US3333078A - Circuit breaker with plug-in type terminal structure - Google Patents

Description

July 25, 1967 F. L GELzHElsx-:R ETAL 3,333,078

CIRCUT BREAKER WITH PLUG-1N TYPE TERMINAL STRUCTURE Filed Oct. 13, 1965 oFF FIG. l

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. wlTNEssEs United States Patent Gffice 3,333,078 Patented July 25, 1967 3,333,078 CIRCUIT BREAKER WITH PLUG-IN TYPE TERMINAL STRUCTURE Francis L. Gelzheiser, Fairfield, and George F. Hawkes,

Jr., Trumbull, Conn., assignors to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Oct. 13, 1965, Ser. No. 495,480 Claims. (Cl. 20G- 166) This invention relates to ci-rcuit breakers of the type comprising a plug-in terminal structure, and more particularly to plug-in type terminal structures for use with molded-case type circuit breakers.

For certain panelboard or load-center installations circuit breakers are constructed with plug-in type line terminals that can be plugged onto bus-bar conducting stabs to electrically connect the circuit vbreakers with bus bars. These plug-in type terminals or sockets are generally resilient sheet-metal conductors that are mounted in the circuit breakers in such a way that the bus bar stabs will engage spaced flat side surfaces of the conductors to force the side surfaces apart flexing the generally resilient conductors .to provide contact pressure in the mounted position. It is sometimes desirable to use an additional spring -means to bias t-he at side surfaces against the conducting stab. It is considered that this type of terminal structure does not always provide the most efficient and effective means for effecting contact pressure.

Accordingly, an object of this invention is to provide a circuit breaker with an improved plug-in type terminal structure constructed to more efficiently provide contact pressure in the mounted position.

Another object of this invention is to provide a circuit breaker with an improved plug-in type sheet metal terminal structure constructed for end-type contact with a conducting stab.

Another object of this invention is to provide an improved double-type circuit breaker comprising two circuit-breaker mechanisms and an improved plug-in type terminal structure that .can be mounted onto a com-mon conducting stab to electrically connect the two mec-ha- `nisms to the conducting stab.

rBhe novel features that are considered characteristic of this invention are set forth in particular in the appended claims. The invention, both as to structure and operation, together with ladditional objects and advantages thereof, will be best understood from the following detailed description when read in conjunction with the accompanying drawings.

In said drawings:

FIGURE l is a side sectional view taken generally alon-g the line I-I of FIG. 2 with the plugin type ter-- minal structure Ibeing shown in side elevation;

FIG. 2 is an end View, on a smaller scale relative to FIG. 1, of the double-type circuit breaker of FIG. 1 and part of a bus-bar stab;

FIG. 3 is a top plan view of the plug-in type terminal structure of FIGS. l and 2;

FIG. 4 is a view taken along the line IV-IV of FIG. 3;

FIG. 5 is a view of the terminal structure of FIG. 4 taken along the line V-V of FIG. 4 with the bus-bar stab being shown in elevation; Iand FIG. 6 is a front elevational view, with parts broken away, of the plug-in type terminal structure of FIGS. 3-5 with an additional spring biasing member connected to the terminal structure.

The general operation and certain parts of the circuit breaker disclosed herein are described more specically in the patent to Earl Bullis, Jr. Patent No. 3,200,217, issued Aug. 10, 1965.

Referring to FIG. 2 of the drawings, a double-type circuit breaker 9 is shown therein comprising an insulating lhousing that is composed of two molded insulating parts, 11 land 13, forming two compartments. Each of the parts 11 and 13 comprises a back portion molded integral with four sides forming an open front. The open front of the part 11 is covered by the back portion of the part 13 which serves as an insulating barrier between the two compartments, and the open front of the part 13 is covered by a molded insulating cover 15. The three molded insulating portions 11, 13 and 15 of the housing are held rigidly together by three rivets 18 (FIG. l).

The housing parts 11, 13 and 15 form two insulating compartments housing two circuit breaker mechanisms which are identical in construction and operation, each of which mechanisms operates independently of the other. For this reason, only the mechanism enclosed by the housing part 11 will be specifically described, it being understood that, unless otherwise mentioned, the description applies to 'both of the mechanisms of the doubletype circuit breaker.

The circuit-breaker mechanism, which is enclosed by the housing part 11 and the back portion of the housing part 13, comprises a stationary contact 21, la movable contact 23, a supporting metal frame 25, an operatin-g mechanism 27 and a trip device 29.

The stationary contact 21 is welded, or otherwise rigidly secured, to la line terminal structure 31 that will be hereinafter more specifically described. A stationary contact 33 (FIG. 3) for the circuit breaker mechanism that is housed in the housing part 13 (FIG. 2) is also welded, or otherwise rigidly secured, to the line terminal structure 31.

The line terminal structure 31 is constructed to cooperate with a rigid load-center or panelboard conducting stab 35 in a manner to be hereinafter more specifically described.

Referring to FIG. 1, the stationary contact 21 cooperates With the movable contact 23 that is welded or otherwise rigidly secured to a generally C-shaped contact arm or switch arm 41. A bearing member 42 is provided with a slot that is complementary with a slot in the upper part of the contact arm 41, and the bearing is provided with two upper leg portions that iit into suitable slots in a molded insulating operating member 47. The bearing 42 transmits motion from the operating member 47 to the movable contact Iarm 41 when the breaker is manually operated, and, as will be hereinafter explained, from the movable contact arm 41 to the operating member 47 when the breaker is tripped automatically in response to an overload current condition.

The operating member 47 is a molded insulating member having an arcuate trunnion `51 molded at each side thereof. The trunnions 51 fit and rotatably ride on two arcuate surfaces 55 that are formed on the metallic supporting frame 25. The operating member 47 is supported between the surfaces 55 of the frame 25 and the bearing 42 which is supported by the contact arm 41. The operating member 47 has a handle part 59 molded integrally therewith, which handle part extends through an opening 61 in the insulating housing to permit manual operation of the circuit breaker. Arcuate surfaces on opposite sides of the handle 59 substantially close the opening 61 in all positions of the operating member 47.

The frame 25 supports an insulating pivot 65. A metallic trip member 79 is pivotally supported at one end 77 thereof on the pivot 65. The other end 82 of the trip member 79 is latched on a ledge in an opening in an armature 85. The armature 85 is part of the trip device 29 which will be hereinafter specifically described. The ends 77 and 82 of the trip member 79 are offset and dis- The movable contact arm 41 is connected by meansV of a liexible conductor 91 to the free end of a bimetal 93 that is attached at its other end to a load terminal conductor 95. A load terminal connecting screw 97, which is externally accessible, is provided at the outer end of the conductor 95 to enable connection of the circuit breaker in an electric circuit. The load terminal conductor 95 is welded or otherwise attached to a projection 99, extending out from the supporting frame 25. The terminal conductor 95 is given additional support by being looped over and welded to another projection 101 extending out from the supporting frame 25.

The closed electric circuit through the circuit-breaker mechanism extends from the line terminal structure 31 through the stationary and movable contacts 21, 23, the contact arm 41, the eXible conductor 91, the bimetal member 93, the load terminal conductor 95, to a conducting wire that would be electrically connected to the conductor 95 by means of the screw 97 when the circuit breaker is in operating position. Since the movable contact arm 41 extends downward from its pivot, the arc is established adjacent the bottom of the housing in an arc chute 105, one end of which is connected by a vent passage 107 to an opening in the end of `the housing beneath the load terminal screw 97.

The circuit breaker is manually operated to 'open and close the contacts 21, 23 -by operation of the insulating handle `59. Movement of the handle 59 clockwise from the full-line on position to the o position in which it is shown in dot-and-dash lines, carries the upper end of v the contact arm 41 to the left of the line of action of the 'spring 87 whereupon the spring acts to move the contact arm 41, with a snap action, to the open position shown partially in dot-and-dash lines. A projection 109, molded integral with the housing part 11, acts as a stop to limit opening movement of the contact arm 41. Movement of the operating handle 59 in a counterclockwise direction from the ott to the on position moves the upper end of the movable contact arm 41 to the right of the line of action of the spring 87 whereupon the spring operates to move the contact arm to the closed position seen in FIG. l.

The trip device 29 is provided to veiiect automatic opening of the circuit breaker upon the occurrence of overload current conditions. The trip device 29 comprises the magnetic armature 85, the bimetal 93, a U-shaped magnetic member 111 that is secured to the bimetal 93 with the free ends thereof facing in the direction of the magnetic armature 85 and a spring 113. The upper end of the bimetal 93 is welded or otherwise suitable secured to the Y terminal conductor 95 which is secured to the projection 99 on the metal frame 25. The flexible conductor 91 is welded or otherwise suitably secured to the lower or free end of the bimetal 93, and it (the conductor 91) electrically connects the bimetal 93 with the movable contact arm 41. The armature 85 is movably mounted on the bimetal 93 by means of the spring 113 that is secured at the lower end thereof to the bimetal 97 and at the upper 'end thereof to the armature 85.

Upon the occurrence of an overload current below a predetermined value, the bimetal element 93 is heated, and when it is heated a predetermined amount, it deilects, with a time delay, to the right as seen in FIG. l to eiect a thermal tripping operation. The armature 85, which is supported on the bimetal 93 by means of the spring 113,

is carried to the right with the bimetal to release the trip member 79. When the -trip member 79 is released, the spring 87 acts to rotate the trip member clockwise about the pivot 65 to'a tripped position. During this movement,

the line of action of the spring 87. moves to the right of lthe pivot 42 of the contact arm 41 whereupon the spring biases the contact arm inan opening direction and moves the contact arm so Vthat the line of action of the force exerted by the spring on the operating member 47 shifts across the pivot 51 whereupon the spring 87 actuates both the contact arm 41 and the operating member 47 to a tripped position. In order to provide a visual indication that the -breaker has been automatically tripped open, movement of the operating member 47 is stopped in an immediate position when a projection 117, molded integral with the operating member 47, strikes the projection 89 that exetends from the trip member 79. The circuit breaker is trip-free in that the breaker will trip upon the occurrence of an overload even if the handle 59 is held in the on or closed position.

Before the contacts can be closed following an automatic opening operation, it is necessary to reset and relatch the mechanism. This is accomplished by moving the operating handle 59 clockwise from the intermediate or tripped position to the full oli position. During this movement, due to the vengagement of the projection 117 of the operating member 47 with the projection 89 of the trip member 79, the trip member is moved counter clockwise about the pivot 65 until the latch end 82 is again supported in the latched position on the armature 86. Thereafter, the circuit breaker can again be manually operated in the same manner Ihereinbefore described.

The circuit breaker is magnetically tripped automatically and instantaneously in response to overload currents above the predetermined value. Upon the ow of current through the bimetal 93, a magnetic flux, which is induced around the bimetal, takes the path of least reluctance through the magnet 111, across an air gap and through the armature 85. When an overload current above the predetermined value occurs, the pull of the magnetic flux is of such strength that the armature is attracted to the magnet 111 whereupon the spring 113 lluxes permitting the armature to move,rre1 ative to the bimetal 93, to the right. This movement releases the trip member 79, and the contacts are opened in the same manner hereinbefore described with respect to the thermal tripping operation.

The line terminal 31 comprises a sheet-metal type generally resilient member of conducting material. The member 31 is a at member having oppositely disposed large- Vsurface-area at face surfaces and small-surface-area end surface means between the faces or face parts. 'Ihe member 31 is formed as a generally U-shaped member (FIG. 4) comprising opposite leg parts 121 and 123 connected by means of a bight part 125. The terminal member 31 is formed with a slot 127 (FIG. 5) therein, which slot extends Ythrough the lengthof the leg part 121 (FIG. 4), through the bight part125, and downward a little more than half of the length of the leg part 123 (FIG .6). A projection 128 is bent-over from the leg part 123 to form a stop to position the terminal 31 relative to the conducting stab 35.Y As was previously described, the two contacts 21 Yand 33 are Welded or otherwise suitably secured to one of the sides or faces of the leg Ypart 123 of the terminal 31. Each of the contacts 21 and 33 cooperates with a different one of the stationary contacts of the two circuit breaker mechanisms of the double-type circuit breakerVY 9. The terminal 31 is mounted in the circuit breaker housing 11, 13, 15 during assembly of the circuit breaker. During the assembly operation, the terminal 31 is moved into position when the compartment of the circuitbreaker part 11 is open. The member 31 fits over a projection 129 (FIG. l) that is molded as an integral part of the housing part 11, and the leg 123 of the member 31 fits in a slot in another projection 131 that is also molded as an integral part of the housing part 11. A third projection 133 that is molded as an integral part of the housing part 11 is provided to engage and position the short leg 121 of the terminal 31. When the terminal 31 is in the position seen in FIG. 1, the housing part 13 (FIG. 2) is moved into position and the cover 15 is then moved to cover the open housing part 13. Thereafter, the parts are secured together by means of the rivets 18 (FIG. l). The back wall of the housing part 13 has an opening in the lower back corner thereof to permit positioning of the terminal 31 in the breaker housing. As can be seen in FIG. 2, the back corner at the line terminal end of the circuit breaker housing 11, 13, is provided with a slot or opening 135 therein to receive the stab 35 when the circuit breaker is moved into the mounted position.

When it is desired to mount the circuit breaker in a panelboard or load-center, the circuit breaker is moved into position to connect the terminal 31 with the conducting stab 35. During this movement, a connecting part of the rigid at conducting stab 35 moves between two facing end parts 139 and 141 (FIG. 5) of the end surface means of the terminal 31. The dimension between the facing end parts 139 and 141 is less than the thickness of the conducting stab 35 so that as the terminal 31 is forced onto the stab 35 the facing end surfaces 139, 141 are biased apart spring charging the generally `resilient terminal member 31 to provide contact pressure between the facing end surfaces 139, 141, and the opposite sides of the stab 35. The member 31 is generally rigid with regard to forces applied in an endwise direction. Thus, it can be understood that as the member 31 is forced onto the stab 35 the member 31 exes with a torsion or twisting action to provide a torsion-type or twisting-type spring bias of the facing end surfaces 139, 141 against the conducting stab 35. This torsion action serves to provide effective contact pressure between the facing end surfaces 139, 141 and the conducting stab 35. As can be seen in FIG. 4, when the terminal 31 is moved into position on the stab 35 the projection or stop portion 128 on the member 31 serves to position the member 31 relative to the stab 35.

If it is desired to further increase the contact pressure between the facing end surfaces 139, 141 and the conducting stab 35 an additional spring member 145 (FIG. 6) can be mounted on the terminal 31 to provide an additional force biasing the facing end surfaces 139, 141 against the stab 35. As can be seen in FIG. 6, the spring 145 is a generally U-shaped member with the end parts thereof mounted in suitable openings in the bight part 125 of the terminal 31.

It is to be noted that the terminal member 31 is supported in the housing 11, 13 and 15; but that the terminal does not cooperate with the insulating housing in order to provide the biasing force for effecting contact pressure between the facing end surfaces 139, 141 and the stab 35 as would be the case, for example, if a spring member were positioned against part of the housing and the member 31 in order to provide contact pressure. Thus, if the insulating housing is distorted or relieved to some extent because of heat that may be generated in the circuit-breaker mechanism under excessive switching and short circuit conditions, this distortion of the insulating housing will not affect the contact pressure between the terminal 31 and the stab 35.

For some applications, only one circuit-breaker mechanism may be utilized in only one compartment. In these cases, only one contact need be welded to the contactsupporting leg 123.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details and arrangement of parts may be made without departing from some of the essential features of the invention. It is desired, therefore, that the language of 6 the appended claims be given as reasonably broad an interpretation as is permitted by the prior art.

We claim `as our invention:

1. A circuit breaker comprising a pair of contacts operable to open and close an electric circuit, a plug-in type terminal structure in electrical series with said contacts, said plug-in type terminal structure comprising a sheetmetal type member of generally resilient conducting material, said sheet-metal type member comprising oppositely disposed flat face surfaces and end surface means between said at face surfaces, said sheet-metal type member comprising facing end parts of said end surface means which facing end parts are positioned to receive a conducting stab therebetween when said circuit breaker is plugged onto the conducting stab, said plug-in type terminal structure constructed to cooperate with a conducting stab having a connecting part that has a thickness greater than the dimension between said facing end parts whereby when said plug-in type terminal structure is forced onto said connecting part said facing end parts are forced apart with a torsion action of said plug-in type terminal structure to spring charge said plug-in type terminal structure to effect a bias of said facing end parts against said connecting part of said conducting stab.

2. A circuit breaker constructed in accordance with claim 1, wherein said sheet-metal type member comprises a one-piece member having a slot therein to form said facing end parts at opposite sides of said slot.

3. A circuit breaker constructed in accordance with claim 1, wherein said sheet-metal type member comprises an inverted generally U-shaped member comprising a first leg and a second leg, said first leg formed with a slot therein to form said facing end parts at opposite sides of said slot, and means connecting said second leg in electrical series with said contacts.

4. A circuit breaker constructed in accordance with claim 3, wherein one of said contacts is supported on a at face surface of said second leg.

5. A circuit breaker constructed in accordance with claim 1, wherein said sheet-metal type member comprises a member having a slot therein to form said facing end parts at opposite sides of said slot, and separate spring means engaging said member on opposite sides of said slot to bias said facing end parts against said conducting stab.

6. Control apparatus comprising a circuit breaker, a conducting stab comprising a connecting part having a thickness,

said circuit breaker comprising a pair of contacts operable to open and close an electric circuit, a plug-in type terminal structure in electrical series with said contacts, said plug-in type terminal structure comprising a sheet-metal type member of generally resilient conducting material, said sheet-metal type member comprising oppositely disposed at face surfaces and end surface means between said flat face surfaces, said sheet-metal type member formed such that said end surface means comprise facing end parts having a dimension therebetween that is less than said thickness of said connecting part of said conducting stab when said plug-in type terminal structure is not connected to said conducting stab,

said circuit breaker removably connected to said conducting stab with said plug-in type terminal structure forced onto said connecting part of said conducting stab, said facing end parts of said plug-in type terminal structure positioned on opposite sides of said connecting part and forced apart by said connecting part to spring charge said plug-in type terminal structure to effect a bias of said facing end parts against said connecting part.

7. Control apparatus 4according to claim 6, said sheetmetal type member comprising a one-piece member having a slot therein to form said facing end parts at opposite sides of said slot.

8. Control apparatus according to claim 6, said sheet-Y metal type member comprising an inverted generally U shaped member comprising a rst leg and a second leg, said rst leg formed with a slot therein to form said facing end parts at opposite sides of said slot, and means connecting said second leg in electrical series with said contacts.

9. Control apparatus according to claim 8, one of said contacts Supported on a at face surface of said second leg.

10. Control -apparatus according to claim 6, said sheetmetal type member comprising a member having a slot therein to form said facing end parts at opposite sides of said slot, and separate spring means engaging said sheet metal type member on opposite sides of said slot to provide an additional bias of said facing end parts against said connecting part of said conducting stab.

References Cited UNITED STATES PATENTS Y Y 3,053,957 9/ 1962 Duield 20D-166 3,111,354 11/1963 Hammerly et al 317-119 ROBERT K. SCHAEFER, Primary Examiner.

H. O. JONES, Assistant Examiner.

Claims (1)

1. A CIRCUIT BREAKER COMPRISING A PAIR OF CONTACTS OPERABLE TO OPEN AND CLOSE AN ELECTRIC CIRCUIT, A PLUG-IN TYPE TERMINALS STRUCTURE IN ELECTRICAL SERIES WITH SAID CONTACTS, SAID PLUG-IN TYPE TERMINAL STRUCTURE COMPRISING A SHEETMETAL TYPE MEMBER OF GENERALLY RESILIENT CONDUCTING MATERIAL, SAID SHEET-METAL TYPE MEMBER COMPRISING OPPOSITELY DISPOSED FLAT FACE SURFACES AND END SURFACE MEANS BETWEEN SAID FLAT FACE SURFACES, SAID SHEET-METAL TYPE MEMBER COMPRISING FACING END PARTS OF SAID END SURFACE MEANS WHICH FACING END PARTS ARE POSITIONED TO RECEIVE A CONDUCTING STAB THEREBETWEEN WHEN SAID CIRCUIT BREAKER IS PLUGGER ONTO THE CONDUCTING STAB, SAID PLUG-IN TYPE TERMINALS STRUC-

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