US3377574A - Circuit breaker resetting and closing mechanism - Google Patents

Description

April 1968 J. c. BRUMFIELD ETAL 3,377,574

CIRCUIT BREAKER RESETTING AND CLOSING MECHANISM Filed Oct. 19, 1966 3 Sheets-$heet 1 JOHN C. B/Fz/MF/HO BY 09/921155 7T HOE/AG April 1968' J. c. BRUMF'IELD ETAL' 3 Sheets-Sheet 2 Filed 001;.

INVENTORS Jd/f V c. JEUMF/Edfl By 099924159 7. fla /A15 A ril 9, 1968 J. c. BRUMFIELD ETAL 3, 4

CIRCUIT BREAKER RESETTING AND CLOSING MECHANISM Filed Oct. 19, 1966 United States Patent 3 377,574 CIRCUIT BREAKER RESETTING AND CLOSING MECHANISM John C. Brumfield, Philadelphia, and Charles T.

Robins, Swarthmore, Pa., assignors to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Filed Oct. 19, 1966, Ser. No. 587,709 9 Claims. (Cl. 335-27) ABSTRACT OF THE DISCLOSURE and tripped posi- This invention relates to circuit breakers, and more particularly relates to mechanism for effecting automatic movement of the movable contact of a circuit breaker from its tripped to its on or closed circuit position in response to the operating handle of such circuit breaker being moved from its tripped to its on position.

In recent years there has been considerable effort 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 inventiop 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 breaker. Further evidence of the present emphasis on reduction in size and simplicity in design is evidenced by United States patent application Ser. No. 632,045, filed Apr. 19, 1967, entitled, Circuit Breaker Mechanism Mounting Plate Assembly, to Carl E. Gryctko, 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, en-

gineers have re-examined the operating characteristics of 'stantaneous fault current trips the latching mechanism whereby an overcenter spring operated mechanism snaps the circuit breaker movable contact to its open circuit po sition. The breaker is now in its tripped position.

After the fault has been cleared and it is necessary to re-establish the circuit being protected, the following steps are normally required. First, the operating handle of the circuit breaker is moved from its tripped position (that is, the position the handle occupies with the circuit breaker contact open and the latching mechanism tripped) ina first direction to a reset position in which the latching mechanism is cocked for subsequent operation. In the reset position, the movable contact of the circuit breaker remains open, and hence the reset position is commonly called the off position. Finally, the operating handle is moved in the opposite direction from the reset position back to the on position. It is obvious that the two-step operation required to convert a circuit breaker from its tripped position to its on position is diametrically opposed to the basic concept of simplicity which today is of primary importance in the circuit breaker field.

. The instant invention addresses itself to both problems outlined above. That is, with conscientious effort it has been specifically designed to cooperate with the circuit breaker operating mechanism of the aforementioned application Ser. No. 632,045, although in no way intended to be limited to such environment; while at the same time it simplifies circuit breaker operation, by providing that in one single movement of the operating handle thereof from the tripped to the on position, the movable contact of the circuit breaker will experience complete, automatic, and continuous movement from its tripped position through the off position and to the on position.

Specifically, and as explained in greater detail in said aforementioned patent application Ser. No. 632,045, a circuit breaker is provided with a common, relatively flat mounting plate upon which all parts of the circuit breaker mechanism are ultimately secured and about points on which various movable parts of the circuit breaker mechanism may rotate. The breaker includes a stationary contact and a movable contact rotatable about a pivot point provided on a cradle member pivotally secured to the aforementioned mounting plate. A handle is connected to the movable contact by means of an overcenter operating spring, with the latch of the tripping mechanism of the breaker maintaining the cradle in its latched position whenever the breaker is in the on or off condition.

Upon the occurrence of a predetermined fault, the tripping mechanism permits the release of the cradle whereby the overcenter spring rotates both the cradle and the movable contact to open the crcuit being protected.

To perform the automatic reclosing of the circuit breaker contacts upon .the movement of the operating handle from its tripped to its on position, there is provided automatic relatching means in the form of a linkage assembly which cooperates with the operating handle, the cradle, and the common mounting plate of the circuit breaker to perform three primary functions. First, the automatic relatching means is so arranged as to define an intermediate or off position for the circuit breaker operating handle when such handle is manually rotated between its on and off position to close and open, respectively, the circuit breaker contacts while the cradle is latched. Second, upon the occurrence of a fault as detected by the circuit breaker tripping mechanism, the automatic relatching means is so arranged as to permit the circuit breaker operating handle to rotate past its off to its tripped position during which'time, of course, the circuit breaker movable contact is experiencing further movement to its tripped position, beyond its 01f position, to assure current interruption. Third, in response to a single continuous movement of the circuit breaker operating handle from its tripped back to its on position, the automatic relatching means is so arranged as to (1) automatically relatch the cradle of the breaker and (2) return the circuit breaker movable contact to its engaged or on position. i

It is to be understood that, although the instant invention has been and will be further described with respect to the particular operating mechanism of the novel circuit breaker shown and claimed in application Ser. No. 632,- 045, it is in no way limited to use in such circuit breaker but rather applicable to any type of circuit breaker mechanism which includes both an operating handle and a latchable cradle.

Accordingly, it is an object of the instant invention t provide automatic relatching means for use in a circuit breaker which achieves both the latching of the cradle thereof and the movement of the movable contact thereof between its tripped and on position in response to a single continuous movement of the operating handle thereof between its tripped and on position.

Another object of the instant invention is to provide such automatic relatching means which is particularly adapted to cooperate with circuit breakers especially designed from the viewpoint of reduction in size and utmost simplicity in operation.

Another object of the instant invention is to provide such automatic relatching means comprised of a linkage assembly of a minimal number of parts so arranged as to perform a multiplicity of functions.

Still another object of the instant invention is to provide such automatic relatching means which defines an oif position for a circuit breaker operating handle; permits such operating handle to pass said off position and reach a tripped position in response to the detection of a fault by the tripping mechanism of such breaker; and causes the operating mechanism of such breaker to be automatically relatched and the movable contact of the breaker to experience movement from its tripped to its on position in response to a single continuous move-ment of the operating handle from its tripped to its on position.

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 internal parts of a circuit breaker constructed in accordance with the teachings of said aforementioned patent application Ser. No. 632,045, and including the automatic relatching means of the instant invention;

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

FIGURE 3 is a partial view of the circuit breaker of FIGURE 2, with the parts thereof occupying the oif position; and

FIGURE 4 is a view similar to FIGURE 3, but showing the circuit breaker in the tripped position.

Referring to FIGURE 1, there is shown the internal mechanism of a circuit breaker constructed in accordance with the principles of the aforementioned patent application Ser. No. 632,045, which mechanism includes the automatic relatching apparatus 12 of the instant invention. It is re-emphasized that although the automatic relatching apparatus 12 will be specifically described with respect to the internal mechanism 10 of said aforementioned pending application, it is to be understood that such disclosure is intended in no way to limit the application of the instant invention, since the instant invention is equally applicable to any circuit breaker mechanism which includes both an operating handle and a rotating cradle as part of its operation.

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 could be appropriately modified (for example, by tying together three linkage assemblies to operate simultaneously) to operate in a circuit breaker for the protection of more than one phase.

The circuit breaker mechanism 10 includes a common plate 14 integrally provided with the following parts: an upstanding cradle-pivoting tab 16; an upstanding relatching-pivoting tab 18; an upstanding tripper mechanismpivoting tab 20; and an upstanding spring-retaining tab 22. In addition the plate 14 includes an elongated slot 24; a generally centrally located operating handle-pivoting aperture 26; and an arcuate slot 28 which receives an upstanding tab portion of the operating handle 30, as hereinafter described.

The operating handle 30 includes an upstanding knob receiving tab 32 at one end thereof, and a pair of upstanding tabs 34 and 36 at the opposite end thereof. Tab 34 is provided with an open-ended slot 38 which fits over a portion 40 of the mounting plate defining the aperture 26 whereby the operating handle 30 may experience rotation in a plane parallel to the plane of the mounting plate 14 about the point 40. The second tab 36 of the operating handle 30 is freely received within the arcuate slot 28 and extends forward of the mounting plate 14 when the operating handle 30 is placed behind the mounting plate 14 with the open-ended slot 38, ridingon the point 40. Biasing means in the form of spring 42 is secured at one end thereof to the tab 36 and at the opposite end thereof to the upstanding spring-retaining tab 22 so as to constantly bias the operating handle 30 in a counterclockwise direction in FIGURE 1 about the pivot defined by the slot 38 and point 40.

A cradle 44 includes a bifurcated end 46, the two arms 48 and 50 of which include aligned apertures 52 which receive the cradle pivoting tab 16 of the mounting plate 14. The opposite end of the cradle 44 includes an upstanding latch tip 54 which cooperates with the latch 56 of the tripping mechanism 80, as will be described in further detail.

. Intermediate the ends of the cradle 44 is an over-turned tab 58 which cooperates with an open-ended slot 60 provided at one end of a movable contact arm 62 to permit rotation of the movable contact arm 62 about point 64 on the cradle 44 when the movable contact arm 62 is inser'ted up and under the over-turned tab 58.

The opposite end of the movable contact arm 62 integrally carries a generally S-shaped spring-retaining portion 66 and also carries a generally L-shaped portion 68 which carries the movable contact pad'70 thereon. Disposed opposite to the movable contact pad 70 is a stationary contact pad 76 secured to the stab 78 of the breaker.

A main operating spring 72 is secured at one end thereof to the S-shaped spring-retaining portion 66 and at the opposite end thereof is secured to a spring-retaining portion 74 which is an integral portion of the upstanding knob-retaining portion 32 of the operating handle 30.

Tripping mechanism generally designated at 80 includes a bimetallic element 82 and a magnetic element 84 to which is secured the latch 56.

In response to predetermined overload or instantaneous fault conditions, tripper mechanism 80 will rotate clockwise in FIGURE 1 to move the latch 56 out'of engagement with the latch tip 54 of cradle 44 to permit the main operating spring 72 to rotate contact arm 62 clockwise and thereby interrupt current flow through'the path defined by stab 78, stationary contact pad 76, movable contact pad 70, conductive braid 86, bimetallic element 82, conductive braid 88, and stab The automatic relatching means 12 of the instant invention includes first and second members 92 and 94, respectively, which are joined as by a pin 96 for rotation relative to one another. The first member 92 includes a centrally located aperture 98 which is received and carried by the upstanding pivot point 18 on mounting plate 14 to permit rotation of the linkage assembly relative to the plate 14. The first member 92 also includes a pair of actuating surfaces 100 and 102, for purposes to be further explained, while the second member 94 terminates in an upstanding actuating surface 104 which terminates in a re-arwardly disposed portion 106 whichlies in a plane behind the planar surface of the second member 94 so that it may ride behind the mounting plate 14 with the upstanding actuating surface 104 projecting through the elongated slot 24 and beyond the front surface of the plate 14. It may be noted that actuating surface 102 of member 92 retains one end of a biasing spring 103, the opposite end of which is secured to a hook-like projection 105 provided on the tripping mechanism 80 to constantly bias the first member 92 of the automatic relatching mechanism in a counterclockwise direction about the pivot point 18. I

Referring to FIGURE 2, there is shown the manner in which the circuit breaker operating mechanism cooperates within a circuit breaker casing generally indicated at 110. The casing 110- normally includes a cover, not shown, which when removed reveals the mechanism housing cavity 112. The casing walls include appropriately located passageways for stabs 78 and 90; a passageway 114 to permit the exit of gases generated during circuit interruption in the manner taught by United States patent application Ser. No. 568,500, filed July 28, 1966, entitled Vented Mounting Block for Circuit Breaker, in in the name of Carl E. Gryctko, assigned to the assignee of the instant invention, and now issued as US. Patent 3,328,553 on June 27, 1967; and a passageway 115 provided th-rough the outer casing wall to house an adjusting screw 117 which is screw-threaded through an upstanding tab 119 provided on the mounting plate 14 to vary the position of the bimetallic element 82 and hence the entire tripping mechanism 80- relative to the latch tip,

54 of cradle 44. (Note that the tripping assembly 80 is constantly biased in a counterclockwise direction in FIGURE 2 by the biasing spring 103 secured between the hook-like projection 105 on the tripping mechanism and the actuating surface 102 provided on the first member 92 of the automatic relatching mechanism.) The external casing wall is also removed at 116 through which an operating knob 118 may 'be secured to the operating handle 30 of the internal mechanism in a manner to be further described. The upper arcuate opening 116 is defined at opposite ends thereof by casing wall projections 120 and 122.

In the interior cavity 112 and upstanding from the rear wall 124 of the casing 110 there is provided an internally generally U-shaped projection 126 which houses the bifurcated end 46 of the cradle 44 which in turn is pivoted upon the tab 16 of the mounting plate 14.

The operating knob 118 is actually an integral portion of a one-piece arc-like member 124a which is guided for movement within the interior 112 of the casing 110 by the internal surfaces of the casing walls as well as the upstanding projection 126. The arc-like member 124a has a cutout notch 127 which receives the upstanding tab 32 of the operating handle 30 whereby rotation of the knob 118 between limits defined by wall projections 120 and 122 will similarly rotate the operating handle 30 v In FIGURE 2 the circuit breaker is in the on position, that is, with the contact pads 70 and 72 completing a circuit path through the stab -78, contact pads 70, 72, the conductive braid 86, the bimetallic element 82, the conductive braid 88 and through the stab 90. In the on condition, the latch 56- of the tripping mechanism 80 is in a blocking relationship with respect to the latch tip 54 of cradle 44, with the operating spring 72 biasing the movable contact arm 62 in a counterclockwise direction about point 64 on cradle 44 to maintain the movable contact pad 70 in firm electrical contact with the stationary pad 76.

It will further be observed that in the on position, biasing spring 103 attempts to establish as short a distance as possible between the projection 105 on the tripping mechanism 80 and-the actuating surface 102 on the first member 92 of the automatic relatching assembly whereby the planar actuating surface 100 of member 92 is necessarily so positioned as to be in the path of movement of an upstanding tab 128 (which cannot be seen in FIGURE 1) provided on the operating handle 30 The function of this last mentioned upstanding tab 128 on the operating handle 30 may best be understood by referring to FIGURE 3 wherein the operating handle 30 has been manually moved from its on position to an off position intermediate the projections 120 and 122, and during which time the operating spring 72 has passed over point 64 on the cradle 44 to rotate the movable contact arm 62 from its on position to its off position. Note that since the opening of the circuit breaker was by manual operation and not in response to the occurrence of a fault, the circuit breaker is in an off position rather thanthe tripped position, with the cradle 44 still being latched by the cooperation of latch 56 and latch tip 54.

As can be most clearly seen in FIGURE 3, the operating handle 30 is maintained in the off position by the cooperation of actuating surfaces 100 and 102 of member 92 with the upstanding tab 128 and the cradle 44, respectively. Specifically, as the operating handle 30 is rotated by means of the knob 118 counterclockwise in FIGURE 3, the tab 128 on the operating handle 30 engages the actuating surface 100' of member 92. However, with the cradle 44 latched, further counterclockwise rotation of the member 92 of the automatic relatching assembly 12 is prevented by the engagement of the upstanding actuating surface 102 thereon with the cradle 44.

Turning now to FIGURE 4, it will be assumed that a time-delayed or instantaneous fault current has been detected by the tripping mechanism so as to rotate latch 56 from it blocking position with respect to the latch tip 54 of cradle 44. At this time the operating spring 72 rotates movable contact arm 62 and necessarily the cradle 44 in a clockwise direction to the tripped position shown in FIGURE 4, whereby there is even a greater separation between contact pads 70 and .76 thereby assuring extinguishment of any arc drawn therebetween. Simultaneously and with the aid of biasing spring 42, the operating handle 30 isurged through its off position in FIGURE 3 to its tripped position in FIGURE 4, it being noted that the upstanding tab 128 thereon is now free to rotate member 92 counterclockwise since the actuating surface 102 thereof is no longer restrained by the cradle 44 as it was in FIGURE 3. It is to be noted that while member 92 -is being rotated counter-clockwise, biasing spring 103 is put under tension whereby once the operating handle 30 has reached its tripped position and the upstanding tab 128 thereof is no longer in engagement with the actuating surface under it (this instant in time being shown in phantom at in FIGURE 4), the member 92 will be rotated clockwise back to the initial position it occupied in FIGURE 2.

To convert the breaker from the tripped condition shown in FIGURE 4 back to the on position shown in FIGURE 2, the operator merely grasps the knob 118 and rotates it (and the operating handle 30) from its position in abutment with the wall projection 120 to its other extreme position defined by the wall projection 122. In so doing, the upstanding projection 128 on the operating handle 30 engages the actuating surface 100 of member 92 once again such that the member 92 rotates clockwise in FIGURE 4 and the second member 94 with the actuating surface 104 are moved toward the left in FIG- URE 4, the movement of the actuating surface 104 being guided by the elongated slot 24 into contact with the cradle 44.

As this motion continues, the upstanding actuating surface 104 causes the cradle 44 to be rotated counterclockwise in FIGURE 4 until the latch tip 54 passes beneath the latch 56 (which has been urged counterclockwise in FIGURE 4 by the biasing spring 103) at which time the cradle 44 will occupy the latched position shown in FIGURE 3.

Finally, when the operating handle 30 passes over center point 64, the operating spring 72 will snap the movable contact arm 62 counterclockwise in FIGURE 4 until it reaches the on position shown in FIGURE 2. Thus the circuit breaker has been converted from trip to on position with one continuous mot-ion of the operating handle 30.

It should be noted that once the upstanding tab 128 of operating handle 30 is free of the actuating surface designated at 100" in FIGURE 4, the biasing spring 103 will again return the member 92 to the position shown in solid in FIGURE 4 (corresponding to FIGURE 2), whereby the automatic relatching mechanism will be in condition to function properly for either the next tripping operation or manual movement from the on to off positions.

Thus there has been described automatic relatching mechanism specifically adapted for cooperation with the novel operating mechanism of a circuit breaker designed to reduce size and simplify operation which makes possible the conversion of a circuit breaker from its tripped to its on condition with one single continuous movement of the operating handle of such breaker from its tripped to its on position.

Although there has been described a preferred embodiment of this novel invention, many variations and modifications will now be apparent to those skilled in the art. Therefore, this invention is to be limited, not by the specific disclosure herein, but only by the appending claims.

We claim:

1. A circuit breaker comprising:

a first contact; a

a second contact movable between a first position engaging said first contact and a second position disengaged from said first contact; an arm upon which said second contact is mounted;

operating means connected to said armmovable between a latched and tripped position for moving said second contact from its first to its second position in response to predetermined conditions;

an operating handle movable between trip and on positions for moving said second contact from its second position back to its first position after said second contact has been moved to its second .position in response to movement of said operating means from its latched to tripped position;

with said operating means in said latched position said operating handle also being operable to an off position wherein said contacts are disengaged;

said off position for said operating handle located intermediate said on and said tr-ip positions; and automatic relatching means engageable by said operating handle and said operating means for automatically moving said operating means to its latched po sition in response to movement of said operating handle from its tripped position toward its on position whereby movement of said operating handle will automatically move said operating means to its latched position and thereafter automatically move said second contact from its second position to its first position.

2. The circuit breaker of claim :1, wherein said operating means includes a cradle member rotatable about one end thereof between its latched and tripper positions; and said automatic relatching means includes linkage means having first and second actuating surfaces, said first actuating surface being movable between a first and second position in response to movement of said operating handle from its trip toward its on position, said second actuating surface coactingwith said cradle to rotate said cradle from its tripped to its latched position in response to movement of said first actuating surface of said linkage means to its second position by said operating handle as it moves toward its on position,

3. The circuit breaker of claim 2, wherein said operating handle is automatically moved from its on to its trip position in response to movement of said second contact to its second position; and said first actuating surface of said linkage means is obstructively positioned in the path of movement of said operating handle as it moves from its on to its trip position in response to movement of said second contact to its second position; and wherein said first actuating surface of said linkage means is momentarily moved to a third position by said operating handle as said operating handle moves from its on to its trip position; and further including biasing means for returning said first actuating surface of said linkage means from its third to its first position after said operating handle passes said first actuating surface of said linkage means.

4. The circuit breaker of claim 3, wherein movement of said operating handle from its on to its off position causes said second contact to be moved from its first position to a third position which is intermediate said first and second positions of said second contact.

5. The circuit breaker of claim 4, wherein said linkage means includes a third actuating surface which coacts with said cradle to maintain said first actuating surface obstructively positioned in the path of movement of said operating handle to prevent said operating handle from being moved to its trip position whenever said cradle is in its latch position.

6. The circuit breaker of claim 5, and further including a plate member, said linkage means comprising first and second members pivotally linked to one another, said first member being pivotally mounted on said plate and having said first and third actuating surfaces thereon, said second member having said second actuating surface thereon.

7. The circuit breaker of claim 6, and further including tripping mechanism for detecting predetermined fault conditions, said biasing means being secured at one end to said tripping mechanism and at its other end to said third actuating surface.

8. The circuit breaker of claim 6, wherein said plate member has an elongated slot which intersects the path of movement of said cradle, and said second actuating surface comprises an upstanding surface which is guided for movement in said elongated slot to rotate said cradle about its said one end from its tripped to its latched position in response to movement of said first actuating surface of said first member from its first to its second position by said operating handle.

9. The circuit breaker of claim 3 further including a second biasing means connected with said operating handle for continuously biasing the same towards said trip position.

References Cited UNITED STATES PATENTS BERNARD A. GILHEANY, Primary Examiner.

H. BROOME, Assistant Examiner.

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