US2769065A - Circuit interrupter - Google Patents

Description

Oct. 30, 1956 R. E. FRlNK CIRCUIT INTERRUPTER 3 Sheets-Shae v 1 Filed Nov. 28, 1952 INVENTOR Fig.l.

WITNESSES: 717 f Russell E. Frink. q; ATTORN Oct. 30, 1956 R. E. FRINK CIRCUIT INTERRUPTER 5 Sheets-Sheet 2 Filed NOV. 28, 1952- Fig.2.

Fig.3.

INVENTOR Russell E.Frink. BY

Oct. 30, 1956 Filed Nov. 28, .1952

R. E. FRINK C IRCUIT INTERRUPTER 5 Sheets-Sheet 3 Fig.5. Fig.9.

' F' Fig.7. 4o

Fig.lO. J K 40- Fig. 38 F1 12.

WITNESSES: INVENTOR Russell E.Frink.

ATTORN United States Patent Ofiiice CIRCUIT INTERRUPTER Russell E. Frink, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania I Application November 28, 1952, Serial No. 323,009

19 Claims. (Cl. 200-147) This invention relates generally to circuit interrupters, and, more specifically, to arc-extinguishing structures for magnetic circuit interrupters.

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

Another object is to provide an improved mounting arrangement for the blowout coil of a circuit interrupter.

Still a further object is to provide improved bracing means for counteracting the terrific magnetic forces exerted in and around the magnetic blowout coils during the interruption of large fault currents.

Still a further object is to provide an improved circuit interrupter of the type in which the blowout coil is at a floating potential in the closed, and in the fully open circuit position of the interrupter, and which provides an improved connection for connecting the potential of the magnetic pole plates to the mid-potential point of the floating blowout coil.

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 Il-II of Fig. 1;

Fig. 3 is a vertical sectional view taken along the line IHIlI of Fig. 1;

Fig. 4 is a fragmentary, vertical sectional view taken along the line IV-IV of Fig. 1;

Figs. 5 and 6 are side elevational and end views of a side magnetic pole plate utilized in my improved circuit interrupter;

Figs. 7 and 8 are side elevational and end views of the thin insulating spacer required in my improved magnet construction;

Fig. 9 is a side elevational view of a coil washer;

Fig. 10 is an end view of my improved shading coil; and

Figs. 11 and 12 are respectively end and side elevational views of one of the transfer arcing horn.

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 certain features of my invention may be applicable to other types of circuit interrupters, say, for instance, one of the liquid-immersed type. Merely for purposes of illustration do 1 describe a specific embodiment 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 2,769,065 Patented Oct. 30, 1956 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, as shown in Fig. 1.

During the opening operation, the movable arcing contact 7 moves away from the stationary arcing contact 6 to establish an are 8, as shown by the dot-dash line of Fig. 1. This are, generally designated by the reference character 8, may be considered as composed of three sections 8a, 8b and 8c. The are S, of course, bows upwardly because of the natural convection current of air, which is heated by the hot are 8, and also because of the magnetic forces set up by the are 8 which act to expand the loop of the arc, as well understood by those skilled in the art.

Adjacent the top portion of the are 8 is a pair of transfer arc horns 10, 11, between which is disposed a transfer arc-extinguishing means 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 are horns 1t) and 11. The are portion extends between the stationary arcing contact 6 and the transfer are horn 11.

The function of the transfer arc-extinguishing means 13 is to interrupt the arc portion Sb, and so bring into series circuit the pair of serially-related centrally-disposed blowout coils 15 and 16, the location of which is more clearly shown in Fig. 2 of the drawings. Such coils, of course, have insulating windings. As mentioned, the centrally-disposed blowout coils 15, 16 are connected in series circuit together, as by a bolt connection 17 (Fig. 3), and the other ends 18, 19 of blowout coils 16, 15, respectively, are secured to the transfer are horns 10, 11, respectively, as shown more clearly in Fig. l of the drawll'lgS.

Because of the reactance of the blowout coils 15, 16, it is difficult 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 812. Generally, the transfer arc-extinguishing means 13 includes a plurality of spaced slotted ceramic plates 20, the configuration of which is more clearly shown in Fig. 3 of the drawings. As shown, each ceramic plate 20 has a slot 21 provided therein, within which the arc portion 812 is moved. The spaced ceramic plates 20 are spaced laterally apart, as shown more clearly in Fig. 1, by pairs of sections of asbestos rope cemented between the plates 20 adjacent the outer edges thereof.

Following extinction of the arc portion 8b within the transfer arc-extinguishing means 13, the blowout coils 15 and 16 are serially connected in the circuit, and the energization of these coils 15, 16 sets up a magnetic flux within the magnetic circuit 22, which includes a pair of side magnetic pole plates 24 having a configuration more clearly shown in Figs. 5 and 6 of the drawings. Preferably, the pole plates 24 are formed of vertically extending sheets of a suitable magnetic material to form a lami nated structure more clearly shown in Fig. 6 of the drawings. Magnetically interconnecting the side pole plates 24 is a central interconnecting core portion 25, about which encircles 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 22 shown, upon the energization thereof, causes magnetic flux to flow between the pole plates 24 in the manner indicated by the arrows 26 in Fig. 4. This magnetic flux extending transversely between the pole plates 24 causes upward movement of the arc portions 8a, 8c upwardly into the arc-extinguishing sections 4, of the arc-chute structure 3.

The left-hand end of the arc portion 8a, as viewed in Fig. I, quickly transfers to an outer arc horn 28, 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 80 quickly transfers to the right-hand arc horn 29 of the device, which is electrically connected to the stationary contact 6 by the connection 12 and hence to the upper te minal L1 of the device.

Disposed within the arc-extinguishing sections 4, 5 are a plurality of spaced slotted ceramic plates 30, the configuration of which is more clearly shown in Fig. 4 of the drawings. As shown, each ceramic plate 30 has a slot 31 provided therein, the upper closed end 32 of which is slightly off-center. The plates 30 are staggered during the assembly operations so as to form a horizontally-disposed zigzag arc passage 9 throughout the length of the arc-chute sections 4, 5 to quickly bring about extinction of the arc portions 6a, 80. The plates 30 are spaced laterally apart, as shown more clearly in Fig. 1, by sections of asbestos rope 27 cemented between the plates 30 adjacent the outer edges thereof, the method being identical to that previously referred to in spacing the plates 20 of the transfer arc-extinguishing means 13 apart.

Certain features of the disclosed structure have been set out and claimed in United States patent application, filed May 26, 1951, Serial No. 228,446, now U. S. Patent 2,692,319, issued October 19, 1954, to Robert C. Dickinson and Russell E. Frink, and assigned to the assignee of the instant application. This patent in part claims the venting passages 33 disposed upon opposite sides of the core 25 to facilitate the upward passage of the arc gases produced during the functioning of the transfer arc-extinguishing means 13. Proper operation of the transfer arc-extinguishing means 13 is necessary to ensure rapid blowout-coil transfer, and a ready venting of the arc gases is provided by the use of the two venting passages 33 claimed in the aforesaid patent.

The particular design illustrated in the aforementioned application is rated at 50,000 kva. at 5 kv. and has a maximum current interrupting rating of 12,500 amperes. In the process of interrupting the arc, the current passes through the blowout coils 15, 16, and the magnetic forces from these currents tend to deform the coils 15, 16 into a circular shape to enclose as great an area as possible, and also to pull the two coils together.

To prevent these coils 15, 16 from actually deforming, they must be strongly braced; and while bracing, as shown in the aforementioned application, may be adequate for 12,500 amperes, it might not be strong enough to withstand the forces from 45,000 amperes (the maximum current interrupting capacity of the largest magnetic breakers made at present). The peak force between the sides of a rectangular coil carrying current can be approximated by the formula:

F=6.36N i (l/b) lbs. where F=Force in lbs. N :Number of turn in the coil i =R. M. S. value of sinusoidal current in coil Z=Length of the coil b=Breadth of the coil Applying this formula to a 9 turn coil carrying 12,500 amperes and having an l/ b force is approximately 2 /2 tons. However, if the current is 45,000 amperes the force is approximately 36 tons. These figures give an exaggerated picture of the true case for the following reasons: (a) The formula is derived for conductors of infinite length, and crosssection small as compared to spacing. The actual coil configuration tends to reduce the force. (b) No account was taken of the internal strength of the coil to resist deformation. (0) Fewer turns would be used in the 45,000 ampere coil, and the force would be reduced by the square of the turns ratio. However, the forces are very large, and experience has shown that extensive bracing must be provided to prevent mechanical failure of the structure. A structure will now be described, which provides this bracing by using the mechanical strength of the insulating arc-chute jacket 34 and uses a minimum of space.

As shown more clearly in Figs. l3, the rectangularlyshaped arc-chute jacket 34 encloses the arc-extinguishing sections 4, 5. One feature of my present invention is to cut substantially rectangular apertures 35 in the side Walls of the arc-chute jacket 34, to accommodate the core 25 and also to accommodate the blowout coils 15, 16. These coils, a shown, are wound in the form of pancake coils disposed in the plane of the side walls of the arc chute jacket 34 of insulating material. Thus, the magnetic forces which tend to expand the blowout coils 15, 16 are resisted, or counteracted, by the mechanical strength of the side walls of the arc-chute jacket 34, with the forces applied thereto edgewise in compression. The wire from which the coils 15, 16 are made is of such a size that the coils 15, 16 replace the insulating material cut away in making the apertures 35.

Mounted to the inside surface of the arc-chute jacket 34,, as by bolting, are coil washers 36 (Fig. 9) of insulating material, preferably glass melamine laminate. These coil washers 36 protect the coils 15, 16 from the arc and at the same time provide support against the forces tending to pull the two coils 15, 16 together. The two blowout coils 15, 16, as mentioned, are connected in series by bolting the two top terminals together by the bolt 17 (Fig. 3). The lower terminals of the coils 1'5, 16 are connected to the transfer arc- horns 10, 11. The transfer are horns, 10, 11 form rigid spacers in compression between the coil washers 36, as shown more clearly in Fig. 2 of the drawings. The coil washers 36 have notches 37 (Fig. 9), which accommodate projections 38 (Fig. 12) of the transfer arc- horns 10, 11. This vertically locates the transfer arc- horns 10, 11.

Formed about the magnetic core 25, and providing an additional spacer in compression between the coil washers 36 is a shading coil 39, preferably made of resistance bronze and shown more clearly in Fig. 10 of the drawings. On assembly, the upper terminals of the blowout coils 15, 16, are clamped by the bolt 17 between the open end of the shading coil 39, which completes the loop. This positively fixes the shading coil 39 at a potential midway between the transfer arc- horns 10, 11, and since the shading coil 39 is electrically in contact with the magnetic core 25, the entire magnet assembly 22 will be at a potential midway between the transfer arc- horns 10, 11. This means that only relatively small voltages can exist between any part of the coils 15, 16 and the magnet 22, and adequate insulation is provided by a sheet of fish paper 40 (Fig. 7), placed between the coils 15, 16 and the side pole plates 24, as shown more particularly in Figs. 2, 3 and 4 of the drawings.

From the foregoing description, it will be apparent that I have provided certain novel additional features in the present embodiment over that described in the aforesaid patent. By locating the blowout coils 15, 16 in apertures 35 cut in the arc-chute jacket 34, the coils are adequately braced without providing additional bracing means. I have also provided an electrical connection between the ratio of 7, we find that the, 76; mid-point of the blowout coil assembly to the magnet .5 iron 22. The use of the shading coil 39 in the improved structure serves a three-fold purpose: First, the shading coil 39 shifts the magnetic field with respect to the cur rent being interrupted so as to provide an adequate magnetic field strength at a current zero on the alternating current wave. Secondly, the shading coil 39 provides sidewise bracing between the coils 15, 16 by bearing against the coil Washers 36. Thirdly, the shading coil 39 forms a terminal for connecting the two blowout coils 15, 16 in series at their upper terminals. The construction described also provides larger venting spaces 33 for the emission of gases from the transfer stack 13 and better utilization of the magneto-motive force of the blowout coils than that previously disclosed in the aforesaid patent. The net result is a more effective arc-extinguishing structure 3 with greatly increased support for bracing the blowout coils 15 and 16 and making possible the interruption of heavier short-circuit currents.

Although I have 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:

1. A circuit interrupter including contact structure separable to establish an are, an arc chute having a housing in which the arc is extinguished, said housing having plate-like side walls with at least one side wall having an opening therein, one or more blowout coils to assist in moving the arc within the arc chute, and at least one of the blowout coils being braced from expanding radially in the plane of said one side wall by the edge of said opening.

2. A circuit interrupter including contact structure separable to establish an are, a substantially rectangularlyshaped arc chute having a substantially rectangularlyshaped housing having a pair of opposed openings in the side walls thereof, an H-shaped magnet structure having the core thereof extending through the two openings, a pair of pole plates on opposite sides of the housing and abutting the core, and a pair of blowout coils disposed within the openings and braced by the side walls of the housing.

3. A circuit interrupter of the magnetic blowout type wherein contacts separate to establish an arc and wherein a blowout coil is energized to effect movement of the are within an arc chute, characterized by the fact that an opening is provided in a plate-like wall of the arc chute within which said blowout coil is positioned, and said blowout coil being braced by the edge of said opening from expanding radially in the plane of said plate-like wall of the arc chute.

4. A circuit interrupter of the magnetic blowout type including means for establishing an are, a housing in which the arc is moved having an opening in a plate-like side wall thereof, one or more blowout coils to effect motion of the arc, and at least one of the blowout coils being braced by the edge of said opening from expanding radially in the plane of said side wall having the opening.

5. A circuit interrupter of the magnetic blowout type including means for establishing an arc, a housing in which the arc is moved having side walls with a pair of opposed openings, a pair of blowout coils to effect motion of the are within the housing, and the blowout coils being disposed within the openings to be braced by the walls of the housing.

6. A circuit interrupter including means for establishing an arc, a pair of blowout coils for effecting movement of the arc, a magnetic core threading the blowout coils, and a short-circuiting shading coil disposed about the core between the blowout coils and serving to brace the same apart.

7. A circuit interrupter including means for establishing an are, a magnet structure for efiecting' movement of the are including a pair of serially-related blowout coils and a magnetic core threading the blowout coils, a U- shaped shading coil disposed about the core between the blowout coils, and the terminals of the coils being connected together at the open end of the shading coil to complete the loop of the shading coil.

8. A circuit interrupter including means for establishing an arc, a magnet structure for effecting movement of the are including a pair of serially-related blowout coils and a magnetic core threading the blowout coils, a U-shaped shading coil disposed about the core between the blowout coils, the terminals of the coils being connected together at the open end of the shading coil to complete the loop of the shading coil, and the shading coil serving to brace the coils apart.

9. A circuit interrupter including means for establishing an arc, a floating magnet structure including a pair of pole plates and a magnetic core, a pair of floating blowout coils about the core, a shading coil about the core and in electrical contact therewith, and means connecting the blowout coils with the shading coil to bring the potential of the magnet structure to that of the point between the coils.

10. A circuit interrupter including means for establishing an arc, an H-type magnet structure at a floating potential including a pair of pole plates and an interconnecting magnet core, a pair of serially related blowout coils at a floating potential about the core, a pair of transfer are horns connected to the ends of the coils, the other ends of the coils being connected together, and a shading coil about the core in electrical contact with both the magnet structure and with said other ends of the coils so that the potential of the magnet structure is that of the point between the coils.

11. A circuit interrupter including contact structure separable to establish an arc, an arc chute having a housing in which the arc is extinguished, said housing having side walls with an opening therein, one or more blowout coils to assist in moving the are within the arc chute, and at least one of the blowout coils being wound in the plane of the side wall and having a close fit within the opening thereby being braced by the walls of the housing.

12. A circuit interrupter including contact structure separable to establish an are, a substantially rectangularlyshaped arc chute having a substantially rectangularlyshaped housing having a pair of opposed openings in the side walls thereof, an H-shaped magnet structure having the core thereof extending through the two openings, a pair of pole plates on opposite sides of the housing and abutting the core, and a pair of blowout coils wound in the planes of the side walls and having close fits within the openings thereby being braced by the side walls of the housing.

13. A circuit interrupter of the magnetic blowout type wherein contacts separate to establish an arc and wherein a blowout coil is energized to effect movement of the are within an arc chute, characterized by the fact that an opening is provided in the wall of the arc chute and the blowout coil is wound in the plane of the wall of the arc chute whereby said blowout coil is braced by the wall of the arc chute.

14. A circuit interrupter of the magnetic blowout type including means for establishing an are, a housing in which the arc is moved having an opening in a side wall thereof, one or more blowout coils to effect motion of the arc, and at least one of the blowout coils being wound in the plane of the side wall and having a close fit within the opening whereby the coil is braced by the side wall of the housing.

15. A circuit interrupter of the magnetic blowout type including means for establishing an arc, a housing in which the arc is moved having side walls with a pair of opposed-openings, a pair of blowout coils to effect motion ofthe are within the housing, and the blowout coils being wound in the planes of the side walls of the housing and having close fits therein whereby the blowout coils are braced bytthe side walls of the housing.

16. A circuit interrupter including contact structure separable to establish an arc, an arc chute having a housing'in which the arc is extinguished, said housing having side walls with a pair of opposed openings therein, a pair of blowout coils to assist in moving the are within the arc chute, the pair of blowout coils being disposed within the openings of the housing and braced by the walls of the housing, a magnetic core threading the blowout coils, and a shading coil disposed about the core between the blowout coils and serving to brace the same apart. 1

17. A circuit interrupter including contact structure separable to establish an are, a substantially rectangularlyshaped arc chute having a substantially rectangularlyshaped housing having a pair of opposed openings in the side walls thereof, an H-shaped magnet structure having the core thereof extending through two openings, a pair of pole plates on opposite sides of the housing and abutting the core, a pair of blowout coils disposed within the openings and braced by the side walls of the housing, and a shading coil disposed about the core between the blowout coils and serving to brace the same apart.

18. A circuit interrupter including contact structure separable to establish an are, an arc chute having a housing in which the arc is extinguished, said housing having side walls with a pair of opposed openings therein, a pair of blowout coils to assist in moving the are within the arc chute, the pair of blowout coils being wound in the planes of the side walls of the housing and having close fits therein, a magnetic core threading the blowout coils, and a shading coil disposed about the core between the blowout coils and serving to brace the same apart.

19. A circuit interrupter including contact structure separable to establish an arc, a substantially rectangularlyshaped arc chute having a substantially rectangularlyshaped housing having a pair of opposed openings in the side walls thereof, an H-shaped magnet structure having the core thereof extending through the two openings, a pair of pole plates on opposite sides of the housing and abutting the core, a pair of blowout coils wound in the planes of the side walls of the housing and having close fits therein, and a shading coil disposed about the core between the blowout coils and serving to brace the same apart.

References Cited in the file of this patent UNITED STATES PATENTS

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