US1966316A - Arc chute - Google Patents

Description

J. SLEPIAN July 1o, 1934.

ARG CHUTE Filed Jan. 10, 1929 lNVENTOR .Josep/2 We/afa n.

A T'oRN Y UNITEDSTATES PATENT OFFICE ARC CHUTE Joseph Slepian, Pittsburgh, Pa., assignor to Westinghouse Electric & Manufacturing Company, a corporation of Pennsylvania Application January 10, 1929, Serial No. 331,469

8 Claims. (Cl. 20o-144) My invention relates to circuit interrupters and My invention comprises, in general, an insu- Dartieuiariy to circuit interrupters of the air lating base 1, upon which is mounted a stationbreak type wherein Vthe arc incident to the separy contact member 2, a magnetic core 3 and aratien f the Contacts iS led into a Space OC- a bracket 4 that supports the movable elements 5 cupied by a plurality of metal plates or grids of the breaker 5. The foregoing elements may 60 and is brokenup into a series of arcs that are be of any type well known in the art to be suitlapidly deionized and extinguished as they move able, their precise structure not being claimed between the grids. herein.

As a particular feature 0f my invention here The magnetic core 3 has a winding 6 mounted l0 described, an arc, consequent upon the opening thereon that may be energized, through leads 7, 65 of the circuit, moves into an arc-extinguishing from any desired control circuit. A movable means adapted to divide it into a plurality of contact member 5 is carried by a pivoted arm 8 short arcs between grids of such form that amaghaving an armature 9 to be attracted by the netic flux is induced by current flow in the grids magnetic core 3 vwhen the coil 6 is energized.

l5 themselves which moves the arc rapidly over the The arm 8 is supported upon a pivot 11 and has 70 grid surfaces. a lateral extension 12 that is attached, by means The rapid movement of the arc within the exof a spring 13, to a stationary bracket 14. tinguishingmeans prevents the burning and va- Line current is conducted to the extension 12 porizin'g of metal which occurs if arc terminals from a terminal bolt 15 through a flexible conmove slowly or stand still for any appreciable' ductor 16. The contact member 2 is fastened to 75 time. the base 1 by volts 17, to one of which is attached I have found that, in circuit breakers of the the terminal piece of a conductor 18. A similar prior art, vaporized metal combines chemically terminal piece for a conductor 18a is attached to with the oxygen of the air for a considerable time the bolt 15. after the electric arc proper is extinguished; and The mode of operation in moving the mecha- 80 that the ionized products of this combustion are nism just described to open-circuit position from a frequent cause of restriking or re-ignition of the closed position shown in Fig. 1 is as follows. the arc. By preventing the formation of such Assuming the contact member 5 and the memvapors, re-ignition of the arc is prevented. ber 2 to be in engagement, as shown n Fig. l,

In the particular embodiment here shown, the a circuit is completed, through the conductor S5 deionizing means comprises an aggregate of 18, bolt 1'7, contact member 2, contact member spaced plates of U-shape, the adjacent surfaces 5, arm 8, conductor 16 and bolt 15, to the other between the spaced plates being traversed by the conductor 18. termini of the short arcs into which the original When the coil 6 is (le-energized, the spring 13 arc is broken. The flow of current from the actuates the arm 8 in a contra-clockwise direc- 90 onef to the other branch of each U-shaped plate tion, thereby moving the contact member 5 away Asets up a magnetic field which causes the short from the member 2, thus producing an arc therearcs to move rapidly across the surfaces of the between that moves upward because propelled. plateseither by the force inherent in the arc itself or 40 -With these and other objects in view, the inby an additional blowoutfmagnet that may be 95 vention comprises the novel structurey and comprovided. The arc will be broken into a plurality bination and arrangement of parts that will be of short arcs by the members of the arc-extinfully set forth in the following description, taken guishing device 21, shown" in Fig. 1, and the in conjunction with the drawing, in which: clrcuitwill be established from the member 2 to Figure 1 iS a Side View, partly in section and a plate 22 and thence, through the plurality of 100 partly in elevation, 0f a Circuit interrupter emshort arcs and U-shaped members 19,. to an end bodying my invention; p plate 26 and a flexible conductor 32 leading to FigS- 2 and 3 are, respectively, VieWS, in side the bolt 15. The series of short arcs just deelevation and in end or edge elevation, of one scribed will move rapidly in the spaces between of the U-shaped plates embodying a modified the members 19, as heretofore mentioned, and 105 form of my invention. will thereby be deionized and quickly extin- Fig. 4 is a fragmentary view, in side elevation, guished. 0f the assembly ShOWn in Fig. 2. It is clearly apparent to any one familiar with Figs. 5 and 6 are schematic diagrams used in the contactor art that any other suitable means explaining my invention. n for effecting engagement and separation of con- 1N tact members might be employed, and, therefore, I do not wish to limit the application of my invention to any particular contactor.

Referring to Fig. 1 of the drawing, a plurality of U-shaped metal plates 19 of the form shown in detail in Figs. 2 and 3 is assembled to constitute the arc-quenching device 21, the lower ends of the U-shaped members 19 being posi-V tioned slightly above the contacts 2 and 5.

In the assembly of the elements of arc-extinguishing device 21, a supporting plate 22 is providedy with a lateral extension which may be attached to the terminal 2 by a bolt 23.

Insulating members 24 and 25 are employed to space the plates apart, the width of each space which has been found to be suitable for most purposes being one-sixteenth of an inch. By making the spaces between the plates in which the arc plays very narrow, the ux is concentrated providing a strong field along this whole length of the short arc to move it rapidly without substantially bowing it out. By making the spaces in which the arcs play very narrow, a high reluctance path for the ux is provided between the plates. Another method of making the reluctance of the flux paths between the legs of the U less than the reluctance in the arc spaces between the plates by the use of iron is described below in connection with Fig. 3. For commercial-frequency alternating-current circuits, a suicient number 0f U-shaped plates should be assembled to provide one intervening gap for each 140 volts of the circuit to be interrupted.

When the required number of U-shaped members 19 have been assembled, an end plate 26 is spaced from the last U-shaped member by insulating members 24 and 25, the entire assembly being clamped together by the. bolts 27 having insulating sleeves 28.

Between the legs of each U-shaped member 19, insulating members 29 are provided to maintain the legs in their parallel relation when the bolts 2'7 are tightened.

As shown in Fig. 1,' the insulating members 29 are of substantially the same length as the legs of the U-shaped members 19 and, when so provided, the'parallel legs of the members may be in closer proximity to each other than other'- wise, as the insulation therebetween reduces the possibility of arcing between the legs of the same member, thereby ensuring that the path of the current will follow the U-shaped portion of the member.

The sides of the assembly 21 are enclosed by insulating plates31 that extend below, and adjacent to, the sides of the movable contact 5 and the terminal 2, thereby conning the arc within the width of the arc-extinguishing device 21. The plates 31 are provided with openings through which the lugs 33 and 34 on' the end plates 26 and 22, respectively, extend in order to retain the plates on the sides of the structure 21 as illustrated in Fig. 4. A flexible conductor 32 may connect end plate 26 to the bolt 15 through conductor 16.

The plates 19 of the device 21 may be made of non-magnetic conducting material and, if so,

under many conditions, insure extinction of the arc. Under other conditions, however, it is advisable to supply a magnetic means of one form or another to assist in transferring the arc to the plates 19 and in moving itin the spaces provided therebetween.

For example, the desiredmagnetic eiect may simply and readily be obtained by forming the plates 19 from magnetic material. Alternatively, the insulating members 29, heretofore referred to, may be replaced by a magnetic member 30 that is covered with insulation 35 but is located between the legs in a position similar to that of the members 29 as shown in Fig. 3. In most cases, in which the iron is provided between the legs of the plates or when the plates themselves are constructed of magnetic material, an additional arc-moving force, such as a separate blowout magnet, need not be provided, although it will be understood that the provision of such blowout magnets as are known in the circuit-interrupter art is within the purview of my invention.

Enough details of thestructure embodying my invention having been set forth to enable its general characteristics to be understood, certain principles underlying its operation will now be explained.

If an arc deionizing and extinguishing device be made as shown in Fig. 6 consisting of a plurality of fiat plates..35 in spaced relation to each other, itis found that, under certain conditions, a portion only of the arcs, as at 36 and 37, are rapidly moved in the spaces intervening between the plates, the other arcs such as at 38 moving very slowly or even remaining stationary. This is probably caused by the magnetic effects resulting from the ow of the current from one plate through the 'arc and down through the adjacent plate to an adjoining arc. A simple analysis shows that current ow between arcs irregularly distributed over the faces of successive plates sets up magnetic fields which drive the arc downward as indicated by arrow 39 if it is at the lower end of a plate, but tend to move the arc upward as indicated by the arrows 40 and 41 if it is at the upper end of a plate due to the reaction between the Vmagnetic ilux set up by the current flowing toward and away from the arcs as indicated by thearrows 42, and the current flowing in the arcs 39, 40, and 41. This effect may be opposed by a suiiiciently strong impressed magnetic field, but this impressed magnetic field needs to be much stronger than would be required if this loop effect did notvoccur. y

It is necessary to the successful operation of my arc deionizing device to have all the short arcs move with sufficient rapidity to prevent the 'termini thereof, when passing over the surfaces of the plates, from evolving metal vapors. In order to prevent such segregation of the arcs at the upper and lower ends of the plates and to obtain a similar movement of the arcs in all of the spaces, I have substituted for the simple fiat plates 35 just described, the plurality of U-shaped plates 19 hereinbefore described. It can be shown that the magnetic effect of current iiow that conducts from each arc to the adjacent one through the U-shaped portion of ,the member is to cause the arcs to take up similar positions in the different spaces since the current indicated by the arrows 43 flows upwardly to each arc 45, 46, and 47 and downwardly away from each arc, irrespective of the position of the arc between the plates 19 and its relation to the other arcs. Thus, the magnetic elds set up by the currents flowing in the U-shaped portion of metal between successive yshort arcs produce a driving force upon these.

arcs, moving them upward, as indicated by arrows 49, 50, and 51, in the spaces between the members with substantially equal forces and like speeds ot movement.

As the speed at which the arcs are moved depends upon the extent; and magnitude of the magnetic iield set up by the arc current and the spacing of the members 19, quantities should be taken into consideration when constructing arc interrupters of this type in order to make certain n that the legs of the U-shaped members 19 and the end plates 22 and 26 are of such lengths that the arcs will have sufficient lengths of surfaces over which to travel without reaching the ends of plates 19 during the half period of the alternatingcurrent cycle which may elapse before the line current passes through zero and then becomes k, extinct.

It will thus be seen that I have provided a deionizing device for an arc established by a circuit interrupter that moves the arc very rapidly across the cool surfaces of a plurality of metallic plates. The said plates may, if desired, be of non-magnetic material, and they may have associated with them magnetic means for assisting in moving the arc. The plates themselves may be constructed of magnetic material, thus strengthening the iield about the current ilowing therethrough.

The plates are preferably made of U-shape in order that the' spaces provided between adjacent members shall form similar current paths with the arc, and that all of the arcs shall be acted upon in "the same manner and with the same speed of movement. The number of plates, the widths of the spaces and the lengths of the plates will all depend upon the circuit in which my interrupting device is to be employed. Under all conditions, such dimensions should be so chosen that the speed of the arc movement shall always be great enough to prevent the arc from burning the plates, under which condition, the arc will be deionized and extinguished within a half cycle of on the whole body of the short arc and drive it quickly upward so `that it does not burn the plates. -Due to the fast driving action of the field, it is not necessary to provide the usual blowout coil required with the widely spacedplates of the prior art.

By closely spaced in the claims is meant such close spacing that the magnetic eld created by the current in the plates affects the whole body of the short arc.

. to be spaced more closely together.

It will be understood that, while I have de- The use of magnetic material for or between the plates has an additional advantage besides strengthening the magnetic eld acting on the arc. The lines of force acting on thearc complete their circuit through the magnetic material and hence do not travel into the space between adjacent plates to conflict with the lines of force acting on the adjacent arcs- Accordingly, the use of magnetic material prevents conflict between adjacent magnetic fields and permits the plates scribed the plates 19 as U-shaped, any other ari rangement in which current is forced tc pursue an outgoing and return path normal to the direction of current flow in the arcs will be effective of the desired results. In general, all arrangements by which the current path between successive arcs is of such form as to set up magnetic fields tending to produce axial alinement of successive arcs are Within the scope ofmy invention.

While I have shown and described but a single embodiment of my invention, I do not wish to be limited to this particular structure, as many changes, substitutions and omissions may be made from the embodiment illustrated, without departing from the spirit of my invention. I desire, therefore, that the language of the appended claims shall be construed broadly to cover all modifications and arrangements within the scope of my invention.

I claim as my invention:

1. The combination with a cuente-interrupting' device having separablecontact members, of a plurality of members of sheet material folded upon themselves in such manner that the folds are spaced from each other, insulating means spacing each said sheet member from an adjacent sheet member and a member of magnetic material between the folds of each of said members.

2. In a circuit interrupter, means for causing an are, means for extinguishing said arc including a plurality of current conducting members yfolded upon themselves with the folds of each current conducting member spaced apart, and each of said folded current conducting members, being spaced from the adjacent current conducting members, and each of the folds of said currentconducting members having a flux path therearound of lower reluctance between the folds of each, member than between adjacent members.

3. The combination with a circuit-interrupting device having separable contact members, of arc extinguishing means comprising a plurality of plates arranged in substantially parallel order, the end members of said plates being connected to the circuit to be interrupted and the plates between said end members being electrically connected in pairs, and each of said plates having flux 'paths therearound of low reluctance inthe spaces between the plates forming each pair and of high reluctance in the spaces between adjacent pairs.

4. The combination with a. circuit-interrupting device having separa-ble contact members, oi' arc extinguishing means comprising a plurality of 125 plates` arranged in substantially parallel order, the end members of said plates being connected to the circuit to be interrupted and the plates between said end members being electrically connected in pairs and a member of magnetic material between the plates forming each of said pairs.

5. The combination with a circuit-interrupting device having separable contact members, of arc extinguishing means comprising a plurality of 1 plates arranged in substantially parallel order, the end members of said plates being connected to the circuit to be interrupted and the plates between said end members being electrically connected in pairs closelyspaced together, a member of magnetic material between the plates forming each of said pairs, and a member of insulating material on each side of said member of magnetic material insulating it from the plates adjacent thereto.

6. In a circuit interrupter, means for causing an arc, means forl extinguishing said arc includ-1 ing a. plurality of plates of good conducting material positioned in spaced planes and electrically connected together in pairs at their edges adjacent said means for causing the arc, said electrically connected pairs having open spaces therebetween -in which the arc is split up into short arcs and providing continuous U-shaped conducting paths of good conducting material connecting the ends of said short arcs, and said U- shaped conducting paths having flux paths therearound of lower reluctance between the legs of the U than in the spaces between the plates in which the short arcs play.

7. In a circuit interrupter, means for causingl an arc, means for extinguishing said arc including a plurality of plates of good conducting material positioned in spaced planes and electrically connected together in pairs at their edges adjacent said means for causing the arc, said electrically connected pairs having open spaces therebetween in which the are is split up into short arcs and providing continuous U-shaped conducting paths of good conducting material connecting the' ends of said short arcs, and a plate of magnetic material positioned betweenv the plates forming each of said electrically connected pairs, said magnetic plate being insulated from at least one of the two plates between which it is positioned.

arcs, and the width of said open spaces between the electrically connected pairs in which the arc plays being of the order of one-sixteenth of an inch.

JOSEPH SLEPIAN.

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