US2590602A - Circuit interrupter - Google Patents

Description

Mmh 2'5, 1952 2 SHEETS-SHEET l Filed Sept. 27, 1947 INVENTOR Fuss el] f'. Fri/2k.

WITNESSES: //f-f 0F/w 31 37 BY N J5 ATTORNEY March 25, 1952 Filed Sept. v27, .1947

R. E. FRINK CIRCUIT INTERRUPTER 2 SHEETS-SHEET 2 Patented Mar. 25, 1952 CIRCUIT TNTERRUPTER Russell E. Frink, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application September 27, 1947, Serial No. 776,50?.

14 Claims.

This invention relates to circuit interrupters in general, and more particularly to arc-extinguishing structures therefor.

A general object of my invention is to provide an improved circuit interrupter of the type utilizing a blowout magnetic structure in which a series coil is inserted in the circuit during at least a portion of the opening operation to energize or magnetize the included blowout structure. As is well known by those skilled in the art, such blowout structure operates to move the arc into any desired interrupting structure to more readily effect its extinction therein.

A further object is to provide an improved circuit interrupter in vwhich the blowout windings are more rapidly inserted into series circuit to decrease the overall time of operation of the interrupter.

Still a further object is to provide an improved blowout structure for a circuit interrupter in which at least two separate windings are used with the blowout structure, and improved interrupting means are provided to interrupt the transfer arc upon the insertion of the second blowout coil into series circuit, the transfer arc being the arc in parallel with the second blowout coil.

Still a more specific object is to provide an improved circuit interrupter of the air-break type in which a conducting probe is disposed intermediate the ends of the arc chute. Preferably, the probe is electrically connected to an auxiliary fine winding coil disposed about the blowout structure in conjunction with a relatively few-turn heavy winding coil. Thus, the transfer arc, which must be interrupted upon the insertion of the fine winding coil into series circuit, is more readily extinguished by the utilization of part of the arc chute structure.

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

Figure l is a side elevational View, partially in vertical section, of an improved air-break type of circuit interrupter embodying my invention and shown inthe closed circuit position;

Fig. 2 is a transverse vertical sectional view taken along the line II-II of Fig. l as viewed in the direction of the arrows; A

Fig. 3 is a fragmentary plan sectional view taken along the line III- III of Fig. l looking in the direction of the arrows, and

Fig. 4 is a diagrammatic View of the electric connections involved in the operation of my improved circuit interrupter.

Any circuit breaker, no matter what its maximum interrupting rating, must be able to interrupt currents of all magnitudes from zero up to and including its rating. A comparatively large number of turns is necessary in the blowout coil of an air-magnetic breaker (8 or 10 or preferably more) to interrupt the load and overload currents. It is not practical to carry the continuous current through the blowout coil because of heating, and the problem then presents itself of getting the coil into the circuit as rapid- 1y as possible during interruption.

An arc chute having a high k. v. a. rating is necessarily physically larger than an arc chute having a lower k. v. a. rating. If both arc chutes have the same flux density over the interrupting region, the total ux threading the coil in the larger' chute will be greater in proportion to the areas of the magnetic pole pieces. When the field is energized a voltage will appear across the terminals of the coil which is equal to sin; dt

where N is the number of turns in the blowout coil and Y is the time rate of change of the iiux threading the coil. This voltage appears immediately when the current is transferred to the coil and is in such a direction as to oppose the transfer. Introducing the current into the coil is then a problem of interrupting the section'of arc across the coil terminals and is an identical problem to that found in interrupting any reactive circuit. The interrupting voltage will be proportional to Nk where N is the number of turns in the blowout coil and k is a factor between l and 2. If the magnetic circuit is a tight iron circuit andhighly saturated, 7c would be approximatelyY 1,' but if the magnetic circuit is air and coupling is near unity then k would be 2. The magnetic circuit in an air circuit breaker is iron with a large air gap so k will lie between the two extremes. Previous experience in circuit interruption shows that the lower the voltage to be interrupted, the more current a given interrupter can handle. Reducing the number of turns will increase the current that can be tansierred to the coil by a represents the factor by which the number of turns is reduced and if: is a number between l and 2.

A structure will now be described which will take advantage of the principles just set forth in a novel manner that will enable it to handle high currents and still introduce a suicient number of turns into the circuit to give the high field strengths necessary.

Referring to the schematic diagram, as shown in Fig. 4, the reference numerals I and 2 indidicate the line terminals of a protected circuit which is controlled by the operation of a circuit interrupter generally designated by the reference numeral 3. Upon the separation of the main contacts 4, 5 of the circuit interrupter 3, an arcis initially established. Because of the loop circuit provided, more fully described hereinafter, the initial arc 6 is readily transferred to the arcing horns 8, 9 to thereby insert into series circuit a relatively heavy winding blowout coil It of few turns. The energization of the blowout coil IU sets up a magnetic field transverse to the spaced plate structure generally designated by the reference numeral iI and forces the arc, designated by the reference numeral I2, up into the plate structure I I. The upward moving arc I2 contacts the conducting probe I3, the latter being electrically connected by a conductor I to a relatively ne winding blowout coll I5 which is disposed about the same bight portion i6 of the blowout structure as is disposed the blowout coil I!! of relatively few turns. Thus the two coils I0, I5 have cores of substantially the same cross-sectional area.

Preferably they are positioned closely together upon the bight portion I5 of the blowout structure so that they are tightly coupled together, and all the flux of the coil I2 passes through the core of the coil I5. The position of the arc is now designated by the reference numeral II, immediately after it has contacted the probe i3. The blowout coil I is quickly and easily transferred into series circuit because it is composed of few turns, say two or three. While this coil I5 will noti supply the strong eld necessary for interruption, it is strong enough to move the arc i2 up into the plate structure Ii. The magnetic iield supplied by the blowout coil i5 causes the section of arc between the are horn 8 and the probel I3, designated by the reference numeral I9, torise` up into the portion I9 of the plate structure I! disposed between the probe i3 and the arc horn 8. This movement of the arc I8 into the plate structure I9 raises the arc voltage across w the section of the arc ito a value' higher than thezvoltage between arcing horns 8, i3 would be if the current were flowing through theV second relatively fine winding blowout coil I5. The result is that thev arc I3 is extinguished and the current transfers to the second auxiliary blowout coil I5, and interruption of the circuit is accomplished with the blowout coils IIJ, I5 in series acting as one coil The combined magnetic effect produced by the joint action of the blowout coils IIl, I5 serves to move the arc portion 20 between the arcing horns I3, 9 up into the portion 2I of the plate structure I I to thereby effect the extinction of the arc portion 20. When this is accomplished the circuit is interrupted.

From the foregoing discussion of the principles of my invention taken in connection with the diagrammatic view of Fig. 4, it will be readily apparent how the invention may be applied to a commercial type of circuit interrupter set forth in Figs. 1-3, the operation and method of arc rupture within the plate structure being set forth and described broadly in U. S. patent application led December l5, 1943, Serial No. 514,362, now U. S. patent 2,442,199, issued May 25, 1948 to Robert C. Dickinson and Russell E. Frink and assigned to the assignee of the instant application.

Preferably the structure involved in the circuit interrupter set forth in Figs. l-3 includes a main contact structure generally designated by the reference numeral 23, a blowout structure generally designated by the reference numeral 24 and a spaced slotted ceramic plate structure generally designated by the reference numeral II. In the closed circuit position of the interrupter, as shown in Fig., 1, the electric circuit therethrough includes a conducting terminal stud. 25 extending through an insulating terminal bushing 2'I. The terminal stud 26 is electrically connected, as by a thread connection, to a main stationary contact plate 23.V The lower end of the contact plate 28 forms a main stationary contact 29, which is contacted, in the closed circuit position, by a conducting bridging member 30, the lower end 3| of which makes engagement with a second main stationary contact 32.

Preferably, the second main stationary ccntact 32 is a portion ci' a second contact plate, not shown, which is eiectrically connected to the other terminal stud of the interrupter. not shown, as is well known by those skilled in theiart.

A rotatable Contact arm 33 carries the bridging member 36 upon studs 34, 35, compression springs t, 3l' being provided to obtain the requisite contact pressure in the closed circuit position. Associated with the plate 28 is an arcing contact structure 39 operable to establishan are 6 between the arcing contacts 4, 5 when separated. For purposes of illustration the arc 6 is shown in Fig. l even though the arcing contacts 5 are in the closed position. characters are made to correspond, as far as possible, with the reference characters already discussed in connection with Fig. 4.

Upon opening rotative movement of the contact arm 33 the arc G is initially established between the arcing contacts 4 and 5. Because of the loop circuit provided between the terminal studs the are 9 bows upwardly to contact rvthe arcing horn B and the arcing horn 9 to thereby cause the insertion into series circuit of the heavy winding blowout coil i5, more clearly shown in Fig. 3. Since the coil I9 is composed of a few turns, say two or three, it is quickly and easily transferred into series circuit.

The energization of the heavy winding blowout coil le causes a magnetic eid to build upv in the blowout structure 24, the magnetic field Also the reference 5. passing transversely through the plate structure II between the magnetic pole plates 39, 4t. The transverse magnetic iield 4I (Fig. 3) established between the pole plates 39, 46 reacts upon the arc I2 to move it upwardly and into engagement with the probe I3. It will be noted that a conductor I4 electrically connects the probe I3 with the relatively ne winding blowout coil I5 which is Wound around the b-ight portion I6 of the blowout structure 24. Preferably the tightly coupled coils I 0, I5 have substantially the same core area, with the entire ilux of coil Ii] passing through coil I5. Both coils I 0, I5 are wound about the same iron yoke I6 of the magnet frame.

The reference numeral 'l indicates the position of the arc when it initially strikes the probe I3. Thereafter, it is divided into two arc portions I3, 20 which respectively move upwardly into the plate portions I9, 2| of the plate structure II. The plate structure II consists of a plurality of spaced slotted ceramic plates 42 which do not evolve gas upon being subjected to the action of an electric arc. Each rectangularlyshaped plate 42 has a slot 43 formed therein, as more clearly shown in Fig. 2. The upper end of the slot 43 is off center, and the plates are alternately disposed so that the are is elongated laterally as it moves toward the upper ends of the several slots 43.

The magnetic field tI continues to move the arc portions l, 2li upwardly to effect their extinction in the closed ends of the slots 43. Preferably, the plates 42 are spaced a relatively short distance apart by insulating spacer strips 44. The aforesaid patent application may be referred to for the details of the plate structure II, as well as for the theory of arc extinction. It suffices here to state that the magnetic iield 4I set up by the energization of the relatively heavy winding blowout coil I eiects the extinction of the transfer arc i8 between the arcing horns 8, I3 within the portion 9 of the plate structure II. As previously mentioned the iiux produced by the coil Il! threads coil I and induces a voltage which appears at the probe i3 and is in such a direction as to maire the arc seek the horn I3.

The ready extinction of the arc portion I8 causes both coils I, I5 to be in series circuit and to cumulatively energize the blowout structure 24. The cumulative action readily moves the arc portion 28 upwardly into the plate structure 2I to eifect the extinction of the are 2U therein.

Although I have shown and described a specific structure, it will be clearly understood by those skilled in the art that changes and modifications may readily be made therein without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. Arc-extinguishing means including an interrupting section having a conducting probe disposed intermediate the ends thereof so that interrupting portions exist on both sides of the probe, means for establishing an arc, a magnetic circuit including magnetizable material for acting upon the arc, a pair of blowout coils shorted out in the closed circuit position of the interrupter and having substantially the same core area wound about the magnetizable material, one of the blowout coils having relatively few turns and the other having a greater number of turns, means for first inserting into series circuit the blowout coil of few turns, one end of the blowout coil of greater turns being connected to the conducting probe, and the established arc moving into the interrupting section into engagement with the probe to insert into series circuit both blowout coils.

2. 'A circuit interrupter including an interrupting section, a pair of stationary arc horns at opposite ends of the interrupting section, a probe disposed intermediate the ends of the interrupting section so that interrupting portions exist on both sides of the probe, means for establishing an arc, blowout means including a pair of blowout coils connected in series and shorted out in the closed circuit position of the interrupter, one of the arcing horns being connected intermediate the coils, and the probe being connected to the end of one of the coils, the arrangement functioning to successively insert the coils into series circuit with the transfer arc of the said one of the coils being interrupted in the portion of the interrupting section between the probe and said one of the arcing horns.

3. A circuit interrupter including an interrupting section, a pair of stationary arc horns at opposite ends of the interrupting section, a probe disposed intermediate the ends of the interrupting section so that interrupting portions exist on both sides of the probe, means including a pair of separable contacts for establishing an arc, blowout means including a pair of blowout coils connected in series and shorted out in the closed circuit position of the interrupter, one of the arcing horns being connected intermediate the coils, and the probe being connected to the end of one of the coils, one of the separable contacts being connected to the other end of the other of the coils, the other of the separable contacts being connected to the other arcing horn, the arrangement functioning to successively insert the coils into series circuit with the transfer arc of the said one of the coils being interrupted in the portion of the interrupting section between the probe and said one of the arcing horns.

fl. In a circuit interrupter, an interrupting section, means for establishing an arc, blowout means including a magnetic circuit composed in part of magnetizable material, a pair of blowout coils of substantially the same core area wound about the magnetizable material and shorted out in the closed circuit position of the interrupter, means for rst inserting into series circuit one of the blowout coils, a probe disposed in the interrupting section intermediate the ends thereof so that interrupting portions exist on both sides of the probe, the probe being connected to the end of the other of the two blowout coils, and one of said portions of the interrupting section, one end of which is defined by the probe, serving as a transfer arc interrupting section to facilitate the insertion of the said other of the two blowout coils.

5. In a circuit interrupter, an interrupting section, means for establishing an arc, blowout means including a magnetic circuit composed in part of magnetizable material, a pair of blowout coils of substantially the same core area wound about the magnetizable material and shorted out in the closed circuit position of the interrupter, means for first inserting into series circuit one of the blowout coils, a probe disposed in the interrupting section intermediate the ends thereof so that interrupting portions exist on both sides of the probe, the probe being connected to the end of the other of the two blowout coils, one of said portions of the interrupting section, one end of which is defined by the probe, serving as a transfer arc interrupting section to facilitate the insertion of the said other of the-two blowout coils, and said one of the blowout coils having relatively few turns and the other of the blowout coils having more turns.

6. A circuit interruptor including an interrupting section, a pair of stationary arc horns at opposite ends of theA interrupting section, a probe disposed intermediate the ends of the interrupting section, means for establishing an arc, blowout means including a pair of tightly coupled blowout coils connected in series and shorted out in the closed circuit position of the interrupter, one of the arcing horns being connected inter'- mediate the coils, the probe being connected to the end of one of the coils, the arrangement functioning to successively insert the coils into series circuit with the transfer arc of the said one of the coils being interruptedfin the portion of'. the interrupting section between the probe and saidone of the arcing horns, and said one of the blowout coils having more turns than the other of the blowout coils.

7. A circuit inteirupter including anV interrupting section, a pair ofV stationary arc horns at opposite ends of the interrupting section, a probe disposed intermediate the ends of the interrupting section, means including a pair of separable contacts for establishing an arc, blowout means including a pair of tightly coupled blowout coils connected in series and shorted out in the closed circuit position of the interruptor, one of the arcing horns being connected intermediate the coils, and the probe being connected to the end of one of the coils, one of the separable contacts being connected to the other end of the other of the coils, the other of the separable contacts being connected to the other arcing horn, the arrangement functioning to successively insert the coils into series circuit with the transfer arc of the said one of the coils being interrupted in the portion of the interrupting section between the probe and said one of the arcing horns, and said one of the blowout coils having more turns than the other of the blowout coils.

8. A circuit interruptor including means for establishing an arc, arc-extinguishing means including an arc chute composed mainly of insulating material including a plurality of spaced insulating portions against the edges of which the arc is forced, a conducting probe disposed intermediate tlie ends of the arc chute so that insulating portions exist on both sides of the probe, a magnetic circuit including magnetizable material for acting upon the arc, a pair of blowout coils shorted out in the closed circuit posiy tion of the interrupter and having substantially the same core area wound about the magnetizable material, one of the blowout coils having relatively few turns and the other having a greater number of turns, means for first inserting into series circuit the blowout coil of few turns, one end of the blowout coil of greater turns being connected to the conducting probe, and the established arc moving into the arc chute into engagement with the-probe to insert into series circuit both blowout coils.

9. A circuit interrupter including means for establishing an arc, arc-extinguishing means including an arc chute composed mainly of insulating material including a plurality of spaced insulating portions against the edges of which the arc is forced, a pair of stationary arc horns disposed at opposite ends of the arc chute, a conducting probe disposed intermediate the ends ci the arc chute so that insulating portions exist Cfl on both sides of the probe, blowout means including a pair of blowout coils connected in series and shorted out in the closed circuit position of the interrupter, one of the arcing horns being connected intermediate the coils, and the probe being connected to the end of one of the coils, the arrangement functioning to successively insert the coils into series circuit with the transfer arc of the said one of the coils being interrupted in the insulating portion of the arc chute between the probe and said one of the arcing horns.

10. A circuit interrupter including a pair of separable contacts for establishing an arc, arcextinguishing means including an arc chute composed mainly of insulating material including a plurality of spaced insulating portions against the edges of which the arc is forced, a conducting probe disposed intermediate the ends of the arc chute so that insulating portions exist on both sides of the probe, a pair of stationary arc horns at opposite ends of the arc chute, blowout means including a pair of blowout coils connected in series and shorted out in the closed circuit position of the interrupter, one of the arcing horns being connected intermediate the coils, the probe being connected to the end of one of the coils, one of the separable contacts being connected to the other end of the other of the coils, the other of the separable contacts being connected to the other arcing horn, the arrangement functioning to successively insert the coils into series circuit with the transfer arc of said one of the coils being interrupted in the portion of the arc chute between the probe and said one of the arcing horns.

1l. A circuit interrupter including means for establishing an arc, arc-extinguishing means including an arc chute composed mainly or" insulating material including a plurality of spaced insulating portions against the edges of which the arc is forced, a conducting probe disposed intermediate the ends of the arc chute so that insulating portions exist on both sides of the probe, blowout means including a magnetic circuit cornposed in part of magnetizable material, a pair of blowout coils of substantially the same core area wound about the magnetizable material and shorted out in the closed circuit position of the interruptor, means for first inserting into series circuit one of the blowout coils, said probe connected to the end of the other of the two blowout coils, and a portion of the arc chute, one end of which is dened by the probe, serving as a transfer arc interrupting section to facilitate the insertion of the said other oi the two blowout coils.

12. A circuit interruptor including means for establishing an arc, arc-extinguishing means including an arc chute composed mainly of insulating material including a plurality of spaced insulating portions against the edges of which the' arc is forced, a conducting probe disposed intermediate the ends of the arc chute so that insulating portions exist on both sides of the probe, blowout means including a magnetic circuit composed in part oi magnetizable material, a pair of blowout coils of substantially the same core area wound about the magnetizable mate-- rial and shorted out in the closed circuit position of the interrupter, means for first inserting into series circuit one of the blowout coils, said probe connected to the end of the other of the two blowout coils, and a portion of the arc chute, one end of which is defined by the probe, serving as a transfer arc interrupting section to facilitate the insertion of the said other of the two blowout coils, and s-aid one of the blowout coils having relatively few turns and the other of the blowout coils having more turns.

13.A circuit interrupter including means for establishing an arc, arc-extinguishing means including an arc chute composed mainly of in sulating material including a plurality of spaced insulatingkportions against the edges of which the arc is forced, a conducting probe disposed intermediate the ends of the arc chute so that insulating portions exist on both sides of the probe, a pair of stationary arc horns at opposite ends of the arc chute, blowout means including a pair of tightly coupled blowout coils connected in series and shorted out in the closed circuitposition of the interrupter, one of the arcing horns being connected intermediate the coils, the probe being connected to the end of one of the coils, the arrangement functioning to successively insert the coils into series circuit with the transfer arc of the said one of the coils being interrupted in the portion of the arc chute between the probe and said one of the arcing horns, and said one of the blowout coils having more turns than the other of the blowout coils.

14. A circuit interrupter including a pair of separable contacts for establishing an arc, arcextinguishing means including an arc chute composedmainly of insulating material including a plurality of spaced insulating portions against the edges of which the arc is forced, a conducting probe disposed intermedi-ate the ends of the arc chute so that insulating portions exist on both sides of the probe, a pair of stationary arc horns at opposite ends of the arc chute, blowout means including a pair of tightly coupled blowl0 out coils connected in series and shorted out in the closed circuit position of the interrupter, one of the arcing horns being connected intermediate the coils, the probe being connected to the end of one of the coils, one of the separable contacts being connected to the other end of the other of the REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 967,280 White Aug. 16, 1910 1,533,251 Johnston Apr. 14, 1925 1,713,229 Hewlett May 14, 1929 1,796,160 Paul Mar. 10, 1931 1,872,387 Baker et al Aug. 16, 1932 2,442,199 Dickinson et a1. May 25, 1948 2,451,669 Eichenberger Oct. 19, 1948 FOREIGN PATENTS Number Country Date 285,774 Germany July 13, 1915 588,261 France Jan. 28, 1925 860,510 France Sept. 30, 1940 560,257 Great Britain Mar. 28, 1944

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