US1899605A - Circuit interrupter - Google Patents

Description

Feb. 28, 1933. B; R B ER 1,899,605

CIRCUIT INTERRUPTER Filed Dec. 10, 1929 s Sheets-Sheet 1 l N V E N TO RS Benjam/r) PBaAer' andfines/Q K ees.

-A'TTORNEY Feb. 28, 1933. B, P. BAKER ET AL. 1,899,6055

' CIRCUIT INTERRUP TER Filed Dec. 10, 1929 5 Sheets-Sheet 2 INVENTORS Berg emf? P50 Ker anaE/nesf & Aeea.

I ATTORNEY Feb. 28, 1933. B. P. BAKER ET AL CIRCUIT INTERRUPTER Filed Dec. 10, 1929 5 Sheets-Sheet 5 ATTORNEY INVENTORS Benjamin P50 Ker and [fr-fies? G Aees.

, Patented Feb. 28, I933 UNITED STATES PATENT OFFICE- BENJAMIN P. BAKER, OF TURTLE CREEK, AND

ERNEST G. KEES, OF WILKTNSBUBG,

PENNSYLVANIA, ASSIGNORS TO WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA CIRCUIT INTEBRUPTER Application filed December 10, 1929. Serial Jim-413,012.

Our invention relates to circuit interrupters and particularly to circuit interrupters of the liquid-immersed type.

' One object of our invention is to provide an arc extinguishing means adjacent to the arc-drawing members of a circuit interrupter of the above mentioned ty e that shall have an improved performance, s all increase the interrupting capacity thereof, shall increase the a speed with which a circuit is interrupted and shall decrease the amount of deterioration of the oil or similarly employed fluid.

Another object of our invention is to provide the contacts of a circuit-interrupter of the above mentioned type with two series of slotted insulating plates that, together with the adjacent fluid shall 0 erate to extinguish the are as the arc is move in the slots.

A further object of our invention is to intersperse the aforementioned slotted insulating plates with plates of magnetic material that shall distort the field about the arc in such manner as to force the are into the slots and thereby insure close proximity of the arc with the fluid adjacent to the insulating plates.

A still-further object of our invention is to provide a series of recesses in conjunction with the slots of the above noted insulating members that shall tra the fluid therein in such manner that the uid will be available for extinguishing the arc as it moves throu h the said recesses under the influence of t e magnetic field.

A further object of our invention is to provide a suitable magnetic field, in such relation to the are drawing members, that the arc will, when partially surrounded by magnetic material, be magnetically forced against the side of the gas bubble that is formed around the arc, as a result of the flow of current in the arc.

A still further object of our invention is to r use the aforementioned magnetic field and recesses in the slotted insulating plates, in such manner that a quantity of oil will be trapped in the recesses and prevented from moving away from the arc, thus causing the arc, as it moves under the influence of the magnetic field, to be brought into intimate contact with the oil. The vaporized oil and gas thus formed is forced to enter the arc stream and thereby produce a very efiective means of deioniza-tion at the zero value of the current wave.

It is well known in the art, that an oilimmersed circuit interrupter is most desirable when considered from the point of view of insulation at the higher voltages. When currents on high power circuits, especially at high potential are interrupted in oil, a gas bubble is immediately formed upon drawing the arc, which separates the are from the column of oil forming the wall of the gas bubble. As a result, the arcing continues until the bubble and are become so distorted that the continuity of the gas bubble is broken and effective deionization takes place in the arc stream. This continued arcin results in oil deterioration, building up 0 excess pressures and excessive generation of explosive ases, which sometimes result in disaster. onsiderable effort has been expended to reduce the hazard associated therewith and many devices such as baflles, vents, pressure casings, etc, have been suggested and tried, which, while relieving the situation somewhat, were unsuccessful in removing the source of danger.

In analyzing the extinction of an alternating current are in oil, we believe that the successful interruption thereof, is caused by the supply of fresh gas, oil globules and vapor that is fed into the arc stream from the decomposing oil, at the periphery of the gas bubble enveloping the arc. The gas bubble may be of any shape and may vary in form from time to time. This fresh gas or product of decomposing oil, is made to pass turbulently through the arc stream and these small volumes of relatively cold and unionized gas serve to remove ions. Therefore, fresh ionization must be produced if conductivity of the arc stream is to be maintained. If this source of fresh gas is kept active up to the time in which the current reaches zero value and in close proximity with the arc stream, ions will be extracted from the arc stream by the dispersed volumes of un-ionized gas thus speeding up the processes of recombination of ions by cooling and ofierin small surfaces on which deionization may ta e place.

In the hitherto conventional oil circuit breaker, the arc is drawn through the oil and such large amounts of gas are immediately evolved that a gas bubble is formed about the arc and the new gas, continually being generated by the heat of the are, is prevented from coming into intimate contact with the are core, either due to the distance it must travel from the source of vaporization or due to the evasive characteristics of the arc and its freedom of motion in moving away from the gas stream. For this reason, the deionizmg effect necessary for rapid extinction of the arc, is absent when the current passes through zero and reignition occurs at many successive zero points, thus evolving large amounts of gas, with high pressures and excessive oil deterioration.

Heretofore attempts have been made to move the oil into the are path by baflies, semienclosed chambers, oil jets, etc., but, because of the mobility of the arc, these attempts have met with only moderate success. It is evident that since the inertia of the arc is negligible and it may bend, stretch and twist with ease, any attempt to move oil into the arc stream will result in the are assuming a new position in the gas bubble and allowing the oil to pass, or it may move freely ahead of the moving oil, carrying its ionized atmosphere with it. If an attempt is made to hold an arc in position mechanically while spraying it with oil, the holding means will un doubtedly be injured.

In practicing our invention we take advantage of the inertia of the oil, the ease with which oil may be held in position and the mobolity of an are when acted upon by a mag-,

netic field. We may either hold an arc magnetically against the force of an onrushing stream of oil, gas or vapor or we may use a magnetic field for forcing the are against the oil or vapor which has been entrapped and prevented from moving out of the way, other than through the arc stream.

In either arrangement, the arc is continually pressed against the side of the gas bubble and bombarded with freshly decomposed oil, so that reignition after current zero value is attained will occur only at a much higher voltage per unit length of arc than has hitherto been the case.

Our invention will better be understood by referring to the following description taken in conjunction with the accompanying drawp ingvs, wherein igure 1 is an elevational view in section of a circuit interrupter embodying our invention;

Figure 2 is aview in elevation of a somewhat difl'erent embodiment of the extinguisher device shown in Fig. 1;

Fig. 3 is an enlarged detail view partly apparatus shown in Fig. 3 taken along the J line IVIV thereof;

Fig. 5 is a bottom plan view of the apparatus shown in Fig. 3;

Fig. 6 is a plan view of a plurality of plates of the extinguishing means shown in Fig. 3;

Fig. 7 is a sectional view of apparatus shown in Fig. 6 taken along the line VlVl thereof;

Fig. 8 is a plan view of a plurality of plates of she extinguishing means shown in Fig. 2; an

Fig. 9 is a sectional View of the apparatus shown in Fig. 8 taken along the line VIII- VIII thereof.

Our invention comprises in general a casing 1. provided with a cover 2 that supports conductor bushings 3 and 4 in a manner well known in the art. Stationary conducting members 5 and 6 are supported on the conductor bushings 3 and 4, respectively, and are immersed in an insulating liquid 7 that is contained within the casing 1. A conducting bridging member 8 is supported on a lift rod 9 that extends through the cover 2 and is connected to an actuating mechanism (not shown), that operates the bridging member 8 to open and closed positions. Associated with the bridging member 8 and supported on the conducting members 5 and 6, respectively, are plate assemblies comprising the arc extinguishing structure 11 in Figure 1 or the structure 12 in Figure 2.

Referring to Fig. 3, the contact arrangement and the arc extinguishing structure are here shown as comprising the combination of the extinguishing devices 11 and 12 of Figures 1 and 2 respectively and it is to be .understood that the extinguisher structure may be such as disclosed in either Figures 1 and 2 or a combination of the two as shown in Figure 3. The stationary conducting member 5 has a conducting plate 13 attached to its lower end that has extensions 14 thereon for supporting a contact member 15 by means of a pin and slot 16. A flexible conductor 17 connects the contact member 15 to the plate 13 by means of bolts 18 and 19. Springs 21 are positioned between the plate 13 and the contact member 15 to bias the latter downwardly when the bridging member 8 is first moved toward the open position.

The ends of the bridging member 8 are rovided with vertically tapered contacting members 22 that have raised portions 23 and 24, thereon the former of which first breaks contact in a similar manner to the main contacts of circuit interrupters heretofore employed in the art. As the member 22 continues to move downwardly, the contacting,

- terrupter is in closed position.

The contact member 15'has an insulating member 25 of U-shape thereabout to confine the arc to the contact member as the arc terminal is moved therealong. A metal shield 26 encloses the plate 13, the shunt 17 and the contact member 15 in order to reduce the corona losses and the possibility of voltage breakdown to the side of the casing 1. The members 25 and 26 are best illustrated in Figures 4 and 5, wherein the plate 13 is shown provided with four apertures 27 through which insulated bolts 28 extend for supporting the arc extinguishing structure 11 on the conducting member .5.

The are extinguishing structure 11 comprises a plurality of plates 29 and 31 of insulating and magnetic material, respectively, as illustrated in Figs. 3 to 9. Each of the insulating plates 29 is provided with a slot 32 and four apertures 33 that conform in dimension and position to the apertures 27 in the plate 13 heretofore mentioned. Each slot 32 has a funnel-like entrance portion 34 and a narrow inner portion 35. One or more magnetic members 31 made of iron or other magnetizable material are disposed between pairs of insulating plates 29, said magnetizable plates having a wide slot 36 which is alined with the inner narrow slot 35 of the insulating plate 29. The magnetic plates 31 have a pair of holes 37 therein that aline with the two rearmost holes 33 in the insulating plate An insulating liner 38 of U-shape is inlaid adjacent the slot 36 of the magnetizable plates 31, in order to prevent the are from coming into contact with the magnetizable plates when the arc is moved in the slot. The insulating liner 38 has a slot 39 which is wider than the slots 35 in the insulating plates 29,

so as to provide a channel 41 adjacent the inner portion of the slot 32, wherein oil is trapped ahead of the arc and is fed thereinto in the form of a vapor blast generated by the heat of the arc, as the arc is moved into the slot. Spacers 42 are provided between a plurality of units 43 of the plates 29 and 31 to form an open stack of lates.

Fig. 7 is a section 0 one of the units 43, a plurality of which are spaced apart and constitute the arc extinguishing structure 11 having spaces 42 wherein portions of the liquid and are may move laterally between the units.

In the arc extinguishing structure 12, shown in Fig. tion of the arc extinguishing structure of Fig. 3, insulating plates 44 are shown as being spaced between a plurality of the groups 43 2 and in the lower broken por in place of the s'a'cers 42 of the open stack construction, to and a continuous vertically-enclosed slot into which the arc is moved. These plates 44, that are employed to fill up the spaces between the units 43, are provided with a plurality of slotted circular openings or recesses 45, as shown in Fig. 8, which are employed to trap the liquid and to prevent it from being moved ahead of thearc. In this arrangement each recess 45 will trap some of the liquid 7 and retain it for engagement with the are core as it is moved within the slot.

Certain advantages have been noted in employing the open and closed stack of plates when interrupting arcs under various circuit conditions. The open stack has the advantage of relievin the plates of a considerable amount of mechanical strain, present when heavy current low voltage arcs are interrupted. ()n the other hand, when heavy current high voltage arcs were interrupted the closed stack of plates had a considerable advantage over the open stack in that the oil is more completely entrapped and available for deionization over a longer period of time. A combination of the open and closed stack of plates is believed to be the most desirable commercial arrangement. The manner in which these two arrangements may be combined and varied is determined by the duty to be imposed on the circuit interrupter and the arrangements are within the purview of the present invention.

It will be noted in Figs. 4, 5, 6 and 8 that the slots 32 are tapered toward their closed ends to provide a chokin actionand a more copious supply of closely entrapped oil to the arc. This arrangement reduces the crosssection of the arc and brings the arc stream into very intimate. contact with the deionizing materials, thus tending to prevent arc reignition after the current has passed through zero value.

The operation of our circuit interrupter will. now be described. When the circuit interrupter is in closed position, as shown in Fig. 1. suitable tripping mechanism, (not shown but well known in the art), is provided, that is actuated upon an increased current condition in the circuit or other predetermined condition, permit the bridging member 8 and its extensions 22 to move downwardly, thereby drawing a pair of arcs in series between the raised portions 24 and the contact members 15. The arcs so drawn will be positioned at the funnel-like entrance 34 of the slots 32 and the field about the arcs will be so distorted by the magnetic plates 31 that the arcs will be moved inwardly into the narrow portion 35 of the slots. The magnetic force available for moving the arc increases with an increase in current.

In order to insure that the oil will not be orm a solid stack of plates to release the lift rod 9 and forced out ahead of the arc and, leave none in the vicinity thereof to be decomposed, and to supply fresh deionizing gas to the are core, the channel 41 between the plates 29 and the plurality of recesses 45 in the plates 44 are provided.

As the are moves inwardly into the slot, the oi. in the interstices will be held adjacent to the arc core, thus causing deionization of the arc path as the arc is moved in the slot.

The continued bombardment of the are by the vaporized oil and the holding action of the magnetic field cause a concentration of the are core which reduces the cross-sectional area of the ionized path and, as the current approaches its cyclic zero value, its cross-section is relatively small and in close contact with a wall of oil that continues to copiously supply suflicient vapor to effect rapid cooling and deionization when the current is at its zero value.

Therefore, the arc will be readily extin-.

guished whether heavy currents or normal currents are present in the circuit to be interrupted.

It will thus be seen that we have provided arc-extinguishing structures for oil-immersed circuit interrupters that operate, to rapidly extinguish high power arcs with small contact separation, and with greatly reduced arc energy as compared with circuit interrupters heretofore employed in the art. This we accomplish by providing means for retaining oil in the vicinity of the arc path and means for moving the are through the retained oil. By such construction, the deionizing effect of the fresh decomposing oil will be effective for high power arcs to ensure their early extinction and to eliminate the hazards that have been present in oil-immersed circuit interrupters when high power circuits were interrupted.

It is to be understood that when the words oil, liquid or fluid are employed in the specification, that the broadest interpretation thereof is to be taken, since gases as well as liquids will operate successfully in conjuncii i tion with ourextinguishing structure and will be within the purview of the present invention.

While we have described particular means comprising plates of insulating material to entrap fluids in immediate proximity to the arc path it will be recognized that this is only by way of illustration of general principles and that our invention is not limited to that particular device but comprehends any means of retaining in spatial distribution along the sides of an arc path a substance adapted to emit vapor when in contact with an are, In the case of fluid arc extinguishing agents enclosures of high resistance material adapted to retain the fiuid by absorption or through capillary forces are effective. It will also be observed that the retained material may be a different substance from the.

insulating fiuid surrounding the contacts; the latter may even be ordinary air in such case; and that solid substances capable of furnishing vapor to the are when brought in contact therewith may compose or be disposed upon the supporting walls. All similar embodiments of its fundamental principles are intended to be within the scope of the following claims.

While we have illustrated several embodiments of our invention, it will be apparent to those skilled in the art that various changes, modifications, substitutions, additions and omissions may be made inthe apparatus illustrated, without departing from the spirit and scope of our invention as set forth in the appended claims.

We claim as our invention:

1. In a circuit interrupter, a body of liquid, a pair of of contact members one of which is movable to draw an arc, and an are extinguishing structure for extinguishing said are in contact with said liquid, including means of insulating material defining a passage in which said contact member is movable, the part of said passage along which said contact member is moved having portions thereof of a width not materially greater than the width of said movable contact member, and portions of said passage along the length of the arc path being closed on three sides and open'on the fourth side whereby the gas formed by the action of the are on said liquid is caused to flow laterally through the are and out said open side of the passage.

2. In a circuit interrupter, a body of liquid, a pair of contact members one of which is movable to draw an arc, and an arc extinguishing structure for extinguishing said are in contact with said liquid including a stack of plates of insulating material having openings therein in which said contact member is movable, the width of said opening in some of said plates at the portion thereof where said contact member is moved being not substantially greater than the width of said movable contact, and the openings through some of said plates being at a distance from the outer edge of the plates on three sides and extending to the outer edge of the plates on the fourth side whereby a lateral vent for the arc gases is provided.

3. In a circuit interrupter, a pair of separable contacts, a body of arcextinguishingliquid surrounding said separable contacts, and an arc extinguishingv structure comprising means of insulating material having a passage in which one of said contacts is movable ,to draw the are, said passage having portions along the path where the arc is initially drawn of a width not materially greater than the width of said movable contact, and said passage being closed along its whole' length on three sides and having open portions on its fourth side leading laterally into said body of arc extinguishing liquid.

4. In a circuit interrupter, a body of liquid, means for causing an arc, and an are extinguishing structure including means of insulating material having a passage for the arc therethrough, said passage having portions thereof indented forming recesses for said liquid, and venting means leading laterally into said body of liquid from said passage, said venting means extending to only one side of said passage from any portion along the length thereof.

5. In a circuit interrupter, a body of liquid, means for causing an arc, and an are extinguishin structure including a stack of plates of insulating material having openings therethrough for the arc, the openings 1n some of said plates having portions of greater width than the corresponding portions of the openings in the plates on each side thereof to form recesses for said liquid, and the openings in some of said plates extending to one outer ed e only of the plates to form lateral vents roin the arc path.

6. In a circuit interrupter, a body of liquid, means for causing an arc, and an arc extinguishing structure including means of insulating material having a passage for the arc therethrough, said passage having portions thereof of greater width than the portions of the passage contiguous thereto forming recesses. for said liquid, said passage being closed on three sides along the portion thereof where the arcis first drawn and having open portions on the fourth side providing vents from said passage laterally into said body of 1i uid.

7. I In a circuit interrupter, a body of liquid, a pair of contact members one of which is movable to draw an arc, and an arc extinguishing structure for extinguishing said are 1n contact with said liquid including means of insulating material defining a passage in which said contact member is movable, the part of said passage along which said contact member is moved having portions thereof of a width not materially greater than the width of said movable contact member, and said passage having portions thereof of a greater width than the portions of the passage contiguous thereto forming recesses for said liquid, and portions of said passage along the length of the arc path being closed on three sides and open on the fourth side whereby the gas formed by the action of the are on said liquid is caused to flow laterally through the arc and out said open side of the passage.

I 8. Irra circuit interrupter, a body of liquid, a pair of contact members one of which is movable to draw an arc, and an arc extinguishing structure for extinguishing said are in contact with said'liquid including a stack of plates of insulating material having openings therein in. which said contact member is movable, the width of said opening in some of said plates at the portion thereof where said contact member is moved being not substantially greater than the width of said movable contact, and the width of said opening in some of said plates being greater at portions thereof than the width of the corresponding portions of the openings in the plates on each side thereof, and the openings through some of said plates being at a distance from the outer edge of the plates on three sides and extending to the outer edge of the plates on the fourth side' whereby a lateral vent for the arc gases is provided.

9. The combination in a liquid immersed circuit interrupter having separable contact members for drawing an arc, of a plurality of slotted insulating plates having means for trapping some of said liquid along the sides of said slots and a plurality of magnetic plates associated with said insulating plates for moving the are into said trapped liquid.

10. The combination in a liquid circuit interrupter having separable contact members for drawing an arc, of means for retaining a considerable quantity of said liquid adjacent the are path after the arc is drawn and means for moving the arc in contact with said retained liquid;

11. In a circuit interrupter, a body of arc extinguishing liquid, an arc extinguishing structure including means of insulating material having a passage therethrough for the arc, a plurality of plates of magnetic material positioned along said passage, said lates of magnetic material having 0 non ed slots and the edges of said slots ad acent said open ends being substantially parallel, and means for initially drawing the are within said slot.

12. In a circuit interrupter, a body of arc extinguishing liquid, means for drawing an arc in said liquid, and an arc extinguishing structure'including a stack of plates, some of said plates being of magnetic material and having slots extending thereinto from the outer edge of the plates, and the edges ofsaid slots being substantially parallel adjacent said outer edge of the plates of magnetic material, and some of said plates being of insulating material and having openings extending thereinto from the outer edge of the plates, and the edges of said openings-adjacent said outer edge of the plates of insulating material being outwardly flared.

13. The combination with oil immersed relatively movable contact members, of a plurality of units comprising insulating plateshaving iron plates associated therewith, the said plates having slots therein that are positioned adjacent a path in which an arc is established by movement of one of said contact members, and the slots in some of said plates having a width where the arc is es- 1 than the width of said contact member for establishing the arc. 14. In a circuit interrupter, a body of arc extinguishing liquid, an arc extinguishing structure in said liquid including means of insulating material defining a relatively narrow passage in which the arc is movable, said passage having a portion of a length several times greater than its width and being closed on at least three sides, a plurality of indentations along the sides of said passage for retaining said liquid, and means for drawing the arc in said passage.

15. The combination in a liquid immersed circuit interrupter having separable contact members for drawing an arc, of an assembly of slotted plates of insulating and magnetic materials having recesses along the sides of the slots in some of said plates for trapping said liquid and means for supporting a plurality of said assembly of plates adjacent said are path.

16. The combination in a liquid immersed circuit interrupter having separable contact members for drawing an arc, of an assembly of slotted plates of insulating and magnetic materials having recesses along the sides of the slots in some of said plates for trapping said liquid, means for supporting a plurality of said assembly of plates adjacent said are path and insulating means spaced between the said assemblies of plates to form a solid stack.

17. In a circuit interrupter, means for drawing an are including a movable contact member, a body of liquid in which said are is drawn, an arc extinguishing structure having a passage in which said movable Eontact member draws the arc, said passage hav- 40 ing portions of a width at the part thereof where said are is drawn by said movable contact vmember not substantially greater than the width of said movable contact member, and said passage having portions along the length thereof closed on three sides and open on the fourth side providing a vent from the arc path through the side of said are extinguishingstructure.

18. The combination with a fluid-immerseddevice for extinguishing an electrical arc, of a plurality of plates having slots registering with the path of said are, the slots in some of said plates having portions which vary from a widened to a reduced width and the slots in other of said plates having their portions corresponding to said portions of reduced width of a width greater than said reduced width for trapping said fluid in said slots.

19. The combination in a liquid immersed circuit interrupter, of means for establishing an are, means for reducing the cross section of said are at a plurality of spaced points throughout its length andmeans forming pockets adjacent said points of contracted cross-section for entrapping said liquid to act upon the are at its contracted points.

20. The combination in a liquid immersed circuit interrupter, of means having a slotted aperture adjacent to the arc path, means for forcing the arc laterally into the slotted aperture and means comprlsing co-operating surfaces on the sides of the slots for contracting the cross sections of the are at a plurality of points throughout its length and permitting the arc to expand in cross section between the contracted points and said contraction taking place at a plurality of laterally spaced points as the arc is moved.

21. The combination in a liquid immersed circuit interrupter having separable contact members for drawing an arc in an arc extinguishing chamber the inner walls of which are of insulating material and form a multiplicity of recesses positioned at intervals spaced laterally of the arc path, of means for moving the arc laterally through said recesses in succession and means for preventing the free escape of said liquid from said recesses other than through the arc stream.

22. The combination in a liquid immersed circuit interrupter having separable contact members for drawing an are, means of insulating material having pockets along the sides thereof for trapping a considerable quantity of said liquid and means for moving 'the arcinto close proximity with said entrapped liquid.

23. The combination in a liquid immersed circuit interrupter having separable contactmembers for drawing an are, means of insulating material having pockets along the sides thereof for trapping a considerable quantity of said liquid, means for moving the are adjacent to said pockets and means for preventing said entrapped liquid from escaping otherwise than through the arc stream.

24. In a liquid circuitinterrupter, means for causing an arc, means defining a groove, said groove having portions of liquid-absorb- 7 ing material for retaining said liquid, and

some of said liquid-in contact with the arc as it is moved.

26. In a circuit interrupter, means for causing an are, means defining a groove having an open side, widened portions at intervals along said groove for holding liquid for supplying an arc extinguishing gas when acted upon by the arc, and means for causing said are extinguishing gas to move laterally through said are and out the open side of said groove.

27. In a circuit interrupter, a body of. liquid, a plurality of plates of absorbent material for retaining said liquid, said plates defining a slot and said slot having a length several times its width and means for causing an arc in said slot.

28. In a circuit interrupter, a body of liquid, a plurality of slotted plates of absorbent insulating material for retaining said liquid, means for causing an arc, and means for moving said arc into said slots.

29. In a circuit interrupter, a body of liquid, a plurality of slotted plates of absorbent material for retaining said liquid, means for causing an arc in said slots, and a plurality of magnetic plates interposed between said absorbent plates at spaced intervals.

30..In a circuit interrupter, a bod of liquid, a plurality of slotted plates 0 absorbent material for retainin said liquid, means for causing an arc in said slots, a plurality of magnetic plates interposed between said absorbent plates at spaced intervals, and means for protecting said magnetic plates from the arc.

31. In a circuit interrupter, a body of li uid, an arc-deionizing structure in contact with said body of li uid, said structure including a plurality 0 groups of plates each including a pair of plates of insulating material having slots therein and a plate of magnetic material having a slot therein interposed between said insulating plates, and a plurality of plates of absorbent material having slots therein between said groups of plates.

32. In a circuit interrupter, a body of liquid, an arc-deionizing structure in contact with said body of 1i uid, said structure including a plurality 0% groups of plates each including a pair of plates of insulating material having slots therein and a plate of 45 magnetic material having a slot therein interposed between said insulating plates, and a plurality of plates of absorbent material having slots therein between said grou s of plates, the slots in all of said plates eing 50 aligned forming a groove in which the arc is moved in contact with the liquid retained along said groove by said plates. I

33. In a circuit interrupter, a body of liquid, an arc-deionizing structure in contact with said body of h uid, said structure including a plurality 0 groups of plates each including a pair of plates of insulating material having slots therein and a plate of magnetic material having a slot therein interposed between said insulating plates, and a plurality of plates of absorbent material havmg slots therein between said groups of plates, the slots in all of said plates being aligned forming a groove in which the are is moved in contact with the liquid retained along said being close said slots.

34. In a circuit interrupter, a body of liquid, an arc-deionizing structure in contact with said body of liquid, said structure including a plurality of groups of plates each including a pair of plates of insulating material having slots therein and a plate of magnetic material having a slot therein interposed between said insulating plates, and an insulating strip between said insulating plates for protecting the edge of said magnetic plate from the arc.

35. In a circuit interrupter, a body of liquid, an arc-deionizing structure in contact with said body of liquid, said structure including a plurality of groups of plates each including a pair of plates of insulating material having slots therein and a plate of magnetic material having a slot therein interposed between said insulating plates, and a plurality of plates of absorbent material having slots therein between said groups of plates, said plates of absorbent material having pockets therein for retaining said liquid.

36. In a circuit interrupter,- a body of liquid, an arc-deionizinz structure in contact with said body of liquid, said structure including a plurality of groups of plates each including a pair of plates of insulating material having slots therein and a plate of magnetic material having a slot therein interposed between said insulating plates, and an insulating strip between said insulating plates for protecting the edge of said magnetic plate from the arc, said plates of absorbent material having pockets therein for retaining said liquid, the slots in all of said plates being aligned forming a groove in which the arc is moved in contact with the liquid retained along said groove by said plates, and said groove being closed on all sides except at one end of said slots.

37. In a circuit interrupter, a body of liquid, means for causing an arc and means (groove by said plates, said groove on all sides except at one end of 'for setting up a magnetic field for moving said are in said liquid, comprising a plurality of spaced slotted members of, mag

netic material surrounding the path of said are and energized thereby, and insulating members extending along the whole length of the edge of the slot for protecting said members of magnetic material from contact with the arc.

38. In a circuit interrupter, a body of liquid, means for causing an arc, and an arc extinguishing structure including a stack of plates of insulating material having openings therethrough for the arc, the openings in some of said plates having portions of greater width than the corresponding portions of the openings in the plates on each side thereof to form recesses for said liquid,

and the openings in some of said plates extending to one outer edge only of the plates, and venting means from the arc path into said body of liquid extending between some of said plates. I

39. In a circuit interrupter, a body of arc extinguishing liquid, an arc extinguishing structure including means of insulating material having a passage therethrough for the arc, a plurality of plates of magnetic material positioned along said passage, said plates of magnetic material having open ended slots and the edges of said slots adjacent said open ends being substantially parallel, means for initially drawing the are within said slot, and venting means from said passage to said body of liquid extending between some of said plates of magnetic material.

40. The combination with oil-immersed relatively movable contact members, of a plurality of units comprising insulating plates having iron plates associated therewith, the said plates having slots therein that are positioned adjacent a path in which an arc is established by movement of one of said contact members, the slots in some of said plates having a width where the arc is established not more than slightly greater than the 'width of said contact member for establishing the arc, and venting means between some of said plates.

41. In a circuit interrupter, a body of liquid, a pair of contact members one of which is movable todraw an arc and initially break the circuit. and an arc extinguishing structure for extinguishing said are in contact with said liquid. including means of insulating material defining a passage in which said contact member which initially breaks the circuit is movable. the part of said passage along which said contact member is moved having portions thereof of a width not materially greater than the width of said movable contact member, andportions of said passage along the length of the arc path being closed on three sides and open on the fourth side whereby the gas formed by the action of the are on said liquid is caused to flow laterally through the arc and out said open side of the passage.

42; In a circuit interrupter, a pair of separable members which initially break the circuit, a body of 'arc extinguishing liquid surrounding said separable members, and an arc extinguishing structure comprising means of insulating material having a passage in which one of said members is movable to draw the arc, said passage having portions along the path where the arc is initially drawn of a width not materially greater than the width of said movable member, and said passage being closed along its Whole length on three sides and having open portions on ber, 1929.

BENJAMIN P. BAKER. ERNEST G. KEESl

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