US2438373A

US2438373A - Electric switch

Info

Publication number: US2438373A
Application number: US661551A
Authority: US
Inventors: John A Oppel
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1946-04-12
Filing date: 1946-04-12
Publication date: 1948-03-23
Anticipated expiration: 1965-03-23

Description

March 23,1948. PPE 2,438,373

ELECTRIC SWITCH Filed April 12, 1946 Inventor:

John A. OppeI, y -M /m His Attorney.

Patented Mar. 23,, 1948 2,438,373 ELECTRIC swrrcn John A. One], Upper Darby, Pa., asslgnor to General Electric Company, a corporation of New York Application April 12, 1946, Serial No. 661,551 8 Claims. (01. 200-169) My invention relates. to improvements in electric switches, especially circuit breakers and the like, wherein under certain abnormal conditions such as shock or rebound or both the movable contact or contacts tend to move from the circuit open position into either actual engagement with or arc-striking proximity to the cooperating stationary contact or contacts.

It has been found that the movable contacts of electric switches, such as circuit breakers used on warcraft, move abruptly from the circuit open position into either actual engagement with or arc-striking proximity to the cooperating stationary contacts under the effects of shock caused by explosions, gunfire and the like. Such action of the movable contacts damages all the contacts by pounding and also by burning, if any of the circuit breaker terminals are energized. Also such action is quite likely to energize a circuit, momentarily at least, when such energization is not only unwanted but also may prove dangerous to associated apparatus and especially to operating and maintenance personnel. Similar dangerous action may occur when a circuit breaker is opened and rebound causes the movable contacts either aotually to re-engage the stationary contacts or to come within arc-striking distance thereof.

An object of my invention is to provide an improved arrangement for preventing the movable contact or contacts of an electric switch from moving from the circuit open position into either actual engagement with or arc-striking proximity to the cooperating stationary contact or contacts under the effects of shock, rebound and the like. Another object of my invention is to prevent such undesirable action of the movable contacts by an improved arrangement which is relatively simple, economical and readily applicable to existing circuit breaker structures and which does not interfere in any way with the inv tended performance of the circuit breaker. These and other objects of my invention will appear in more detail hereinafter.

In accordance with my invention, I provide, for an electric switch having a stationary contact and a cooperating movable contact and wherein the movable contact tends to move from the circuit open position into either actual engagement with or arc-striking proximity to the of the movable contact toward the stationary contact, means for biasing the catch out of engagement with the stationary element and means for eifecting movement of the catch about the element into holding engagement therewith against the action of the biasing means upon the occurrence, while. the movable contact is in the circuit open position, of an eflect tending abruptly to move the movable contact toward the stationary contact. Also in accordance withjmy invention, this movement effecting means is arranged to cooperate with the biasing means to prevent movement of the catch into holding engagement with. the stationary element during a normal circuit closing operation of the movable contact.

My invention will be better understood from the following description when considered in con- I nection with the accompanying drawing, and its scope will be pointed out in the appended claims.

In the accompanying drawing, Fig. 1 is a side elevation, with parts broken away, of an enclosed circuit breaker embodying my invention, the parts being shown in the circuit open position: Fig. 2 is a side elevation to a larger scale illustrating the embodiment of my invention shown in Fig. 1 on the basis that a shock has eifected a partial circuit closing movement of the movable contact; Fig. 3 is a side elevation similar to Fig. 2 showing the movable contact arrested in its movement toward the stationary contact} and Fig. 4 is a side elevation similar to the other figures, showing the parts after a normal circuit closing operation of the movablecontact.

For the purpose of illustrating my invention, I have shown an embodiment thereof as applied to a multipole circuit breaker of the enclosed type, only as much of the circuit breaker being shown as is necessary to an understanding of my invention. As shown,. the circuit breaker comprises a base, I of suitable insulating material on which the circuit ,breaker mechanism and parts are operating mechanism whereby mounted and a cover 2 also of suitable insulating material. It is to be understood that the illustrated circuit breaker is a three-pole circuit breaker with an operating and latching mechanism applied to the middle pole in a manner well understood by those skilled in the art. My invention, however, is not limited to a three-pole circuit breaker but is applicable to a switch regardless of the number of poles. The operating mechanism is actuable to open and close the circuit breaker by a pivotally mounted operating handle '3, counterclockwise movement of which closes the circuit breaker. The circuit breaker further includes automatic tripping mechanism 4, examples of which are well known to the art.

Each pole of the circuit breaker comprises a stationary contact I and a movablecontact 6, only the contacts of the near outside pole showing in the drawing. As shown, the stationary contact 5 is pivotally supported at I on the base I and is arranged for a limited clockwise movement under the bias of a leaf spring 8. The movable contact 8 is pivotally supported at 9 on a terminal bar l0 suitably secured to the base I as shown in Fig. l. A flexible lead, not shown, interconnects the contact 6 and the terminal bar Ill. For actuating the movable contacts 6 simultaneously into and out of engagement with their respectively associated stationary contacts 5, the

operating mechanism includes a cross bar II..

This bar is carried in bearings l2 which are rotatabiy mounted in supports l3 secured to the base i. For effecting movement of the movable contacts 8 by the turning of the cross bar ii, the operating mechanism includes a connecting linkage such as a toggle comprising links M and i5 pivotally joined at IS. The link i4 is rigidly secured to and insulated from the bar ii and the link [5 is pivotally connected at I! to the movable contact 6. The cross bar I l mayhave mounted thereon a resilient back stop l8 for cushioning the movable contacts 6 at the end of the opening movement.

It will be obvious that any shock, which produces, for example, impact against the base I in the direction indicated by the arrow is in Fig. I, will cause abrupt movement of the movable contact 6 toward its cooperating stationary contact 5. If the shock is severe enough, the contact 8 may come within arc-striking proximity to the contact 5 or even momentarily engage this contact. Similarly, with circuit breakers in which large opening forces are used to cause a quick circuit breaker opening operation, rebound may cause the movable contact abruptly to move close to or even momentarily engage the cooperating stationary contact. In either case, serious arcing, damage to associated apparatus and danger to personnel are almost certain. In order to avoid these undesirable probabilities, I provide, in accordance with my invention, means for so limiting or arresting the abrupt movement of the movablecontact 8 that it cannot engage or come within arc-striking distance of .the stationary contact I.

In the illustrated embodiment of my invention, this motion limiting or arresting means comprises a catch which is mounted to partake of. the

movement of the movable contact 8 and to move relatively thereto. As shown, the catch 20 is piv-' otally mounted on a pin 2| carried by the toggle link it. The catch 2| isthus pendulously supported from and movable with the circuit breaker to partake of the movement of the movable contact 6. For arresting the movement of the catch 20 and thereby.

stopping the movement of the contact 6 toward the contact], I provide a stationary element 22 which, as shown in Fig. 3, is engageable by the biasing the catch out of engagement with the pin 22. As shown, this spring is secured between the outer end of the bracket 23 and the lower end of the catch 20.

Further in'accordance with my invention, I provide means for effecting movement of the catch'20 about the pin 22 into holding engagement therewith against the action of the spring 24 upon the occurrence, while the movable contact is in the circuit open position shown in Fig. 1, cl an eiIect, such as shock or the like, tending abruptly to move the contact. 6 toward the contact 5. As shown, this means comprises 'a guideway on the catch 20 so formed as to have oppositely inclined deflecting and catch

surfaces

25 and 26, respectively, and a straight portion having substantially parallel sides 21 and 28 extending downwardly from the adjacent edges of the deflecting and catch surfaces respectively. The distance between the sides 21 and 28 is such as to permit a relatively free sliding movement between them and the pin 22. In the arrangement shown, the guideway is a longitudinal slot in the catch 20 into which the pin 22 projects. The upper portion of the slot is generally curved, but the catch surface 28 is preferably a plane surface for better engagement with the flat side of the pin 22. The straight sides 21 and 28, of which the side 21 is the longer, intersects the deflecting and catch

surfaces

25 and 26, respectively. The upper portion of the slot is wider than the lower portion and the left side 25 of the upper portion produces an initial deflecting action of the catch 20 in a clockwise direction immediately prior to engagement oi the pin 22 with the plane catch surface 26.

gage the flat side of the pin 22 as shown in Fig.

3, whereby to arrest movement of the contact 6 in the circuit closing direction.

It will further be apparent that, upon subsidence of the condition causing such sudden movement of the contact 8, the catch 20 is relocated relatively to the pin 22 in consequence of the-action oi the spring 24 as shown in. Fig. 1, whereby to permit a normal circuit closing operation of the circuit breaker when desirable. It is also to be noted that impact, on the base I in the direction indicated by the arrow It in Fig. 1. tends to turn the catch 20 clockwise about its pivot 2! whereby to supplement the deflecting reaction betweenthe catch 2t and the pin 22,

resulting from the movement of the contact i toward the contact 6.

Assuming now the parts positioned in the ciraesasvs is engaged by the left edge of the upper portion of the guideway and the catch 20 is held against the pin by the spring 24. Then in case of impact, such as indicated by the arrow il in Fig. 1, the movable contact 8 tends to move abruptly toward the contact I. As a result, the catch 20 is raised and suddenly turned clockwise around pivot 2i because of the impact resulting in the deflecting reaction between the left edge 25 of the guideway and the stationary pin 22 until at some intermediate position the parts are positioned as shown in Fig. 2, the catch 20 still bear-' ing against the left edge of the pin 22 as a fulcrum. But because ofthe abrupt movement causing the deflecting reaction between the catch 20 and the pin 22 and also the clockwise turning eflect of the impact on the catch, even though it is relatively light in weight, the catch surface 28 is quickly moved under the flat side of the pin 22 as shown in Fig. 3. As soon as this occurs, movement of the contact 8 and its con: nected parts is arrested. Then upon subsidence of the condition causing the abrupt movement of relatively wide over a .portion of its length and relatively narrow over the remainder of its length,-

' one side of the wide portion of the slot being the contact 2 toward the contact 5. the contact 6 and its connected parts return to the circuitopenposition shown in Fig. 1. the spring 24 turning the catch 20 counter-clockwise until the left edge of the upper portion of the catch 20 again engages the pin 22. The parts are then again positioned as shown in Fig. 1. In the normal circuit closing operation of the circuit breaker, there is no abrupt movement of the contact 8 and no tendency for the catch to turn clockwise. Consequently, the left side or edge of the guideway is continuously maintained against the left edge of the pin 22 by the spring 24 and the catch 20 moves up freely as the contact 8 approaches the contact 5 'with the pin moving into the lower or straight portion of the guideway as shown in Fig. 4. From the foregoing, it will be noted that the catch 20 does not interfere with the normal operation of the circuit breaker or any locking mechanism for holding the circuit breaker closed. In other words the circuit breaker can be opened either manually or automatically or closed or locked in the closed position without interference from the action of the catch 20. Also, since rebound produces an abrupt movement of the contact 8 toward the contact 5, my

I invention may be used for the purpose of preventing the movable contact 8 from engaging the contact 5 or moving into arc-striking proximity thereto.

While I have shown and described my invention in considerable detail, I do not desire to be limited to the exact arrangements shown, but

1-. For use with a circuit breaker provided with v a stationary contact, a movable contact and operating mechanism connected to the .movable contact for actuation thereof into engagement .with the stationary contact and wherein the movable contact tends to move from the circuit open position into engagement with or arc-strik- I ing proximity to the stationary contact under the abrupt. effects of shock and rebound, an ar- [rangement for preventing such movement of the movable contact under such conditions comprising a catch pendulously supported from and movable with the circuit breaker operating mechanism and provided with a longitudinal slot pin mounted to proiect into'the slot in. said catch.

and biasing means tending to turn said catch in a direction to cause the side of the slot havin the deflecting surface to bear on said pin, the construction and arrangement of parts being such that when the movable contact is in the circuit open position sudden movement thereof toward the stationary contact eifects movement of the catch against the bias thereon to cause the catch surface of the slot to engage said pin whereby to arrest movement of the movable contact in the circuit closing direction and upon subsidence of the condition causing such movement the narrow portion of the slot becomes relocated relatively to said pin whereby to permit a normal circuit closing operation of the'circuit breaker; v

2. For use with a-circult breaker provided with a stationary contact and a movable contact and wherein the movable contact tends to move from the circuit open position into engagement with or arc-striking proximity to the stationary contact under the abrupt effect of a shock, an arrangement for preventing such movement of the movable contact under such a condition comprising a catch mounted to partakevof the movement of the movable contact and to move relatively thereto, said catch being provided with a slot having a relatively narrow straight portion with substantially parallel sides of different lengths and a wider portion having a deflecting surface intersecting the longerside of the straight portion and a catch surface'intersecting the shorter side of the straight portion, a stationary pin mounted to project into the slot in said catch, and means biasing said catch for movement in a direction to cause the side of the slot having the deflecting surface to bear on said pin, the construction and arrangement of parts being such that when the movable contact is in the circuit open position sudden movement thereof toward the stationary contact effects movement of the catch against the bias thereon to cause the catch surface of the slot .to engage said pin whereby to arrest movement of the movable contact in the circuit closing direction and upon subsidence of the condition causing such movement the narrow portion of the slot becomes relocated relatively to said pin whereby topermit a normal circuit closing operation of the circuit breaker.

"3. For use with a circuit breaker provided with a stationary contact and a movable contact and wherein the movable contact tends to move from the circuit open' position into engagement with or arc-striking proximity to the stationary contact under the abrupt effects of shock and rebound. an arrangement for preventing such movement of the m'ovable'contact under such conditions comprising a catch mounted to partake of the movement of the movable contact and to move relatively thereto. said catch being provided with a longitudinal slot having a relatively narrow straight portion with substantially parallel sides of different lengths and a wider portion having a a plane deflecting surface intersecting the longer side of the straight portion and a plane catch surface intersecting the shorter side of the straight portion, a semicylindrical stationary pin mounted to project into the slot in said catch for engagement of its plane surface with one or the other of the plane surfaces of the slot, and means biasing said catch for movement in a direction to cause the side of the slot havingthe deflecting surface with the element whereby to arrest movement of the movable contact in the circuit closing direction but a relatively slow movement of the movable contact in said direction causes movesurface to bear on said pin. the construction and arrangement of parts being such that when the movable contact is in the circuit open position sudden movement thereof toward the stationary contact efiects movement of the catch against the bias thereon to cause the catch surface of the slot to engage the flat side of said pin whereby to arrest movement of the movable contact in the circuit closing direction and upon subsidence of the condition causing such movement the narrow portion of the slot becomes relocated relatively to said pin whereby to permit a normal circuit clostively thereto, said catch being provided with a guideway having oppositely inclined spaced deflecting and catch surfaces and a straight Portion having substantially parallel guide surfaces exment of the catch deflecting surface along the elementand engagement of the element in said intervening guide portion whereby to permit a normal circuit closing operation of the movable contact. I a V 6. For use with an electric switch provided with a stationary contact, a movable contact and operating mechanism comprising a toggle connect-v ed to the movable contact for actuation thereof a into engagement with the stationary contact and tending downwardly from the adjacent edges of said deflecting and catch surfaces, a stationary pin positioned for engagement with said guideway surfaces, and means biasing said catch for movement in a direction to cause the side of the guideway having the deflecting surface to bear on said pin, the construction and arrangement of parts being such that a sudden movement of the movwherein the movable contact tends to move from the circuit open position into either engagement with or arc-striking proximity to the stationary contact under the abrupt effects of shock and re-. 7

bound, an arrangement for preventing such movement of the movable contact under such conditions comprising a catch pivotally sup orted on one of the links of said toggle, a stationary pin engageable by said catch to limit the movement of the movable contact toward the stationary contact, biasing means tending to maintain said catch out of holding engagement with said pin when said contacts are separated, means on said catch for efiectlng a turning movement thereof aboutsaid pin into holding engagement therewith against the action of said biasing means only upon the occurrence while 'the movable contact is in the circuit open position of an effect tending abruptly to move the movable contact toward the stationary contact, and means on said catch coacting with said biasing means to prevent movement of the catch into holding engagement with said pin during a normal circuit closing operation of the movable contact.

able contact in the circuit closing direction causes movement of the catch deflecting surface along said pin to effect enagement oi the catch surface with the pin whereby to arrest movement of the movable contact in the circuit closing direction but a relatively slow movement of the movable contact in the circuit closing direction causes movement of the catch deflecting surface alon said pin and engagement of the pin between said parallel guide surfaces whereby to permit a circuit closing operation of the movable contact.

5. For use with a circuit breaker provided with a stationary contact and a movable contact and wherein the movable contact tends to move from the circuit open position into either engagement with or arc-striking proximity to the stationary contact under the abrupt effect of a shock, an arrangement for preventing such movement of the movable contact under such a condition comprising a catch mounted to partakeof the movement of the movable contact and to move roletively thereto, said catch being provided with a guideway having spaced deflecting and catch surfaces and an intervening guide portion comprising ment, the construction and arrangement of parts being such that a sudden movement of the movable" contact in the circuit closing direction causes movement of the catch deflecting surface along said element to eflect engagement of the catch 7. For use with an electric switch provided with a stationary contact and'a cooperating movable contact and wherein the movable contact tends to move from the circuit open position into I either engagement with or arc-striking proximity to the stationary contact under the abrupt effect of a shock, an arrangement for preventing such for effecting movement of said catch about said element into holding engagement therewith against the action of said biasing means only upon the occurrence while the movable contact is in the circuit open position of an effect tending abruptly to move the movable contact toward the stationary contact, and means on said catch coacting with said biasing means to prevent movement of the catch into holding engagement with said element during a normal circuit closing operation of the movable contact.

8. For use with an electric switch provided with a stationary contact, a movable contact and operating mechanism comprising a toggle connected to the movable contact for actuation thereof. into engagement with the stationary contact and wherein the movable contact tends to move from the circuit open position into either engagement with or arc-striking proximity to the stationary contact under the. abrupt eifects of shock and reacaaava I 9 bound, an arrangement for preventing such movement of the movable contact under such conditions comprising a catch pivotally supported on one of the links of said toggle, a stationary pin engageable by said catch to limit the movement 5 of the movable contact toward the stationary contact, biasing means tending to maintain said catch out of holding engagement with said pin I when the contacts are separated, and means on said catch foreffecting a turning movement thereof about said pin into holding engagement therewith against .the action of said biasing means only upon the occurence while the movable contact is in the circuit open position of an efiect The following references are of record in the file of this patent:

UNITED STATES PATENTS 10 Number Name Date 1,750,693 Steinmayer Mar. 18, 1930 1,797,959 Larzelere et a1. Mar. 24, 1931 2,374,615 Nickell Apr. 24, 1945 2,425,648

Schaelchlin et a1; Aug. 12, 1947