US2780699A - Circuit interrupter - Google Patents

Description

Feb. 5, 1957 w. M. LEEDS 297805Q9 CIRCUIT INTERRUP'I'ER Filed March 24, 1954 2 Sheets-Sheet l WITNESSES INVENTOR Winthrop M. Leeds.

Feb. 5, 1957 w. M. LEEDS 2,780,599

CIRCUIT INTERRUPTER Filed March 24, 1954 2 Sheets-Sheet 2 Fig.3.

United States Patent F Chi-Chill ENTERRUPTER H Winthrop M. Leeds, Pittsburgh, Pa., assignor to Westinghouse Eiectric Corporation, East Pittsburgh, Pa, a corporation of Pennsylvania Application March 24, 1954, Serial No. 418,302

11 Claims. (1. 200-150) This invention relates to circuit interrupters in general,

and, more particularly, to arc-extinguishing structures therefor.

A general object of my invention is to provide an improved circuit interrupter which will effectively'interrupt currents over a wide current range.

A more specific object of my invention is to provide an improved circuit interrupter which utilizes a highcurrent interrupting section in series with a low-current interrupting section, wherein the arc is successively drawn through both sections. I

it is difficult to design a circuit interrupter, particularly for high-voltage circuits, which will have extra-high interrupting capacity, such as 15,000,000 kva. at 230 kv. or 25,000,000 lava. at 330 kv., and which will also be able (I to efiectively interrupt relatively small currents, such-as the order of magnitude of charging currents, or .relatively low magnetizing currents. To prevent the attainment of excessive pressure Within the interrupting unit during the interruption of high short-circuit currents, it is possible to provide considerable venting area to re-: lieve the pressure. Also, the orifice area and the inlet areas leading toward the arc may be increased. However. when this is done, there is the danger that the venting area, orifice cross-section, and inlet area are so great thatthere will not occur effective interruption of relatively low-magnitude currents. .It is a further object of my invention to provide an improved circuit interrupter which will surmount the foregoing difiiculty and will be adequate to interrupt both high and low currents in a very short period of time.

Still a further object of my invention is to provide an improved circuit interrupter in which two lnulti-orifice interrupting sections are provided. One section will have large venting area with relatively large orifices, whereas the other multi-orifice section will have relatively small venting areas with relatively smaller orifices so as .to eifect a more intimate engagement of the forced fluid with the arc. it is a particular feature of my invention that the arc is successively drawn through both sections in series, so that the arc may be readily interrupted within the section which is best adapted for interrupting the particular current.

Yet another object of my invention is to providean improved high-voltage liquid-break circuit interrupter; in which high-current and low-current interrupting sections are present, and wherein a barrier plate, which is preferably valve-controlled, separates the two sections and renders the particular interruptin section operative to interrupt the current which it is particularly designed to interrupt.

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

Figure l is a side elevational view, partially in vertical section, of a circuit interrupter embodying my invention and shown in the closed-circuit position;

intermediate contact 23 aientecl Feb. 5, 1957 Fig. 2 is an enlarged vertical sectional view through the left-hand arc-extinguishing unit of Fig. l, the contact structure being in the partially open-circuit position, and the several parts being in the position for the interruption of relatively low-value currents, such as charging currents, or the like;

Fig. 3 is a view similar to that of Fig. 2 but indicating the state of afiairs during the interruption of relatively hgh-rnagnitude currents, such as fault currents or the like;

4 is a sectional view taken along the line IVIV of FigI Z, looking in the direction of the arrows;

Fig. -5 is a sectional view taken along the line VV of Fig. 2, looking in the direction of the arrows; and

Fig.6 is a sectional view taken along the line VI-VI of Fig. 3.

Referringto the drawings, and more particularly to Fig; 1 thereof, the reference numeral 1 designates a tank filled to the level 2 with a suitable arc-extinguishing fluid 3, in this instance circuit breaker oil. Depending from the cover 5 are a pair of terminal bushings 6, 7, to the, lower ends of which depend a pair of identical arcextinguishing units 8.

Electrically interconnecting the two arc-extinguishing units 8 in series is a conducting cross-bar 9, actuated vertically in a reciprocal manner by an insulating operating rod 10. The operating rod 10 may be actuated by anysuitable operating mechanism, which forms no part of my invention. p, I

Referring to Fig. 2, taken in conjunction with the crosssectional views of Figs. 4 6, it will be observed that a contact foot 11 isprovided, which is threadedly secured and clamped by a bolt 12 (Fig. 1) to the lower threaded end of the terminal stud extending interiorly upwardly within the left-hand terminal bushing 6, as viewed in Fig. l. The contact foot 11 is preferably a casting, which with fabrication defines a pressure-generating chamber, generally designated by the reference numeral 13. Movable within the pressure-generating chamber 13 is a rotatable pressure generating contact 14, pivotally mounted as at 15 and having its outer end of bifurcated construction in the form of two arms 16. These arms 16 are pivot-ally connected by a pin 17 to the upper end of a side insulating operating rod 18 spring biased downwardly by a compression spring 19.

The compression spring 19 has its lower end seated upon a cap. 20 disposed at the lower end of the side operating rod 18, and has its upper end seated upon the under side of an insulating plate 21, which preferably forms a portion of the laminated arc-extinguishing unit 8.

The pressure-generating contact 14 cooperates with an intermediate contact 23, generally indicated, which comprises a pair of opposed contact portions 24, 25 spring-biased apart by a compression spring 26 and being electrically interconnected by shunts 27.

Cooperating with the lower contact portion 25 is a lower movable interrupting contact 2 8 spring-biased downwardly inthe circuit-opening direction by a compression spring 29 and which is moved upwardly in opposition thereto by the outer extremity 30 of the conducting cross-bar 9.

As is well known by those skilled in the art, the pressure-generating contact 14 moves upwardly away from the contact portion 24 of the intermediate contact 23 during the opening operation to establish a pressure-generating are '31 within the pressure-generating chamber 13. Also, the lower movable interrupting contact 28 separates downwardly away from the contact portion 25 of to establish an interrupting are 32, asshown in Figs. 2 and 3 of the drawings. A check valve 33, associated with the pressure-generating chamber 15, is spring-biased by a compression spring 34 to an open position, thereby venting the pressure-generating chamber 13 out of the unit 8 by means of a vent opening 35 formed in the casting '11. As will be noted later on, the check valve 33 remains open during the interruption of relatively low currents, and will close during the interruption of relatively high currents when a greater amount of pressure exists within the pressure-generating chamber 13.

Suitably configured insulating plates are provided const-ituting the arc-extinguishing unit 8 and maintained in contiguous relation adjacent one another by insulating tie-rods 36 having nuts 37 threaded thereon, as shown more clearly in Fig. 1 of the drawings. The tie-rods 36 extend through openings provided in the plates, and serve to maintain the insulating plates in the desired position.

With particular reference to Fig. 2 of the drawings, it will be observed that I have provided a high-current interrupting section 38 immediately below the intermediate contact 23, and also a low current interrupting section 39 in series therewith, which is preferably disposed below a barrier plate 48. The barrier plate 40 has a pair of apertures 41 associated therewith, which, as seen in Figs. 2 and 3, are valve-controlled. The controlling valves 42 are spring biased by compression springs 43 to the closed position against seats 44, associated with an insulating plate 45. The valves 42 may be opened by the attainment of a predetermined pressure within the pressure-generating chamber 13. The enlarged vertical flow passages 46 are formed by the alignment of registering openings provided in the several insulating plates disposed at the upper end of the arc-extinguishing unit 8, as shown in Fig. 2. It will be observed that the interrupting arc 32 is successively drawn into the high-current interrupting section 38 and then through the barrier plate 40 and into the low-current interrupting section 39, the purpose for which will become more apparent hereinafter.

Disposed adjacent the lower end of the arc-extinguishing unit 8 is a piston 47 spring-biased downwardly by a compression spring 48, and picked up during the closing stroke by a cap 49 disposed at the lower end of the interrupting contact 28. It will be observed that the cap 49 provides a lower seat for the compression spring 29. The upper ends of both springs 29 and 48 seat against the lower side of an insulating plate 50, as shown in Fig. 2.

Downward driving motion of the piston 47, as caused by the expansion of the compression spring 48, will effect the driving of fluid, in this instance oil, upwardly within the fiow passages 51, and toward the low-current interrupting section 39, as indicated by the arrows in Fig. 2.

From the foregoing description, it will be apparent that during the closing operation the insulating operating rod moves upwardly carrying with it the conducting crossbar 9. The upward movement of the cross-bar 9 and the extremities 30 thereof strikes the caps 49 of the two units 8 and drives the interrupting contacts 28 upwardly to elfect engagement with the intermediate contacts 23, while at the same time picking up the pistons 47 by engagelligent of the cap portion 49 therewith, as is obvious from Near the end of the closing stroke, the cross-bar 9 will also engage the cap portion 20 disposed at the lower end of the side operating rod 13 to move the same upwardly against the opposition exerted by the compression spring 19. This will efiect through the pivotal connection at 17, a downward closing rotative motion of the pressuregenerating contact 14 to cause it to engage the intermedi ate contact 23, the compression spring 26 providing the requisite contact pressure between the contacts 14, 28 and the contact portions 24, 25 of the intermediate contact 23.

During the opening operation, the insulating operating rod 10 moves downwardly being actuated by suitable mechanism, not shown. 'The downward opening motion of the insulating operating rod 10 efiects corresponding downward opening motion of the cross-bar 9 and the extremities 30 associated therewith. The compression spring 19 will cause the operating rod 18 to maintain engagement with the cross-bar 9, thereby causing opening rotative motion of the pressure-generating contact 14 away from the intermediate contact 23 to establish the pressure-generating arc 31 therebetween. Meanwhile the compression spring 29 maintains the cap 49 of the interrupting contact 28 in engagement with the extremity of the cross-bar 9 to thereby elfect separation between the upper end of the contact 28 and the lower contact portion 25 of the intermediate contact 23 to establish a serially related interrupting are 32 therebetween.

As will be more apparent hereinafter, the pressure generated at the pressure-generating are 31 is efiective to send fluid toward the interrupting are 32 to effect extinction of the latter during high-current interruption, with the piston 47 assisting in the interruption of low-current values, and following the extinction of the arcs 31, 32, the cross-bar 9 separates away from the cap portions 49, moving to the isolating position 52 of Fig. 1, thereby inserting two isolating gaps in clear oil between the arcextinguishing units 8.

The high-current interrupting section 38 will now be described. It will be observed that two plates 53, 53a have a cutout portion 54 removed therefrom, as more clearly shown in Fig. 5 of the drawings. The cutout portion 54 has its extremities 54a of substantially kidneyshaped configuration. There is thereby provided a pair of opposed inlet passages 55, more clearly shown in Fig.

plurality of inlet passages particular reference to Fig. 6 of the drawings, which 5, leading from the vertical flow passages 46 toward the upper portion of the interrupting arc 32. I provide a pair of spaced orifice plates 56 having orifices 57 therethrough, through which the interrupting are 32 is drawn.

Disposed intermediately between the spaced orifice plates 56 is an insulating vent plate 58, which provides a pair of enlarged vent or exhaust passages 59 extending from the arc passage 68 defined by the orifices 57, to the region externally of the extinguishing unit 8, as more clearly shown in Fig. 5 of the drawings. Below the second orifice plate 56 is a relatively wide plate 61 having a cutout portion similar in configuration to that indicated by the reference character 54 of Fig. 5. This then provides two additional inlet passages 55, which are available for the flow of fluid passing downwardly through the vertical flow passages 46, as indicated by the arrows 62. The resulting multi-orifice high-current interrupting section 64 is characterized by inlet passages 55 and exhaust passages 59 of large cross-sectional area, as indicated in Figs. 2 and 5, particularly adapted for the rapid, effective interruption of high currents. If desired, additional inlet plates 61, orifice plates 56 and venting plates 58 could be added, depending on the voltage requirements, as well known by those skilled in the art. Merely for purposes of illustration have I shown only two sets of inlet passages 55 and a single vent plate 58 providing only two opposed vent passages 59.

It will, moreover, be noted that the multi-orifice highcurrent interrupting section 64 is disposed above the barrier plate 40. Below the barrier plate 40, I have provided plate structure, suitably configured, to provide a 65, as indicated in Fig. 2. With shows a cross-section through the low-current interrupting section 39, it will be noted that here the inlet plates 67 have a cutout portion 68 providing the inlet passages 65 of reduced cross-sectional area. Also, orifice plates 69 are provided which likewise have orifices 70 of smaller cross-sectional area than the orifices 57 of the orifice plates 56 of the upper multi-orifice high-current interrupting section 64.

Similarly, a vent plate 71 of composite construction is provided furnishing two laterally spaced plate halves 72, more clearly shown in Fig. 6, which provide opposing vent passages 73 of relatively smaller cross-sectional area than the vent passages 59 of the vent plates 58 of the upper high-current interruption section 38.

As shown in Figs. 2 and 3, I provide three vent plates I i 71 and six pairs of inlet passages 65. If desired, additional multi-orifice sections "could be added, as 'well ltnownby thos'e'skilled inthe art;

the purpose for which will become clear hereinafter. It 'will be noted that the region 75 in back of the piston 47:i's vented freely by the'opening 76 of the piston 47 to'the pressure externally of the unit 8, as indicated in Figs.- 2 and 3. Thus, during high-pressure conditions within the unit 8, the piston 47 may become stalled, due tothe high pressure, and will not move downwardly until the pressure subsides within the unit 8, at which time a flushing flow of liquid, such as oil, will take plaice,

cleaning the unit 8 of sition. High-voltage circuit breakers contaminated particles of decompofor extra high interrupting"capacity, such as.l5,000,000 kva. at.230 kv. or

25,000,000 kvaat'330 kv., are diflicult to design soas to handle the high short-circuitcurrents without building up dangerous internal pressures within the interrupters, and without at the same time venting the chambers so freelyas to reduce the efiectiveness when opening .very light currents, such as transmission line charging current.,..lnstead of attempting to interrupt both high and low-currents in the same section of the interrupter, my invention segregates the .two functionsas follows:

For low current interruption, the large flow channels 46 and the big vents 59 result in negligible pressure .buildup. .The spring 34. holds the top; check yak e33 open. -No attempt is made to interrupt until the .lqwer contact 23 pulls through the barrier plate 40. Pressure rorn the oil pump 47 then produces effective interrupting action as the are 32 is drawn into the multi-orifice low-current interrupting section 74. ,During this time,

. the barrier valves 42 areclosed, conserving oil flow from the piston 47. This, of course, for ces the oil flow from the piston 47 to flow through the three pairs of inlet passages 65 through the relatively small orifices 70 and into intimate engagement with the arc 32. The liquid then flows out of the multi-orifice low-current interrupting section 74 through the three opposed pairs of vent passages '72, as indicated by the arrows 77 of Fig. 6.

Interruption soon follows.

During the interruption of high currents, such as fault currents, or heavy load currents, the high-pressure generated in the upper pressure-generating chamber 13 closes the top check valve 33 and opens the barrier valves 42. The oil pump action is held back due to the stalling of the piston 47, it being remembered that the region 75' back of the piston is freely vented by the opening 76 to the relatively low pressure exteriorly of the unit 8. The large channels and vents 59 permit the interruption of high currents without developing dangerously high pressure within the unit 8. If interruption is not completed when the contact 23 pulls below the barrier plate 40, oil flow through the valves 42 maintains additional interrupting action in the lower multi-orifice low-current interrupting section 74. Extinction of the are soon follows.

It will be observed that the interrupter of my invention, as shown in Figs. 2 and 3, is provided with separate sections of the main gap for high and low-current arcextinguishing action. The upper section 64 is particularly adapted for the interruption of fault currents and relatively high magnitude currents with large orifice areas and vent areas. The attainment of excessive pressure is thereby avoided. The lower multi-orifice low-current interrupting section 7'4 with its relatively small crosssectional area orifices 70 is particularly designed for the interruption of relatively small currents, which generally will not be interrupted prior to being drawn below the stresse barrier plate 40. As mentioned, the piston 47 is particularly effective for theinterruption of su'ch low currents, 'the barrier valves 42 at this time remaining closed.-

Although I have described my invention as being particularly suitable for a high-voltage circuit interrupter adapted for extra high-interrupting capacity, it will be readily apparent to those skilled in the art that certain features of the invention may be applicable to circuit interrupters of lower interrupting capacity, and I intend to cover such adaptations in the appended claims.

It may be noted that following the interruption of high-current values, during which the piston 47 may become stalled due to the high pressure then present within the unit 8, that subsequently, following interruption of the high-current interrupting arc 32 the-pressure will subside and effectivefiushing action may then be obtained by the piston 47, which was temporarily stalled. In all cases, thecross-bar 9 separates away from the units 3 to insert the disconnect gaps in clear oil and maintaining the circuit open.

' Although I have shown and described aspecific structure, it is to be clearlyunderstood that the same was 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.

v 1 claim as my invention:

1. A circuit interrupter including means for establishing a pressure-generating arc and a serially related interrupting arc, a multi-orifice high-current interrupting section and a multi-orifice low-current interrupting section through each of. which the interrupting arc is successively drawn, and piston means for forcingfiuid into the multiorifice low-current interrupting section.

2. A circuit interrupter including means for establishing a pressure-generating arc and a serially related interrupting arc, a multi-orifice high-current interrupting section and a multi-orifice low-current interrupting section through which the interrupting arc is successively drawn, piston means for forcing fluid into the multi-orifice lowcurrent interrupting section, a barrier plate between the two sections having a fluid opening therethrough, and valve means controlling the opening.

3. The combination in a circuit interrupter of an arcextinguishing 'unit, a movable pressure-generating c0ntact, a relatively stationary intermediate contact, a movable interrupting contact, an arc passage along which the movable interrupting contact moves during the opening operation, a multi-orifice high-current interrupting section along said are passage having relatively large orifices and at least one relatively large vent, a multi-orifice lowcurrent interrupting section along said are passage having relatively small orifices and at least one relatively small vent, the pressure-generating contact cooperating with the intermediate contact to establish a pressure-generating arc, and the interrupting contact separating from the intermediate contact to draw an interrupting arc successively through said two sections in series.

4. The combination in a circuit interrupter of an arcextinguishing unit, a movable pressure-generating contact, a relatively stationary intermediate contact, a movable interrupting contact, an arc passage along which the movable interrupting contact moves during the opening operation, a multi-orifice high-current interrupting section along said arc passage having relatively large orifices and at least one relatively large vent, a multi-orifice low-current interrupting section along said are passage having relatively small orifices and at least one relatively small vent, the pressure-generating contact cooperating with the intermediate contact to establish a pressuregeuerating arc, the interrupting contact separating from the intermediate contact to draw an interrupting arc successively through said two sections in series, a barrier plate between the two sections having a fluid opening therethrough, and valve means controlling the opening.

- into one of said multi-orifice sections,

greases interrupting arc within the unit, a plurality of multioriflce interrupting sections through which the interrupting arc is drawn, liquid driving means for driving liquid a barrier plate separating the two multi-oriflce interrupting sections, and valve means controlling an opening in the barrier plate to prevent the liquid driving means from driving liquid into the other multi-orifice interrupting section.

6. A circuit interrupter including contact means separable to establish an arc, a multi-orifice interrupting section of relatively large cross-sectional area through which 'the arc is drawn, means for forcing fluid toward the are through said multi-orifice interrupting section of relatively large cross-sectional area, a multi-orifice interrupting section of relatively small cross-sectional area through which said are is subsequently drawn, and separate fluid forcing means for forcing fluid into the second said multi-orifice interrupting section of relatively small cross-sectional area.

7. A circuit interrupter including contact means separable to establish an arc, a multi-orifice interrupting section of relatively large cross-sectional area through which the arc is drawn, means for forcing fluid toward the are through said multi-orifice interrupting section of relatively i large cross-sectional area, a multi-orifice interrupting section of relatively small cross-sectional area through which said are is subsequently drawn, separate fluid forcing means for forcing fluid into the second said multiorifice interrupting section of relatively small crosssectional area, a barrier plate between the two sections having a fluid opening therethrough, and valve means controlling the opening.

8. A circuit interrupter of the fluid-blast type including a multi-orifice high-current interrupting section and a multi-on'fice low-current interrupting section, means for establishing an arc and for drawing said arc successively through each of said interrupting sections, fluiddriving means for forcing fluid through the multi-orifice high-current inten'upting section, and separate fluid driving means for forcing fluid through the multi-orifice low-current interrupting section.

9. A circuit interrupter of the fluid-blast type including a multi-orifice high-current interrupting section and'a multi-orifice low-current interrupting section, means for establishing an arc and for drawing said are successively through each of said interrupting sections, fluid- -driving means for forcing fluid through the multi-orifice high-current interrupting section, separate fluid driving means for forcing fluid through the multi-orifice lowcurrent interrupting section, a barrier plate between the two sections having a fluid opening therein, and valve means controlling the opening.

10. The combination in a circuit interrupter of an arc-extinguishing unit, means defining an arc passage within the unit, a multi-oriflce high-current interrupting section disposed along said are passage having relatively large orifices and at least one relatively large vent, a multi-orifice low-current interrupting section disposed along said arc passage having relatively small orifices and at least one relatively small vent, means for establishing an arc within said arc-extinguishing unit along said are passage and for drawing said arc successively through each of said interrupting sections, fluid driving means for forcing fluid through the multi-orifice highcurrent interrupting section, and separate fluid driving means independent of the first said fluid driving means for forcing fluid through the multi-orifice low-current interrupting section.

11. The combination in a circuit interrupter of an arc-extinguishing unit, means defining an arc passage within the unit, a multi-orifice high-current interrupting section disposed along said are passage having relatively large orifices and at least one relatively large vent, a multiorifice low-current interrupting section disposed along said are passage having relatively small orifices and at least one relatively small vent, means for establishing an are within said arc-extinguishing unit along said are passage and for drawing said arc successively through each of said interrupting sections, fluid driving means for forcing fluid through the multi-orifice high-current interrupting section, separate fluid driving means independent of the first said fluid driving means for forcing fluid through the multi-orifice low-current interrupting section, a barrier plate separating the two interrupting sections and having a fluid opening therein, and valve means controlling the opening.

References Cited in the file of this patent UNITED STATES PATENTS 2,463,029 Fry Mar. 1, 1949

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