biasing means in the form of spring 27 is secured at one end thereof to the tab 23 and at the opposite end thereof to the upstanding spring-retaining tab so as to constantly bias the operating handle in a counterclockwise direction in FIGURE 1 about the pivot defined by the point 25.

A cradle 30 is provided and includes a bifurcated end 31, the two arms 32 of which include aligned apertures 33 which receive the cradle pivoting tab 12 of the mounting plate 11. The opposite end of the cradle 30 includes an upstanding latch tip 34 which cooperates with the latch 59 of the tripping mechanism 55, as will be described in further detail. Intermediate the ends of the cradle 30 is an overturned tab 35 which cooperates with an open-ended slot 41 provided at one end of a movable contact support arm to permit rotation of the movable contact arm 40 about point 37 on the cradle 30 when the movable contact arm 40 is inserted up and under the over-turned tab 35.

Cradle 30 has attached to it the circuit breaker contact separation initiator 43, shown clearly in FIGURE 1. The initiator 43 shown in FIGURE 1 is comprised of a projection extending outward from the side of the cradle 30. The cradle 30, as has been noted above, is pivotally mounted at its end 31 on pivot projection 12, whereby the cradle 30 is enabled to pivot in a manner more fully described below.

While the initiator 43 is shown as being fixedly mounted on the cradle 30, it may be otherwise connected with the cradle 30, so long as it is adapted to move into engagement with the support arm 40 of the movable contact, once the cradle 30 begins to pivot, as described below.

Since the present invention may be employed in a circuit breaker where the movable contact support arm and the tripper for the contact are not in close proximity, the initiator 43 merely must comprise a structure so connected with the tripper as to be able to engage the movable contact support arm when the tripper has begun to operate. The operation of the initiator 43 will be described below in conjunction with the description of the trip operation of the circuit breaker.

In the specific embodiment illustrated in the figures, the

movable contact arm 40 is mounted directly to the cradle 30 and is adjacent to the side of the cradle upon which projection 43 is positioned.

The end of the movable contact arm 40 opposite notch 41 integrally carries a generally S-shaped spring-retaining portion 45 and also carries a generally L-shaped portion 46 which carries the movable contact pad 47 thereon. Disposed opposite the movable contact pad 47 is a stationary contact pad 48 secured to the terminal 49 of the breaker. The contact pads 47 and 48 comprise the cooperating contacts in the breaker.

A main operating spring 50 is secured at one end thereof to the spring-retaining portion 45 and at the opposite end thereof to a spring-retaining portion 51 which is an integral portion of the upstanding knob-retaining portion 21 of the operating handle 20.

The tripping mechanism generally designated at 55 includes a bimetallic element 56 for responding to moderate or time delay overloads; and includes a magnetizeablev element 57 and a fixedly mounted armature 58 adjacent to element 57 for attracting element 57 when it is magnetized by a high fault current.

Tripping mechanism 55 has an aperture 58a ihrough which is passed mounting plate tab 14 about which tab tripping mechanism 55 is enabled to pivot.

Latch 59 is connected with both of elements 56 and 57 and is removed from its supportive position with respect to latch tip 34 of cradle 30 whenever either of elements 56 and 57 is activated. The tripping mechanism is explained in greater detail in copending patent application Ser. No. 692,561 filed Dec. 21, 1967, in the name of F. Meyers and W. Goodnow, entitled Circuit Breaker Thermal and Magnetic Tripping Mechanism, which is assigned to the assignee of the instant invention.

An automatic relatching means may be employed in conjunction with the circuit breaker mechanism 10. The automatic relatching means 60 is more fully described in aforementioned copending patent application Ser. No. 587,709, now Patent No. 3,377,574, and includes first and second members 61 and 62 respectively, which are joined as by a pin 63 for rotation relative to one another. The first member 61 includes a centrally located aperture 64 which is received and carried by the upstanding pivot tab 13 on mounting plate 11 to permit rotation of the linkage assembly relative to the plate 11. The second member 62 terminates in an upstanding actuating surface 65 which itself terminates in a rearwardly disposed portion 66 which lies in a plane behind the planar surface of the second member 62 so that it may ride behind the mounting plate 11 with the upstanding actuating surface 65 projecting through the elongated slot 16 and beyond the front surface of the plate 11.

Current flow through the circuit breaker is through the path defined by terminal 49, stationary contact pad 48, movable contact pad 47, conductive braid 70, bimetallic element 56, conductive braid 71 and terminal 72. When the circuit breaker is tripped, the current path is broken at the point of contact between terminals 47 and 48.

The circuit breaker components shown in exploded perspective in FIGURE 1 are shown assembled in a circuit breaker casing 80 in FIGURE 2. The casing normally includes a cover, not shown, which when removed reveals the mechanism within the casing.

The operation of the circuit breaker, and especially the role of the circuit breaker contact separation initiator in the present invention, will now be described. In FIG- URE 2, the circuit breaker is in the on or closed position, i.e., the contact pads 47 and 48 complete the current path through the breaker. The latch 59 of tripping mechanism 55 is in abutting, blocking engagement with respect to latch tip 34 of cradle 30.

Operating spring 50 draws spring retaining portion 45 of movable contact arm 40 toward spring retaining tab 51 on operating handle 20. A toggle comprising spring retaining portions 45 and 51 and pivot point 37 is formed. The spring 50, pulling on spring retaining portion 45, attempts to cause the aforementioned toggle to collapse to the right, as viewed in FIGURE 2, pulls the movable contact support arm counterclockwise, and presses movable contact pad 47 into secure engagement with stationary contact pad 48. Because the toggle is unable to collapse to the right, the movable contact support arm 40 pushes on pivot point 37 in such manner that cradle 30 would be pivoted clockwise about its pivot 12, were it not for the fact that latch 59, in engagement with latch tip 34 of cradle 30, supports cradle 30 stationary and prevents its pivoting around pivot 12.

Starting with the circuit breaker in its closed condition of FIGURE 2, and turning now to FIGURE 3, it will be assumed that a time delay or instantaneous fault current has been detected by tripping mechanism 55, which rotates latch 59 clockwise, as viewed in FIGURE ,3, from its blocking position with respect to latch tip 34 of cradle 30.

FIGURE 3 illustrates the situation immediately after latch 59 has released latch tip 34. Movable contact support arm 40 is still substantially in the position shown in FIGURE 2. The pull exerted by spring 50 on spring retaining portion 45 pulls portion 45 toward spring retainer 51. This exerts a pull on pivot point 37 of cradle 30, thus causing the cradle, which is no longer restrained by the latch, to begin to rotate clockwise. The toggle formed of spring retainers 45 and 51 and of pivot point 37 begins to collapse to the right, as viewed in FIGURE 3, whereby the movable contact 47 wipes over the surface of stationary contact pad 48, while the force of spring 50- retains these contacts in secure engagement.

In FIGURE 2, with the breaker in the closed condition, note that contact separation initiator or projection 43 is spaced slightly away from movable contact support arm 40. Turning to FIGURE 3, as cradle 30 begins to rotate clockwise, pivot point 37, moves upward, and because the toggle comprised of retaining portions 45 and 51 and pivot point 37 is collapsing, movable contact support arm 40 experiences slight rotation counterclockwise, as viewed in FIGURE 3, about pivot 37. At the same time, cradle 30 is pivoting clockwise about its pivot 12 and the pivoting of cradle 30 and of contact arm 40 soon brings projection 43 into abutting engagement with contact support arm 40. By the time projection 43 first engages contact arm 40, cradle 30 and support arm 40 are both pivoting rapidly, respectively, clockwise and counterclockwise. Projection 43 strikes support arm 40 with an impact suflicient to separate movable contact pad 47 from stationary contact pad 48 and sufficient also to drive movable contact support arm 40 over-center past pivot point 37.

The initial impact provided by projection 43 against contact support arm 40 is suflicient to drive support arm 40 over-center. Therefore, support arm 40 and projection 43 are only instantaneously in engagement. Spring 50 must be sufliciently weak that it will not prevent movable contact support arm 40 from pivoting over-center past pivot 37.

As cradle 30 is rotating, when point 37 passes to the right, as viewed in FIGURE 4, of the force line of spring 50, the toggle formed by spring retainer 51, point 37 and portion 45 collapses to the left. Once spring 50 has passed beyond, or to the left as viewed in FIGURE 4, of the tab 22 of operating handle 20, the handle 20 rotates counterclockwise from its position of FIGURE 3. At this stage, spring 50, although not necessarily completely relaxed, is not sufficiently tensed to rotate handle 20 counterclockwise all the way to its position of FIG- URE 4.

Spring 27, attached to tab 23 of handle 20, is provided to pull operating handle 20 further counterclockwise, thereby moving handle 20 all the way to the tripped position of FIGURE 4.

As can be seen in FIGURE 4, cradle 30 rotates clockwise until it abuts relatch actuating surface 65. Movable contact support arm 40 rotates clockwise until its portion 45 abuts upturned tab 81, wihch prevents further opening of contact 47.

The apparatus for relatching the circuit breaker is not part of the present invention and is fully described in aforementioned copending application Ser. No. 587,709, now Patent No. 3,377,574. Briefly, to relatch the circuit breaker for another trip operation, handle 21 is rotated from its position of FIGURE 4 clockwise to its position of FIGURE 2. A projection 82 on handle 20 strikes actuating surface 83 of relatch mechanism 61 and causes the mechanism to pivot clockwise about its pivot tab 13. The pivoting element 61 draws link 62 to the left, as viewed in FIGURES 2 and 4, and pulls actuating surface 65 against cradle 30. As surface 65 moves to the left, as viewed in FIGURE 2, cradle 30 is pivoted counterclockwise about its pivot 12 to the position of FIGURE 2, where the latch tip 34 again engages the latch 59.

When the operating handle 21 passes over pivot point 37, operating spring 50 snaps movable contact arm 40 counterclockwise, as viewed in FIGURE 2, and movable contact 47 is snapped into engagement with stationary contact 48, thereby placing the circuit breaker of FIG- URE 2 in the closed or on position.

There has just been described a circuit breaker having a contact separation initiator which is connected with the tripper of the circuit breaker, in order to initiate the separation of the movable contact of the breaker from the stationary contact upon, the occurrence of a fault current.

Although this invention has been described with respect to its preferred embodiments, it should be understood that many variations and modifications will now be obvious to those skilled in the art, and it is preferred, therefore, that the scope of the invention 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. In a circuit breaker comprising,

a cooperating contact assembly comprising a movable contact assembly and a stationary contact;

a tripper connected with said movable contact assembly; said tripper being movable to a first position, wherein said movable contact assembly and said stationary contact are in engagement, and to a second position, wherein said movable contact assembly and said stationary contact have been tripped apart;

a means for supporting said tripper in the first position and a means for urging said tripper to the second position;

the improvement comprising, said tripper having thereto connected a circuit breaker contact separation initiating means; said movable contact assembly being operatively positioned, with respect to said tripper, and said initiating means being operatively positioned, with respect to said tripper, so that as said tripper moves from its first to its second position upon removal of the said supporting means for said tripper, said movable contact assembly is caused to travel in a direction toward said initiating means and said initiating means is caused to move toward said movable contact assembly so as to cause Said initiating means to engage said movable contact assembly and to initiate the separation of said movable contact assembly from said stationary contact;

said initiating means comprising a member fixedly mounted to said tripper.

2. In the circuit breaker of claim 1,

said tripper comprising a cradle; a first pivot for said cradle; said cradle being pivotably mounted on said first pivot for pivoting between its said first and second positions;

the improvement comprising, said initiator being fixedly mounted to said cradle.

3. In the circuit breaker of claim 1,

said movable contact assembly comprising a movable contact and a support arm for said movable contact;

the improvement comprising, said initiator being engageable with said support arm.

4. In the circuit breaker of claim 3,

' the improvement further comprising, said initiator contact and a support arm for said movable contact; with improvement comprising, said initiator being engageable with said support arm.

References Cited UNITED STATES PATENTS 1,610,213 12/1926 De Ville. 2,902,560 9/1959 Stanback. 3,171,921 3/1965 Woods. 2,934,624 4/ 1960 Middendorf.

BERNARD A. GILHEANY, Primary Examiner H. BROOME, Assistant Examiner U.S. Cl. X.R.

Images