US2479331A

US2479331A - Electric switch

Info

Publication number: US2479331A
Application number: US685929A
Authority: US
Inventors: John A Favre
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1946-07-24
Filing date: 1946-07-24
Publication date: 1949-08-16
Anticipated expiration: 1966-08-16

Description

Aug. 16, 1949.

Filed July 24, 1946 J. A. FAVRE ELECTRIC SWITCH ITM/ent OT His Attorn John* A. Favre,

1 bym Aug. 16, 1949.

J. A. FAVRE ELECTRIC SWITCH Filed July 24, 1946 2 SheeCS-Shee(l 2 Inventor: John A. Peu/Pe His Attowney.

Patented Aug. 16, 1949 ELECTRIC SWITCH John A. Favre. Drexel Hill, Pa., assigner to General Electric Company, a corporation of New York Application July 24, 1946, Serial No. 685,929

7 Claims. 1

My invention relates to improvements in electric switches and more particularly circuit breakers and especially automatic trip-free air circuit breakers, the opening or which must be sensitively responsive to predetermined circuit conditions.

In an automatic trip-free circuit breaker wherein a thermally responsive tripping element is used to maintain the circuit breaker mechanism in the closed circuit position, there arises a conict between the requirements of a strong opening force and a sensitive tripping action for releasing the circuit breaker mechanism in response to deflection of the thermal element. A

strong opening force is desirable for rapid sepa-4 ration of the contacts. The more of this opening force the thermally responsive tripping element has to overcome, the larger the element has to be and the greater the space required. Also, the sensitivity and consistency of response is weakened especially for currents in the nature of overloads for which a relatively long time delay is desired.

An object of my invention is to provide, for maintaining a circuit breaker mechanism in the closed circuit position against a relatively strong opening force, a holding mechanism which has a relatively sensitive release for effecting the opening of the circuit breaker. Another object of my invention is to provide an improved circuit breaker mechanism which, although held in the closed circuit position by electro-responsive tripping means, is readily releasable thereby in response to abnormal circuit conditions whether of overload or short circuit magnitude. A further object of my invention is to provide an improved automatic trip-free circuit breaker mechanism which, although maintained in the closed circuit position by a thermally responsive tripping element against a relatively strong opening force, is sensitively releasable by the action of the thermally responsive tripping element in case of abnormal currents through the circuit breaker. These and other objects of my invention will appear in more detail hereinafter.

In accordance with my invention, I provide an electric switch comprising a movable circuit controlling member and means for moving the member to and maintaining it in the closed circuit position against a relatively strong opening force. This holding means includes a pivotally mounted latching lever, a wedgy catch for the lever biased into self-releasing engagement therewith,

and a trip device having a sensitive latch for holding the catch in self-releasing wedging en- (Cl. 20G-116) sagement with the lever. Also in accordance with my invention, I provide biasing means tending to move the catch and trip latch into holding engagement with the latching lever and catch, respectively. For biasing the circuit controlling member to the open circuit position, I provide an overcenter spring operating mechanism having an operating element movable in one direction to effect engagement of the latching lever and the catch and in the opposite direction to eiect engagement of the trip latch and the catch and then to move the circuit controlling member to the closed circuit position. Also in accordance with my invention, the movement of the trip latch to the holding position is limited by a movable stop which is actuable in response to abnormal conditions of the circuit controlled by the circuit breaker for effecting a release of the latch to cause the opening of the circuit breaker.

My invention will be better understood from the following description when considered in connection with the accompanying sheet of drawings, and its scope will be pointed out in the appended claims.

In the accompanying sheet of drawings, Fig. 1 is a side elevation of one pole of a circuit breaker embodying my invention showing the circuit breaker in the closed circuit position; Fig. 2 is a front elevation of the embodiment of my invention shown in Fig. 1; Fig. 3 is a sectional elevation similar to Fig. 1 with certain parts broken away for clearness; Fig. 4 is an elevation Similar to Fig. 3 showing the circuit breaker reset and ready for closing; and Fig. 5 is an elevation similar to Fig. 3 showing the circuit breaker in the tripped open position.

In the several gures of the accompanying drawing, I have illustrated a circuit breaker provided with an operating mechanism embodying my invention. In these gures only one pole of the circuit breaker is shown, but it will be understood by those skilled in the art that the circuit breaker may have any desired number of poles and that in case of an odd number of poles the operating mechanism will be associated with the middle pole and in case of an even number of poles the operating mechanism will be positioned intermediate the two central poles. As shown. the circuit breaker comprises a base I of suitable insulating material for supporting'the various parts which may be protected from dust and falling objects by a cover 2 preferably of suitable insulating material. Also, suitable insulating barriers, not shown, may be interposed between adjacent poles of the multipole breaker as is well known to the art.

As shown, the circuit breaker comprises one or more circuit controlling members 3, one for each pole of the circuit breaker. 'Each circuit controlling member 3 is mounted for movement into engagement with a cooperating relativeLv sta-v tionary contact 4. In the illustrated arrangement, the circuit controlling member 3 is mounted on a pin 5 supported in extensions 5 of the ilanges 1 of a channel-shaped support 8. This movable contact support 8 is mounted on a shaft 9 and insulated therefrom by an insulating block IIB of square cross section projecting through registering openings in the anges I of the support. A locking and Clamping member II embracing the block I and projecting through apertures in the web of the support 8 serves to secure the assembly. In order to prevent rotation of the movable contact 3 relatively to its support 8, the lower end of the contact is slotted for locking engagement with the web of the support. A flexible connection I2 extends between the movable contact 3 and a terminal I3. In conductive connection with this terminal through a terminal block I4 is the U-shaped current conducting and heating element I5 of a thermally responsive device such as disclosed in the patent of Albert R. van C. Warrington, No. 2,412,483, filed July 22, 1943, and assigned to the assignee of this invention. Above the heating element I5 is an equalizing element I6 which is electrically insulated from the terminal block Il and is heat insulated from the outer end of the element I5 so as to prevent direct heat conduction therefrom. The lower leg of the member I5 is connected to a main circuit breaker terminal i1. While I have shown and briefly described a thermally responsive element which is particularly suited for tripping circuit breakers, it is to -be understood that my invention is not limited in its application to any para ticular tripping element.

The relatively stationary contact I is resiliently suspended from an upper terminal block I8 by a leaf spring I9 and connected to the terminal block by a flexible conductor looped around the web 2| of a U-shaped magnetic member. the flanges 22 of which are perforated and secured to the side members 23 of an arc chute, all as disclosed in the copending application of Robert M. Bennett, Serial No. 606,374, filed July 21, 1945, now Patent No. 2,460,118, dated January 25, 1949, and assigned to the assignee of this invention. The terminal block I8 is connected to the circuit breaker terminal 24.

For moving the circuit controlling member 3 to and maintaining it in the closed circuit pition, I provide an overcenter spring operating mechanism having a latchlng lever 25 which is supported on a pivot pin 2B. As shown, the pin 2-5 is mounted in a generally U-shaped frame 21 secured to the base I. The latching lever 25 is interconnected with the circuit controlling member 3 by a

toggle comprising links

28 and 29. The toggle link 28 is pivotally connected to the latching lever 25 at 33, and the link 23 is pivotallv connected to the circuit controlling member 3 at the pin 5. The two

links

28 and 28 are pivotallv1 interconnected at 3|. For holding purposes in both the circuit closed and open positions, the link 28 is provided with a projection such as an arm 32, shown more clearly in Figs. 4 and 5, which comes to rest against the inner edge of the latching lever 25 near the pivot pin 28 when the circuit breaker mechanism is tripped -to the circuit open position, as shown in Fig. 5, and also when the circuit breaker is closed, as shown in Figs, l and 2, to maintain the toggle 28-29 in an overset position whereby to hold the circuit controlling 5 member 3 in the closed circuit position as long as the latching lever 25 is held in the latched .position. The pivot pin 23 is provided with a compound spacer against which the circuit controlling member 3 comes to rest in the circuit open position, as shown in Figs. 4 and 5, and against which it remains until the circuit breaker is closed.

For self-releasing wedging engagement with the latching lever 25 in the latched position, I

15 provide, in accordance with my invention, a

of a U-shaped member pivotally supported on the frame 2l at 34. For obtaining the desired self-releasing wedging engagement, the latching lever is provided with a relieved shouldered portion which abuts against the rear side of the web portion' of the catch 33 at an angle such as to tend to move the catch 33 clockwise about its pivot 3d when the latching lever is in the latched position shown in Figs. 1, 3 and 4. For limiting the counterclockwise movement of the latching lever 25 during the circuit opening operation so that it may not ride off the web of the catch 33, the lever is provided with a second shouldered portion 36. For biasing the catch 33 into engagement with the shouldered portion 35 of the latching lever 25 when the lever is moved clockwise to the latching position, I provide means tending to move the catch 33 into engagement with the latching lever 25. As shown, this means comprises a hair spring type of torsion spring 3l which is carried on the pin 3e and which is provided with an arm 38 bearing against the latching lever and an arm 38 bearing against a pin 39 mounted between the legs of the catch 33.

Further in accordance with my invention, I provide a trip latch 30 for holding the catch 33 in self-releasing engagement with the trip lever 25 to maintain the circuit controlling member 3 in the closed circuit position after it has been moved to such position. As shown, the trip latch 4I) is mounted on a support ll pivoted in the frame 2l at 32. In the tripped open position of the circuit breaker, the trip latch lill is in the rear of the web portion oi the catch 33 under the bias of suitable means such as a relatively light spring Q3 which tends to move the trip latch support ll clockwise into the latching position shown in Figs. 1, 3 and 4. The spring 133 is connected between the pin 39 on the catch 33 and the support 4I. It will be noted that the pivotal axes of the latching lever 25, the catch 33 and the trip latch 43 are substantially parallel and that the respective pivotal axis of the latching lever 25 and the trip latch 40 are substantially in line with the points of engagement of the latch by the catch and the lever by the latch to provide a sensitive release oi the lever upon rotary movement of the trip latch out of the line. For limiting the clockwise movement of the trip latch support 4I produced by the spring I3 so 'as to maintain its under the web portion of the catch 33, the outer end of the support 4I is 7o arranged to abut a projection lill carried by the thermally responsive means heretofore described so that the circuit breaker mechanism may be tripped in response to predetermined current conditions of the circuit through the circuit breaker. A projection 3l' on the frame 2l prevents overtravel in the clockwise direction oi the trip latch 40. However, when current above a predetermined amount passes through the heated portion l oi' the thermally responsive means, the resultant enect oi this portion and the equalizer portion I6 is to move the projection 44 upward whereby to eiiect counterclockwise movement of the trip latch support 4l so as to release the catch 33 and eiiect the opening of the circuit breaker.

For resetting the latching lever 25 and moving the circuit controlling member 3 to the closed circuit position, I provide an operating element 45 which is movable in one direction, clockwise as viewed in the drawing, to eil'ect engagement of the latching lever 25 and the catch 33. Further in accordance with my invention, I provide a resilient overcenter connection between the operating element 45 and the toggle 23-23 which is operative during the reverse or counterclockwise movement of the operating element 45 to effect engagement of the tripping latch 40 and the catch 33 and to move the toggle 23-23 overcenter and the circuit controlling member 3 to the closed circuit position. As shown, the operating element 45 is pivoted in the trame 21 at 45 and is interconnected to the toggle pin 3| by one or more relatively strong springs 41 which extend between the toggle pin 3| and projections 48 on the operating member. In the closed circuit position of the circuit controlling member 3, the operating member 45, which as shown consists of two parallel portions interconnected by an insulated bridging pin 49, comes to rest against parallel projecting arms 50 on the frame 21 with the springs '41 under relatively high tension to insure a quick openingV of the circuit breaker. In the circuit open position, the insulated pin 43 on the operating element 45 comes to rest against the outer upper edge 5I oi' the latching lever 25 adjacent the pin 30, as shown in Fig. 5, with the springs 41 under a materially relieved tension.

For easy manipulation of the operating element 45, I provide a manually operable member 52 which is siidably positioned within the cover 2 between

guides

53 and 54 and provided with a handle projection 55 which rides between the sides of a slot 56 in the cover. The member 52 is provided with notched portions 51 which engage the pins 48 on the operating element 45. It will be observed that the position of the operating member 52 is indicative of the circuit breaker position. Thus, for example, in the closed position of the circuit breaker shown in Figs. 1 and 3, the projection 55 is at its highest point in the slot 55; and in the reset' or manually opened position of the circuit breaker mechanism, the projection 55 is at its lowest point in the slot 56; while in the tripped open or automatic trip indicating position of the circuit breaker mechanism, the projection 55 is at an intermediate point in the sloi'l 55.

Assuming the parts in the closed circuit position as shown in Figs. 1, 2 and 3, then in the event of current ilow through the circuit breaker of sufficient magnitude and duration to produce an upward movement o1' the projection 44 in consequences of the heating of the thermally responsive element l5, then the trip latch support 4I will be turned counterclockwise against the bias of the relatively light spring 43 to release the latch 40 from the catch 33, whereupon the pressure existing between the shoulder 35 on the trip lever 25 and the web of the catch 33 in consequence oi the tension in the springs 41 will cause the catch 33 to rotate in a clockwise direction about its pivots 34 and thus cause the trip lever to ride up over the top of the catch 33. In so doing, the support or pin 30 at one end of the toggle 23-23 is free to move to the right whereby the toggle is caused to collapse under the action of the springs 41 and thus to cause the circuit opening movement of the movable contact 3. During this circuit opening movement, the operating element 45 is caused to move clockwise about its pivots 45 and the parts are positioned as shown in Fig. 5. In this tripped open position, the circuit controlling member 3 comes to rest against the compound spacer on the pin 23, the arm 32 of the toggle link 23 comes to rest against the latching lever 25, and the insulated pin 43 on the operating element 45 comes to rest against the outer upper edge 5I of the latching lever 25. 'I'he shoulder 35 on the latching lever 25 is to the right of the web portion of the catch 33, and the trip latch 43 is in back of the web portion of the catch 33. The operating handle 52 is in its intermediate position.

When it is desired to close the circuit breaker, the operating handle 52 must first be moved downwardly to the reset position shown in Fig. 4. During this movement, the stress in the overeenter springs 41 is increased and the insulated pin 43 rides downwardly along the upper outer edge 5| of the latching lever 25 to turn this lever clockwise and move the shouldered portion 35 back of the web portion of the catch 33, as shown in Fig. 4. Under these conditions, the force of the springs 41 exerted on the pin 3l may be resolved into two components, one in line with the link 25 and the other in line with the link 23. 'I'he force in line with the link 23 merely tends to hold the circuit controlling member 3 against the insulated pin 23, and the force in line with the link 23 tends to turn the latching lever 25 counterclockwise. 'I'he force of the springs 41 exerted on the pins 43 tends to turn the operating element 45 clockwise labout its pivot 43. This clockwise effect of the operating element is transmitted to the latching lever 25 by virtue of the insulated pin 43 which gears against the upper outer edge 5I of the latching lever. This turning eiiect of the operating element on the latching lever accordingly tends to move the latching lever clockwise in opposition to the counterclockwise torque exerted through the line 28. In accordance with my invention, these two torques on the latching lever 25 are so proportioned by the arrangement of the parts that the counterclockwise torque is slightly predominant whereby to maintain the latching lever in engagement with the catch which is moved up into engagement with the latching lever by the torsion spring 31. Following the upward or counterclockwise movement of the catch 33, the support 4I of the trip latch is m`oved clockwise under the bias of the spring 43 into engagement with the projection 44 on the thermally responsive element. There is now a small clearance between the web of the catch 33 and the top of the latch lever 40, as shown in Fig. 4. When it is desired to close the circuit breaker, the operating handle 52 is moved upward from the reset position shown in Fig. 4 to the closed position shown in Fig. l. During the initial part of this upward movement, the operating element 45 is turned counterclockwise thereby moving the insulated pin 43 away from the outer edge 5I of the latching lever i5 25. When this occurs, the clockwise torque exertthe trip latch support 4I.

acusar It will be noted that the torce exerted on the trip latch support Il by virtue of the tendency of the catch 33 to move clockwise in the releasing direction is exerted substantially in line with or only slightly to the right of the pivot pin 42 oi' This adds to the sensitivity of the tripping action consequent upon the double latch arrangement, and this is further enhanced by the application of the force of the engagement with said lever, a trip device having a latch for holding said catch in engagement with said lever to maintain the circuit controlling member in the closed circuit position, biasing means tending to move said latch into holding .engagement with said catch, a toggle interconnecting said lever and said member and arranged to be overset to hold the member in the closed circuit position, a pivotally mounted operating element movable in one direction to eiIect engagement of said lever and said catch, and a resilient overcenter connection between said element and said toggle -for biasing said member to the open thermally responsive element at a much greater distance from the pivot 42. During the upward movement of the operating handle 52, the operating element 45 is moved clockwise to straighten the toggle 2&-29 and move it overcenter into the holding position, shown in Figs. 1, 2 and 3, where it is maintained by the latching lever 25 while in the latching position.

While I have shown and described my invention in considerable detail, I do not desire to be limited to the exact arrangements shown, but seek to cover in the appended claims all those modincations that fall Within the true spirit and scope of my invention.

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

1. An electric switch comprising a movable circuit controlling member, means for maintaining said member in the closed circuit position including a pivotally mounted latching lever, a wedgy catch for said lever biased into self-releasing engagement therewith, a trip device having a latch for holding said catch in engagement with said lever to maintain the circuit controlling member in the closed circuit position, and an overcenter spring operating mechanism for biasing said member to the open circuit position and having an operating element movable in one direction to eiect engagement of said lever and said catch and in the opposite direction to eiect engagement of said latch and said catch and to move said member to the closed circuit position.

2. An electric switch comprising a pivotally mounted circuit controlling member, means` for maintaining said member in the closed circuit position including a pivotally mounted latching lever, a wedgy catch for said lever biased into self-releasing engagement therewith, a trip device having a latch for holding said catch in engagement with said lever to maintain the circuit controlling member in the closed circuit position, a toggle interconnecting said lever and said member and arranged to be overset to hold the member in the closed circuit position, a pivotally mounted operating element movable in one direction to effect engagement of said lever and said catch, and a resilient overcenter connection between said element and said toggle for biasing said member to the open circuit position and operative on reverse movement of the element to eiIect engagement of said latch and said catch and to move said toggle overcenter and thereby operate said member to the closed circuit position.

3. An electric switch comprising a pivotally mounted circuit controlling member, means for maintaining said member in the closed circuit position including a pivotally mounted latching lever, a wedgy catch for said lever, biasing means tending to move said catch into self-releasing circuit position and operative on reverse movement of the element to effect engagement of said latch and said catch and to move said toggle overcenter and thereby operate said member to the closed circuit position.

4. An electric switch comprising a pivotally mounted circuit controlling member, means for maintaining said member in the closed circuit position comprising a pivotally mounted latching lever, a pivotally mounted catch for said lever, biasing means tending to move said catch into self-releasing engagement with said lever, a pivotally mounted trip latch for holding said catch in engagement with said trip lever to maintain said member in the closed circuit position, biasing means tending to move said latch into holding engagement with said catch, electroresponsive means for moving said latch in the releasing direction, and an overcenter spring operating mechanism for biasing said member to the open circuit position and having an operating element movable in one direction upon the release of said latch into engagement with said lever during .the circuit opening movement of the member and movable further in said direction to eilect reengagement of said lever and said catch,vsaid operating member being movable in the opposite direction to eiect reengagement of said latch and said catch and to move said member to the closed circuit position.

5. An electric switch comprising a movable circuit controlling member, means for maintaining said member in the closed circuit position including a pivotally mounted latching lever, a wedgy catch for said lever pivotally supported for movement about an axis substantially parallel to the pivotal axis of said lever, biasing means tending to move said catch into self-releasing engagement with said lever, a trip device having a latch for holding said catch in self-releasing engagement with said lever to maintain said member in the closed circuit position and pivoted for movement about an axis substantially parallel to the pivotal axis of said catch, biasing means tending to move said latch into holding engagement with said catch, and an overcenter spring operating mechanism for biasing said member to the open circuit position upon operation of said tripping device and having an operating element movable automatically thereby in one direction and manually movable further in said direction to eiect reengagement of said lever and said catch. said operating member being movable in the opposite direction to eiect reengagement of said latch and said catch and to move said member to the closed circuit position.

6. An electric switch comprising a movable circuit controlling member, means for maintaining said member in the closed circuit position including a plvotally mounted latching lever, a wedgy catch for said lever pivotally supported for movement about an ams substantially parallel to the pivotal axis oi said lever, a spring connected between said lever and catch tending to move said catch into self-releasing engagement with said lever, a trip device having a. latch for self-releasing said catch in holding engagement with said lever to maintain said member in the closed circuit position and pivoted for movement about an axis substantially parallel to the pivotal axis of said catch, a spring connected between said latch and catch tending to move said latch into holding engagement with said catch, a movable stop for limiting the movement of said latch in the holding direction having electroresponsive means for actuating said stop to move said latch in the releasing direction, and an overcenter spring operating mechanism for biasing said member to the open circuit position having an operating element movable automatically in 'one direction upon release of said latch into engagement with said lever during the circuit opening movement ol said member and manually movable further in said direction to eifect reengagement oi said lever and said catch, said operating member being manually movable in the opposite direction to eiiect reengagement of said latch and said catch and to move said member to the closed circuit position.

"l. An electric switch comprising a pivotally mounted circuit controlling member, means for maintaining said member in the closed circuit position comprising a pivotally mounted latching lever, a pivotally mounted catch for said lever having self-releasing movement in one direction, biasing means tending to move said catch into self-releasing engagement with said lever, a pivl0 otally mounted trip latch for holding said catch in engagement with said trip lever to maintain said member in the closed circuit position, biasing means tending to move said latch into holding engagement with said catch, electroresponsive means for moving said latch in the releasing direction, the respective pivotal axis of said lever and latch being substantially in line with the points of engagement of the latch by the catch and the lever by the latch to provide a highly sensitive release of the lever upon rotary movement oi' the trip latch out of said line by the electroresponsive means when energized in response to a predetermined abnormal circuit condition, and an overcenter spring operating mechanism for biasing said member to the open circuit position and having an operating element movable in one direction upon said release of said lever into engagement with said lever during the circuit opening movement of the member and manually movable further in said direction to effect reengagement of said lever and said catch, said operating member being manually movable in the opposite direction to eii'ect reengagement of said latch and said catch and to move said member v to the closed circuit position.

JOHN A. FAVRE. REFERENCES CITED UNITED STATES PATENTS Name Date Runke Sept. 5, 1944 Number