US2604565A - Circuit breaker employing a pair of arc chutes - Google Patents

Description

JIuly 22, 1952 G. A. BURNHAM CIRCUIT BREAKER EMPLOYING A PAIR OF' ARG CHUTES Filed Nov. 10, 1949 SQA y pa'city'iof thebreakerfit would bene'ceslsury, increase the'i'pressure and theintensity ofl the ga/s blast.y if it is impraeucaito nicreas'ethe gas pressure',A the size of thejblastpassage orth'e Patented July 22, 1952 STATES PATENT y C .CIRCUIT Bananen EMPLOYING A` PAIROF i ARC cHU'rEs f i' George-. Burnham,l Saugus, Mass., assigner to Allis-Chalmers Manufacturing Company, Mil-y Waukee, Wis., acorporation ckfvfrDclaware I .Application:November 10, 1949 lVScrial'eNo...126,531.2

, 1 i i A'Iihis :invention `relates .to Ycircuit interrupting devices ,and kmore particularly to arc extinguishing means for use in connection therewith.

V`In the construction and operation .of circuit ,interrupters it vis frequently necessary to provide vmeans for extinguishing quickly the are which is ldrawnbelniveen separable arcing contacts. This garnis usually yblown byblowout means, .such as :anjair blast, into Aan arc chute which is arranged `'to quench the arc byrlengthening it, cooling it, or

otherwise.` 4 ,y The'int'errupt'ing capacity of avfcircuitybreaker y`ina high voltage circuit de nds tov a greatfexf tent on the `'circuit characte'rls'tics relatingto the rate jof increase of yrecovery voltage Whenthe of the lgap. To increase the v.i,n tf-:lrrupting'l-ca- `type of gas passage or passages maybe variedV to ,provide forl .greater vgas volume or u greater. inter; vruptlngability. Such changes, howeve k'i'isuall'y 'result in either a inoreexpensivefor `larger breakert I 1. 1f "-"In accordance with the f invention {clairned a `fluid lblast circuitl interru'pter`l is provided lwhich lcomprises Aapair/of arcing contacts Vmountedwith:

in an arc .chamb'eror manifold. Theu nianiold is *connectedjtoa source of flui'dunder pressure and 'to an varc 'extin'fguis'hing` structure. v ,The are extinguishing":structure comprises a y rst and. a second arc chute.'V Thesec'ond "arcjnchutefco- 'operates with the .eyeing Lwinnaars te @amature tinguishes they 'arc clear the circuit.' l u l In addition, the chutes are so; arranged'thatif the back pressure developed in the'rst arc chute renders4 that `are,` chute",inor'ueratve', the hack pressure ,established will `tend to extinguishjthe are in the second, arc chute, and'vicevers'afkk v`A pjair ofnozz'les 'Arnay be, provided rbetween if vthe IFirst are chute" 'iailsjto ,tac'ts and the initial blast, the second. nozzle ,may Y claims. (c1. 20,044,148)

, i ,40. a completebackup or standby breaker,l whichy ex yterr'upft ing, device.

provide .asecond blast of uidto `flow l,through .the second .nozzle and rinto thasecond arc-chute. Byinserting a suitable resistor Y.in the circuit, `the voltage .recovery rate .of the circuit may be decreased, and if the circuit is not interrupted. by :the rst blast 4of iluid through'the first arc chute, it maybe interrupted in the second chute vat a :greatly decreased current. at av much more favorable recovery .frate .by thefvsecond .blastof fluid through the Second arc-chute. `liny this manner, the interrupting .capacity off `th'e circuit vbreaker .for a l.given blast pressure and gas, `consinnptior'i `isf-greatly finc'reased.l` u Itk is', thjereioiel one yrolbject.ofi the present V,iria vention to lprovide a ,newlandimproved 'arc` 1in,-

' Y. Anotherobject.ofgtheinvention isfto provide a Anew and improvedarc ,interrupting device lin which an arc chute acts vas astandby to lextinguish krthe are if another 2arc `.chute fails 'to' ,clear the .A. furthrlobject `o'f A,this ,invention is to provide .a- "newv and yimproved are j extinguishing vflslca'ns .which ff utilizes ,fluidesirable, back `.pressure inv .one a'rcc'hute to aid in extinguishing .the arc .in .ano'tliery arc chute.,

caused tdloivthrougha second arc'chute only after contact separation andthe initial blast. .5 A still ,further objectl of4 thisinventionjisto ,provide .an ,improved l fluid blast circuit "interv,- 'ruptei"` in vvwhich a plurality ofja'rc chutesand'gas 'blasts'l extinguish 1 afseries ,ofarcs' drawn jb '7a Single movable.farcinadonwt- .f

Obiectsand advantages other than those above As 'forth will befapparent from ,the followingdel scription when'read in connectionA withdthe acl conipanying drawinginQwhich; Y,

Figllf cross sec is ,La diagrammatic yshcpvvinlat .partly in i`..-a.lflufid blast circuit brealierem.- esentinvention; y :u Fig'. '.2 isy a Viewv .in c' section of the; embvd mento-illustrate Figalvftaken along fthe line .'Fig. B'isfa view in cross section oftheemlpod-l mentillustra-ted yin Eig-.u l ,takenfalongf Athe-'line The cross blast type air blast circuit breaker shown by way of examplein 11;,comprisesrelatively.,movable arcing contacts, -.such=as:flxed enne tact structure 1 of the nger type and blade-like contact 8. The fixed contacts structure may comprise a plurality of current carrying contacts and an arcing contact as is well known, and is electrically connected to one line terminal 9 of the breaker, The blade-like movable contact 8 is connected to the other line terminal I0. Although in general, circuit breakers of the type considered in Figs. 1, 2 and 3 are provided with a plurality of similar pole structures, one for each phase of a polyphase electric circuit, only one such pole structure is shown in the drawing and the circuit breaker will be described in detail as if it were of the single pole unit type.

The movable contact 8 is suitably connected to an actuating mechanism (not shown) through a connecting rod I I for operating the movable contact between closed and open circuit positions.

For the purpose of extinguishing the arcs formed between the contacts when a power circuit connected thereto is opened, an insulating arc extinguishing structure I2 is arranged with respect to the contacts so that the arc is drawn at the entrance of the structure directly opposite a gas blast supply conduit I3. The conduit I3 is suitably connected through a blast valve (not shown) to a source of compressed gas, such as air, comprising for example a storage tank and compressor equipment (not shown).

vThe arc extinguishing structure I2 may, for example, comprise a first arc chute I4 and a second arc chute I5 mounted adjacent to an arc chute I4.l A fixed arcing contact I9 is mounted between arc chutes I 4 and I5 at the upstream end thereof. Arc chutev I5 is so arranged in relation to arc chute I4 that it acts as a standby or backup for arc chute I4, but functions cooperatively as well. vThe arc chutes I4 and I 5 may be rectangular or circular in form. I

An arc chamber or manifold I 6 of insulating material is arranged between the gas supply conduit I3 and the arc extinguishing structure I2 for distributing the fluid under pressure from the point where it arrives in highly concentrated form by the supply conduit I3 to the arc chutes I4 and I5. Arcing contacts 'I and 8 are mounted within manifold I6 and the arc drawn upon separation of the contacts is enclosed by the manifold upon inception thereof. Manifold I 6 provides a pair of arcing zones 25 and v2li which are located at the upstream end of a pairy of nozzles I'I and I8, respectively. Nozzles II and I8 direct the iiuid under pressure from manifold I 6 to arc chutes I4 and I5.

Nozzle II may be so arranged that some fluid under pressure may pass therethrough even when movable arcing contact 8 is in the closed position, while nozzle I8 maybe arranged similarly to nozzle I 'I or may be so arranged that the movable arcing contact 8 effectively seals nozzle I8 until contact 8 has traveled a predetermined distance in contact opening direction.

One end wall of manifold I6,.as illustrated in Fig. 1, defines a passage therethrough which accommodates the movable sickle-shaped blade contact 8. This wall closely surrounds contact 8 and controls the escape of compressed air or arc products through passage 20 into the atmosphere. A pluralityr of transversal grooves 2I vprovided in the walls of passage 20 tend to establish eddies in the small ow of escaping air and arc products through passage 2U and thus minimize the rate of thatnow.

A pair of probe electrodes- 22 and 23 may be mounted within' arc chutes I4 and I5, respectively, for aiding arc extinguishment. A current limiting resistor 24 may interconnect electrode 22 and the multiple linger contacts of the fixed contact structure 'I, thus lowering the Value of the arc current during arc extinguishment.

The circuit breaker illustrated in the drawing is shown with the cooperating arcing contacts in the closed circuit position. An opening operation is initiated by admission of air under pressure to supply conduit I3 and manifold I6. As illustrated in Fig. 2, nozzle I'I is open at all times to manifold I6, thus allowing air to iiow through arc chute I4 substantially simultaneously with its admission to manifold I5. The flow of air through nozzle I8 and arc chute I5 is at first substantially prevented by contact 8, which occupies the entire entrance portion of nozzle I8 as illustrated in Fig. 3, thus effectively sealing it.

Actuation of the connecting rod I I moves blade contact 8 toward the right to open the electric circuit. As the blade contact 8 is separated from the iixed contact 1, an arc is drawn across the arcing zone 25 of the first arc chute I4 and substantially concurrently therewith a path is opened for blast of air of high intensity through the supply conduit I3, manifold I6, nozzle I'I to the first arc chute I4. Although contact 8 does not seal nozzle I'I when in its closed position, it may obstruct nozzle I1 sufliciently to prevent a blast of high intensity air from flowing into nozzle I I and arc chute I4 until after a predetermined movement of the contact. This blast includes all the air being supplied through conduit I3, and drives or loops the arc from zone 25 into arc chute I4. The heat of the arc causes vaporization of metal from the contacts and also causes violent expansion of the air surrounding the arc. The production of the arc thus is accompanied by a virtual explosion, which tends to reverse the air blast in pipe I3 and chamber I6 by its back pressure.

Frequently the arc is interrupted in the first arc chute by the blast of air flowing through nozzle Il, at least if the back pressure does not actually reverse the blast. If the arc is lnot al.- ready extinguished when the tip of the blade moves beyond contact I9, the arc islengthened and divided into a number of serially connected arcs extending between contacts 'I, I9 and 8. The second arc chute I5 and nozzle I8 are uncovered upon a predetermined movement 0f contact 8 and at least one part of the arc is driven or looped from zone 26 into arc chute I5 by a separate and distinct blast of air from nozzle I8. Thus, a single arc in each arc chute is acted upon by a separate and distinct air blast. Manifold I6 is large enough so that the blasts may be of substantially the same intensity.

In case the explosive or back pressure created in arc chute I4 is great enough to prohibit extinguishing the arc in that particular chute, the second arc chute I5 will cooperate vwith the contacts to act as a backup breaker to extinguish the arc .and clear. the electric circuit. Eachl arc chute has a common contact system and a. common source of air under pressure, but each arc chute has sufficient interrupting capacity to in,- terrupt the circuit. In fact. the arc chutes are so arranged that if back pressure in the first arc chute renders that arc chute inoperative, that back pressure will reduce the air iicw in that arc chute and therefore make an increased air flow available to extinguish the arc segment in the second arc chute which has a free path to atmosphere. This same operating condition occurs if the second arc chute is rendered inoperative by back pressure, that back pressure Will reduce the air flow in the second arc chute and help to extinguish the arc in the first arc chute. Thus, the efficiency of either arc chute is increased by the back pressure of the other arc chute.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In a fluid blast circuit interrupter, the combination comprising: a source of fluid under pressure, arcing contacts comprising a stationary contact and a movable contact for establishing an arc, an arc extinguishing structure mounted adjacent said contacts comprising a first arc chute and a second arc chute, a probe electrode mounted within said ilrst arc chute, a resistor for connecting said probe electrode in series with said stationary contact, said first arc chute receiving the arc drawn upon initial separation of said contacts and said second arc chute receiving at least a portion of said arc thereafter if said arc is not extinguished in said first arc chute, and means for providing a first blast of fluid from said source through said rst arc chute immediately before and during separation of said contacts and only after separation of said contacts providing a second blast of fluid from said source through said second arc chute.

2. In a fluid blast circuit interrupter, the combination comprising: a source of fluid under pressure, a manifold connected to said source for providing blasts of fluid under pressure, a pair of arcing contacts mounted within said manifold for establishing an arc upon separation thereof comprising a relatively stationary contact and a movable contact, and an arc extinguishing structure mounted adjacent said contacts comprising a first arc chute and a second arc chute both connected to said manifold, a probe electrode mounted Within said first arc chute, a resistor for connecting said probe electrode in series with said stationary contact, said ilrst are chute receiving the arc drawn upon initial separ-ation of said contacts and said second arc chute receiving at least a portion of said arc thereafter if said arc is not extinguished in said rst arc chute. said manifold providing a first blast of fluid through said first arc chute immediately before and during separation of said contacts and only after separation of said contacts providing a second blast of fluid through said second arc chute.

3. In a fluid blast circuit interrupter, the combination comprising: a source of fluid under pressure, separable arcing contacts for establish- CII ing an arc, a conduit for conveying a blast of fluid from said source adjacent said contacts for extinguishing the arc drawn upon separation of said contacts, an arc extinguishing structure mounted adjacent said contacts comprising a rst arc chute and a second arc chute, a probe electrode mounted Within said rst arc chute, a resistor for connecting said probe electrode in series with one of said arcing contacts, an arc chamber surrounding said contacts connecting said conduit with said arc extinguishing structure for enclosing the arc upon inception thereof, and means comprising a pair of nozzles for directing blasts of iluid from said chamber into said arc chutes, one of said nozzles directing a irst blast of fluid through said first arc chute immediately before and during separation of said contacts and the other of said nozzles directing a second blast of fluid through said second arc chute only after separation of said contacts.

4. In a fluid blast circuit interrupter, the comblnation comprising: a source of fluid under pressure, a manifold connected to said source for providing blasts of fluid under pressure, contact means mounted within said manifold comprising stationary multiple finger contacts and a cooperating movable blade Contact for establishing an arc, an arc extinguishing structure mounted adjacent said contacts comprising a first arc chute and a second arc chute, a probe electrode mounted within said first arc chute, a resistor for connecting said probe electrode in series with said multiple finger contacts, said first arc chute provided for extinguishing the arc drawn upon separation of said contacts and said second arc chute provided for extinguishing said arc if it exists after a predetermined movement of said movable contact, and means comprising a pair of nozzles one for each of said arc chutes for directing blasts of fluid from said manifold into said arc chutes, said movable blade contact obstructing the nozzle for said rst arc chute to limit the ilow of fluid from said source through said first arc chute until said contacts have separated and effectively sealing said nozzle for said second arc chute until said movable blade contact has traveled a predetermined distance.

GEORGE` A. BURNHAM.

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

I UNITED STATES PATENTS Number

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