US2760032A - Circuit interrupters - Google Patents

Description

Aug. 21, 1956 Filed Sept. 26. 1952 B. P. BAKER ETAL 2,760,032

CIRCUIT INTERRUPTERS 2 Sheets-Sheet 1 Fig.2.

INVENTORS Benjamin P. Baker 8 GYeorge B. Cushin B Aug. 21, 1956 Filed Sept. 26,

B. P. BAKER EIAL CIRCUIT INTERRUPTERS 2 Sheet s-Sheet 2 Fig.7. /*r

L m l\\mm Fig.8.

WITNESSES: INVENTORS Benjamin P. Baker 8 Geor e.B. Oushin BY 9 9 ATTORN United States Patent CIRQUIT INTERRUPTERS Benjamin P. Baker and George B. Cushing, Turtle Creek, Pa., assignors to Westinghouse Electrie Corporation, East Pittsburgh, Pa, a corporation of Pennsylvania Application September 26, 1952, Serial No. 311,766

10 Claims. (Cl. 209-150) This invention relates to circuit interrupters in general, and, more particularly, to arch-extinguishing structures therefor.

A general object of our invention is to provide an improved circuit interrupter in which excessive arc elongation is prevented, thereby preventing the occurrence of excessive pressures within the arc chamber.

A more specific object is to provide an improved arcinghorn construction whereby the arc length is controlled to prevent the excessive elongation thereof.

Another object is to provide an improved circuit interrupter of the type establishing a pressure-generating arc and a serially-related interrupting arc, in which an improved arcing-horn construction is utilized adjacent the path of movement of the pressure-generating arc to prevent the excessive elongation thereof.

Further objects and advantages will readily become apparent upon reading the following specification, taken in conjunction with the drawings, in which:

Figure 1 is a side elevational view, partially in section and partially diagrammatic, showing a circuit interrupter embodying our invention, the contact structure being shown in the closed-circuit position;

Fig. 2 is a vertical sectional view taken through the lefthand arc-extinguishing unit of the interrupter of Fig. 1, drawn to an enlarged scale, and the contact structure being shown in the closed-circuit position;

Fig. 3 is an enlarged top plan view of our improved arcing horn;

Fig. 4 is a vertical sectional view taken through the arc horn of Fig. 3 along the line IV-IV, looking in the direction of the arrows;

Fig. 5 is an end elevational view of the arc horn shown in Figs. 3 and 4;

Fig. 6 is an enlarged fragmentary vertical sectional view taken through a modified type of circuit interrupter, showing an alternate form of embodiment of our invention, the contact structure being shown in the partiallyopen-circuit position;

Fig. 7 is a vertical sectional view taken along the line VII-VII of Fig. 6; and

Fig. 8 is an inverted plan view of the top dome casting forming the pressure-generating chamber of the modified type of circuit interrupter set out in Figs. 6 and 7.

In circuit interrupters of the fluid-blast type, particularly those in which the fluid is a circuit-breaker liquid, such as oil, especially for the high-capacity circuit breakers in which heavy current arcs may be drawn, it has been observed that the pressure-generating are, which may vary in length from 1V2 inches to 3 inches, may very suddenly move from its normal position on the contacts to strike to a remote point on the inside of the pressure chamber, thereby increasing the length thereof suddenly and producing a tremendous pressure surge. Such a pressure surge, caused by the sudden increase of length of the pressure-generating arc, may create a hazardous condition, which may fracture the interrupter tie-rods, fiber Patented Aw. 21., was

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plates or even the pressure-chamber casting itself. While it is possible to strengthen these parts, the extra length of the uncontrolled arc produces excessive pressure which does no good and results in undesirable breaker stress and external demonstration. Our invention is particularly concerned with controlling the length of an arc, which may be a pressure-generating arc, by a novel arcing-horn construction.

Referring more particularly to Fig. l, the reference numeral 1 designates a tank filled to the level 2 with an arc-extinguishing liquid 3, in this instance, circuit breaker oil. Depending from the cover 4 of the tank 1 are two terminal bushings 5, 6 to the lower ends of which are appended arc-extinguishing units 7, 8.

Electrically interconnecting the arc-extinguishing units 7, 8, and operating the same is a conducting cross-bar 9, vertically actuated in a reciprocal manner by an insulating lift rod 10. The lift rod 10 is actuated by any suitable mechanism, which forms no part of our invention.

Fig. 2 shows, on an enlarged scale, the left-hand arcextinguishing unit 7 of Fig. 1. Referring to Fig. 2, it will be observed that threadedly secured to the terminal stud 11, extending interiorly through the left-hand terminal bushing 5, is a contact foot 12. The contact foot 12 has a bifurcated clamping portion 13, interiorly threaded to match the threads at the lower end of the terminal stud 11, and a clamping bolt 14 extends through apertures 15 provided at the extremities of the two legs of the bifurcated clamping portion 13 to clamp the contact foot 12 fixedly in position once adjustment has been made.

The contact foot 12 is secured by three triangularlydisposed bolts 16 to a top dome casting 17, which defines a pressure-generating chamber 18. Within the pressure-generating chamber 18 a movable hook-shaped pressure-generating contact 19 separates upwardly away from an intermediate contact, generally designated by the reference character 2%, to establish a pressure-generating arc therebetween. Certain features of the contact foot 12 and pressure-generating chamber 18 are set forth and .claimed in United States patent application filed July 31, 1951, Serial No. 239,462 by Benjamin P. Baker and Wayne S. Aspey, now U. S. Patent No. 2,695,349, issued November 23, 1954, and assigned to the assignee of the present application.

Cooperable with the intermediate contact 20 is a lower movable interrupting contact 21 having a lower cap portion 22, which serves as a lower seat for a battery of accelerating compression springs 23, clearly shown in Fig. 2.

The left-hand end 24 of the conducting cross-bar 9 strikes the lower end of the cap portion 22 of the lower movable interrupting contact 21 and moves the same upwardly during the closing operation, in opposition to the biasing action exerted downwardly by the battery of compression springs 23. The end 24 of the cross-bar 9 has an insulting block 24' of fibre which strikes an insulating side operating rod 25, which is biased downwardly by an accelerating compression spring 26, the latter seating upon a washer 2'7 resting upon a nut 28 threadedly secured to the lower metallic threaded portion 29 of the operating rod 25.

The upper end of the side operating rod 25 has a slot 25a therethrough, through which passes a pivot pin 90. The pin passes, with slight clearance, through a movable spring housing 91, enclosing a compression spring 91a, and also through the upper ends of two links 92 disposed on opposite sides of the spring housing 91. The lower ends of the links 92 are pivotally secured, as at 93, to two actuating arms 94. The actuating arms 94 are part of an integral casting including the pivot shaft 95 and the pressure-generating contact 19.

Thus, upward movement of side operating rod 25 will close the pressure-generating contact 19, through the pin 99 and interconnecting linkage 92, 94, with the pin 90 moving down slightly in slot 25a of rod 25 for contact compression. Downward movement of the side operating rod 25 will first effect engagement of pin 90 with the upper end of slot 250 of rod 25 to initiate movement of the contact 19. Further downward movement of rod 25 will. through the linkage, effect clockwise opening motion of pressure-generating contact 19.

The separation of the lower movable interrupting contact 21 from the intermediate contact 20 draws an interrupting are, not shown, within an interrupting chamber, generally designated by the reference numeral 30 in Fig. 2. This interrupting chamber 30 is defined by a plurality of superimposed suitably configured insulating plates forming collectively a plurality of orifices 31, through which the rod-shaped movable interrupting contact 21 passes. A plurality of pairs of inlet passages 32 is also defined by the plate structure, and these pairs of inlet passages connect with two vertical flow passages, generally designated by the reference character 33, and hydraulically interconnecting the pressure-generating chamber 18 with the interrupting chamber 30.

The particular features of the passage arrangement defined by the plate structure form no part of our invention, and reference may be had to U. S. Patent Number 2,467,760, issued April 19, 1949, to Leon R. Ludwig, Benjamin P. Baker and Winthrop M. Leeds, and assigned to the assignee of the instant application, for a full description of the details of the plate arrangement, together with a full explanation of the theory of arc interruption.

For our purpose, it is merely necessary to know that liquid under pressure generated within the pressure-generating chamber 18, by the drawing of the pressure-generating are between contacts 19, 20, passes downwardly through the vertical flow passages 33 and through the several pairs of inlet passages 32 to strike the interrupting are, drawn between the contacts 29, 21 through the orifices 31. The oil, after passing through the orifices 31, is exhausted out of the extinguishing unit 7 through a plurality of pairs of exhaust passages 34 indicated in Fig. 2. For a full description of the configuration of the exhaust passages 34, reference may be had again to the aforesaid Patent 2,467,760.

The plate structure is mounted upon insulating tie-rods 35, and compression springs 36, encircling the tie-rods 35 serve to compress the several plates together under a suitable pressure.

Disposed at the lower end of the arc-extinguishing unit 7 is a cylindrical piston member 37, picked up during the opening operation after a predetermined time delay by an actuating ring 33 disposed interiorly within the cylindrical piston member 37, and serving as a lower seat for a piston compression spring 39. This time delay is described and claimed in United States Patent 2,592,635 issued April 15, 1952, to Winthrop M. Leeds, Robert E. Friedrich and Francis J. Fry, and assigned to the assignee of the instant application. Thus, during the opening operation, the piston 37 remains stationary until a shoulder 40, or externally extending flange portion, on the actuating ring 38 strikes an inwardly extending flange portion 41 of the piston 37, at which time the piston 37 moves downwardly with the actuating ring 38 to create pressure within a piston chamber 42.

The piston chamber 42 hydraulically interconnects through passages, not shown, with the interrupting chamber 30 so that during low current interruption, or during the interruption of charging currents of relatively low amperage, where the pressure generated within the pressure-generating chamber 18 is weak, at this time liquid will flow upwardly from the piston chamber 42 into the inter- 4 rupting chamber 34) to effect extinction of the interrupting arc therein.

Preferably, an inlet valve 43, or one-way acting flap valve, is provided to close upon the downward working stroke of the piston 37, and to open during the closing operation of the interrupter, at which time the piston 37 moves upwardly with the cap 22 of the lower interrupting contact 21. Obviously, the return upward stroke of the piston 37 tends to cause cavitation within the piston chamber 42, and at this time the inlet valve 43 will open to permit the drawing of fresh oil into the piston chamber 42 in readiness for the subsequent opening operation.

Substantially normal oil pressure inside the tank exists upon the top, or non-working side, of the piston 37 by virtue of ports 44 leading to the region cxtcriorly of the unit 7. These ports 44 are simply slots provided in the lower plates 45 and collectively provide a passage to the outside of the unit 7. Since normal oil pressure inside the tank exists on the rear side of the piston 37, it will be inoperable during high current interruption when high pressure exists within the extinguishing unit 7. Thus, this high pressure existing during high current interruption will prevent downward working motion of the piston 37 under the influence of piston spring 39, so that at this time the interrupting contact 21 will move downwardly with the cross-bar 9 separating from the actuating ring 38 and piston 37. Following a subsidence of the pressure Within the unit 7 following circuit interruption, the piston 37 will then move downwardly and provide a flushing flow of liquid into the interrupting chamber 30.

Figs. 3-5 show more clearly the novel arcing-horn construction 46 of our invention, which controls the length of the pressure-generating arc 47 shown by the dotted lines in Fig. 2. Referring to Figs. 35, it will be observed that the arcing horn 46 is of bifurcated, or forked, construction, having a pair of laterally extending legs 48, 49, each of which includes an open-loop portion 50, more clearly shown in Fig. 4 of the drawings.

Bolts 51 (Fig. 2) secure the arcing horn 46 fixedly in position, and the legs 48, 49 straddle the upward opening movement of the tip 52 of the pressure-generating contact 19, as more clearly shown by the dotted lines 53 in Fig. 2.

If the upper end of the pressure-generating are 47 should strike to the point A of Fig. 4, the current will pass through the arcing horn 46 in the direction indicated by the arrows 54, thereby providing a lateral magnetic biasing force, indicated by the arrow 55 moving the upper terminal of the pressure-generating are 47 toward the gap 56.

Should, however, the upper terminal of the pressuregenerating are 47 strike to the point B of the arcing horn 46, the current flow thereto within the arcing horn 46 will pass through the arcing horn 46 in a manner indicated' by the arrows 57, thereby providing a lateral magnetic biasing force, indicated by the arrow 58, which again moves the upper terminal of the pressure-generating are 47 toward the gap, or open space 56.

As a result, no matter where the upper terminal of the are 47 attaches, to either leg 48 or 49, it will be magnetically biased toward the gap 56 and will remain localized at this point, thereby providing a relatively fixed arc length. Excessive pressures are, hence, avoided, which might otherwise result from the upper terminal of the pressure-generating are 47 striking to the points C, D, or'E of the top dome casting 17. It must, of course, be remembered that the are, as initially established, does not extend in a straight line, but is wavy and irregular in shape. Such instability in the form of the arc brings about a looping or bowing configuration thereof, which maybe cumulative and, hence, will bring about such a striking of the are from the tip '52 of the pressuregenerating contact 19 to 'a remote point of the top dome casting 17, as indicated heretofore at the positions C, D or E, if the present invention is not used.

Thus, the arc horn 46 effectively controls the length and, hence, the pressure of the pressure-generating are 47, thus relieving the interrupter 7 from excessive internal stress.

Figs. 6-8 indicate an alternative form of our invention in which a plurality of inwardly-extending arcing horns 59 is provided. The inner extremity of each of these horns 59 extends adjacent to the path of movement of the tip 52 of the rotatable pressure-generating contact 19. We provide additionally an arcing horn 60 of bifurcated, or forked, construction having two legs 61, 62, which straddle the opening path of movement of the tip 5'2 of the pressure-generating contact 19.

To prevent inhibition of movement of fluid within the modified top dome casting 17a, we provide apertures 63 in the arcing horns 59.

The theory of operation of this form of our invention is similar to that heretofore described; namely, the attachment of the upper terminal of the pressure-genome ing are 47 to either of the arc horns 59, or to either of the legs 61, 62 of the bifurcated arcing horn 60 will cause the current flow within the arcing horn to move in laterally, as indicated by the arrow 64 of Fig. 6, indicating the state of affairs should the arc strike the arcing horn 60. The lateral magnetic biasing force indicated by the arrow 65 will. run the arc out to an extremity of one of the legs 61, 62 where it will remain, thereby being of substantially fixed length.

Should, however, the arc strike to a portion of one of the other are horns 59, as indicated in Fig. 7, the current flow through the arcing horn 59 will be in the direction indicated by the arrow 66 with a lateral magnetic biasing force indicated by the arrow 67. This will force the arc inwardly to the inner extremity of the are born 59 where it may possibly remain, being of fixed length.

Consequently, no matter where the upper terminal of the pressure-generating are 47 strikes to the arc horns 59, 60, it will be fed by a current flow passing laterally inwardly within the respective arc horn, thereby providing a lateral magnetic biasing force which will move the arc toward the region 68 (Fig. 8) disposed adjacent the central meeting point of the inner extremities of the several arc horns 59, 6t), and adjacent the path of opening movement of the tip 52 of the pressure-generating contact 19.

From the foregoing description of two different forms of our invention, it will be seen that we have eliminated excessive elongation of the pressure-generating are by the upper terminal of the same jumping to diflerent conducting points of the pressure-generating chamber. By controlling the length of such pressure-generating arc, the pressure generated thereat is controlled, and internal stress is relieved within the interrupter.

Although we have shown and described specific structures, it is to be clearly understood that the same were merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art without departing from the spirit and scope of the invention.

We claim as our invention:

1. A circuit interrupter of the fluid-blast type including an arc-extinguishing fluid, a pair of cooperable contacts separable in said fluid to form an IBIC, one of said contacts being rotatable, a bifurcated arcing horn with separate legs extending laterally inwardly with respect to the direction of arc lengthening with the legs substantially straddling the rotatable contact to control the arc and prevent excessive arc elongation, and said bifurcated arcing horn being at the same potential as the movable contact and spaced from the other contact a distance substantially equal to the desired arcing distance.

2. A circuit interrupter of the fluid-blast type including ing an arc-extinguishing fluid, a pair of cooperable contacts separable in said fluid to form an arc, one of said contacts being movable, a bifurcated arcing horn at the same potential as said one movable contact extending laterally inwardly with respect to the direction of arc lengthening and substantially straddling the movable contact to control the arc and prevent excessive arc elonga tion, and each leg of the bifurcated arcing horn having an open loop associated therewith.

3. A circuit interrupter of the fluid-blast type including an arc-extinguishing fluid, a pair of cooperable contacts separable in said fluid to form an arc, one of said contacts being movable, "a bifurcated arcing horn extending laterally inwardly with respect to the direction of arc lengthening and substantially straddling the movable contact to control the arc and prevent excessive arc elongation, each leg of the bifurcated arcing horn having an open loop associated therewith, and the gap of each open loop facing the other contact.

4. A circuit interupter of the fluid-blast type including an arc-extinguishing fluid, a pair of cooperable contacts separable in said fluid to form an arc, one of said contacts being movable, and a plurality of laterally-inwardly extending arc horns all at the potential of the movable contact having their inner extremities spaced apart but extending closely about the path of movement of said movable contact.

5. A circuit interrupter including contact means for establishing a pressure-generating arc and a seriallyrelated interrupting arc, the pressure-generating arc sending fluid under pressure toward the interrupting arc to effect the latters extinction, said contact means including a movable pressure-generating contact, and a forked arcing born at the same potential as the movable pressure-generating contact extending substantially at right angles to the path of movement of the pressure-generating arc and having the legs thereof disposed on opposite sides of the path of movement of said movable pressure-generating contact.

6. A circuit interrupter including contact means for establishing a pressure-generating arc and a seriallyrelated interrupt-ing arc, the pressure-generating arc sending fluid under pressure toward the interrupting arc to effect the latters extinction, said contact means including a movable pressure-generating contact, a forked arcing horn extending substantially at right angles to the path of movement of the pressure-generating are and having the legs thereof disposed on opposite sides of the path of movement of said movable pressure-generating contact, and each leg having an open loop associated therewith.

7. A circuit interrupter including contact means for establishing a pressure-generating arc and a serially-related interrupting :arc, the pressure-generating are sending fluid under pressure toward the interrupting arc to effect the latters extinction, said contact means including a movable pressure-generating contact, a forked arcing horn extending substantially at right angles to the path of movement of the pressure-generating arc and having the legs thereof disposed on opposite sides of the path of movement of said movable pressure-generating contact, each leg having an open loop associated therewith, and the gap of each open loop facing the cooperable pressure-generating contact.

8. A circuit interrupter including a pressure-generating chamber, pair of cooperable contacts for establishing an are substantially centrally of said chamber, one of said contacts being movable, a plurality of separate :arc horns all at the potential of the movable contact extending convergingly inwardly from the walls of the chamber substantially at right angles to the path of arc drawal, and the inner extremities of the arc horns spaced apart but extending closely adjacent the path of movement of said movable contact.

9. A circuit interrupter including a pressure-generating chamber, a pair of cooperable contacts for establishing an are substantially centrally of said chamber, one of said contacts being movable, a plurality of separate arc horns all at the potential of the movable contact extending convergingly inwardly from the Walls of the chamber substantially at right angles to the path of arc drawal, the inner extremities of the arc horns spaced apart but extending closely adjacent the path of movement of said movable contact, and one of said are horns being bifurcated with the legs thereof straddling the path of movement of said movable contact.

10. A circuit interrupter including a pair of cooperable contacts separable to establish an arc, one of said contacts being movable, means for restricting lengthening of one end of said are terminating at said one movable contact including an arcing horn configured as an open loop extending inwardly laterally with respect to the direction of are lengthening, said arcing horn being disposed adjacent the path of opening movement of the movable contact and at the potential of said movable contact, the plane of the open loop being substantially parallel to the direction of contact movement with the gap of the open loop facing the other contact, and one end of the arc terminating at the gap of the open loop during the latter portion of the interruption process.

References Cited in the file of this patent UNITED STATES PATENTS 1,961,475 Clerc June 5, 1934 1,982,134 Clerc Nov. 27, 1934 1,984,035 Schwager Dec. 11, 1934 2,227,507 MacNeill Jan. 7, 1941 2,271,989 Prince Feb. 3, 1942 2,470,611 Friedrich May 17, 1949 2.62l,273

Friedrich et a1. Dec. 9, 1952

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