US1916418A - Circuit breaker - Google Patents

Description

July 4, 1933. A, c AGQ 1,916,418

CIRCUIT BREAKER Filed Aug. 29, 1927 3 Sheets-Sheet 2 Fig.

a Load Generator INVENTOR A1077 a'f'aggzai y Sam 1/8711 Q Administrazoz ATTORNEY A. C. CRAGO CIRCUIT BREAKER July 4, 1933 Filed Aug. 29', 1927 3 SheetswSheet 3 Fig. 6.

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9 0, dead ago, Admz'mlszm/on INVENTOR Alan 0 6m by SdmueZD. Cr

AT'OEY Patented July 4, 1933 UNITED STATES PATENT OFFICE ALAN C. GBAGO, DECEASED, LATE OF PITTSBURGH, PENNSYLVANIA, BY SAMUEL ID.

CBAGO, ADMINISTRATOR, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOB TO WEST- INGHOUSE ELECTRIC & MANUFACTURING COHI PANY, A CORPORATION OF PENNSYL- VANIA CIRCUIT BREAKER Application filed August 29, 1927. Serial No. 216,032.

The invention relates to circuit-interrupting devices and particularly to are extinguishing means for use in connection there- I with.

The principal field for immediate application of the invention is in connection with alternating current circuit breakers, and there will be hereinafter described an embodiment of the invention as applied to such circuit breakers without in any way intending to restrict the scope of the invention, except as indicated in the appended claims.

One object. of the invention is to provide means for interrupting the flow of electricity through a gaseous medium.

Another object of the invention is to provide a circuit breaker with an arc-interrupting device capable of opening high voltage, large current arcs in air or gas without recourse to oil or other are quenching media. In some of its aspects, however, the invention is applicable in connection with low power circuit interrupting devices and to a variety of other uses.

Another object of the invention is to provide a structure wherein an arc may be operated in proximity to metallic deionizing means without being split up into a plurality of short'sections operating from cathodes on the metallic members. 1

A further object of the invention is to provide a deionizing chamber for circuit interrupters comprising a plurality of metallic rods so arranged that an arc can be forced to operate in the interstices between them withgut destruciive melting of the metallic memers.

Further objects of the invention will become apparent through reading the following description taken in connection with the drawings wherein Figure 1 is a View in elevation, partly in section, of a circuit interruptingdevice embodying the deionizing structure of the invention, I Fig. 2 is a sectional view taken on the lines from 11-11 of Fig. 1,

Fig. 3 is an enlarged plan view of the interrupting device shown in Fig. 1,

Fig. 4 is adiagram illustrating certain circult connections employing the invention,

Fig. 5 is a diagram used in explaining the v invention, 1

Fig. 6 is a similar explanatory diagram,

Fig. 7 is a detail of one form of an element of the deionizing structure embodying the invention, and

Fig. 8 is a detail of another form of an element embodied in the deionizing structure of the invention.

Patent 1,819,207, issued Aug. 18, 1931, on an application of Joseph Slepian, assigned to the Westinghouse Electric & Manufacturing Co. describes a circuit breaker provided with a deionizing structure which extingui shes the arc incident to the opening of its main contact, this deionizing structure comprising a series of sheets of metallic gauze through the openings of which the arc is compelled to run, and by which the arc path is rapidly deionized at the instant when the main current falls to -zero in its alternating current cycle.

While deionizing structures of this type have been, in general, found to be eminently satisfactory, certain conditions of line voltage, frequency and current may exist in which the arc has been found to cease to operate in the interstices of the gauze and to split up into a series of short arcs between successive gauze sheets.

Figure 5 diagrammatically illustrates such a breaking up of the are into a series of short sections. Each of these short arcs has a cathode and an anode on the wire gauze and these may cause a melting of the metal, and a destruction of the sheet thereby. the arc plays between arc termlnal members 35 and 36 between which are placed wire gauze sheets 37, as disclosed in the patent referred to above. In such a structure, under some conditions, the'arc may be split up into short sections such as shown at 38a, 38b, and 380, etc. The path of the current would then be, for example, from terminal 35, through arc section 38a to gauze sheet 37a and then in the sheet 37a to the terminal of arc section 38?) which conducts the current to sheet 376. The current then flows in sheet 100 In Fig. 5'

37% to the tcrminui of arc section 38c'u-nd so on through the remaining are sections and sheets to the arc terrninei member 36, This means that the totui are current wiii he flowing' vertically in the sheets and must tronsfor from each sheet to the arc sections ploy ing thereon, This transfer of the current- .irorn the sheets to the arc sections makes it possihie for s hot cathode to term st one terminci oi each arc section end on anode ct the other terminci with s resuiting burning of the genes sheets, uniess the are moved quite In accordance with the invention, hreohing up cit-the are into short sections with the consequent destruction of the deionizing sheets verticci cross conductors as when wire) gauge is used, so that the current could oniy flow through the series of short orcs by pussing from s rod in one horizontui row to a rod in another horisontoi row through the end connections 26. Since these int-liter ore" of high resistance there must he s considerehie voltage drop through this resistance and it is consequently more diiiicuit for theerc to opcrate in or series of short srcs interconnected by this high resistance than it is for it to operute us a single tong are 39, such as that illustrated in Fig. 7 t, in n path confined to sir spaces between the rods. The conducting hers 25 thus provide conducting puths ecross the ore extinguishing chsmher 021317 in c direction which is hoth trensverse to the iength of the ore end trans verse to the direction of movement of the arc. This meshes more dificuit for the ore to he split up into short us it is moved into the conductin eierneuts and uroids the formstion of t ermionic cathodes which would cause turning off the conducting elements st the hose or eech short one.

Referring to the drawings, the circuit hrecher in which the invention is here emhodied comprises s, pair of main contact menuhers 1 end 2 arranged to he bridged by a contact brush 3 heid upon as rosin contecturm 4. The srni is pivoted to swing the hrush hetween the position in which it hridges the mein contract members and the position away from said contact members in which the circuit oreuher is-opened. I

7 The arm i is moved hetween its closed and 7 open position by rneensof u iinh 5 end toggle mechanism or at design too weii imown in the ert to require extended description here}.

moronic The circuit hreoher is further provided with an arc interrupting structure 6 com prising on arcing contact arm. 7 having at its upper end so arcing contact shoe 8 to engage u stationery arcing contact member-9 for finally interrupting the circuit. The arcing shoe 8 end the stationery arcing Contact incinher 9 ere suitehiy connected as by means of conductors it, 12 and 13, that include main hiow-out windings 3.4; which are thus in pereiiei to the resin contuct members.

To open the circuit the main contact arm and the ercing contact orrn ere swung to the right, in Fig, 1 toy menus or the toggle mechsnisrnend 5, chore mentioned. This iinksge is so errenged that in opening the circuit hreuker, the brush 3 is first titted from the contact mernhers thereby diverting the line current from the hrush 3 into the shunting circuit through the ercing contact arm 7, arcing contact shoe 8, stationery contact memher 9, conductors H, 12 end 13, and hiowout winding it. Further movement of the linkage tuiiy opens the circuit by swinging the arm 7 further to the right thus tiringing shout disengagement oit the arcing con tact shoe 8 from the stctionery srcingcontact member 9 at their nrcing tips.

k A pair of euxiiiery contact mernhers15 thst ere arranged to he opened somewhat inter then the main contact members i, 2, 3., hut somewhat earlier then the resin contact tips 8 end 9, ere usushy provided to reiiere the main contact melnhers oi dent to the transfer oi current from the resin brush to the inductive shunt circuit which includes the blowout coii it end the urcing contact members 8 and 9. Contact urrn is connected near its hinge to contact nicrnher 2.

through the previously mentioned flerihie conductor 13 to complete at path through the contacts 21. end 2 from contact memher 8 to contact roemher 9.

The are extinguishing structure 6, to which the invention is principally directed coroprises so are chute which extends shove the space where the ore is drown hetwcen tips of the arcing contact members. 8 and 9, The are shoe comprises at pair of horn-hire inciined arcing pistes it and 1'? to which the are drawn hetween the arcing tips of the arcing contact members 8 and 9 is trensterred hy the action of the resin blow-out magnet. The hiow-out magnet comprises a terminated core 18 that iscncited hy the previousiy mentioned hiow-out winding 14:, and s pair of pole shoes l positioned on op site sides of the urcing-horn plates it end 1 e upper ends of the inclined arcing horn pistes are ,nletciiiccliy connected to vertical arcin pistes 21,22 as shown by Fig.1.

The poleshoes 19 end the vertical arcing pistes 21, 22 thus define a straight rectangutor chamber having at its lower end an upwardiy-tapered arc entrance chamber 23 orthe arcing incithe inclined arcing-horns 16, 17 and then upwardly along the latter through the entrance chamber 23 until it reaches the straight portion of the arcing chamber.

The straight portion of the arcing chamber between the arcing plates 21, 22 is filled with a series of what may be termedsectionalized or ladder grids 24, each one comprising a series of parallel metal rods 25, the ends of which are fastened in side plates 26 of high resistance material; the magnitude of the resistance of the side plates will depend, in ways that will be obvious to those skilled in the art, on the voltage and current rating of the circuit breaker; but for most ordinary purposesit will be found suflicient to proportion the side plates 26 so that the resistance intervening between successive bars 25 is about equal to that of a ten ampere arc of the same length in the atmosphere by which the bars are surrounded; that is to say the resistance may be about three ohms for 0 an air breaker, Figs. 7 and 8 illustrate such ladder-grids in detail and Fig. 2 clearly shows their position in the deionizing chamber. As shown by Figs. 1 and 3, the entire horizontal length of the chamber is occupied by a series of these vertical ladder-grids. The thickness of the side plates 26 is such that the metallic bars 25 are separated from each other by equal spacings. Insulating strips 27 may be provided between the high resistance end members 26 of the adjacent grids to separate them electrically from each other. To obtain a material for the plates 26 having suificiently high resistance, an insulating composition may be emplo ed into which a small amount of lamp black as been introduced.

The chamber containing these ladder-grids is closed onits two vertical sides by plates 28 of insulating material but is left open at the top so that it is possible for the heated gases incident to the operation of the arc to pass out of the chamber vertically.

The deionizing structure thus constituted may conveniently be held together by through bolts 29 linking the end plates and compressing the ladder-grids into a unitary rigid structure.

One desirable modification of thesimple structure just described consists in subdividing the deionizing chamber lengthwise by two metallic partitions 31, 32 as shown in the section in Fig. 1, As illustrated in Fig. 4, resistances may be shunted between two pairs of the metallic plates. One'of these resistances may be of smaller value than the'other.

As a consequence of this arrangement, the arc drawn between the arcing tips 8, 9 will be forced by the blow-out magnet into the deionizing chamber and will'subdivide into three shorter sections. Just after the alternating current passes through zero, the voltage tending to reignite the arc will rise more slowly on the section which is shunted by the lower resistance and the arc will be permanently extinguished in this section at this time. The arcs in the remaining sections may reignite, but the current now is limited by the resistance shunting the section in which the are is extinguished.

In a similar manner, that one of the remaining arcs which is shunted by the other resistance will be more readily extinguished than the arc in the section which is not so shunted. It will be extinguished, therefore, in its turn, leaving the current flowing through the two shunting resistors in series, and then through the arc in the remaining section. The effect of this considerable resistancein series with the arc is to decrease the current therein and to facilitate its extinction on the next passage of the alternating current through zero. When it is so extinguished the entire circuit is, of course,

By this ex edient of interrupting the are by a series 0 separate steps, it is possible to interrupt heavier currents than would be possible if the entire interrupting operation had to take place at a single instant.

The voltage necessary to maintain the arc in the grids, is very considerably greater than that necessary to maintain an arc of the same length and current in the open air. On this account it is sometimes diflicult to blow the are into the structure, since in splite of the magnetic field, a lower voltage may be able to maintain the are just outside the grids than within them. It is also found that with greater spacing between the bars, the arc voltage in the grids is less, and the arc passes more easily into the grid structure. The arrangement of Fig. 8 has, therefore, been found to be of advantage in many instances, inasmuch as the spacing of the bars is there made greatest at the lower end of the grid thus facilitating the entry of the are into the grids, and the spacing is made less and less with a corresponding increase of efficiency in deionization at the upper end of the grid wherethe arcis' to be extinguished.

While this modification of the invention is of advantage in many cases, certain others 1 arise in which this more elaborate structure is not warranted, and the simpler structure of Fig. 7 may then be employed with advanta e.

The mode of operation of the circuit breaker will now be clear. Upon the opening of the main contacts, 1, 2, 3, the line current is transferred through the conductors 11, 12,

i3 and blowout-magnet to the arcing arm 7 and the arcing-horn the arcing arm moves further to c right, its tip passes the lower end of the arcing horn 9 and thereby draws an arc therefrom. Upon its still further movement to the right, the end of this are is transferred Tom the arcing arm 7 to the other arcing horn l? as the arc is blown upward in the arcing chamber under the influence or? the biBW-fiufi magnet. The deflecting action of this magnet on the arc causes it to travel upward alcng the arcing horns l6, 17 into the dcionizing structure above described. There it is c-ompeiied to opcrate in the spaces between the rods oi the Rudder-grids, and the proximity of metallic members tend to dcionise such portions of the arcs as are in proximity thereto.

As soon as it has been forced into contact with the vertical metal partitions 31, 32, the arc is subdivided into three shorter sections as has already been described. 'll'hc deflecting force of the blow-out magnet forces the are continually upward through the deionizing chamber, thereby preventing it from remaining at any one place long enough to destructively overheat the bars of the ladder-grids. In the course of the alternating current cycle, the line current passes its maximum and decreases to the value zero. When it reaches this value the interior of the deionizing chamher is still conductive due to the presence therein of a large number of positive and negactive ions which constituted the current carriers of the arc, and which momentarily remain free due to the high temperature of the gases constituting an arc path. However, the metallic rods absorb the thermal energy and take up the electrical charge from such ions as come in contact withthem, and thereby rapidly deionize' the space in their immediate neighborhood. As the alternating voltage starts to rise on the reverse half cycle, it draws such free ions as may still remain uncombined in the arc path into contact with one or the other of the metal bars and immediately discharges them and efiects their rapid recombination. The metallic bars,thcrefore, rapidly deionizc the arc path and may do this so rapidly that the alternating voltage is insuificient to produce an appreciable amount of ionization by collision. Accordingly the flow of current through the are never rises beyond a small leakage value and the circuit is eifectively interrupted.

As has been stated, the expedient of subdividing the are by three separate chambers, and th; use of resistance shunts, makes it possible. that this electrical instabiiity may occur in the chamber shunted by the lowest resistance although it does not occur in the unshunted chamber. By this expedient of extinguishing the arc in stages, total currents which would be too great for a singie satanic unsliunted structure to eliectively deionize can be successfully coped with.

The deionizing structure which has been described, therefore, renders it possible to cause deioniz-ation of arcs of large current value without danger of transfer of. the arc to the separate metallic members constithb;

While in accordance with the patc'ntstatutcs the foregoing details of the practical embodiment of the invention have been given,-

it is to be understood that many of these are merely illustrative and that variations from the precise formwill be desirable in designing circuit interrupters for other voltages and currents than those specified above.

The principles which have been embodied in the circuit breaker interrupter are applicable to many other purposes than those here described as will be evident to persons skilled in the electrical arts. I is desired, therefore, that the language of the accompanying claims shall be accorded the broadest construction of which it is reasonably susceptible and that the invention shall belimited only by what is explicitly stated in the claims and by the prior art. i What is claimed is:

1. In an arc'extin hing device, an arc chamber substantially filled with a multi licity of rods of conducting material, eac of said rods being s aced from all of the other of the rods in t e an chamber and being mountedb means providing a considerable resistance etween each rod and each of the other rods adjacentthereto in any direction.

2. In an arc extinguishing device, an arc chamber having therein a plurality of rows of rods of conducting material, each of said.

rods being spaced from all of the other of the rods in t e are chamber and being mounted by means interposing an impedance between adjacent rods in any direction at'least equal to the impedance of an are at 10 amperes in the atmosphere of said chamber and of the. same length as the distance between adj acent rods. 7 I

3. In combination, means to establish an are, means forming an arc extinguishing chamber and having amultiplicity of sepafrom adjacent the end of said chamber adja cent said means to establish the are to adja cent the opposite end thereof, said conduct ing elements providing conducting paths. across the arc; extinguishing chamber only rate conducting elements positioned therein 1% from side to side, and the resistance between adjacent conducting elements in any direction being substantially more than three ohms.

4. In combination, means to establish an are, means forming the side walls of an arc extinguishin device, a multiplicity of separate conductrn elements extending between said side we s over a considerable area thereof, said conducting elements being insulated from each other in all directions for the portion of their length between said side walls and having their ends supported by said side walls, and said means forming the side walls providing considerable resistance between the ends of said conducting elements.

5. In combination, means to establish an arc, an arc extinguishing device, means for causing movement of the arc in said are extinguishing device, and a multiplicity of conducting elements positioned in'said are extinguishing device at intervals s aced along the direction of movement of t e arc, said conducting elements extending only in a direction which is both transverse to the length of the arc and transverse to the direction of movement of the arc. v

6. In combination, means for causing an are, means for extinguishing the arc includin a stack of grids each positioned in a plane su stantially transverse to the arc, each of said grids including a pair of edge members and a plurality of conducting wires spaced from each other and having their ends secured to said edge members, and the material of said edge members providing a resistance between adjacent wires at least as great as the resistance of a 10 ampere arc in air.

7. In combination, means to establish an arc and deionizing means comprisin bars of conducting material transverse to t e are path and resistance means interposed between the adjacent ends of the bars, the spacing of said bars var ing with their distance from said are establishing means.

8. In combination, means to establish an arc and deionizing means comprisin bars of conducting material transverse to t e are path and resistance means interposed be-' tween the adjacent ends of the bars, the spacing of the bars nearest said arc-establishing means bemg greater than that of the bars farthest from said arc-establishing means. 9. In combination, means to establish an arc and a deionizing chamber containing bars of conducting material transverse to the arc path, means to interpose between adjacent bars a resistance of substantially more than three ohms, the spacing of the bars nearest said arc-establishing means being greater than that of the bars farthest from said are establishing means.

10. In combination, means to establish an arc and deionizing means comprising conductors transverse to the arc path, the spacing of said conductors varying with their distance from said arc-establishing means.

11. In combination, means to establish an arc, deionizing means comprising conductors transverse to the path of saidarc, means to move the arc across said conductors, the spacing of said conductors varying with their distance from said are establishing means.

12. In combination, means to establish an arc, deionizing means comprising conductors transverse to the path of said arc, means to impel the arc towards said conductors, the spacing of the conductors nearest said are establishin means being greater than that of the con uct-ors farthest therefrom.

13. In combination, means to establish an arc, deionizing means comprising conductors transverse to the path of said are, resistance means interposed between the adjacent ends of the conductors, means to move the arc across said conductors, the spacing of said conductors varying with their distance from said are establishing means.

14. In combination, means to establish an arc, deionizing means comprising conducting bars transverse to the path of said arc, resistances of substantially more than three ohms interposed between the adjacent ends of the bars, and means to deflect the arc towards said bars, the spacing of said bars varying with their distance from said are establishing means. 7 V

In testimony whereof, I have hereunto subgcribed my name this 18th day August, 192 i SAMUEL'D. CRAGO, Administrator of the Estate of Alan 0.

Orago, Deceased.

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