US2795675A

US2795675A - Circuit interrupter

Info

Publication number: US2795675A
Application number: US473991A
Authority: US
Inventors: Russell E Frink
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1954-12-08
Filing date: 1954-12-08
Publication date: 1957-06-11
Anticipated expiration: 1974-06-11
Also published as: JPS326479B1; DE1047904B; FR1144655A; GB785957A

Description

June 1.1, 1957 R. E. FRINK CIRCUIT INTERRUPTER 3 Sheets-Sheet 1 Filed Dec. 8, 1954 IIIIIIIIIIII 5. I r..

mveiwon Russell E Frnk.

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June 1l, 1957 R. E. FRINKY A Fig.2. 38 -35 4o 21 sa 13:34 le 2s 25 3644 3 Sheets-Sheet 2 Figs.

United States Patent l 2,795,675 CIRCUIT INTERRUPTER Russell E. Frink, Forest Hills, Pa., assigner to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application December 8, 1954, Serial No. 473,991 11 Claims. (Cl. 20G-147) This invention relates generally to circuit interrupters, and, more specifically, to arc-extinguishing structures for magnetic air circuit interrupters.

The general object of my invention is to provide an improved circuit interrupter, in which improved and more elective arc-extinguishing action takes place.

Another object is to provide an improved transfer arcextinguishing means for a circuit interrupter of the type having an electrically floating blowout coil to which the current is transferred by the extinguishing of a portion of the arc playing between two arc terminal members connected to the ends of the blowout coil.

Still, a further object is to speed up the transfer into series circuit of the magnetic blowout coil so as to bring about more rapid and effective operation.

A further object of my invention is to utilize the shading coil for the blowout magnet in a novel manner so as to provide one or more terminals for the transfer arc-extinguishing means.

Still a further object is to provide an improved longer plate structure for the transfer arc-extinguishing means of a circuit interrupter to bring about improved performance and to minimize the possibility of flashover.

Further objects and advantages will readily become apparent, upon reading the following specification taken in conjunction with the drawings, in which:

Figure 1 is a side elevational View, partially in vertical section, of a circuit interrupter embodying the principles of my invention, and the contact structure being shown in the closed-circuit position;

Fig. 2 is a plan sectional view of the circuit interrupter of Fig. 1, taken along the line II-II thereof;

Fig. 3 is a vertical sectional View taken along the line III- III of Fig. 1;

Fig. 4 is a side elevational view of one of the plates utilized in the arc-extinguishing sections;

Fig. 5 is a side elevational view of one of the transfer arc-extinguishing plates;

Fig. 6 is a sectional View taken substantially along the line VI-VI of Fig. 7; and

Fig. 7 is an enlarged fragmentary sectional View taken substantially along the line VII- VII of Fig. 3.

Referring to the drawings, and more particularly to Fig. l thereof, the reference numeral 1 generally designates a circuit interrupter, in this instance being one 0f the air-break type. Although the illustrated specific embodiment of my invention is an air-break. type of circuit interrupter, it is to be clearly understood that certain features of my invention may be applicable to other types of circuit interrupters, say for instance one of the liquid-immersed type or one operating in a gaseous medium. Merely for purposes of illustration do I describe a specific embodiment of my invention which operates in air.

Generally, the circuit interrupter 1 includes contact structure 2 operable to establish an arc, which is moved upwardly into an arc-chute structure 3, including a pair of arc-

extinguishing sections

4 and 5 of substantially identical construction.

As well understood by those skilled in the art, one terminal L1 of the circuit interrupter is connected to the stationary contact 6 of my device, whereas the other terminal L2 of the interrupter is electrically connected to the movable contact 7 of the device. If desired, suitable bridging and secondary contacts may be employed ICC to relieve the stationary and movable arcing contacts 6, 7 from carrying the current in the fully closed-circuit position shown in Fig. l.

During the opening operation, the moving arcing contact 7 moves away from the stationary arcing contact 6 to establish an arc 8, as shown by the dash line of Fig. l. This arc, generally designated by the reference character it, may be considered as composed of three

sections

8a, 8b and 8c. The arc 8, of course, bows upwardly because of the natural convection current of air, which is heated by the hot arc 8, and also because of the magnetic forces set up by the arc 8 which act to expand theloop of the arc, as well understood by those skilled in the art.

Adjacent the top and central portion of the arc 8 is a pair of transfer arc horns 1G, 11, between which is disposed a transfer arc-extinguishing means, generally designated by the reference numeral 13. The arc portion 8a extends between the movable arcing contact 7 and the transfer arc horn 10. The arc portion 8b extends within the transfer arc'extinguishing means 13 between the transfer arc horns 10, 11. The arc portion 8c extends between the stationary arcing contact 6 and the transfer archorn 11.

The function of the transfer arc-extinguishing means 13 is to interrupt the arc portion 8b, and so bring into series circuit the pair of serially related, centrally disposed

blowout coils

15, 16, the location of which is more clearly shown in Fig. 2 of the drawings. Such coils, of course, have insulated windings. As mentioned, the centrally disposed

blowout coils

15, 16 are connected in series circuit together, as by a connection 17 at the top of the coils (Figs. l and 3), and the other

lower ends

18, 19 of the

blowout coils

16, 15, respectively, are secured to the transfer arc horns 10, 1l, respectively, as shown more clearly in Fig. 1 of the drawings.

Because of the reactance of the

blowout coils

15, 16, it is diflicult to force current to flow through them because of the countervoltage set up in the coils. The transfer arc-extinguishing means 13 is, therefore, desirable to assist in this transfer into series circuit of the

blowout coils

15, 16 by extinguishing the arc portion 8b. Generally, the transfer arc-extinguishing means 13 includes a plurality of spaced insulating plates 21, the configuration of which is more clearly shown in Fig. 5 ot' the drawings. lt will be noted that each insulating plate 21 has a slot 22 provided therein which tapers inwardly to one side of the center line 23 of the plate. rhe plates 21 are spaced laterally apart by asbestos rope spacers 21a, as more clearly shown in Fig. 2 of the drawings. Adjacent plates 21 may be positioned oppositely so that the slots 22 are alternately on opposite sides of the center line of the plates and provide a zigzag path for the arc.

Referring to Fig. l it will 'be noted that a plurality of the plates 21 are disposed between the transfer arc horns 1t), 11 and the single-turn shading coil 25. The shading coil 25 in t-urn encircles the core or yoke portion 26 magnetically interconnecting the pole plate portions 27, more clearly shown in Fig. 2 of the drawings.

Referring more specifically to Fig. 7 of the drawings, it will be noted that the arc portion `or section 8b moves upwardly to strike the lower end 28 of the shading coil 25 to establish two serially related arms 129, 30 which are electrically in series. These arcs'move upwardly within the slots 22 of the insulating transfer plates 21 to become extinguished.

Following extinction of the arc portion Sb within the transfer 'arc-extinguishing means 13, the

blowout coils

15 and 16 `are serially connected into the circuit, and the energization -of these

coils

15, 16 sets up a magnetic flux within the magnetic ycircuit 24, which includes the pair of side magnetic pole plates 27 and the interconatesora necting yoke 26. Preferably, the pole plates 27 are formed of vertically extending sheets of 'a suitable magnetic material to forma laminated structure, more clearly shown in Fig. 2 of the drawings. Magnetically interconnect-ing the side pole plates 27 is the central interconnecting core or yoke portion 26, which is encircled by the two serially

related blowout coils

15 and 16.

As will be obvious to those skilled in the art, the H- type of magnetic circuit 24 shown, upon the energization thereof, causes magnetic flux to ow 'between the pole plates 27 in vthe manner indicated by the arrows 20 in Fig. 2. This magnetic flux extending transversely between the pole plates 27 causes upward movement of the are portions Sa, 8c upwardly into the are-

extinguishing sections

4, 5 of the arc-chute structure 3.

The left-hand end of the arc portion 8a, as viewed in Fig. l, quickly transfers to the outer arc horn 12, the lower end of which is connected, as shown, to the movable arcing contact 7 and hence to the lower terminal L2 of the device. Also, the right-hand end of the arc portion 8c quickly transfers to the right-hand arc horn 9 of the device, which is electrically connected to the stationary contact 6 lby the connection 9a and hence to the upper terminal L1 of the interrupter.

The current path through the interrupter (as viewed in Fig. l) may then be traced, beginning at line L1, through connection 9a, are horn :and terminal plate 9, across the arc in right-hand main extinguishing section 5 to the transfer arc horn or plate 11, lower end 19 of front lblowout coil `15, through -coil 15 to the connection 17 at its upper end t-o the upper end of the rear blowout coil 16, through coil 16 to its lower end 18 connected to the arc transfer plate or horn 10, through the arc in main left-hand extinguishing section 4 to the arc terminal plate er horn 12 on thence to line L2.

Disposed within the arc-

extinguishing sections

4, 5 are the plurality of spaced, slotted, ceramic plates 40, the configuration of which is more clearly shown in Fig. 4 of the drawings. As shown, each ceramic plate 40 has a slot 41 provided therein, the upper closed end 42 of which is slightly off-center. The plates 40 are staggered during the assembly operations so as to form 1a 'horizontally disposed, zigzag arc passage 43 throughout the length of the are-

chute sections

4, 5 to quickly bring about the extinction of the arc portions 8a, 8c. The plates 4t) are spaced laterally apart, as shown more clearly in Fig. 2, by sections of lasbestos rope 44 cemented between the plates 4.0 adjacent the outer edges thereof, the method being identical to that previously referred to in spacing the insulating plates 21 of the transfer arcextinguishing means 13 apart.

Certain features of the disclosed structure have been set out and claimed in my pending United States patent application, filed November 28, 1952, Serial No. 323,009, and issued October 30, 1956, as Patent No. 2,769,065, entitled Circuit Interrupter, and assigned to `the assignee '.f the instant application. This application, in part, claims the disposition of the serially

related blowout coils

15, 16 in the plane of the arc-chute jacket 35 to brace the blowout coils against the magnetic forces occurringl during the interruption of high-fault currents.

Proper operation of the transfer arc-extinguishing means 13 is necessary to ensure rapid blowout-coil transfer, and it is an important object of my invention to provide a more effective transfer arc-extinguishing means 13, while at the same time providing a more compa-ct and effective structure. It was found that with relatively short transfer arc-extinguishing plates the transfer are portion 8b extending between the transfer are horns 10, 1l sometimes flashed over across the top of such short transfer arc-extinguishing plates to prevent the blowout coils 15, 16 vbeing inserted into series circuit.

l have discovered that by making the yoke portion 26 somewhat longer and narrower than previous constructions of this type, yet having the same cross-sectional area,

that there was adequate space on both sides of the shading coil 25 to dispose the relatively long transfer arc-extinguishing plates 21. This is all obtained without increasing the overall size of the farc chute 3. As shown in Fig. 7, with this arrangement the transfer stack is made ofsubstantially full length plates 21 and divided into two

sections

31, 32 and placed in the spaces between the transfer horns 10, 11 and the shading coil 25. The transfer are 8b now divides into two sections 29, 39, with the shading coil 25 forming a common terminal between them.

This change accomplishes a number of desirable -results. Whereas formerly an are t-o the shading coil shorted out the transfer stack `and resulted in unsatisfactory performance, -in the present `arrangement the are is still confined to the stack. Also, the ability to use longer plates 21 in the transfer stack permits the use of a more efficient slot shape, and the length of the plates 21 beyond the ends of the slots 22 eliminates the tendency toward hashing over the top of the transfer stack.

Aside from improving transfer performance, this new construction results in two additional distinct improvements. First, it will be seen that the transfer arc-extinguishing means 13 is not disposed so close to the contact structure 2 to result in adequate space for a desired initial looping effect of the are. Thus, the are 8 is able to get away faster from the contacts 2, resulting in less ionization in the region of the contacts 2, which reduces the tendency to restrike. Secondly, by disposing the transfer plates 21 above the fire plates 33, the latter need not be grooved to support plates below the shading coil 25, which was used in constructions heretofore. The strength of the fire plates 33 is, consequently, considerably improved, resulting in a stronger structure.

To rigidly support the

coils

15, 16 within the apertures 34 disposed in the insulating arc chute jacket 35, coil washers or plates 36 of insulating material are employed surrounding the yoke 26 and maintained separated by the shading coil 25, as more clearly shown in Fig. 2.

Also, preferably an insulating spacer plate 38 is utilized between the pole plate portions 27 and the blowout coils 13, 14 for insulation purposes.

It will be noted that there is an open space indicated at A in Fig. 7. This space may be left open, as shown, so that the initial arc portion 8b may move rapidly upwardly within this space A to contact the lower end 28 of the shading coil 25 resulting in two are

portions

29, 30, the extinction of which occurs in the manner heretofore described. However, for certain applications, it may be desirable to interpose within the space A additional insulating plates of shorter length to assist in the extinction of the are 8b, particularly during low current values and my invention is intended to cover such a modification. For higher current values, the central portion of the arc 8b would move through such shorter plates, contacting the shading coil 25 and being extinguished in the manner as set forth above.

From the foregoing description it will be apparent that the invention concerns improvements particularly adapted for circuit interrupters of the center-coil type. However, certain features may be applied to circuit interrupters utilizing a magnetic circuit of substantially U-shape, in which a transfer arc-extinguishing means is associated with the core of such magnet. Merely for purposes of illustration have I illustrate-d my invention as applied to an H-shaped magnet arrangement in which a centrally disposed floating center-coil magnet is utilized.

The foregoing construction has been experimentally tested in the laboratory, and has been found to Vgive greatly improved results over prior constructions in which relatively short transfer arc-extinguishing plates were utilized. Thus, the use of long transfer plates 21 having more suitable slot configuration greatly speeds up interruption of the transfer arc 8b, thereby rapidly inserting the series blowout coils 15, 16 into the circuit to quickly set up the desired magnetic field within the

arc chute sections

4, 5 of the inteirupter 1.

Certain features of the construction are described and claimed in United States patent application led January 21, 1954, Serial No. 405,322, by Russell E. Frink and Samuel A. Bottonari, issued January 8, 1957 as Patent No. 2,777,036, and assigned to the assignee of the instant application.

Although I have shown and described a particular structure, it is to be clearly understood that the same was merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art without departing from the spirit and scope of the invention.

I claim as my invention:

1. A circuit interrupter including means for establishing an arc, a magnet structure including an elongated core and pole plate portions for assisting in the extinction of the arc, one or more blowout coils encircling the core, a transfer arc horn spaced away from a long side of the core, one terminal of one of said blowout coils being connected to said transfer arc horn, and a relatively long transfer arc-extinguishing structure disposed between the transfer arc horn and the long side of the core to eifect extinction of -a portion of said arc.

2. A circuit interrupter including means for establishing an are, a magnet structure including an oblong core and pole plate portions for assisting in the extinction of the arc, one or more blowout coils encircling the core, a pair of transfer arc horns on opposite sides of the long sides of the core and spaced therefrom, one terminal of a blowout coil connected to each transfer arc horn, and a transfer arc-extinguishing structure of insulating material disposed between the long sides of the core and each transfer arc horn.

3. The combination in -a circuit interrupter of means for establishing an are, an H-shaped magnet structure for extinguishing the arc including a core and a pair of pole plate portions, a shading coil about the core, one or more magnetic blowout coils encircling the core to set up a magnetic eld therein, a pair of transfer are horns on opposite sides of the core and spaced from the shading coil, one terminal of a blowout coil connected to each transfer arc horn, and transfer arc-extinguishing means disposed between the shading coil and each transfer arc horn.`

4. The combination in a circuit interrupter of means for establishing an arc, an H-shaped magnet structure for extinguishing the arc including a core and a pair of pole plate portions, a shading coil about the core, one or more magnetic blowout coils encircling the core to set up a magnetic field therein, a transfer arc horn disposed along one side of the shading coil and spaced therefrom, and one or more transfer arc-extinguishing plate portions disposed between the transfer arc horn and the shading coil.

5. A circuit interrupter including means for establishing an arc, a magnet structure including an elongated core and pole plate portions for assisting in the extinction of the arc, one or more blowout coils encircling the core, a transfer arc horn spaced away from a long side of the core, one terminal of one of said blowout coils being connected to said transfer -arc horn, and transfer arc-extinguishing plate means disposed between the transfer arc horn and the core to effect extinction of a portion of said arc.

6. The combination in a circuit interrupter of means for establishing an arc, an H-shaped magnet structure for extinguishing the arc including a core and a pair of pole plate portions, a shading coil about the core, one or more magnetic blowout coils encircling the core to set up a magnetic field therein, a pair of transfer arc horns on opposite sides of the core and spaced from the shading coil, one terminal of |a blowout coil connected to each transfer arc horn, said arc contacting the pair of transfer arc horns to establish a transfer arc portion, and means providing two Sections of insulating arc-extinguishing plates to effect extinction of the transfer arc portion.

7. A circuit interrupter including means for establishing an arc, a magnet structure including an oblong core and pole plate portions for assisting in the extinction of the arc, one or more blowout coils encircling the core, a transfer arc horn spaced away from :a long side of the core, one terminal of one of said blowout coils being connected to said transfer arc horn, a main arc horn spaced from said transfer arc horn, said arc moving into engagement with the two arc horns, and a relatively long transfer arc-extinguishing structure disposed between the transfer arc horn and a long side of the core to effect extinction of a portion of said anc.

8. A circuit interruptor including means for establishing an arc, a magnet structure including an elongated core and pole plate portions for assisting in the extinction of the arc, one or more blowout `'coils encircling the core, a transfer `arc horn spaced away from a long side of the core, one terminal of one of said blowout coils being connected to said transfer a-rc horn, a main arc horn spaced from `said transfer arc horn, said arc moving into engagement with the two arc horns, arc-extinguishing plate portions for effecting the extinction of the arc extending between the two arc horns, and a relatively long transfer arc-extinguishing structure disposed between the transfer arc horn and the long side of the core to effect extinction of a portion of said arc.

9. A circuit interrupter including means for establishing `an arc, a magnet structure including an oblong core and pole plate portions for assisting in the extinction of the arc, one or more blowout coils encircling the core, a pair of transfer arc horns on opposite sides of the long sides of the core and spaced therefrom, a pair of main arc horns spaced :away from said pair of transfer arc horns on opposite sides thereof, said arc moving into engagement with the four a-rc horns, one terminal of a blowout coil connected to each transfer arc horn, and a transfer anc-extinguishing structure of insulating material disposed between the long sides of the core and each transfer arc horn.

10. A circuit interrupter including means for establishing an arc, a magnet structure including a core and pole plate portions for assisting in the extinction of the arc, one or more blowout :coils encircling the core, a transfer arc horn positioned substantially parallel to one side of the core, one terminal of one of said blowout coils being connected to said transfer arc horn, and a transfer arcextinguishing structure including a plurality of spaced plates disposed between said transfer arc horn and said one side of the core, and the spaced plates being substantially parallel to said one side of the core and effecting extinction of a portion of said established are.

1l. A circuit interrupter including means for establishing an arc, an H -shaped magnet structure including a core and pole plate portions for assisting in the extinction of the arc, one or more blowout coils encircling the core, a pair of transfer arc horns positioned substantially parallel to and on opposite sides of the core, one terminal of each of said blowout coils being connected to one of said transfer arc horn-s, and a transfer arc-extinguishing structure including a plurality of spaced plates disposed between each said transfer arc horn and the adjacent side of the core of the H-shaped magnet structure, and the spaced plates being substantially parallel to said adjacent sides of the core Iand effecting extinction of a portion of said established arc.

References Cited in the tile of this patent UNITED STATES PATENTS 1,398,982 Tritle Dec. 6, 1921 1,872,387 Baker et al. Aug. 16, 1932 2,616,007 Dickinson et al. Oct, 28, 1952