US2942086A

US2942086A - Chimney cooler for air circuit breakers

Info

Publication number: US2942086A
Application number: US644251A
Authority: US
Inventors: Victor A Mortenson; Donald E Weston
Original assignee: Allis Chalmers Corp
Current assignee: Allis Chalmers Corp
Priority date: 1957-03-06
Filing date: 1957-03-06
Publication date: 1960-06-21
Anticipated expiration: 1977-06-21
Also published as: GB850307A

Description

June 21, 1960 v. A. MoRTENsoN E'r AL 2,942,086

CHIMNEY COOLER FOR AIR CIRCUIT BREAKERS 2 Sheets-Sheet 2 \/2 l if V. A. MORTENSON ETAL CHIMNEY COOLER FOR AIR CIRCUIT BREAKERS lhnq-Q lll June 21, 1960 Filed March 6, 1957 United States Patent O CHIMNEY COOLER FoR AIR CIRCUIT BREAKERS Victor A. Mortenson, Scituate, and Donald E. Weston,

Brookline, Mass., assignors to Allis-Chalmers Manufacturing Company, Milwaukee, Wis.

Filed Mar. 6, 1957, Ser. No. 644,251

3 Claims. (Cl. 20o-147) This invention relates tocircuit interrupting devices and more particularly to means for reducing the amount of ionized gas discharge above the arc chute of a circuit breaker structure.

In the construction and operation of circuit breaker structures, it is frequently necessary to provide means for extinguishing quickly the are which is drawn between separable arcing contacts. This arc is usually blown by blowout means, such as a magnetic blowout coil or an air blast, into an arc chute which is arranged to quench the arc by lengthening it, cooling it, or Aa combination of both.

Arc chutes having spaced insulating plates to lengthen the arc or squeeze the arc into narrow slots have been used to rapidly increase the arc voltage, decrease the arc current and greatly improve the power factor, thereby facilitating interruption of the are at a natural or'forced current zero. However, it has been found in many cases that the arc voltage developed by the arc chute was not the most favorable for interrupting the power circuit.

The arc chute for an electromagneitc type of circuit breaker is designed to perform two functions, namely, to interrupt a power circuit and to enclose the arc products. As a circuit interrupting device the arc chute of the magnetic breaker must be capable of controlling the arc voltage, the arc current, the arc energy, the rate of rise of recovery voltage and the phase relationship between arc current and line voltage at the instant of interruption. As an enclosing structure for cooling and deionizing the arc products, the arc chute of the magnetic breaker must protect all the surrounding operating parts from the effects of the arc or its arc products. All of the gases exhausted from the arc chute must be rendered harmless before being exposed to any of the surrounding circuit breaker `structure or allied equipment. In many cases, however, the gases exhausted from the arc chute remained ionized and caused a visible discharge, such as flame emission, at chute structure. t

Therefore, in accordance with the invention claimed a new and improved arc interrupting device is provided which cools the gases exhausted from the interrupting device within the arc chute enclosure before final discharge of the gases to atmosphere, thereby eliminating or substantially reducing ionized gas discharge or llame emission from above the arc chute of the interrupting device. The arc chute comprises a plurality of spaced insulating plates arranged to extend longitudinally of the axis of the arc chute at the arc receiving end thereof, a pair of spaced arc runners, one of said arc runners being arranged adjacent each of the contacts for providing a conductive path for the terminals of the arc from the contacts into the arc chute, and a-plurality of spaced cooling elements arranged above the arc runners and spaced from the insulating plates at the exhaust end of the arc chute for deionizing the arc products.

It is, therefore, one object of the present invention to vprovide a new and improved arc interrupting device in the exhaust end of the arc ice which reduction of ionization and visible discharge at the exhaust end of the arc chute is accomplished by cooling the arc products and gases within the arc chute enclosure before discharge to atmosphere.

Another object of this invention is to provide a new and improved arc interrupting device in which arc discharge cooling means function to cool the arc products and gases without offering a pneumatic impedance to their flow.

A further object of this invention is to provide a new and improved are interrupting device in which cooling elements are arranged in a predetermined manner above the arc runners in the exhaust end of an arc chute structure to reduce ionization and visible discharge therefrom.

A still further object of this invention is to provide a new and improved arc interrupting device in which arc Adischarge cooling means arranged in a chimney vent above the .arc runners at the exhaust end of the arc chute are staggered and insulatingly separated from each other.

A still further object of this invention is to provide a new and improved arc interrupting device in which are discharge cooling means are arranged downstream of the arc runners and across the exhaust end ofthe arc chute structure.

Objects and advantages other than those above set forth will be apparent from the following description when read in connection with the accompanying drawings, in which:

Fig. 1 is a view in cross section of a magnetic blowout type circuit breaker employing the present invention;

Fig. 2 is a partial, cross sectional view of a modification of the cooling element arrangement illustrated in Fig. 1;

Fig. 3 is an end view ofthe structure illustrated in Fig. 2 with the arc chute end plate removed;

Fig. 4 is a plan view of the structure illustrated in Fig. 2;

Fig. 5 is an enlarged perspective view of the cooling elements arranged above the arc runners shown in Fig. l; and

Fig. 6 is a partial cross sectional view of a modification of the arc runner cooling element arrangement illustrated in Figs. 2, 3 and 4.

Referring more particularly to the drawings by characters of reference, Fig. 1 illustrates a magnetic blowout type of circuit breaker including as elements thereof a pair of terminal studs 6 and 7 for connecting the circuit breaker to line conductors (not shown). Although in general, circuit breakers of the type considered in Fig. l 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 drawings and the circuit breaker will be described in detail as if it was ofthe single pole type.

The circuit interrupter or breaker in Fig. 1 comprises essentially means for opening the circuit to form .the interrupting arc and an arc extinguishing structure. Specically the circuit opening means comprises a fixed current carrying contact 8, a tertiary contact 9, a fixed arcing contact 10, and a movable arcing contact 11. Arcing contact 11 is mounted on a contact arm 12 which is pivyotally mounted'at 13 on an extension 14 of the circuit `breaker stud 6 and is operated by means of a reciprocally movable rod 15. The operating rod 15 is suitably connected to an actuating mechanism (not shown) for operating the movable contact between closed and open circuit positions. Fig. 1 illustrates the movable contact 11 in closed positon. The arcing contacts are electrically connected to the lower ends of terminal studs 6 and 7. Accordingly, when the breaker is connected in series in a power circuit and the arcing contacts are separated, an arc amigos@ may be initiated across the gap formed between the contacts.

For interrupting this power are, an arc extinguishing structure, such as an larc chutel, may be .mounted so lasV to receive the power arc which is underl theliniuence of thefrnagneticfblowout means.. 'The` arc chutefspreferably isdisposed directly about andabovethelarcing contacts, asshown, lwhen the blowout means act upward, 'but may be mountedin any othersuitablelocation when the blowout means act inv other directions. Theiswitch orarcing contacts andthe magnetic blowout' structure can assume any preferred form so that a brief description thereof will belsufficient. The magnetic blowout'-means may comprise a core 17, -poles 18 and a coil 19..which fis electrically connected :tothe terminal'r stud. 7 andto fa metallic arc runner 20 so that therar'c current (as "the arc travels along therunner) flows through the blowout coil inamanner wellknown inthe art.l f I v Normally the-current is carried in `the closed circuit position -of the breaker by the spring biasedcontact. `'As lthemovablc arcingl contact 11 is Vactuated to open circuit position, current is shunted from fixed contact '8 viirst to Vtixed `contact 9 and afterwards to fixed arcing -contact"'10. As 'the arc is drawn by the movable arcing contact '11, the larc terminal of arcing contact 10 is transferred `to larcrunner 20, which is usually an extension arm of the fixed arcing contact 10. As the movable arc- 'ing"conta'ct `11 'approaches or reaches its full..opening istroke `thearc .terminal transfers troml the movable arcing contact =1-1 to anarc runner 21iwhich directsthefarcvin the arc chute 16. The arcing contact 10 and thelzarc "runner 20 are electrically connected 'in :series with :the

' blowout-coilf19 and stud v7. Accordingly, the v-bl'ovvout coil'is alreadyenergized at the inception of the 'arc to finuence the arc in a well known manner, i.e. to drive it in the arc chute 16 in an expanding loop. It willbeap- .parent to one skilled in the art that the blowout tieldcan be utilized in the'most eicient manner by disposingthe siren-poles l18 so as to-cooperate with the blowout coil in the conventional manner outside of the arc chute.

*Arc chute 416 is'provided with af-plurality of slotted jacentfthe` zone 'ofi arc initiation to Y-form Tan"y arc passage.

yAsfwellV known'in the'ait the slots maybe arranged'in A4staggered relation-'at their downstream ends.vr Thisfout of'registryror staggered relationship ofthe slots' causes theformation of azigzag shaped arc path. Barrierfplates k22'may be provided in some applications of this invention with alpluralityrof apertures or perforations which may be arranged to extend from the downstream ends of Vslots'23' toward the exhaust end of the arc chute.

Chimney vents

24 and 25 are arranged at each end'or :sidevof the stack-'of barrier plates 22 above arc runners Z0 and 21. lThese vents direct the arc products and gases created'by the arc terminals moving alongA the arc runners-out of the are chute to atmosphere. The extent'of the ionization of the gas and the volumeofthe 'arcproductsv produced by the actionfof the'arclon the arc runners varies 'directly with the amount 'of-current being interrupted and the voltagefcharacteristics ofthe interrupter. It is recognized that the arc products may interfere with the action of the barrier plate stack. Consequently

chimney vents

24 and 25 are separatedfrom the barrierplate stack and discharge the gases and arc prod- )ucts from the arc runners directly Ato atmosphere without going through the barriergplate stack. As noted from Vthe" drawings the arc runners direct the terminals of the Aarc into'the chimney vents. i v Y f "A "The chimney' vents while accomplishing their purpose fof `separating the'arc products of thev arc runners from the barrierplate stack produce a concentrationof theseproducts downstream of the arcrunners. It has been found that these arc products from the chimney vents are the chief cause of dielectric difficulties outside of the confines of the breaker. Since the arc products from the arc runners are discharged. froma live terminal, this terminal is in effect extendeditothe full distance the produetsaraverfwhil-e an ionized condition. If fno; insulation is .present to isolate the terminals, the terminals will dischargetogrounm YForfl'iigl'r current .interruption this means that the circuit breaker enclosure 'must blewell insulated or that the'distances between the ionized 'gas discharge ffron?:"the'l"chimney vents.=.and-a'r1y grounded structure be suflicienttoassure that ionized arc products do not touch grounded metal.

It has been noted that the arc within the breaker structure will not travel beyond the height of the barrier plate stacks.'v Thereforeyfitis possible:pneumatically to place metalliccooling:elements 'inf-close vproximityto and down- :streams/of.: the` :tops of :the arc runnersxwithout the arc terminals jumping from one cooling elementv to another. 4Eventhoughrtheipotentialio the arcrunner is impressed 'to the distance the gases remain ionized withinthe chim- ,ueyz vent, nevertheless-beyond the arcirunner the dielec- 'tricstrengthofsrtheair column is increased proportionally `to the :condition of the gas `or airy within the breaker structure and laterrto `thermixt'ureofgas and air between .the arc chutezstructure Ior chimney .vents and the ygrounded .enclosurer' :Thecurrentfinterrupting-limitation of the lbreaker structurethereforafis.: that -amount of'current frequiredto; causeuionizedgases .tozextend from the-chim- 'neyrventsto'theegrounded circuit'breaker enclosure and vcausean. arcdischarge togroundto occur.

In order `to increase the interrupting ability of air typ circuit: brealcenstructures the arc .chutesy in accordance rwithxthe'inventionclaimed are `provided with aplurality ofucoolingelemeirts,which, for example, may-be'metal- .lic .or nonmetallic tubular members 30, arranged Iabove *they 4arci runners z201and 21 yandspaced from the 'barrier .platesiZznat the4 exhaust `end of-thearc chute. lf so de- 'sired,.*these,cooling .-elementsfmay be solid or hollow 'tubulan'niembers oxamaterial having a high specic heat -value.'z.whenf.chirnney vents are: employed above the arc "runnersfas Ashown inFigs. Al and 2 of the drawings, 'thecoolingelementsf1are,arranged ,to extend from and lare'supportechby.the insulating vmembers 34 forming the .asides `ofzthez:chimney:ventsA and vare arranged transversely :to the longitudinal; axis-ofthe iarc chute. --'Becausey of Ltherectangular.' `shape*offtheusualchimney vent the longitudinali axis vof; the cooling *elements* extends sub- 'stantiallys.parallel,- with 'the V'short Vaxis ofl the vent,n how- 'evergit isrintended'to be .withirr'the scope of this invention to f'providefzcooling elements of fany suitable vcross sec- -"tionalfiformarrangedto extend in 'any desirable direction within the chimney structure. n most applications the rcoolirigsurfaces` ofuthe Velements Y`are :so arranged that l.they 'oir'er'the'rlestiamountof pneumatic impedance to theoW-of gases and arcproducts through the chimney -ventsuxForxthis reason and* for the further reason Athat "the-.voltage vof the Y'arc-'runner is impressed onlyv asfar asionization travels-throughfthechimney vents, separate cooling elements30 fare tpositioned' in rows lin lspaced staggered E'relationship-to-c'ine another, such that, while ostensibly presentingga-solid'sfront of cooling elements to animee 51 are arranged in isolated groups to extend transversely to the longitudinal axis of ythe arc chute and to the direction of movement of the arc, arc products and gases through the arc chute structure. Each group may be separated or compartmented from the adjacent groups by insulating material 33. The s ize and number of compartments used in a particular arc chute structure is determined by the voltage gradient across the arc chute. Each group of tubes is exposed to and reacts on only a portion of the voltage across the arcing contacts or arc runners. i

Compartmentization of the arc chute structure assures that each group of tubes or cooling elements functions to its fullest capacity by cooling only a certain portion of the generated gas and arc products. The number of tubes used and their geometrical arrangement within the arc chute enclosure is determined by the amount of cooling required and the particular position and amount of discharge volume of arc products and gases from the barrier plate stack. Tubes 31 are staggered in such a .manner that the space between them provides full discharge of the arc products and gases from the arc chute structure at the same time being so arranged that the are products and gases discharged from the barrier` plate stack must pass adjacent to -the cooling elements 31 before being discharged to atmosphere. In this manner cooling is accomplished without restriction to the normal flow of gases or arc products. Y

The group of cooling elements arranged adjacent each end of the arc chute barrier plates comprises a greater number of cooling elements which extend farther downstream from the arcing contacts than do the elements of the groups arranged intermediate the ends of the arc chute structure. This arrangement provides a larger number of cooling elements immediately above the zones of the greatest arc product and gas discharge production from lthe barrier plate stack, namely, above the areas adjacent the ends of the arc chute structure and near` the zones of the are runners than do the groups intermediate the ends of the arc chute structure.

`If so desired the respective groups of cooling elements 31 may be arranged in removable or detachable compartments which can be temporarily arranged in a given position in the arc chute structure and later moved to another more eiective position. The tubes of each compartment are arranged in a plurality of rows wherein each cooling element of each row is arranged in staggered relationship to tbe elements of adjacent rows. At least some of the cooling elements in at least one of the groups may be composed of insulating material. In the removable compartment structures the walls of Athe compartments are made of insulating material of the type capable of withstanding the heat of the arc products and gases.

The cooling elements 36 and 31 are arranged as after coolers in the exhaust end of the arc chute structure and are spaced a predetermined distance downstream from the arc runners and the barrier plates. These elements or tubes function -to cool the arc products or gases without oiering a pneumatic impedance to their flow. In other words, the performance of the barrier plate stack is not affected by pneumatic blocking and the full arc interrupting ability of the barrier plate stack is developed.

Fig. 2 illustrates an enlarged partial cross sectional View of a modification of the arc chute structure shown in Fig. l wherein the insulating tubes 31 are arranged in similar groups across substantially the full length of the exhaust end of the arc chute structure. Fig. 3 is an end view of Fig. 2 with the arc chute end plates removed wherein the particularly geometrical arrangement of the cooling elements 30 is evident. lFig. 4 illustrates a plan view of Fig. 2 showing the manner -in which the cooling elements or tubes extend across the exhaust ends of the barrier plates 22.

Fig. 5 is a perspective View of the cooling elements 30 Shown rin Fig. l but illustrates one way of fastening the tubes to a wall of the chimney structure.. As noted from Fig. 5 the chimney vent and cooling elements may be separately assembled and detachably connected to the circuit breaker structure.

Fig. 6 illustrates a further modification of the cooling element chimney vent arrangement shown in Figs. l to 5, inclusive, wherein the cooling elements 30 extend part way .finto and are firmly held by the side walls of the chimney structure.

Although but a few embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without depart-A fing from the spirit of the invention or from the scope of theappended claims.

What lis claimed is:

1. An electric circuit interrupter comprising a pair of relatively movable contacts, means for drawing an arc between said contacts, an arc chute for receiving the arc at one end thereof and exhausting the arc products at the other end, said arc chute comprising a plurality of spaced insulating plates arranged to extend longitudinally of Ithe axis of said chute at the arc receiving end thereof, a chimney vent arranged adjacent said plates outside of said chute, an arc runner arranged adjacent one of said contacts for providing a conductive path for the terminal of the arc from said one of said contacts into said vent, a plurality of spaced tubular cooling elements arranged to extend transversely to the longitudinal axis of said chute above said runner and within said vent, and a plurality of groups of spaced tubular cooling elements arranged adjacent said plates at the exhaust end of said chute, said groups of said cooling elements being arranged transversely to said plurality of spaced tubular cooling elements, said cooling elements in said vent and adjacent said plates cooling and deionizing the gases and arc products occurring during circuit interruption.

2. An electric circuit interrupter comprising a pair of relatively movable contacts, means for drawing an arc between said contacts, an arc chute for receiving the arc at one end thereof and exhausting the arc products at the other end, said arc chute comprising a plurality of spaced insulating plates arranged to extend longitudinally of the axis of said chute at the arc receiving end thereof, a pair of chimney vents arranged adjacent said plates outside of said chute, a pair of spaced -arc runners, one Vof said runners being arranged adjacent each of said contacts for providing a conductive path for the terminals of the arc from said contacts into each of said vents, a plurality of spaced tubular cooling elements arranged to extend transversely to the longitudinal axisy of said chute above said runners and within said vents, and a plurality of groups of spaced tubular cooling elements arranged adjacent said plates at the exhaust end of said chute, said cooling elements of said groups being arranged substantially ninety degrees out of phase with said plurality of spaced tubular cooling elements, said cooling elements in said vents and adjacent said plates cooling and deionizing the gases and arc products occurring during circuit interruption.

3. An electric circuit interrupter comprising a pair of relatively movable contacts, means for drawing an arc between said contacts, an arc chute for receiving the arc at one end thereof and exhausting the arc products at the other end, said arc chute comprising a plurality of spaced insulating plates arranged to extend longitudinally of the axis of said chute at the arc receiving end thereof, a pair of chimney vents arranged adjacent said plates outside of said chute, a pair of spaced arc runners, one of said runners being arranged adjacent each of said contacts for providing a conductive path for the terminals of the arc from said contacts into each of said vents, a plurality of spaced tubular cooling elements arranged to extend transversely to the longitudinal axis of said chute above said runners and within said vents, a plurality of groups of' spaced metallic tubular cooling elements arranged adjacent saidfplate's at the exhaust end of said chute, said cooling elements of 'said groups being arranged substantially ninety degrees out of phase with said 'plurality of spaczedtnlula'r coolingelex'ne'nts, and insulating 5 means Aajrra'nged between each of said groups 'of said elements for isolating said 'groupsof elements from each other, said grops of elements adjacent each yside portion of said chute comprising a greater number of said elei ments than lsaid groups intermediate `the side portions of `10 said chute.

References Citedin thefile of this patent UNITED `STATES"PATENTS p 1,916,418

crago Jiny 4, 1933 15 8 yClerc f` Dec. 18, 1934 Prince Allg. V1941-2 Linde Aug. 18, 19212 Healis Dec. S, 1942 Bardem Feb. 9, 1943 Walle Dec. 28, 1943 Sc'Ott July 27, 1948 R'idgley June 23, 1953 Taylor Mar. 13, 1956 FOREIGN PATENTS Great vBritain Mar. 19, 1931 GreatBritan Sept. 8, 1954 Great Britain Dec. 1'2, 1956