US3024331A - Circuit interrupter - Google Patents

Description

March 6, 1962 Filed Nov. 6. 1957 3 Sheets-Sheet 1 A (Ll n rL2 l v |9- mvsNToR BWITNESSES: Russell E. F rink Mcm-Q R BY m mw? mf ATTORNEY 3 Sheets-Sheet 2 R. E. FRINK CIRCUIT INTERRUPTER March 6, 1962 Filed Nov. e. 1957 Fig: 4.

United rates 3,024,331 Patented Mar. 6, 1962 3,024,331 CIRCUIT INTERRUPTER Russell E. Frinlr, Forest Hills, Pa., assigner to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Nov. 6, 1957, Ser. No. 694,882 9 Claims. (Cl. 20u-147) This invention relates to circuit interrupters in general and, more particularly, to arc-extinguishing structures therefor.

A general object of the present invention is to provide an improved circuit interruptor, which will be capable of interrupting relatively high currents, which would tend to deform the shape of the oblong magnetic blowout coil for the interruptor, but which, employing the improved coil bracing structure of the present invention, is capable of withstanding such high stresses. b

Another object of the invention is to provide an improved magnetic blowout coil bracing construction utilizing the structural strength inherent in the steel side magnetic pole plates.

Another object of the present invention is to provide an improved magnetic coil bracing construction, which will not take up much space, and the elements of which may be easily manufactured and will be of low cost.

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 elevation view, partially in vertical section, of a circuit interrupter embodying the principles of the 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 an enlarged, fragmentary, sectional view taken substantially along the line VI-VI of FIG. 3;

FIG. 7 is a fragmentary sectional View taken substantially along the lines VII- VII of FIGS. 2 and 6;

FIG. 8 is a detailed view of one of the coil bracing strips utilized in the present invention; and,

FIG. 9 is a sectional view taken along the line IX-IX of FIG. 8.

Referring to the drawings, and more particularly to FIG. 1 thereof, the reference numeral 1 generally designates a circuit interrupter, in this instance being one of 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 cere tain 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 to relieve the stationary and movable arcing contacts 6, 7 from carrying the current in the fully closed-circuit position shown in FIG. 1.

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. 1. This arc, generally designated by the reference character 8, may be considered as composed of three sections Sn, Sb and 8c. The arc 8, of course, bows npwardly 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 3 which act to expand the loop of the arc, as well understood by those skilled in the art.

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

The function of the transfer arc-extiguishing means 13 is to interrupt the arc portion 8b, and so bring into series circuit the pair of serially related, centrally disposed oblong or oval- shaped 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 oblong blowout coils 15, 16 are connected in series circuit together, as by a connection 17 at the top of the coils (FIGS. 1 and 3), and the other lower ends 18, 19 of the blowout coils 16, 15, respectively, are secured to the transfer arc horns 10, 11, respectively, as shown more clearly in FIG. 1 of the drawings.

Because of the reactance of the blowout coils 15, 16, it is diilicult to force current to flow through them because of the countervoltage set up in the coils. The transfer-arc 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 arc-extinguishing means 13 includes a plurality of spaced insulating plates 21, the conguration of which is more clearly shown in FIG. 5 of the drawings. It 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. The 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 zig-zag path for the arc.

Referring to FIG. 1, it will be noted that a plurality of the plates 21 are disposed between the transfer arc horns 10, 11 and the single-turn shading coil 25. The shading coil 2S in turn 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. 1 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 arcs 29, 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 8b Within tbe arc-extinguishing means 13 for the transfer arc, the blowout coils 15 and 16 are serially connected into the circuit, and the energization of these coils so, 16 sets up a magnetic flux within the magnetic circuit 24, which includes the pair of side magnetic pole plates Z7 and the interconnecting yoke 26. Preferably, the pole plates 27 are formed of vertically extending sheets f a suitable magnetic material to form a laminated structure, more clearly shown in FlG. 2 of the drawings. Magnetically interconnecting the side pole plates 27 is the central interconnecting core or yoke portion 26, which is encircled by the two serially related blowout coils l5 and 16. Each magnetic pole plate 27 has a pair of magnetic side pole-plate extensions 27a extending in opposite directions, as shown in FIG. 2.

As will be obvious to those skilled in the art, the H-type of magnetic circuit 24 shown, upon the energizetion thereof, causes magnetic flux to flow between the pole plates 27 in the manner indicated by the arrows Z0 in FlG. 2. This magnetic flux extending transversely between the pole plates .27 causes upward movement of the arc portions 5a, 3c upwardly into the arc- extinguishing sections 4, 5 ofthe arc-chute structure 3.

The left-hand end of the arc portion 3a, as viewed in FlG. l, quickly transfers to the outer arc horn l2, 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 de quickly transfers to the rig .t-hand arc horn 9 of the device, which is electrically connected to the stationary contact 6 by the connection 9a and hence to the upper terminal Ll of the interrnpter.

The current path through the interrupter (as viewed in FlG. l) may then be traced, beginning at line Ll., through connection 9a, arc horn and terminal plate 9, across the arc in right-hand main extinguishing section 5 to the transfer arc horn cr plate ll, lower end 19 of front blowout coil l5, through coil l5 to the connection i7 at its upper end to the upper end of the rear blowout coil la, through coil l to its lower end l5 connected to the arc transfer plate or horn l0, through the are in main lefthand extinguishing section E to arc terminal plate or horn l2 on thence to line L2.

Disposed within the arc-extinguishing sections fs, 5 are the plurality of spaced, slotted, ceramic plates the configuration of which is more clearly shown in FIG. 4 of the drawings. As shown, each ceramic plate 40 has a slot 4l provided therein, the upper closed end d2 of which is slightly off-center. The plates 40 are staggered during the assembly operations so as to form a horizontally disposed, zig-zag arc passage i3 throughout the length of the arc- chute sections 4, 5 to quickly bring about extinction of the are portions 3a, Se. The plates i0 are spaced laterally apart, as shown more clearly in FIG. 2, by sections of asbestos rope 1M cemented between the plates itl adjacent the outer edges thereof, the method being identical to that previously referred to in spacing the insulating plates 2l of the transfer arc-extinguishing means i3 apart.

Certain features of the disclosed structure have been set out and claimed in my pending United States Patent No. 2,795,675, issued .lune l1, 1957, entitled Circuit Interrupter, and assigned to the assignee of the instant application.

The present invention is particularly concerned with bracing the two serially related oblong blowout coils l5 and 16 so as to adapt them to carry a heavy series current without deformation thereof. `In blowout structures for magnetic air circuit interrupters it has been found advantageous, from the standpoint of both performance and space required, to use elongated or oblong blowout coils 15, ld, the area enclosed by which may be of the order of ll/z inches X 91/2 inches. When current flows through these coils, magnetic forces are set up which tend to deform the coils to make them enclose the largest possible areain other words, tend to make them circular in shape. The entire current interrupted flows through these coils 15, 16, and the magnetic force is proportional to the square of the current. As a result, for the higher interrupting ratings, the force may be of the order of several tons.

ln the past, for particular ratings, the coils l5, 16 have been spirally wound and placed in windows cut in the walls of the arc chtite jacket 35. Reference may be had to U.S. Patent No. 2,769,065, issued October 30, 1956, to Russell E. Frink and assigned to the assignee of the instant application.

For the higher current rating breakers, however, such a construction was tried with a 3/8 inch thick insulation plate material of high strength, but the magnetic forces were so great that they broke the arc-chute jacket plate material. ln order to obtain satisfactory performance, the side sheets of the arc-chute jacket were changed to a very expensive material, such as glass melamine, which possesses considerable structural strength.

The present invention is particularly concerned with avoiding the use of such expensive arc-chute jacket insulating plate material, and instead utilizes the inherent structural strength of the metal side magnetic pole plates 27. For the very high interrupting ratings, such as interrupters adaptable for controlling a 5 kv. circuit with 350 mva. interrupting capacity, it is required to interrupt 50,000 amperes, the highest interrupting current of any magnetic air breaker to date. To avoid the high cost of glass melamine material for the arc-chute jacket 35 (which possibly might not even be adequate for this rating), a new construction has been provided, which constitutes the subject matter of the present invention.

With particular reference to FIGS. 6 and 7 of the drawings, it will be noted that the side magnetic pole plates 27 have recesses 46 provided therein which accommodate a pair of elongated coil bracing strips or elongated bracing means 47, 48 of glass melamine laminate. The coil bracing strips 47, 48 are bolted to the side pole plates by socket head screws 49 and bolts 50. Coil washers 5l bear against the blowout coil l5, as shown in FlG. 6. ln addition, a formed rectangularly-shaped fishpaper shield 52 is positioned in the manner illustrated in FIG. 6, so that there is insulation provided between thc side pole plate 27 and the blowout coil l5.

The magnetic forces which tend to deform the oblong coils 15, 16 are transmitted to the bracing blocks 47, 48, which transmit the forces to the iron side pole plates 27, which are well able to withstand such forces. The blocks 47, 48 are in compression and can withstand 26,000 p.s.i. A sample interruptor, built as described and tested, was able to interrupt 58,000 amperes without damage, and such sample was built with relatively low-cost, relatively low-structural-strength, side insulating plates constituting the arc chute jacket 35.

From the foregoing description it will be apparent that there is provided an improved magnetic blowout coil bracing construction, which adapts the magnetic oblong blowout coils 15, ll6 to withstand the extremely high magnetic forces encountered during the interruption of very high-amperage currents. As mentioned above, these eX- tremely high magnetic forces are transmitted through the bracing strips 47, 4S to the side magnetic pole plate 27 itself. Since the pole plate 27 is of metallic material itself, possessing very high strength, it can readily withstand such forces, and relieves the arc-chute jacket 35 from the necessity of withstanding such forces, as was necessitated by constructions heretofore used.

Although there has been shown and described a specific 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:

l. A circuit interruptor including means for establishing an arc, means for extinguishing the arc including a magnetic blowout structure, said magnetic blowout structure including an oblong blowout coil, a magnetic core and a magnetic pole plate, one or more bracing strips, means clamping said one or more bracing strips to said magnetic pole plate, and said one or more bracing strips lying against the outer side of said oblong blowout coil to prevent deformation of the latter on high-current interruption.

2. A circuit interrupter including means for establishing an arc, means for extinguishing the arc including a magnetic blowout structure, said magnetic blowout structure including an oblong blowout coil, a magnetic core and a magnetic pole plate, said magnetic pole plate being provided with a recess, one or more bracing strips, means clamping said one or more bracing strips to said magnetic pole plate within said recess, and said one or more bracing strips lying against the outer side of said oblong blowout coil to prevent deformation of the latter on high-current interruption.

3. A circuit interrupter of the magnetic air-break type including an H-shaped magnetic blowout structure, a centrally disposed magnetic core and a pair of side magnetic pole plates forming a generally H-shaped construction, means for establishing an arc, means for moving two portions of said arc up between the two pairs of legs of said l-l-shaped magnetic blowout structure, an oblong magnetic blowout coil encircling said magnetic core, at least one bracing strip lying against the outer side of said oblong blowout coil to brace the latter, and means clamping said bracing strip to the adjacent magnetic pole plate.

4. A circuit interrupter of the magnetic air-break type including an H-shaped magnetic blowout structure, a centrally disposed magnetic core and a pair of side magnetic pole plates forming `a generally H-shaped construction, means for establishing an arc, means for moving two portions of said arc up between the two pairs of legs of said H-shaped magnetic blowout structure, an oblong magnetic blowout coil encircling said magnetic core, at least one magnetic pole plate having a recess therein, at least one bracing strip lying against the outer side or" said oblong blowout coil to brace the latter, and means clamping said bracing strip within said recess of said one magnetic pole plate.

5. An air-break circuit interruptor including separable contact means for establishing an arc, a magnetic blowout structure for extinguishing said arc including a pair ot magnetic side pole-plate extensions and an interconnecting elongated magnetic yoke, said interconnecting yoke being elogated in a direction parallel to the planes of the poleplate extensions, an oblong blowout coil encircling said elongated magnetic yoke to set up a magnetic eld across the magnetic pole-plate extensions, means for electrically connecting said oblong blowout coil in series circuit during the opening operation, one of said magnetic side poleplate extensions having a shoulder portion, and a long side of said oblong blowout coil being braced by said shoulder portion to prevent circular deformation of the oblong blowout coil by the series current.

6. An air-break circuit interrupter including separable contact means for establishing an arc, a magnetic blowout structure for extinguishing said arc including a pair of magnetic side pole-plate extensions and an interconnecting elongated magnetic yoke, said interconnecting yoke Abeing elogated in a direction parallel to the planes of the poleplate extensions, an oblong blowout coil encircling said elongated magnetic yoke to set up a magnetic field across the magnetic pole-plate extensions, means for electrically connecting said oblong blowout coil in series circuit during the opening operation, one of said magnetic side pole-plate extensions having a shoulder portion, an insulating bracing strip disposed against said shoulder portion, and said insulating bracing strip also being disposed against a long side of said oblong blowout coil to brace the latter against circular deformation during the ilowing of heavy current through the oblong blowout coil.

7. A circuit interrupter including means vfor establishing an arc, means for extinguishing the arc including a magnetic blowout structure, said magnetic blowout structure including an oblong blowout coil, a magnetic core and a pair of magnetic pole plate extensions, and bracing strip means for preventing deformation of said blowout coil including at least one pole plate extension by utilizing the tensile strength of said one pole plate extension.

8. The combination in a circuit interrupter of means for establishing an arc, means for effecting the extinction of said arc including a magnetic blowout structure, said magnetic blowout structure including a magnetic core and a pair of magnetic pole plate extensions, a generally oblong blowout coil encircling said core for creating a magnetic iield between said pole plate extensions during arc interruption, elongated bracing means extending generally parallel to the long direction of the generally oblong blowout coil for bracing the same laterally to resist expansive deformation forces, and said elongated bracing means utilizing the tensile strength of at least one magnetic pole plate extension in its bracing action.

9. A circuit interrupter including means for establishing an arc, means for extinguishing the arc including a magnetic blowout structure, said magnetic blowout structure including an oblong blowout coil, a magnetic core and a pair of magnetic pole plate extensions, and bracing means including a recessed portion of at least one of said magnetic pole plate extensions for bracing said oblong blowout coil against deformation by utilizing the tensile strength of said one magnetic pole plate extension.

References Cited in the file of this patent UNITED STATES PATENTS 2,138,391 Van Sickle Nov. 29, 1938 2,632,075 Rawlins et al. Mar. 17, 1953 2,646,481 Wood et al July 21, 1953 2,692,319 Dickinson et al. Oct. 19, 1954 2,769,065 Frink Oct. 30, 1956 FOREIGN PATENTS 1,036,291 France Apr. 22, 1953

Images