US2039080A - Circuit interrupter - Google Patents

Description

, April 28, 1936. .1. w. HUFFSTUTTER CIRCUIT INTERRUPTER Filed March 1'7, 1954 l l. .n /9 .l Il /9 l. n. 39 529 6, 3j //.V////'///////y/////////////////,f

ITNESSES;

Patented Apr. 28, 1936 PATENT OFFICE CIRCUIT INTERRUPTER John W.'Huistutter, Pitcairn, Pa., assigner to Westinghouse Electric & Manufacturing Company, East `Pittsburgh, Pa., a. corporation of Pennsylvania Application March 17, 1934, serial No. 716,071

13 Claims.

My invention relates generally to circuit interrupters and particularly to circuit breakers wherein the arc which is established incident to thebpening of the controlled circuit is extinguished within a narrow slot type arc extinguisher.

This type of arc extinguisher is a comparatively recent development in the art of circuit interruption, although the principles on which it operates have been known for a number of years.

Essentially, the device comprises a substantially closed chamber of narrow width which is formed by the proper positioning of a pair of opposed wall members having a relativelylarge area. The wall members are usually substantially fiat and are positioned in parallel planes, which are disposed in proximity to each other'. The space enclosed by these wall members thus comprises a very narrow passageway having a large surface area and a small volume. The breaker contact members are movablewithin this passageway to establish an arc therein.

In the preferred form, the inner surfaces of walls of the passage are formed of a gas evolving material, and immediately upon the establishing of the arc, this material decomposes to form a blast of arc extinguishing gas which flows lateraly through the arc with an expulsive action and thereby effects its extinguish- The operation of these devices has proven very satisfactory under most ordinary circuit conditions, but one diiiiculty has arisen, due to the particular characteristics of the device. -The 35 blast of arc extinguishing gas which effects the extinguishment of the arc results directly from the heating produced by the arc itself, and as a result, the volume of this gas is almost a direct function of the intimacy of contact between the 40 gas evolving walls and the outer surfaces of the arc. Furthermore, the physical dimensions of an electric arc depend, under ordinary conditions, upon the magnitude of current flowing through the arc circuit. Thus, if a narrow slot 45 type circuit interrupter is to effectively extinguish an arc, it is necessary that the spacing of the walls be not greater than the mean diameter of the smallest arc which may be drawn therein, because if the walls are spaced apart further 50 than this, an adequate gas blast will not be pro-l While it is imperative that the walls be spaced sufficiently close together to assure an adequate gas blast when interrupting low current arcs, it is equally important that the spacing of the walls be sufficiently great to prevent the production of dangerous internal pressures which i might damage the device when interrupting arcs of large current magnitude. The result of these conflicting requirements has been the production of a circuit interrupter which was operable 10 over a rather limited range of current values, especially in the higher voltage ratings, and the principal object of my invention is to provide a narrow slot circuit interrupter which shall be capable of extinguishing arcs whose current 15 magnitude may vary over a considerable range.

' In accomplishing this object of my invention, I provide a circuit interrupter having the conventicnal narrow slot chamber wherein the arc is established, and a means for establishing an '20 arc within that chamber. In contrast to the usual form of narrow slot arc extinguisher, however, wherein the passage is of substantially uniform width, I provide a device wherein the arc passage has at least one portion of less width 25 than the remaining portions thereof, and I provide means whereby, during the operation of the interrupter, the arc is initially established externally of the portion of least width and is then drawn into that portion, if not already extinguished. This arrangement permits the operation of a narrow slot type arc extinguisher over a very wide range of current values. Arcs of large current magnitude are extinguished within the wider portions of the arc chamber without the production of excessive volumes of gas or dangerous internal pressures which might tend to mechanically injure `the device and if the magnitude of the arc is low, its ultimate extinguishment is still assured by virtue of the fact that it is drawn into the narrow portion of the chamber subsequent to its. being established within the wider portion.

It is, of course, within the province of my invention that a. narrow slot arc extinguisher having a plurality of portions each progressively smaller in width than the preceding portion could be provided. Through the'arrangement, the range of arc current magnitudes which 5 might be successfully interrupted by the device could, of course, be extended to any desired value.

' A further object of my invention is to provide an improved contact structure particularly suitable for use with the narrow slot arc extinguishing device oi' my invention.

An ancillary object of my invention is to provide an improved lining for a narrow slot arc. extinguishing device constructed according to the principles of my invention, my improved lining to increase the arc extinguishing efiiciency of the device and to minimize any danger from fire or the` like.

These and other objects of my invention will be made more apparent by reference to the accompanying drawing, wherein Figure 1 is an elevational View of a single pole circuit interrupter embodying the principal features of mv invention, a portion of one oi the side walls has been cut away to more clearly illustrate the structural features involved.

Fig. 2 is an elevational view of one of the two wall members which together make up the narrow slot arc extinguisher shown in Fig. 1, and the contact structure of the device shown in that figure. The contacts are in the fully closed position.

Fig. 3 is an elevational view similar to Fig. 2 except that the contacts are in the partially open position.

Fig. 4 is a view likewise similar to Fig. 2 eX- cept that the contacts are in the fully open position.

Fig. 5 is a sectional view on the line V-V of Fig. 2, and

Fig. 6 is a sectional view on the line VI-VI of Fig. 3`

The preferred embodiment of my invention illustrated in the drawing comprises, generally, a pair of wall defining members I, of insulating material which are adapted to be spaced apart by three rectangular members 3, 5, and 1 of insulating material to form a narrow passageway 9 having considerable surface area. This passageway 9 is open at the top, which is the direction toward `which the arc is moved during the normal operation of the device, and is substantially closed on the other three sides by the spacing members 3, 5 and 1. A plurality of bolts which extend through suitable openings in the wall defining members I and the spacing members 3, 5 and 1, are provided for holding the wall dening members and the spacing members in position, and three bolts |3 which extend through insulating sleeves l5 positioned in the wall members I are provided for preventing the internal pressures developed within the device from causing a bulging of the walls. Suitable metallic washers l1 serve to increase the effective contact area of the bolts I3.

'I'he inner surface ot each of the two wall members I is lined with a plurality of tile-like members I9 of compressed borlc acid which are cemented or otherwise securely aiiixed to the opposed inner surfaces of those members. As is shown particularly in Figs. 5 and 6, the tile-like members I9 in the left hand portion 2D of the narrow passageway 9 are thinner than the similar tile-like members I9 'in the right hand portion 2l of the passageway. Thus, the passagel wherein the arc is drawn is divided into two portions, one of which (2|) is considerably less width than the other. This arrangement makes possible the eiiicient operation of the device when interrupting arcs of either of large or small current magnitude.

The contact structure comprises a pair of separable contacts 23 and 25, each of which is provided with a curved arsing horn 21 and a main current carrying portion. The left hand contact 23 is rigidly affixed to the wall members I oi the arc extinguishing device by a bolt 26 and an insulating sleeve 28 and is normally adapted to remain stationary during the operation of the interrupter. The right hand contact 25 includes, as mentioned above, a similar arc horn 21 and a movable main contact member 29 which is adapted to be engaged at the right hand end by the breaker operating mechanism (not shown). The right hand arcing horn 21 is supported upon this main contact member 29 and is movable with respect thereto. A substantially U-shaped saddle 3| extends down from the right hand arcing horn 21 and serves to aid in guiding the movement of that member lwith respect to the main contact member 29, and a pair of springs 32 bias the arcing horn so that the sides of the downwardly projecting saddle 3| tend to engage a pair of stop members 33, one of which is disposed on either side of the main Contact member 29. The stationary Contact 23 is provided with a pair of opposed resilient jaws 35 for engaging the current carrying surfaces 36 of the main contact member 29 when the breaker is in the closed circuit position, and a flexible shunt 31 serves to electrically connect the right hand arc horn 21 with the main moving contact. All portions of the moving contact 25 which move through the narrow portion 2| of the passageway 9 are of slightly less Width than that portion of the passageway in order that no friction or interference shall develop during the operation of the interrupter.

The circuit breaker contacts are shown in the closed circuit position in Fig. 2. During the circuit opening operation, the main moving contact member 29 is moved by the operating mechanism from the position shown in Fig. 2 toward the position shown in Fig. 4. The initial portion of this movement causes the current carrying surfaces 36 of the main moving contact to disengage the cooperating jaws 35 afiixed to the stationary contact 23. This portion of the movement does not, however, open the circuit through the interrupter, by virtue of the fact that the right hand arcing horn 21 is movable with respect to the main movable contact member 29, and by virtue oi the fact that the springs 32 bias the right hand are horn. 21 into engagement with the cooperating left hand arcing horn. Further movement of the main current carrying member 29 of the movable contact 36 causes the stops 33 to engage the sides of the saddle 3|,

whereupon the right hand arcing horn disengages the left hand arc horn and moves to the position shown in Fig. 4. The circuit interrupter is then in the fully open position.

An arc is established immediately upon the separation of the arc horns 21 and by virtue of the location of those members, is initially established within the wider portion 2U of the narrow passage 9. The heat of the arc decomposes the boric acid lining of the opposed side walls, end if the magnitude and physical dimensions of the arc are su'licient to intimately contact those walls, produces a very large outiiowing blast of arc extinguishing gas. Since the arc extinguishing device is substantially closed on all sides except the top and since the contour of the arcing horns 21 is such that the magnetic effect of the arc current tends to move the are upwardly along those horns, the outfiowlng gas produced by the decomposition of the walls flows laterally through the arc as it escapes, and the arc is extinguished within a very short interval of time.

If the magnitude of the arc current is insumcient to effect an extinguishment of the arc in the wider portion 20 of the narrow passage 9, the movement of the right hand arcing horn 21 during the final stages of the circuit opening operation causes the arc to be drawn into the narrower portion 2l of the passage, wherein it intimately contacts the adjacent walls and its extinguishment is effected.

The operating mechanism for use with this type of circuit interrupter is not an important part of my invention, and any means whereby the main movable contact 29 can be moved from one position'to the other may be used. It is preferable that the contact be moved to the open position at high speed, although at least one or two cycles should elapse before the arc is drawn into the narrower portion 2| of the passageway in order that suincient time r'nay be allowed for extinguishing the large current magnitude arcs in the wider portion 2U of the passageway.

Both the right hand arc horn 21 and the main moving contact 29 are adapted to move within an opening 39 formed in the side member 1. The

sides of this opening 39 slidably engage the sides of those members and serve, in conjunction with the operating mechanism, to accurately guide the movable contact 25 during the operation of the interrupter,

It should be noted that while the several current carrying portions of the contacts 23land 25 are formed from relatively thin sheets of conducting material, the cross sectional area of the current carrying portions of those contacts is quite large. This is of course accomplished by providing members which are wide in a plane parallel to the planes of the wall defining members 29.

The lining of the passageway 9 is preferably of boric acid, as stated above, because that material, when placed in proximity to an electric arc, evolves a, large quantity of an arc extinguishing gas which is substantiallyinorganic in composition. It is, of course, within the province of my invention that other solid materials might be used for securing this gas blast. Another advantage of boric acid arises from the fact that substantially all of the gas evolved is non-inflammable, and from the fact that the surface of boric acid when exposed to the action of an electric are does not become conducting. Thus, any possibility of the device short circuiting itself during operation is prevented.

From the foregoing, it will be seen that I have disclosed a new and improved circuit interrupter which utilizes the narrow slot principle of arc extinction much more efiiciently than the devices previously known to the art. My improved circuit interruptor is capable of eicient operation over a very wide range of arc current values and', at the same time, is relatively simple in design and inexpensive to manufacture. In addition, I have disclosed an improved contact structure which is particularly suitable for use with all types of narrow slot type circuit inter# rupters wherein relatively heavy currents have to be carried during the normal operation of the device. K

While, in accordance with the patent statutes, I have disclosed the foregoing details of a preferred embodiment of my invention, it is, to be understood that many of these details are merely illustrative and that variations in their precise form will be both necessary and desirable for certain applications. It is my desire, therefore, that the language of the accompanying claims shall be accorded the broadest reasonable construction, and that my invention shall be limited only by what is vexpressly stated therein and by the prior art.

I claim as my invention:

1. In a circuit interrupter, a pair of wall members of extended surface area, means for supporting said wall members in close proximity to each other so as to define the opposed walls of a narrow passageway, the Width of at least one portion of said passageway being less than the width of the remaining portions thereof, and means comprising contact means movable in said portion of less width and in said remaining portions to establish an arc within said passageway, said arc being initially established externally of the narrow portion of said passageway and a portion thereof being subsequently drawn within the said narrower portion of said passageway, said arc drawing means comprising conducting means at least a portion of which has a width not greater than the width of the narrower portion of said passageway.

2. In a circuit interrupter, means defining a pair of wall members of considerable surface area, means for supporting said wall members in close proximity to each other so as to define the opposed walls of a narrow passageway, said wall members being so formed and so positioned that at least one portion of said passageway is of less width than the remaining portions thereof, contact means movable within said portion of less width and within said remaining portions to establish the arc incident to each opening of said interrupter within said passageway, said arc being initially established externally of said portion of less width and being subsequently drawn within said portion of less width if not already extinguished, at least one of said wail defining members being lined with a solid material that is capable of evolving considerable quantities of an arc extinguishing gas when placed in proximity to an electric arc, and means for so venting said passageway that substantially all the gas which is evolved from said lining is caused to flow laterally through said arc during the progress of the circuit opening operation.

3. In a circuit interrupter, means defining a pair of wall members of considerable surface area, means for supporting said wall members in close proximity to each other so as to define the opposed walls of a narrow passageway, the opposed surfaces of said wall defining members being disposed substantially parallel to each other and being so formed that at least one portion of said passageway is of less width than the remaining portions thereof, contact means movable within said portion of less width and within said remaining portions to establish the arc incident to each opening operation of said interrupter within said passageway, said arc being initially established externally of said portion of less width and being subsequently drawn within said portion of less width if not already extinguished, at least one of said wall defining members being lined, at least in part, with a solid material that is capable of evolving an arc extinguishing gas when placed in proximity to an electric arc, said gas evolving lining extending across a substantial portion oi' said portion of less Width and said remaining portions of said passageway, and means for so venting said passageway that substantially all of the gas which is evolved from said lining is caused to flow laterally through said arc 'during the progress of the circuit opening operation.

4. In a circuit interruptor, means defining a pair of wall members of considerable surface area, means for supporting said wall members in close proximity to each other so as to denne the opposed Walls of a narrow passageway, said wall members being so formed and so positioned that at least one portion of said passageway is of less width than the remaining portions thereof, contact means movable within said portion of less width and said remaining portions to draw an arc within said passageway, means for moving said arc laterally within said passageway, and means for substantially totally enclosing said passage except for vents disposed adjacent the side toward which the arc is moved by said arc moving means.

5. In a circuit interrupter, means including a pair of oppositely disposed wall members of considerable surface area for dening the walls of a narrow passageway, said wall defining members being so formed and so positioned that at least one portion of said passageway is o! less width than the remaining portions thereof, a substantial portion of the inner surface of at least one of said wall defining members, both in said portion of less width and in said remaining portions, being lined with a material which is capable of evolving an arc extinguishing gas when placed in proximity to an electric arc, contact means movable in both portions of said passageway to establish an arc having a portion Within said portion of less width and a portion within said remaining portions, said portion of said arc which is established within said portion of less width being drawn subsequently to said other portion of said arc, and means for so venting said passageway that the gas evolved from said lining is caused to flow simultaneously through said portion of less width and said rcmaining portions in order to move said arc laterally theren during the progress of cach cir cuit opening operation.

6. In a circuit interrupter, means including a pair of opposed wall members of considerable area for defining the walls of an are passage which has the substantial form of two connecting rectangular parallelopipecls of diilcring thicknesses, the surface area of said opposed wall members being at least several times the cross sectional area of said arc passage along either the longitudinal or the vertical axis thereof, a substantial portion of the inner surface of at least one of said wall members being lined with a material which is capable of evolving an arc extinguishing gas when placed in proximity to an electric arc, contact means movable both portions cf said passageway to establish an arc having a portion within said wider portion and a portion within said narrower portion of said arc passage, and means for venting said passage in such manner that the gas evolved from said lining effects a substantial lateral movement of the portion of said arc which is drawn within each of said portions of said passage during the progress of each circuit opening operation.

7. In a circuit interrupter, means including a pair of oppositely disposed plate members of considerable surface area for defining the walls of a narrow passageway, said wall defining members being so formed and so positioned that at least one portion of said passageway is of less width than the remaining portions, means for substantially completely enclosing said passageway except for venting means located adjacent one end thereof, a substantial portion of the inner surface of at least one of said plate members in said portion of less width and in said remaining portions being lined with a material which is capable of evolving an arc extinguishing gas when placed in proximity to an electric arc, and contact means movable in both portions of 4said passageway to establish an are having a portion within said portion of less Width and a portion within said remaining portions, said portion of said arc which is established within said portion of less Width being drawn subsequently to said other portion of said arc, said venting means being so arranged that the gas evolved from said lining by the heat of said arc is caused to flow laterally through said portion of less width and said remaining portions during each circuit opening operation, the portion of said arc' which is established within said portion of less 'width and within said remaining portions being thereby moved laterally a considerable distance within said passageway during the progress of each cir cuit opening operation.

8. In a circuit interrupter, means including a pair of oppositely disposed plate members of considerable surface area for defining the walls of a narrow passageway, said wall defining members being so formed and so positioned that said passageway comprises a pair of connecting rec ltangular parallelopipeds, means for substantially enclosing said arc passage except for venting means located adjacent one end of each of said rectangular paralielopipeds, a substantial portion of the inner surface of at least one of said plate members being lined with a solid material which is capable of evolving an arc extinguishing gas when placed in proximity to an electric arc, means including a pair of separable contacts for establishing an arc within said passage adjacent one of its closed sides, said arc drawing contacts being movable within both of said parallelopipeds in order that said arc shall be initially established within said parallelo piped of greater width and that a portion of said arc shall be subsequently established within said parallelopiped of less width, said venting means being so arranged that the gas evolved from said lining by the heat of said arc is caused to ow laterally through each of said connecting parallelopipeds during each circuit opening operation, the portion cf said arc which is drawn with in'each of said peraliciopipeds being thereby moved laterally in the direction of said vented end during the progress of the circuit opening operation.

9. In a circuit interrupter, means, including a pair of oppositely disposed wall members of considerable surface area, for denng the walls of an arc chute, said wall defining members being sovformed and so positioned that at least one portion of the passageway within said chute is of less width than the remaining portions thereof, a substantial portion of the inner surface of said wall defining means both in said portion of less width and in said remaining portions being lined with a solid material which is capable of evolving an arc extinguishing gas when placed in proximity to an electric arc, means for establishing the are incident to each opening operation of said interrupter within said are chute,-one portion of said arc being established within said portion of less width and another portion of said arc being established within said remaining portions, and

ing lined with a solid material which is capablel of evolving an arc extinguishing gas when placed in proximity to an electric arc, means for establishing the arc incident to each opening operation of said interrupter within said arc chute, one portion of said arc being established within said portion of less width and a second portion of said arc being established within said por-- tions of greater width, diverging arc horns disposed within said arc chute for providing termi- A nals for the ends of said arc, and means for causing said arc to be moved laterally on said arc horns to effect its extinguishment during each operation of said interrupter,

11. In a circuit interrupter, means, including a pair of oppositely disposed wall members of considerable surface area, for defining the walls of an arc chute, said wall defining members being so formed and so positioned that at least a portion of the passagewaywithin said arc chute is of less width than the remaining portions thereof, a substantial portion of the inner surface of said wall defining means both in said portion of less width and in said remaining portions being lined with a solid material which is capable of evolving an arc extinguishing gas when placed in proximity to an electric arc, means for establishing the arc incident to each opening operation of said interrupter within said chute, said arc establishing means drawing a portion of said arc within said portions or portions of greater width and subsequently drawing a portion of said arc into said portion of less Width, diverging arc horns disposed within said arc chute for providing terminals for said arc, and means for venting said chute in such manner the gas evolved from said lining effects a substantial lateral movement of said arc on said arc horns during the progress of each circuit opening operation, said portions of less width and said portions of greater width being arranged side by side and extending in the direction in which said arc is moved on said arc horns in order that the portion of said arc which is established within each oi' the portions of said passageway shall remain therein throughout the entire arc extinguishing operation.

12. In a circuit interrupter, means, including a pair of oppositely disposed wall members of considerable surface area, for defining the walls of an arc chute, the passageway within said chute having a substantial form of two, connecting, rectangular parallelopipeds, the surface area of said opposed Wall members being at least several times the greatest cross sectional area of said arc passage alongeither the longitudinal or the vertical axis thereof, a substantial portion of the inner surface of said wall defining means being lined with a material which is capable of evolving an arc extinguishing gas when placed in proximity to an electric arc, means for establishing the arc incident to each opening operation of said interrupter within said arc chute, said arc being initially established within said parallelopiped of greater thickness and a portion thereof being subsequently established within said parallelopiped of less thickness, diverging arc horns disposed within said chute for providing terminals for said arc, and means for venting said chute in such manner that the gas evolved from said lining effects a substantial lateral movement of the portion of said arc which is drawn within each of the portions of said passageway during the progress of each circuit opening operation.

13. In a circuit interrupter, means, including a pair of oppositely disposed wall members of considerable surface area, for defining the walls of an arc chute, said wall defining means being so formed that at least one portion of said passageway is of less width than the remaining portions thereof, a substantial portion of said wall defining means both in said portion of less width and in said remaining portions being lined with a material which is capable of evolving an arc extinguishing gas when placed in proximity to an electric arc, means for establishing the arc incident to each opening operation of said inter-- rupter within said arc chute, one portion of said arc being established within said portion of greater width and another portion of said arc being established within said portion of less Width, diverging arc horns, one of which is disposed within said portion of greater width and one of which is disposed within said portion of less width during at least the final stages of each circuit opening operation, for providing terminals for said arc, and means for venting said chute in such manner that the gas evolved from said lining effects a substantial lateral movement of said arc on said arc horns during the progress of each circuit opening operation.

JOHN W. HUFFSTUTTER.

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