US2424343A - Circuit interrupter - Google Patents

Description

July 22, 1947.

R. C. VAN SICKLE ET AL CIRCUIT INTERRUPTER Filed May 2'7, 1943 5 Sheets-Sheet l Insulation .5 10 5 2 6 6 ,iE-T 5 PE 3 23- 2a 2a T'J'il' 1 12 15 Z4" Z4 15 I2 35 :5

3 t ii ij 'jij I V WITNESSES:

INVENTORS Roswell 6'. Van Sickle, Haber! E Wise rich l flame/'5 Iii 11.:

July 22, 1947.

R. C. VAN SICKLE ET AL CIRCUIT INTERRUPTER Filed May 27, 1943 3 Sheets-Sheet 3 INVENTORS v Roswell 65 l/anfiakle, Robert E Friedrich 1 Francis .1. Fly.

Patented July 22, 1947 1,424,343 CIRCUITfINTERRUPTER Wilkinsburg, and. Robert E. Friedrich and-Francis J..":F1T-1,-Pittsburgh,--Pa.,

.Roswell C. 'Van: Sick assignorstoWestinghouse-Electrio Corporation,

East Pittsburglnlfa a corporationoi' lennsylvania Application'May 21, mia-iseriarno. 488,624 .moiaims. (o zoo-15o) 1 This invention relates to circuit interrupters and, in particulanto arc-extinguishing structures therefor.

There are piston arrangements of the prloria tt I which operate only during lowcurrents and'iare inoperative during high currents beoauseof :the high pressure produced at the arcing region. This high pressure produced atthearcing region serves to overcome the spring pressures biasin the pistons of the prior art, and hence'serves to make theminoperable during the interruption :of high currents. On-the other hand,'by an equalizing of the arcing pressure on both'si'des of, the piston, we are able to; provide. an'improved :circuit breaker structurein which piston action-.zis effective during. both high: and low current interruption.

The principal object of our inventionis', therefore, to provide an improved circuit interrupter of the type which employs,pistonactionzto.assist in the interruption of the-circuit.

In United States patentflipplication entitled Circuit yinterrupters, by Winthrop. M. Leeds, which was filedApril 2, 1943, Serial No. 148L529, and which vwasassigned .tothe nassigneeof :the instant invention, there is discloseriand claimed a high speed piston construction in which a: piston member substantially surrounds. av relatively stationary contact and moves independently there-.- from. ,The piston memberischarged duringthe closing operation by the closing movement 01:. a relatively movable contact which cooperatesgwith the relatively stationary contact. It is a :further object of our invention to improve thehigh speed pistonconstruction set forth in the aforesaidapplication so as to provide .pressureeequalizing means acting upon the .high-speedpiston totem able the piston to be efiective both during the interruption of low and high currents. I J

Another object is toprovideanimproved circuit interrupter of the type which establishes both a pressure-generating and an interrupting are by bringing piston actionnto bear upon the-pressure-generating arc.

Another object is to provide an improved 'ciri cuit interrupter of theltype employinga piston in which thepiston'has an. improved configuration to assist in eiiectively directingfiuid-iflow toward an arc.

Another object is to provide an improvedpiston construction in a circuitinterrupter in whiohithe arcing pressure acting upon .the pistonzaresub stantially neutralized. i

Another object is to provide an improvedpiston construction in acircuit interrupterof'the-type which establishes .both a pressure-generating arc and an interrupting arc by'causing the piston to send fluidsuch as oil wward both. arcs. Preferahly;pressure-equalizing means. are employed in conjunction with such a piston to neutralize .the arcingpressures acting thereon.

-.--By.aniapp1icati0n.0f, our. invention, since the arcing pressuresacting upon the piston are neutralized. rthe pistonxisefiectiveboth during the interruption of high currents as well as during the interruptionrofylow currents. Where the piston forces ,fluid toward the pressure-generating iatfifithc .fiuid'motion created at the pressuregenerating arc is increased, and during the interruption oi 110w currents, the pressure-generating are ecnsequentlymay itself act, as an interrup arc. LA rsinsle pit nmay b mp n a portion for sending fluid toward the pressureenerating arc, and another portion 'for sending fluid .towardthe interrupting arc. If desired, the aroing'ipressuremaysbe neutralized on such a piston to;render the'latter operative independzentiy .oi current -magnitude.

fi rt inzaspects of: our invention m y be cem- "ployed in. circuit'interrupters of'the single break time, :buts'merely Jior purposes of illustration we describetourinventionasapplied to a high-speed circuitinterrupter 10f ithe r threeecycle type which establishes zboth aprcssure-generating arc and a serially rel tediinterruptin arc.

. Eurtheraoioiects and advantages will readily .heoomezapparentunon a reading oi-the iollowing specificationtaken inconjunction with the accompanying drawings, in which:

Figure, 1 .is' an .e evational view, partly in sec- "tionnoi acoircuitdnterrupter embodying our inventionandzshown inithe closed circuit: position;

.iBigzz iscan enlarged view in vertical section of OIIQZ-Ofllhe arc-,extinsuishing'units shown in Fig. v1, theppartsibcingshown in the closed circuit position; i 2 '3:Fiz'.-13::is aview similar toFigv 2 but howin .ther'd 'sposition orthe: parts during a circuit openingi operation;

Fist 4, is. airagmentary enlarged vertical section-a1 viewitakenion the; line-IV-JV of Fig. 2;

cl 9 181 51 is an invertedxplan .view in cross-section :taken alongthei :line VV of Fig. 3

:1- Eig; J6; .is:an-inverted planview in section taken alongtheilinezVkeVI-ofFig. 3 with the compression :springs -55 --omitted for purposes-of clarity;

Fig. 7 is a plan view in section taken .onqthe iinelvfl vll of Fig. 3.; -rEis.:;8.- is"anenlarged fra tary vi win v rticalwsectionof a circuit interrupter embodyin 3 a modification of our invention, the parts being shown in the closed circuit position;

Fig. 9 is a fragmentary vertical sectional view taken on the line IX-IX of Fig. 8, the parts being shown during an opening operation;

Fig. 10 is a plan view in section taken on the line X-X of Fig. 9;

Fig. 11 is a plan view in section taken on the line XIXI of Fig. 9;

Fig. 12 is an inverted plan view in section taken on the line XIIX[I of Fig. 9;

Fig. 13 is a fragmentary view in vertical sec tion of still another circuit interrupter embodying a modification of our invention, the parts being shown in the closed circuit position;

Fig. 14 is a view in vertical section taken on the line XIV-XIV of Fig. 13, the parts being shown during a circuit opening operation;

Fig. 15 is an inverted plan view in section taken on the line XV-XV of Fig. 13; and

Fig. 16 is an inverted plan View in section taken on the line XVI-XVI of Fig. 13.

Referring to the drawings, and more particu larly to Fig. l, the reference numeral designates a tank filled to the level 2 with a suitable arcextinguishing fluid 3, in this instance oil. Depending from the cover 4 of the tank I are two insulating bushings 5 which enclose terminal studs 5. Threaded to the lower end of the terminal studs 6, and suitably clamped thereto, are contact feet 1 which support two arc-extinguishing units, generally designated by the reference numeral 8. In the closed circuit position of the interrupter, as shown in Fig. 1, the arc-extinguishing units 8 are electrically connected by a conducting cross-bar 9 which is reciprocally operated in a vertical direction by an insulating operating rod l9.

Referring more particularly to Fig. 2, it will be observed that the arc-extinguishing unit 8 comprises a top dome casting |2 which forms a pressure-generating chamber, generally designated by the reference numeral 3. Operating within the pressure generating chamber 3 is a pressure-generating or third contact l4 pivotally mounted at IE to the casting |2 and operated by an insulating operating rod IE extending externally of the arc-extinguishing unit 8. The operating rod l5 is guided through an aperture provided in the bottom metallic plate I8. A compression spring l9 encircles the operating rod |6 and is disposed between the metallic plate I 8 and a head 20 integrally formed with the operating rod |6.

An annular flange 2| integrally formed with the operating rod 16 serves as a lower seat for a compression spring 22, the upper end of which engages a washer 23 slidable upon the operating rod IS. The pressure-generating or third contact is operated externally of the casting |2 by two actuating arms 24, only one of which is shown. Both actuating arms 24 have relatively wide apertures 25 formed therein through which extends a pin 25 rigidly connected to and movable with the insulating operating rod IS. A check valve 21' disposed in the casting 2 closes during the existence of high pressure conditions within the pressure generating chamber 3, and opens following a circuit opening operation to permit accumulated gas to escape out of the pressure generating chamber 3 through the check valve 22'.

A flexible conducting strap 28 is secured by a.

Therefore, the pivot 9 are lower movable or second contacts 3|, which cooperate with the relatively stationary or first contacts 29 to establish interrupting or first arcs designated by the reference numeral 32 in Fig. 3 (only one'being shown). An inspection plate 33 covers an opening provided in the top dome casting 2 and permits an operator to inspect the interior of the arc-extinguishing unit 8 without disassembling the unit 8.

In the closed circuit position, as shown in Figs. 1, 2, and 4, the electrical circuit through the interrupter comprises left-hand terminal stud 6, left-hand contact foot 1, casting l2, flexible strap 28, actuating arm 24, pressure-generating or third contact l4, relatively stationary or first contact 29, lower movable or second contact 3|, conducting cross-bar 9 through the right-hand arcextinguishing unit 8 in a similar manner to righthand terminal stud 6.

It will be observed that the relatively stationary or first contact 29 is raised slightly in Fig. 2, as compared with its position in Fig. 3. By such a construction, the compression spring 22 not only serves to supply the desired contact pressure between the pressure generating or third contact l4 and relatively stationary or first contact 29, but also the desired contact pressure betweenrelatively stationary or first contact 29 and lower movable or second contact 3|. When it is desired to open the electrical circuit passing through the interrupter, or in response to overload conditions existing in the electrical screw at one end to the actuating arm 24 and at its other end by a screw to the casting |2.

circuit controlled by the interrupter, suitable operating mechanism, not shown, is actuated to cause a downward movement or the insulating operating rod I0. The downward movement of the'linsulating operating rod 0 also causes downward movement of the lower movable Or second contact 3| and downward movement of the insulating operating rod Hi, the compression spring l9 biasing the latter in a downward direction. The relatively stationary or first contact 29 follows the initial downward movement of the lower movable or second contact 3|. Meanwhile, the compression spring 22 maintains the pressure generating or third contact M in engagement with the relatively stationary or first contact 29 until the pin 26 strikes the bottom of the apertures 25 formed in the two actuating arms 24. When this occurs, the pin 25 positively rotates the pressure-generating or third contact M in a clockwise direction about the pivot |5 to establish a pressure-generating or second are 30, as shown in Fig. 3.

Substantially at the same time the pressuregenerating or third contact |4 separates from the relatively stationary or first contact 29, the lower movable or second contact 3| separates from the relatively stationary or first contact 29 to simultaneously establish an interrupting or first are 32, as shown in Fig. 3. The simultaneous establishing of both a pressure-generating are 30 and an interrupting are 32 leads to high-speed operation of the'interrupter, the time interval between the energizing of the breaker trip coil and the time of extinction of the two arcs being only three cycles.

The arc-extinguishing unit 8 comprises a plurality of suitably shaped insulating platesheld in position by insulating tie rods 34. The upper ends of the insulating tie rods 34 extend through apertures provided in an offstanding flange por tion of the top dome casting |2. The lower ends of the insulating tie rods 34 extend through apertures provided in the bottom metallic plate I8. Nuts 36, threaded to the tie rods 34, maintain the insulating plates comprising the 'u i-ii-ts 8 in compressed relation.

Referring to Figs. 2 and '1, it will be observed that the insulating plates form two vertical flow passages, generally designated by the reference numeral 31 or a first passage means interconnecting the two arcs. Fluidunder pressure from the pressure-generating chamber l3 passes downwardly through the two vertical flow passages 31, passes through a plurality of inlet passages 38, and enters the arcing passage, generally designated by the reference numeral 39, in which the interrupting are 32 is established. After entering the arcing passage 39 through the inlet passages 38, the fluid under pressure passes through apertures 40 provided in insulating orifice plates 4| and exhausts out of the unit 8 through vents 42 provided by a plurality of pairs of insulating venting plates 43, the configuration of which is more clearly shown'in Figs. 4 and '1.

Certain features of the vertical flow passages 31, inlet passages 38, apertures 40, and vents 42, together with certain aspects of the contact pressure construction shown in the drawings, are disclosed and broadly claimed in Ludwig, et a1. Patent 2,406,469, issued August 27, 1946, entitled Circuit interrupters, and assigned to the assignee of the instant application.

An axial passage 45 is provided in the lower movable or second contact 3| which communicates with a transverse passage 46, the purpose of which will appear more clearly hereinafter. We associate piston means with the relatively stationary or first contact 29. In this-instance, the piston means comprises an annular piston member 41 which is guided in an enlarged ape-rture 43 provided in an insulating plate 49, as more clearly shown in Figs. 3 and 6. The region above the piston 41, generally designated by the reference numeral 50, communicates with the region below the piston 41, generally designated by the reference numeral 5!, through a transverse passage 52 for-med in the stationary contact 29 which communicates with an axial passage 53 also formed in the stationary contact 29, and as clearly shown in Figs. 2 and 4.

The region 59 alse'communicates with region 5| through a plurality of apertures 54 formed in the insulating plate 51,'through the vertical flow passages 31 and the top inlet passage 38. Consequently, a substantially equalization of arcing pressure on both sides of the piston 41 takes place during the opening operation. It will, therefore, be apparent that conditions of high pressure existing in the arcing passage 39 will not serve to prevent downward movement of the piston 41, since the high pressure within the arcing passage 39 may communicate with the region above the piston 41 through the stationary contact 29 itself and alsothrough the apertures 54.

A battery of compression springs 55 biases the piston 41 in a downward direction. Since the compression springs 55 do not need to work against the high pressure formed in the arcing passage 39 because of the pressure-equalizing means which we have provided, the springs 55 consequently do not need to be as strong as the piston springs of the prior art. Consequently, the design'of the c'ompression'springs 55 is facilitated by the arcing pressure-equalizing means which we have used in this construction of our invention. An annular recess 56 is formed in the pistonmember 41. The recess 56. not only increases the turbulence in the arcingpassage 39, but also increases the insulation surface which is susceptible to electrical breakdown caused by carbonization of the insulation surfaces. 7

The lower portion of the piston 41 is provided with two fluid-directing passages, generally designated by the reference numeral 58, and shown more clearly in Fig. 5. The fluid-directing passages 58 comprise, in this instance, two inclined grooves '59which may be machined out of the piston member 41, asshown in'Fig. 5. It will be observed that the insulating plate 8| ('Fig. 5) has a considerable portion 62 removedtherefrom to form passages'63 which cooper-ate with the passages 58 provided in the piston member 41 to constitute the top inlet passages 38 of the arc-extinguishing unit 8. Consequently, when the piston 41 is at its lowest position (not shown) the passages 63 cooperate with the fluid-directing passage 58, regardless of the orientation of the inclined grooves 59 at this time, to form the top inlet passages 38. In other words, if during successive operations of the interrupter, the inclined rooves 59 should become oriented at right angles to their position as shown in Fig. 5, still, even in this position, fluid under pressure passing downwardly through the vertical flow passages 31 could pass through the passages 63 and. into the fluid directing passages 58 to strike the interrupting are 32.

From the above description it will be apparent that during the opening ope-ration the pressuregenerating are 39 and the interrupting are 32 are established practically simultaneously. The piston 41 may move downwardly independently of the stationary contact '29. Consequently, the arcing gap for the main or interrupting arc 32 is not shortened. During low and high current interruption, due to the pressure equalization means which We have provided, the piston 41 will be operative to move downwardly and to" force fluid from the region 5| toward the arcing passage 39 to contact the interrupting are 32. During the closing operation, the lower movable contact 3| moves upwardly to first engage the piston 41 in abutting relation and to carry the latter upwardly until the movable contact 3| strikes the intermediate contact 29, at which time the movable contact 3|, the piston 41, and the intermediate contact 29 move upwardly together as a unit for approximately one-fourth inch. Thus,

the piston 41 is charged, and the requisite contact pressure between the several contacts is obtained by the compression spring 22.

We have found that especially during low current interruption the passages 52, 53 providedin the intermediate or stationary contact 29 facilitate interruption, as well as furnishing a means forequalizing the arcin pressure onboth sides of the piston 41. The apertures 54, the passages 52, 53 disposed in the intermediate contact 29, and the passages 45, 46 provided in the movable contact 3| all cooperate to cool the contact structure during the closed circuit position of the interrupter. In this connection, it will be observed, referring to Fig'Z, that the transverse passage 46, provided in the movable contact 3 I, is opposite the top vents 42 of the unit '8. Consequently, circulation of cool oil through the vents 42,'through 7 the several passages formed in the contacts 3|, 29, through the apertures 54 and through the check valve 2'! is facilitated.

Not only do the passages 45, 46 in the movable contact 3| facilitate the circulation of oil in the closed circuit position of the interrupter to cool the contact structure, but also during the opening operation when the transverse passage 46 is opposite a vent 42, oil under high pressur within the arcing passage 39 tends to pass through the movable contact 3| itself. As the movable contact 3| continues its downward movement, the transverse passage 45 in movable contact 3| is drawn adjacent an inlet passage 38, at which time oil is forced through the transverse passage 46, through the axial passage 45 and into the arcing passage 39 to engage the interrupting are 32. As a result of the provision of the passages 45, 46 in the movable contact 3|, turbulence within the arcing region 39 is not only increased, but oil flow through the movable contact 3| is caused and results in rapid interruption of the interrupting arc 32.

Following interruption the movable contact 3| is withdrawn out of the arc-extinguishing unit 8 and assumes a position shown by the dotted lines in Fig. l. The direction of the oil flow during the opening operation is shown by the arrows in Fig. 3 and Fig. 7. The arcing pressureequalization means which we have provided causes the piston 47 to be operative both during high and low current interruption to decrease the arcing time for the interrupter. It will be noted that the intermediate contact 29 may be removed through the opening in the casting l2 covered by the plate 33 without disassembling the unit 8. Certain aspects of charging the piston 41 by movement of the movable contact 3| so that the main arcing gap is not shortened during the opening operation together with the removable feature of the intermediate contact 29 are disclosed and broadly claimed in a patent application, Serial No. 481,529, filed April 2, 1943, by Winthrop M. Leeds and assigned to the assignee of this application.

The following table shows the marked improvement using a piston 41 of the type shown in Figs. l7 with one unit 8 shunted out, over operation not using a piston 41. The voltage was 33 kv, and the frequency 60 cycles.

It will be observed that the piston 47 shortened the arcing time considerably. The data for the arcing time without the piston is the average for three successive interruptions at the same current. The data for the arcing time with the piston is the average for six successive interruptions at the same current.

In the modification of our invention shown in Figs. 8 through 12, we employ a modified relatively stationary or first contact 13 which cooperates with a loWer movable Or second contact 74 to establish an interrupting are 32, as shown in Fig. 9. A modified piston member 15 surrounds the intermediate contact 13 and is movable relative thereto, being biased downwardly by the compression springs 55. It will be observed that an annular recess 16 is provided in the piston member 15 which, in this instance, does not communicate with the fluid-directing passages 58 as was the case in the previous embodiment of our invention. The intermediate contact 13 has integrally formed therewith a plurality of offstanding guide projections 17 shown more clearly in Fig. 10.

In this embodiment of our invention, the downward movement of a second portion of the piston member 15 compresses oil within the region, generally designated by the reference numeral 19, to force the oil upwardly through inclined apertures (see Fig. 11) to direct the oil upwardly between the guide projections 17 and through the annular or second passage means 8|, through an orifice 84 provided by a box-shaped insulating member 85 and into the pressure-generating or second are 30, as shown more clearly by the arrows in Fig. 9. The box-shaped insulating member 85 is held in position by screws 86. It will, therefore, be apparent that in this embodiment of Our invention, the operation of a first portion of the piston 15 serves to direct a flow of fiuid toward the interrupting arc 32. A second portion of the piston serves to direct a flow of fluid upwardly through second passage means 8| and through the orifice 84 and into the pressure-generating arc 30 to increase the pressure fonned thereat. Not only is the pressure increased at the pressure-generating arc 30, but also the pressure-generating arc 30 may itself be interrupted by the fiow of oil through the orifice 84.

The introduction of oil into the pressure generating arc cools the arc and tends to deionize it. This interference with the arc tends to increase the arc voltage. This is necessary in order to maintain the arc in equilibrium. This increase in arc voltage and consequent increase in the amount of energy liberated in the arc increases the rate of oil vaporization, and the pressure produced by the arc. This increase in are energy in the pressure producing arc increases the flow of oil into the interrupting are which is intended to produce the extinction of the higher currents. The increase in the eiiectiveness of this arc as a pressure generating arc is the equivalent of using a longer less effective arc. The longer are in the chamber I3 i not desirable because of dielectric problems introduced into the construction of the chamber l3. That is, the longer the are which is drawn, the greater is the dielectric strength across this gap when the breaker is being closed, and the greater is the voltage impressed on the parallel insulation. It is, therefore, very desirable to use a short effective pressure producing arc.

The oil introduced into this are not only cools and deionizes it but may, when the currents are low, actually participate in the extinction of the arc. That is, the deionizing action of this stream of oil flowing into the pressure producing arc may be sufficient at low currents to produce arc extinction, and in that case this arc acts as an interrupting arc in series with interrupting are 32, both doing their share in the opening of the circuit.

Vents 32 provided in the insulating plate 83 permit a circulation of oil through the vents 82 and along the intermediate contact 13 within the annular passage 8| in the closed circuit position, as shown in Fig. 8. This circulation tends to maintain the intermediate contact I3- cool. During the carrying of heavy load currents, the intermediate contact 13 tends tobethe hottest partof the interrupter in the closed circuit position. Therefore, a circulation of oil along the intermediate contact 13 is desirable to maintain it relatively cool.

It will be apparent that in this embodiment of our invention we provide a piston arrangement, with the apertures 54 serving as the pressure; equalizing means, which results in the piston I being operable during both high and low current interruption to send a new of oil not only toward the interrupting are 32, butalso toward the-pressure-generating are 30. It will be observed that during the initial part of the opening operation, the piston itself; closes the vents 82 to; result in a compressing of the oil withinthe region 19.

Durin the closing operation, the lower movable contact 14 first picks up the piston 15 until the contact 14 engages the intermediate contact 13-, at which time the contacts 13, 14, and the piston 15 move upwardly together as a unit for a short interval of time. It will be observed that in this embodiment of our invention, the lower portion of the piston '15 contains the inclined grooves 59 constituting the fluid-directing passagesifl. Also in this embodiment of our invention theapertures 54 constitute substantially the entire arcing -pres-' sure-equalizing means for the piston 15. I

In the embodiment of our invention shown in Figs. 13 through 16, we provide a modified piston member 81. It will be observed in this construction that we have provided an annular recess 88 by the use of the insulating plate 89. The annular recess 88 not only increases turbulence in the arcing passage 39, but also retains a fresh supply of oil adjacent the interrupting are 32 to beacted upon when the interrupting are 32 is initially drawn bythe contacts 3 I, 29. The modified piston member 81 has an annular second portion 90 which compresses oil within an annular region 9| during the downward travel of the piston 81 to force oil upwardly through vertical passages or in this instance second passage means 92 (see Fig. 14) and to a chamber generally designated by the reference numeral 93. The chamber 93 is formed by a rectangular box-shaped member 94. The configuration of the chamber 93 is more clearly shown in Fig. 15,- and has an orifice 95 through which the upwardly moving o-il passes to strike the pressure-generating are 3D to increase the pressure formed thereat. In this embodiment of our invention we again provide passages 45, 46 in the lower movable contact 3|, andalso passages 52,- 53 in the intermediate contact 29. The passages 52, 5 3 cooperate with the apertures 54 to constitute the arcing-pressure equalizing means for the piston 81. Consequently, in this embodiment of our invention the'pressure-equalizing means for the piston 81 permits the piston to move downwardly independently of the value of current being interrupted. The downward movement of the piston 81 not only forces oil into the interrupting arc 32 by a first portion thereof, but also a secondportion BO thereof forces oil upward-1y through the second passage means and into the chamber 93 and through the orifice 95 into the pressure-generating are 30. The forcing of oil toward the pressure-generatingaro 30 not only increases the pressure thereat, but also tends to interrupt the pressure-generating arc 30. Other features of the embodiment of our invention shown in Figs. '13 through are similar to features previously described in connection with theothertwo embodiments of our invention disclosedin the drawings; therefore, a further discussion seems unnecessary. It suffices to state that in the constructionshown inFigs. 13 through 16, bother the contacts may be provided with passagestherethrough which'iunction in a manneridentical to that described in connection with the interrupter shown in Figs. 1 through 7.

H The following table shows the marked improvernent usingfa piston 'B'I with one unit 8 shunted ut as compared with operation not using a pisten 81 Again the voltage was 33 kv. and the frequency was 60 cycles.

I Theiabpve table shows how the arcing time was shortened using a piston 81. The data for the arcing timewithout the'piston is the average for three successive interruptions at the same current. The data-for thearcing time with the piston is the average for six successive interruptions atthesame current.

It will be apparent from the above description that we have provided a novel piston arrangementoperable both during the interruption of high and low currents to send fluid not only toward the interrupting arc, but also toward the pressure-generating arc.

It will be observed. that, in the above embodiments of our invention, a flow of a small quantity of oil is produced by the pressure exerted by a spring "acting upon a piston. The pressure exerted by fthespring'is adequate to cause the flow of the oil through passages and to the points where it is to perform its function. The pressure produced bythe arc'would act against the pressure of the piston unless the pressure produced by this are is'applie'd'to both sides of the piston. We do this and thus in efiect raise the pressure on both sides or the piston by the same amount. However, there still exists between the two sides of the piston a pressure differential set up by the action of the spring. Thus our device distributes the pressure 01' the arc to both sides of the piston and leaves the pressure "differential. Thus the pressure of the are is equalized on both sides of the piston, leaving the pressure head produced by the spring to be absorbed by the flow of the oil throughthe passages. I Consequently the spring may sodesigned" that the oil flows at the rate desired fo-rbest operation.

In our device the pressure produced by the spring is'adequateto cause the desired oil flow. That is it provides adequate pressure to overcome the pressure drop produced by oil flow through the oil passages. It is not necessary to provide pressure adequate for overcoming the arc pressure; since our device is so designed that the arc pressure is superimposed on the pressure exerted the spring and hence normally existing between the two sides of the piston.

Although we have shown and described specific structures, is to be clearly understood that the same are merely for purposes of illustration, and thatchang es and modifications may readily be 11 made by those skilled in the art without departing from the spirit and scope of the invention.

We claim as our invention:

1. In a circuit interrupter, an arcing passage, a pair of contacts cooperable to establish an arc in the arcing passage, an inlet passage leading into the arcing passage through which fluid may be forced toward the are during the opening operation, a vent passage leading from the arcing passage through which fluid may be exhausted away from the arc, one of the pair of contacts having passage means formed therein, the arrangement operating to sequentially move the passage means past the inlet passage and the vent passage to cause movement of fluid within the passage means for facilitating the extinction of the arc.

2. In a circuit interrupter, an arcing passage, a pair of contacts cooper-able to establish an arc in the arcing passage, an inlet passage leading into the arcing passage through which fluid may be forced toward the arc during the opening operation, a, vent passage leading from the arcing passage through which fluid may be exhausted away from the are, both of the contacts having passage means formed therein, and one of the contacts being moved along the arcing passage so that the passage means formed therein may sequentially move past the inlet and vent passages.

3. In a circuit interrupter, a first contact cooperable with a second contact to establish a first are, a third contact cooperable with the first contact to establish a second are, a piston substantially surrounding the first contact but separately movable therefrom and operable to simultaneously send fluid toward both arcs, the piston being charged by abutting engagement with the second contact.

4. In a circuit interrupter, a pressure-generating contact cooperable with a relatively stationary contact to establish a pressure-generating are, a movable contact arranged to make abutting engagement with the stationary contact in the closed circuit position and separable therefrom during circuit opening to establish an interrupting arc, a piston substantially surrounding the relatively stationary contact and movable relative to said stationary contact, and spring means biasing said piston in a direction to simultaneously move fluid under pressure toward both said pressure-generating and interrupting arcs to facilitate arc extinction, said movable contact engaging said piston during the closing stroke to charge the same against the biasing action of said spring means before the movable contact strikes the stationary contact in abutting engagement.

5. In a circuit interrupter of the fluid immersed type, means defining a pressure chamber, means defining an interrupting chamber adjacent to said pressure chamber, a relatively stationary contact extending between said chambers, a movable contact operable in said pressure chamber and arranged to coact with said stationary contact to establish a pressure-generating arc, movable contact structure at least a portion of which is arranged to coact with said stationary contact to establish an interrupting are within said interrupting chamber, operating means for simultaneously moving said movable contact and said movable contact structure to open and closed circuit positions, a cylinder in communication with at least one of said chambers, a piston movable in said cylinder, spring means operative during opening of said interrupter for moving said piston in a direction to force fluid under pressure into engagement with at least one of said arcs to assist in extinguishing said one arc, pressure equalizing passage means extending from said chambers to said cylinder for subjecting both sides of said piston to pressure created by said arcs to facilitate piston movement, and means providing abutting engagement between said movable contact structure and said piston whereby during the closing operation of the interrupter said piston is moved by said contact structure against the action of said spring means to the substantially charged position prior to engagement of the interrupter contacts.

6. In a circuit interrupter of the fluid immersed type, means defining a pressure chamber, means defining an interrupting chamber adjacent to said pressure chamber, a relatively stationary contact extending between said chambers, a movable contact operable in said pressure chamber and arranged to coact with said stationary contact to establish a pressure-generating are, a second movable contact operable in said interrupting chamber and arranged to coact with said stationary contact to establish an in terrupting are, means for simultaneously operating said movable contacts to open circuit position to establish said arcs, passage defining means for directing fluid under pressure from said pressure chamber toward said interrupting arc, a piston slidably disposed about said stationary contact and movable relative to said stationary contact, spring means operable during an opening operation for moving said piston in a direction to set additional fluid in motion, and a second passage means for directing said additional fluid under pressure into engagement with said pressure-generating arc to increase the are energy thereof during the interruption of high current arcs and to assist in extinguishing the pressure generating arc during the interruption of low current arcs.

7. In a circuit interrupter of the fluid immersed type, means defining a pressure chamber, means defining an interrupting chamber adjacent to said pressure chamber, a relatively stationary contact extending between said chambers, a movable contact operable in said pressure chamber and arranged to coact with said stationary contact to establish a pressure-generating are, a second movable contact operable in said interrupting chamber and arranged to coact with said stationary contact to establish an interrupting arc, means for simultaneously operating said movable contacts to open circuit position to establish said arcs, passages defining means for directing fluid under pressure from said pressure chamber toward said interrupting arc, a piston slidably disposed about said stationary contact and movable relative to said stationary contact, spring for moving said piston in a direction to force an additional quantity of liquid toward said interrupting arc, and additional passage means extending from both the pressure chamber and the interrupting chamber and communicating with ach side of said piston to equalize the pressure from arcing on both sides of said piston and thereby facilitate piston movement during high arcing pressure conditions.

8. In a circuit interrupter of the liquid immersed type, means defining a pressure chamber, a cylinder having a substantially closed end adjacent to said pressure chamber, the other end of said cylinder being substantially open, a sta tionary contact extending from said pressure chamber into said cylinder through the closed end thereof, a movable pressure generating contact in said pressure generating chamber arranged to coact with said stationary contact for establishing a pressure generating arc, an interrupting contact movable through the open end of said cylinder and cooperable with said stationary contact for establishing an interrupting are, means defining liquid flow passages leading from said pressure chamber to said interrupting arc whereby the pressure created by said pressuregenerating arc forces liquid into engagement with said interrupting arc to assist in extinguishing the latter, an annular piston within said cylinder slidably disposed about said stationary contact and movable relative to said stationary contact, a spring arranged between the closed end of said cylinder and said piston for moving said piston in accordance with an opening movement of said interrupting contact toward the open end of said cylinder to force an additional quantity of liquid int the region of said interrupting arc, passage means through the closed end of said cylinder whereby the back side of said piston is subjected to the pressure within the pressure chamber, and a second passage means through said stationary contact providing a by-pass around said piston whereby the back side thereof is also subjected to the pressure created by the interrupting arc.

9. A circuit interrupter of the fluid immersed type comprising means defining a pressure chamber, means defining an adjoining interrupting chamber, a cylinder joining said chambers, said cylinder having two bores of different diameter, the larger of said bores being disposed adjacent said pressure chamber and the smaller of said bores terminating in said interrupting chamber, a substantially stationary contact extending from said pressure chamber into said cylinder, a movable contact in said pressure chamber arranged to coact with said stationary contact to establish a pressure-generating arc. a second movable contact in said interrupting chamber arranged to coact with said stationary contact to establish an interrupting arc, flow passages for directing fluid under pressure from said pressure chamber to said interrupting chamber to assist in extinguishing the interrupting are, an annular piston slidably disposed about said stationary contact and movable relative to said stationary contact, said piston having two portions of different diameter respectively operable in said larger and said smaller bores of said cylinder, spring means for {biasing said piston in a direction to displace fluid from the respective bores of said cylinder, passage means directing fluid from said larger bore to said pressuregenerating arc, and means directing fluid from said smaller bore to said interrupting arc.

10. A circuit interrupter of the fluid immersed type comprising means defining a pressure chamber. means defining an adjoining interrupting chamber, a cylinder joining said chambers, said cylinder having two bores of different diameter, the larger of said bores bein disposed adjacent said pressure chamber and the smaller of said bores terminating in said interrupting chamber, a substantially stationary contact extending from said pressure chamber into said cylinder, a movable contact in said pressure chamber arranged to coact with said stationary contact to establish a pressure-generating are, a second movable contact in said interrupting chamber arranged to coact with said stationary contact to establish an interrupting arc, flow passages for directing fluid under pressure from said pressure chamber to said interrupting chamber to assist in extinguishing the interrupting arc, an annular piston slidably disposed about said stationary contact and movable relative to said stationary contact, said piston having two portions of different diameter respectively operable in said larger and said smaller bores of said cylinder, spring means for biasing said piston in a direction to displace fluid from the respective bores of said cylinder, passage means directing fluid from said larger bore to said pressure-generating are, means directing fluid from said smaller bore to said interrupting arc, pressure-equalizing passages leading from said pressure chamber to said larger bore of said cylinder, and an additional pressure-equalizing passage extending through said stationary contact providing a by-pass about said piston, said pressure-equalizing passages subjecting the back side of said piston to the pressure created by arcing in both the pressure and interrupting chambers to facilitate piston movement during high current high pressure conditions.

ROSWELL C. VAN SICICLE.

ROBERT E, FRIEDRICH.

FRANCIS J. FRY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,061,301 Dufling Nov. 17, 1936 1,981,404 Whitney et a1 Nov. 20, 1934 2,075,749 Paul Mar. 30, 1937 2,077,338 Lingal et a1 Apr. 13, 1937 2,292,547 Sadler Aug. 11, 1942 2,102,768 Trencham et al. Dec. 21, 1937 2,158,846 Balachowsky May 16, 1939 1,955,215 Whitney et al Apr. 17, 1934 2,100,182 Clerc Nov. 23, 1937 2,250,599 Ortensi July 29, 1941

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