US2602868A - Fluid pressure assembly - Google Patents

Description

July 8, 1 B. P. BAKER ETAL FLUID PRESSURE ASSEMBLY 2 SHEETS-SHEET 1 Filed Feb. 5, 1949 ll I'l III:

Fig. l.

INVENTORS Benjamin P. Baker, Erling Frisch.

WITNESSES:

8 Howard M.Wilcox.

ATTORN EY July 8, 1952 Filed Feb. 3, 1949 Fig.2.

WITNESSES:

2 SHEETSSHEET 2 INVENTORS 43 Benjamin P. Baker, Erling Frisch 8 Howard M.Wilcox.

ATTORNEY Patented July 8, 1952 L FLUID'PRESSURE ASSEMBLY :BenjaminJP. Baker, .Turtle 'Creek, :Erling Frisch and Howard jWilcox, Pittsburgh, -Pa., as-

- signors to Westinghouse Electric Corporation,

East Pittsburgh, Pa a corporation of Pennsylvania "Application February a, 1949, Serial No. 74,407

. 1" I H Our,inventionrelates tocom'pressed-air circuits-breakers, and it hasrparticular relationto a yieldable :assembly means for holding :the various parts of the. single-columninterrupter- :structure together in .substan'tially air-tight abutting-engagementwitheach other, while providing'for sudden and unequal thermal expansions and contractions '01. 'the various parts. While zourinventionis mainly directed to such .a circuit-breaker;structure, the .g'eneralsprin- "ciples thereofiare.iapplicablealso to other assemblies :and structures, where: similar problems are encountered.

The .pri-ncipalobject of our invention is ;to provide a captivatedespring assembly, for cooperating with a plurality :of TlSiB-JIOds for: holdin the assemblediparts together.

- In .a specific circuitrbreaker yapplicationgour invention relates "-tOLthG .:blast-:tube and interrupter-assembly part of a .compressedegas cir- "a blastevalve which is accessible and operable izfrom Ithe bottom .sideotithe "tank and "which inormally .:closes the bottomiofthe :blastetuhe ezdzerrsion.twithin the tanky'and a:suitable "airibl'ast l interrupter-assembly .amountedwon :atop .IOf the -blast-tube .-'so-.;as to :betphysically supported by the blast-tube, as well. as being insulated 'from i ground by the blast-tube With the foregoing and other objects in :view, our inv'ention consists in the combinationa a's- "semblies, systems, structures, parts, and methods of design and operation, hereinafter described and claimed, and illustrated in '-'theaccompanyi-ng' drawing, wherein -Fi-g. '1 is a side-elevational view, -partly in section},

- 'm'at'ic', not =-to scale ind-icating the general prinoiples of our invention as} applied to a singlepoleassembl-yrand Fig. 2 is *a detailedelevational -view',-'partly in longitudinalsection, showing our "novel captivated-spring assembly-means for holding "the various interrupter=parts together and in air-tightinechanical connection wiith -the ---1top'.oftheblaststube. k

\ ..Figure 1.:showsJa singlespoleiof :a compressed- ;air; breaker-assembly;embodying; our invention. "It is to beunderstoodg however; that our! invention, is often-or usually applied to a three phase teams. (on. 200 14s) power-system, in which case each pole would consistoi the structure as shown in Fig. 1,'ex-' cent-that a single operating-mechanism maybe used for gang-operation of all three poles, and possibly also a single compressed-air tank might be used for supporting the blast-tubes of all three poles.

Each pole of the breaker preferably has its owncompressed-air tank or reservoir I, which is madeof'steel, and which serves also as a of theblast-tube 2, so that said internal tubemeans 3 serves, in effect, as a blast-tube extension which extends downwardly, within the tank,

to a point near, but spaced from, the bottom of the tank, as indicated at 4. Physically, this blast-tube extension, inside of the tank, could be a part of the insulating blast-tube 2, which could be madelong enough to extend down to the point 4 near the bottom of the tank, but actually, itismore convenient to make the internal tube-means out of iron or steel'which is welded or otherwise properly, secured'within thetank I. Also, in a practical construction, it would be possible for the internal tube-means 3 to comprise the toppart of an internal'tube which physically extends from the top of the tank all the way down'to the bottom of the tank, but which is provided with side-openings at the effectivetube -bottom 4, so that said tubemeans would be'intact, as atube, onlyjabovefthe ,point 4.

Disposed withinl' the tank I, under the bottom 4fof the tube-means}, is ablastvalveS,

which .is accessible and operable from the 'bottom of theta-nk. The blast-valve 5 is preferablya difierential-pressure valve having 'a vertically movable inverted-cup member 6,'which ispressed up, by acompreSsion-sprififi. 1, into tight :seating-engagment with the bottom ,end 4 of the tube-means '31 The compressionspring 1 acts as aweak closing spring, which does not exert enough pressure to close the valve against the air-pressure in the tank I, which may be at something of the order of 250 pounds per square inch. .Normally, the .blast-valvej is held closed by being supplied, from underneath,

with-airat the same pressure as the air in the tank |,-as by means of la valve-controllingpipe tube-means 3 and through the insulating blasttube 2.

On top of the insulating blast-tube 2, we

mount a single-column interrupter-assembly I6,

which is preferably supported in a-vertical position, in alignment with the blast-tube 2, and which is physically supported solely, or substantially entirely, by the blast-tube, so as to be electrically insulated from ground by said. b1asttube. This single-column interrupter-assembly comprises a plurality of vertically aligned, self-opening, longitudinal-blast interrupter-gap devices II and I2, two such gap-devices being used on a 69-kilovolt breaker as illustrated. These gap-devices II and I2 are electrically connected in series, so that the current-flow, in the normal closed position of the breaker, is from the top l3 of the interrupter-assembly III to the bottom I4 thereof, a suitable line-terminal [5 being provided at the top I3. Each interrupter-gap device II and I2'comprises a stationary contact-member HS or I2S, as the case may be, and a vertically movable contact-memberv I IM or 12M, as the case may be. The-two movable contact-members IIM and IZM are normally biased towards closed position by means of biasing-springs IIB and IZB respec- In the preferred construction, the two movable contact-members HM and IZM are mounted within a metallic moving-contact assembly or ,housing I1 which is in the form of two concen- I'triccylinders, namely an inner cylinder Hi and anouteri cylinder [10, so as 'to provide an annular space I'Is between these cylinders, through which the air-blast may pass. V

-The moving-contact housing I! is vertically .spacedirom the lower exhaust-chamber i6 by means-of an insulatingtube I8, which supports theloutercylinder Ho, and which is larger than the lowerstationary contact-member I IS, so as to provide an annular space I8s therearound,

through which the air-blast may pass; In order to guide the air-blast from the blasttube 2"into the, annular space His, the lower exhaust-chamber I6 is provided with a funnel-like air-guiding duct, I9, which is spaced fromthe lower end I6 of the lower stationary contact-member IISpso as to provide an annular space I9s through'whi'ch the air-blast may pass, in moving upwardly from the blastetube 2 into the annular space I8s;

The upper stationary contact-member IZS is integrally. or electrically united with an upper exhaust-chamber 20, which is similar to the lower exhaust-chamber 56, except that it lacks the funnel or duct I9 for carrying the blast air' 'upwardly on through the upper exhaust-chamber 20." The upper stationarycontact-member I28 is likewise of hollow construction, and its upper 4 end is in communication with the space within the upper exhaust-chamber 26. This upper exhaust-chamber is supported on the top end of an insulating tube 2|, which is similar to the tube I8, except that the lower end of the top insulating tube 2| resists on top of the outer cylinder IIo of the moving-contact housing IT. This upper insulating tube 2| is also larger than the upper stationary contact-member I2S, so as to provide an annular space 2Is which forms a closed upperend for the blast-air, as this blast initially moves upwardly through the interrupter-assembly I '0 In the construction which is very much preferred, as illustrated, the upper end of the lower stationary contact-member IIS, and the lower end of the upper stationary contact-member IZS are each provided with a centrally disposed orifice 22, which is normally closed by the cooperating movable contact-member I IM or IZM, as the case may be. The configuration of these movable contact-members HM and'IZM is such that the pressure of the blast-air operates on these movable contact-membersIIM and I2M to press them back awayfrom their respective stationary contact-members IIS and HS, thus making the gap-devices II and I2 self-opening, that. is, making them open automatically, by themselves, as soon as a sufficient gas-pressure is built up in the spaces around them, without requiring any other device, not a part of the moving-contact assembly IT, for causing a separating-movement of the movable contactmembers IIM or IZM. This opening-movement of the movable contact-members IIM and HM draws arcs between said "members and their associated stationary contact-members IIS and I2S, respectively, thus initiating acircuit-interrupting operation of the breaker. x

As soon'as each movable contact-member HM or I2M moves away from its normal contactmaking engagement with the end of its'associated stationary con'tact-memberi IS or [23,- as the case may be,1 it uncovers theorifice -22 inthe hollow stationarycontact-member IIS oryIZS,

thus permitting a blast of air to moveilongitudinally, or in a vertical direction; through the orifice 22 and thence through thelhollow stationary contacteme'mber I IS or I 23; and thusjactingf powerfully to extinguish :the arcbetween the movable and stationary. contact.-members.-; The upper fend of.the hollow upper stationary contact-member I2S dumps its air directly into the upper exhaust-chamber 20, and the-lower end of the lowerhollow stationary contact-member IIS exhausts its blast of air into the lowerexhaust-chamber I6 by meansof-a plurality of tubular openings 23, which pass through ,the lowerend I6 of the hollow lower stationary contact-member II S, and also through the tunnel or duct, Win the lower exhausts-chamber I6; These upper and lower exhaust-chambers 20 and I6 thus provide an expansion-space in which v the longltudlnally moving air-blasts within the 65- twoystationary contact-members IIS- and- HS may accumulateduring the brief time which is required for a complete circuit-interruption. It may take the blast something like 4 cycle, (assuming a (SO-cycle line) .;before the arcing-contacts begin toseparate, and then a timelsomething like cycle for the 'maximumcontactseparation to beachieved. p'I'hen thearc. may

'z euefses asymmetric-wave conditions. jfItis desirable for the are to'be interrupted at the first important current='zero, '(orsometimes possibly the second one), "after full contact-separation *haslb'een achieved, disregarding, (as unimportantfrom an arc injterrupting standpoint) f any j currenez'e whlch'inay occur very soon after full contactseparat'ion isobtained. Then it 'isdesirab1eto prevent'a"restriking'of the 'arc'on the next halfcycle, and "to this end it is necessary to "have a large quantity of air-movement, a high "air- 'yel'o'city, high turbulence, and cooling, ora'co'rn binationof these factors. And then, in "subs'e duenthalf -cycles, it is desirable to continueto have a sufiicient dielectric strength of the 'air in the arcing-gap, so as to prevent "any subsequent arc restrikin'gja'nd for this purpose, the air-pressure "of the once-deionized andcooled gap air is of service in providing'dielectric strength'to pree tent a later breakdown of theygap. I Qurupper'and lowerexhaust-chambers i6 "providethe gas-pressure in thejgap spa'ce. Theinitial blast must be maintained until at least the first (or second) important current- 'zer o"after full gap-separation has been reached,

but when the back-pressure in these exhaustchambers reaches as much as something like "50% o'f'the pressure at the high-pressure'side of the orifice or arcing-gap, theblastno longer'trayels at'approximately the speed oi's'ound, but begins toslow down. The size of the exhaust-chambers chambers l6 and'20 should'be present, and that a they should develop an important back pressure after'said period of 2% cycles or the like, and it is importa'nt that these exhaust-chambers should be, able to hold theirback-pressures fora few cycles, or until a serially connected isolatingswitch 26 can be opened, aswill subsequently be described. During'this timepwhen 'a substantial Becki-pressure is being held in the exhaustchambers 16 and 20, the blastvalve 5 must be kept'opemas will readily be understood.

The air which accumulates in the two exhaus'tchambers l6 and 20 is cooled, in these chambers, and is slowly "dissipated to the atmosphere,

through 'su-itable exhaust openings 24, which are provided ineach'of the'exhaust-chambers l6 and f2 0,'ia nd which maybe provided with any desirablefmufiling or sound-deadening or flame-extinguishing means (notshown). asis well understood in the compressed-air circuit-breaker art.

in and Since'the movable contact-members ,l [M and ,f

12M are opened by the 'air pressure which is exblast'which movesat'a velocity approaching the velocity of sound, it is impractical to sustain such air 'or gas'whichis stored in the tank or reservoir I. Consequently, after a circuit-interrupting members l Is and vIZS, so thatthe'se contact- "members thereafter'remain closedthroughout the 'alargefmovement or blast of air forany' con- 's'dferable'length of time. It isnecessary, there'- "ior'e',to' close the blast-valve Si very quickly after it is'o'p'ened, "so as to conserve the high-pressure 6 time "when the" circuitshould remaininterriipted. It is necessary, 'theretorefas in "the case or are viously known "self-opening, "longitudinal-blast, orifice-type circuit-breakers, to provide the previously mentioned*is0lating=switch2i5 which is electricallyconnected in series "with the interrupter assembly l0. We also provide a second vertically dispose insulating column "21, which is'spaced ifron iushe blast tube Zfland "which "also extends upwardly above theto'pf'of the"tankfl','s'o that 'it is su 'portedby the 'tank, although it is not in pneuinatic communication with the fair within the tank I Thissecond insulating column?! is surmounted by -a metalterminal rnember 28, which is provided With. a line-"terminal 2'9," soas to bro- "vide the second line t'erminal of the breakerassembly, the first line-terminal bingthe terminal'li at the top of the interrupter-assembly '10 I The "isolating' switch '26 is movable so; as to close or 'open anelectrical circuit between this metal terminal-member 28 atthe top' ofthe second insulating column--21jand-the bottom-14 or it of the interrupter-assembly it) which is "mounted at the top of the insulating blast-tube 2. Inthe illustrated construction, the isolating -switch 261is pivotally connected to thelower exhaust=chamber [6, as indicated at 30, and its free end is movable into and'outofcontactwith suitable contact-fingers 3'I carried'by themtal termina meniber 28. i

It is also a fe'aature o fjthe type of breaker' to whichour invention is applicable, that'an operating-mechanism is provided, as 'diag'rammatically indicated at 33, in "a location which is onj'or close to, the tank I "and which is at substantially the same electrical "potential as the tank, which would normally be grounded. Thus, this operating-mechanism 33 is physically and electrically at the ground-level, which is of considerable advantage from the -standpoint of the amount and size of the equipment which must be insulatedly supported, up in the air, as by the two insulating supporting-columns '2 and 21. The'operatingmechanism 33 is operatively -joined to the switch '26 through an insulating switch-operating rod 34, for opening and -closing "the isolatin switch 26. p

The operating-mechanism 33 may "be con-- trolled injany desiredmanneigso that it'will open the isolating-switch '26," and lock it open, "after the completion of the 'arc interruption during the opening-operation of the interrupter-assem I My "l0,"-and before the two movable contactmembers i I IM and HM "are spring-closed again,

after a reclosure of the blast-valve '5. In theparticular design illustrated, the operatinigdorce, and thetiming, for the operatingsmec'hanismf 3'3 are both provided by asrnall tube'or-pipe35,

which .is in communication with the lower end of the insulatingblasttube'z, orthe upper'end or the internal tube means 3"i1'ithe tank I.

When the blast-valve s f rst opens, the uralblast is. moving upwardly very rapidly fin the blast-tube '2, so that its'static 'airapressui''fis timea sufficient air-"pressure'is applied, through "thetube 35,to begin'to initiate the operation of the operating-mechanism. The inertia of the operating-mechanismfl, the.v insulating connecting rod 34, andthe isolating-switch 26' is such that the isolating-switch '26 breaks its contact with the contact-fingerstfi afterlthe arcs have beeninterrupted by the longitudinally. flowing gas-blast in the two interrupterrgap devices, and I2. 1 l

' As shown in Fig. 2,'our invention relates more particularly to theassembly-mea'risior thev interrupter-parts whichare mounted'at the top of the blast-tube 2." fit will be noted' that this interrupter-assemblycomprises a number of separate hollow parts or. pneumatic elements, which are stacked up, one on top, of each other, and which must befirmly. held together, not only to afford a structure haiiingtheadequate mechanical strength and s'tability,, but also to enablet'he abutting-joints .betweenQ'the several parts to withstand the airpressure, of the order of 250 pounds per square inch, of thecompressed-air blast' without substantial air leak'ag'e, while at the same time providing .for eon's iderable and unequal thermal expansiops'an'd contractions.

, Our'novel assemblyemeans, asshown in Fig.2, comprisesa plurality of insulating tie-rods 36, which are provided with nuts 31 for drawing the assembled parts] tightly together in an: axial direction. In order ltoljprovide for ,theneces'sary :yieldability ,to admit of thermal expansions and contractions, we provide a; captivated-spring head for. anchoringone endbf said tie-rods, said captivated-spring, head comprising a .movable pressure-plate 38 which' is illustrated as being mounted withinthe upper exhaust-chamber 20, although it could obviously be disposed at either end of the vertically"disposedtie-rods 36. The movable pressure-plate 38 is strongly biased, in an upward direction, by a nest of powerful compression-springs 39, which press against the underside of said pressure-plateso as to make it keep the tie-rods" in tension,

The compression springs 39 exert 'a rather considerable pressure on" the pressure-plate 38, and it would be rather inconveiiient,to have to turn up the nuts 31,011 the .tie-rodsf36for'a Sufficient distance to 'set up the compression-springs 39 far enough to make them exert this considerable pressure, every time the assembly is put together, even though there were suflicient room, in the upper exhaust-chamber 20, for a sufficient axial threaded movement of the nuts 31 to accomplish this spring-compression. In accordance with our present invention, therefore, we initially set up the compressionsprings 39'by substantially the desired amount to provide the desired strong spring-force against the underside of the pressure-plate ,3 8, using,'for this purpose,pan'y convenient jack'orfixture (not shown) for temporarily holding. the pressureplate assembly in' its compressed state; We then provide shortretaining-bolt's 40, or other equivalent retainingemean s, for holding down the pressure-plate 38,"in"to' very.nearly its; fullylowered position,with"very nearly the full Iodin press'ion on the compression-springs 39', after which the assembly can bejrerr ove'd from 'the temporary holding-fixture (not'showjmz The aboveedescribed construction provides, a

,partsare assembled, asshown in Fig. 2, the nuts 31' are tightenedfon'thelseveral' tie-rods 3t; and this tightening movement 'i's 'eontinued until the tie-rods ,pullthe pressure-plate 38 down fora certain clearance-distance below the heads or the retaining-bolts' lfl, as indicated at D. Thisprovidesi thedistanc'e D which is available for thermal, expansions}. while automatically maintaining eachcf the tieerods 36in strong tension, so as to flexibly hold the parts firmly together.

The lower ends of theti-rod's 36 ,may -be anchored in any suitable manner, which'resultsin holding together the parts which are; to beassembled. ,In the'particular design showninFig. 2, the lower ends'of'the tie-rods are provided with heads 41 which, engage the lower exhaust-- chamber I6, and this lower exhaust-chamber I8 is secured'to the'top of the blast-tube by means of a sort of mortise jointwhich is provided by a clamping ring 42 which is affixed to theupper end of the insulating blast-tube 2,, andfwhichis secured to 'thelower endof Ithe lower, ighau'stchamber l6, as byrm'ean's' of bolts 43J'It'lwill be understood, of course, however, thatthe'lower ends of the tie-rods 3B. couldlhave been anchored directly to the clar'n'ping' ri ng'v 42,'if fitliad not been desirable to provide'the semi-permanent bolted connectionbetweenthe lower eXhaust chamber IE and the top of the blast-tube 2. I

Various details of ,the'b'reaker-assembly, which is herein generically orbroadly described and claimed, are described and claimed in more detail in other copending applications. Thus, c ertain improvements and novel features of the pneumatic operating assembly, including the operating-mechanism 33', insulating switch-"operating rod 34, isolating-switch 2'6, pneumatic controlling-means including the tube 35, a nd]an inter'- locking-means (not here shown) for automatically reclosing the'blast-valve-Ei when the isolating-switch 26 has completed enough of'iits opening-movement, are shown and claimed in a copending application, Serial No.- "73,516,.1filed January" 29, 1949, by Baker and 'WilcoX, And finally,certain details. and improvements in the interrupter-assembly I0, relatingto, the' func-'- tional bperatiouof .this assemblyfand a'"practical operating f orm thereof, are disclosedjand claimed in the aforesaidapplicatio-n, Serial No. 74,406, filed February 3,- l'949, by Benjamin P. Baker, Erli'ng 'Fri'sch,,Wayne"Sl Aspey, and John 13. MacNeill. I; .7: -.j 1

While we have" described and illustrated our invention in but a'single illustrativeform, which is'shown somewhatdiagrammatically or ideally, we'wish it to be understood that we aren'ot limiited to; the precise form Whichis'illustratted,as

captivated-spring assembly, in which thecompression-springs 39 are held captive, in the upper those skilled in theart' could readilymakevarious ,changesofl substitution, omissions jor'additions, without djepartingjfrom the essentialjspirit "of our ihventioii.' .l/Yede'sire'therefoie; that. the appended" claims shall be accorded the broadest construction jeonsi'stentwith their language.

5 We'claim'as'ourinvention: f f :1, A fluid-pressure" assemb1yf;,comp'rising a stack of separate abutting hollow parts'havingfa substantially fiuicl-t'tight c n'necti'0n therehetween, said assembly of separate'abutting hollow parts 'bein'g capable of withstanding a considerable internal fiuid pressure and capable of withstanding a wide "range of thermal'expansions, a plurality of tie-rods for draWing'said parts together in an axialidirection, andajc'aptivatedspring head for' said tie-rods. said captivated spring head comprising'a movable pressure-plate for keeping said tie-rods intension, one or more 9 compression-springs for pressing against said pressure-plate so as to make it keep said tie-rods in tension, nuts whereby said tie-rods may be removed, and retaining-means for limiting the expansion of said compression-springs when said tie-rod nuts are loosened, whereby said compression-springs are retained under a considerable pressure.

' 2. A fluid-pressure assembly comprising a stack of separate abutting hollow parts having a substantially fluid-tight connection there between, said assembly of separate abutting hollow parts being capable of withstanding a considerable internal fluid-pressure and capable of withstanding a wide range of thermal expansions, a plurality of tie-rods for drawing said parts together in an axial direction, and a springhead for said tie-rods, said spring-head comprising a movable pressure-plate for keeping said tie-rods in tension, one or more compressionsprings for pressing against said pressure-plate so as to make it keep said tie-rods in tension, nuts whereby said tie-rods may be removed, and means, pressing on said plate, separate from said nuts, for building up a considerable pressure in said compression-springs.

3. A circuit interrupter of the compressed-gas type wherein contacts are separated and the are drawn therebetween is extinguished by a flow of gas and wherein one or more abutting pneumatic elements are employed to effect a pneumatic connection, characterized by the combination of one or more insulating tie-rods for drawing said pneumatic elements together in an axial direction, and a captivated-spring head for said tierods, said captivated-spring head comprising a movable pressure-plate for keeping said tie-rods in tension, one or more compression-springs for pressing against said pressure-plate so as to make it keep said tie-rods in tension, nuts whereby said tie-rods may be removed, and retaining-means for limiting the expansion of said compression-springs when said tie-rod nuts are loosened, whereby said compression-springs are retained under a considerable pressure.

4. A circuit interrupter of the compressed-gas type wherein contacts are separated and the are drawn therebetween is extinguished by a flow of gas and wherein one or more abutting pneumatic elements are employed to effect a pneumatic connection, characterized by the combination of one or more insulating tie-rods for drawing said pneumatic elements together in an axial direction, and a spring-head for said tie-rods, said spring-head comprising a. movable pressureplate for keeping said tie-rods in tension, one or more compression-springs for pressing against said pressure-plate so as to make it keep said tiercds in tension, nuts whereby said tie-rods may be removed, and means, pressing on said plate, separate from said nuts, for building up a considerable pressure in said compression-springs.

BENJAMIN P. BAKER.

ERLING FRISCH. HOWARD M. WILCOX.

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

UNITED STATES PATENTS Number Name Date 1,065,633 Stone June 24, 1913 1,109,823 Golf Sept. 8, 1914 1,429,303 Sumbling Sept. 19, 1922 1,451,146 Fate Apr. 10, 1923 1,533,173 Egloff et al. Apr. 14, 1925 2,336,316 Thommen Dec. 7, 1943 2,364,254 Thommen et a1. Dec. 5, 1944 2,399,412 Webb Apr. 30, 1946 2,428,575 Ludwig et a1. Oct. 7, 1947 2,440,995 Wilcox May 4, 1948 2,477,810 Leeds et a1. Aug. 2, 1949 FOREIGN PATENTS Number Country Date 9,387 Great Britain 1902

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