US2314292A - Electric arc-extinguishing apparatus - Google Patents

Description

March 16, 1943. o. c. TRAVER ELECTRIC ARC-EXTINGISHING APPARATUS Filed oct. 2, 194o` CLSSSSXSSX e .Tr-*avec y m.

Irverwtf @lh/er C Ala/)dy s His Attovrwey,

chute into which Patented Mar. 16, 1943 ELECTRIC Anc-Exmem'snmc APPARATUS Oliver C. Travel', Drexel Hill, Pa., to General Electric Company York a corporation of New Application october 2, 1940, serial No. 359,371

.'12 claims. (ciano-141i l My invention relates to electric arc-extinguishing apparatus having particular application to electric circuit-interrupting devices, such as circuit breakers, lightning arresters, and the like, of the magnetic blow-'out type employing an arc the arc is directed and extinguished. l

The use of insulating arc chutes in connection with interrupting electric currents is a wellknown and accepted practice. In general, the arc is forced into the arc chute by suitable means, such as a magnetic blow-out coil and is stretched and elongated, thereby increasingthe arc resistance until the arc is extinguished. In'the case of heavy currents, however, this method alone may be insuillcient for the arc may be blown entirely through they chute without being extinguished. f

In a more effective form of arc chute it has been proposed appreciably to elongate the Varc path within the chute by means of spaced interleaving ribs or ilns extending from the opposite walls of the chute so as to form a restricted 'tortuous passage, generally of zigzag form, for

the arc as it proceeds through the chute. The closely confining walls of this passage also extract heat from the arc stream, thereby increasing the resistance of the arc to a further extent and aiding in the interruption thereof.

It is an object of my invention to provide a new and improved arc-extinguishing apparatus of the aforesaid type in which the configuration of the arc passageway is such as'to increase the interrupting ability of the apparatus.

It is another object of my invention to provide.

a new and improved arc-extinguishing apparatus including a plurality of arc chutes serially arranged with respect to said arc.

Incircuit-interrupting devices of the prior art.

- arc chutes of the general type comprised interleaving fins which were evenly spaced and madel as plates or ribs' of uniform thickness projecting perpendicularly from the walls ofk the arc chute. Such a device is y shown, for example, United States LettersPatent No. 2,293,513, Linde, granted August 18, 1942,l and assigned to the same assigneev as the present application. It is recognized by those skilled'ln the artthat the circuitinterrupting ability of an arc-extinguishing device of the type'referred to above is increased when the heat transfer between the arc and the arc chute is increased and arrangements have been proposed for obtaining more extensive heat transfer between the arc andthe arc chute'. ySuch an arrangement is disclosed and extinguishing apparatus.

pose to provide a circuit-interrupting device iny Since arc chutes of the interleaving type may be constructed oi? fragile material, such as cfa ceramic nature, the probability of fracture would be relativelygreat, which might make the circuit-interrupting device practically useless in so far as its intended purpose is concerned. I prowhich the' probability of rendering the circuitinterrupting device useless by virtue of fracture of ther fragile arc chute is greatly decreased.

vide a new and improved circuit-interrupting device comprising a plurality of arc chutes and means for forcing the arc drawn into said chutes to extinguish the same rapidly. n

Still another object of my invention is to provide a new and improved electric circuit-interrupting device including a plurality of arc chutes and fluid-pressure generating means to force said arc into said arc chutes to extinguish the same rapidly.

Further objects and advantages of my invention will become apparent as the following description proceeds and the features of novelty which characterize my invention will'be `pointed out with particularity in the claims annexed to and forming a part of this speciilcation.

. For a better understanding of my invention, reference Lmay ber had to the accompanying drawing in which Fig. l is a schematic diagram partly in section of an electric circuit-interrupting device embodying my invention, Figs. 2 and 3 are complete sectional views taken respectively on lines 2-2 and 3 3 of Fig. 1, assuming Fig. 1 to be a complete view although actuallyL shown in section in the interest of clearness.v Fig. 4 is similarly a view only of the interleaving arc chute taken from line 1 4 of Fig. l, and Figs. 5 and 6 are sectional views taken respectively on lines 5-5 and 6--6 of Fig. land, except for being sectional views, are similar to Fig. 4.

Referring now to the drawing, I have illustrated my lnventionkspeciflcally as applied to an air circuit breaker of the magnetic blow-out type but lit will be understood by thoseskilled in the art that my invention is equally applicable to lighting arresters, and fluids other than air might also be used successfully. The circuit-interrupting device of Fig. 1 is illustrated as comprising a pair of relatively movable contacts II and I2 arranged in a suitable arc-extinguishing structure generally indicated at I3 and supported on suitable insulating means I 4 and I5, which means might, as illustrated, also serve to house the electrical connections leading from contacts and I2 to the associated power circuit, not shown. This circuit may preferably be connected to stationary contact II through a spirally arranged blow-out coil I6 which includes a magnetic core I1. For electrical and mechanical reasons, blow-out coil I6 is illustrated as comprising two spiral portions I6' and I6" separated by an insulating barrier I8 (Figs. 2 and 3), whereby both the terminals thereof are on the outside of the spiral. For the purpose of simplifying the disclosure, the insulation around blow-out coil I 6 has not been shown but it will, of course, be understood by those skilled in the art that such insulation will be provided and, furthermore, the cross section of this blow-out coil will be determined by the amount of current to be carried thereby.

Movable contact I2 may be connected to the other terminal of the circuit-interrupting device in any well-known manner. Also, any suitable means, such as the solenoid shown, may be provided for operating contact I2, and, consequently, producing relative movement between contacts I I and I2. In the event that the arc-extinguishing device of my invention is to be used as a lightning arrester, it will be understood that contacts I| and I2 will be permanently separated to form a gap across which an arc will be formed upon the occurrence of a lightning surge and, consequently, means for producing relative movement between contacts II and I2 will notbe re quired.

The arc-extinguishing structure, generally indicated at I3, comprises a pair of disk-shaped plates I9 and 20, Figs. 2 and 3, mounted parallel with one another and between which are'supported the arc chutes to be described hereinafter. These plates engage respectively the ends of magnetic core I1. A plurality of arc chutes 2| are supported between disk-shaped plates I! and and, as illustrated in Fig. 1, are circumferentially arranged around blow-out coil II. Preferably, suitable insulating members 22, Figs. 2 and 3, separate disk-shaped plates I9 and 20 from the arc chutes 2| which they support. The arc chutes 2| are spaced from one another by means of triangular inserts 23, 2l, 25, and 23, which are'formed of a. suitable insulating material with the inner edges thereof, 23', 24', 25', and 26', respectively, adjacent the arc drawn in arc-extinguishing structure I3 being formed of an insulating material of a type preferably composed of a gas-evolving or gas-emitting substance, such as horn ber or the like, so as to produce an arc-extinguishing gas when subjected to the heat and other action of the arc. 'I'hese arc chutes 2| are preferably constructed `of a ceramic material and, as illustrated, may be sup ported so as to form a strong unitary structure by being keyed to triangular inserts 23, 2l, 25, and 26, as indicated at 21 so as to provide a cylindrical structure with the arc chutes 2| arranged around the circumference thereof suitably spaced from one another by virtue of the triangular inserts 23 to 2B. It will be obvious that, by this arrangement, any one of the fragile are chutes 2| of ceramic material might be replaced in the event that it should break, thereby considerably reducing the cost of repair. Furthermore, the fact that one of the arc chutes I1 was broken would not render the circuit-interrupting device useless as the remaining arc chutes would interrupt the arc with somewhat decreased emciency.

I have illustrated the arc chutes 2| as all identical in structure but the inserts 23, 2l, 25, and 2B are diil'erent in that the inserts designated by the higher numerals are larger and extend farther into the cylindrical arc-extinguishing structure I3 so that the arc is forced into more intimate contact with the gas-evolving portions 23', 24', 25', and 26' thereof as it is extended in length. Incidentally, these gasevolvingportions 23', 24', 25', and 2l' should preferably be replaceable as will be understood by those skilled in the art.

A suitable arc runner 2l is circumferentially arranged within the arc-extinguishing structure I3 in such a manner that, as the arc travels along the arc runner by virtue of the magnetic forces produced by blow-out coil I3, it is forced into more and more intimate contact with the gasevolving material 23', 2l', 2l', and 23', respectively.

In order that a suitable fluid blast may be provided to aid blow-out coil I3 in forcing the arc into arc chutes 2|, the walls of the cylindrical arc-extinguishing structure between arc runner 23 and arc chutes 2| are each preferably covered with a layer of gas-evolving insulating material 29. This gas-evolving material is illustrated in Fig. 1 as being suitably keyed at 35 at one end thereof to one of the arc chutes 2| while, at the other end thereof, it is keyed at 3| to triangular insert 23. It will be obvious to those skilled in the art that, instead of keying arrangements 21, 30, and 3|, illustrated in Fig. 1, any other fastening means may be utilized which provide a structure suillciently strong to withstand the forces involved. It will be observed that the arc chutes 2i, inserts 23, 2l, 25. and 23, and gasevolving material 23 are keyed together as a unitary structure which is further supported by plates I! and 2l.

The two layers of gas-emitting insulating ma teriai 20 are separated sufficiently to define a space 32 therebetween, Figs. 2 and 3, for the are, which space leads to the entrances 33, Figs. 1 and 6, of arc chutes 2|. This space will be proportioned so as not to impede the arc in its movement into are chutes 2| and yet so that sumcient gas is evolved from the gas-emitting insulating material 29 so that a blast of huid under pressure aids the blow-out coil I3 in forcing the are into arc chutes 2| In order to decrease the possibility of restriking of the arc, I may provide means for displacing the ionized air adjacent contacts II and I2 during a circuit-interrupting operation and replacing it with un-ionized air. In the drawing. I have illustrated an arcuate recess Il cut in each of the gas-evolving insulating members 23 to ac commodate a movable vane 35 which is integrally connected with the means for operating movable contact I2. The vane 35 and movable contact I2 are shown dotted in Fig. 1 in the positions which they assume when the circuit breaker is open.

Each of the arc chutes 2| is arcuate in shape and comprises a pair of plates preferably composed of arc-resisting material, such as. for. example, an asbestos compound or a suitable arcresisting ceramic material. Each wall of the chute is provided with a plurality of radially extending rib-like fins or ridges IB and 31, respectively,and those ridges 38 and 31 are preferably integral with the side walls of the arc chutes 2|. As best shown in Figs. 4 and 5, these ridges or fins are saw-toothed in shape kand the projection of the fin is a maximum at the outer circumference of the circuit breaker structure I3 and chute 2i. The ridges of the two parallel plates comprising arc chutes 2i are yso arranged with respect to each other as to be interleaved when the plates are in position, as shown in Fig. 2,

so as to form a zigzag passage 33", as shown in Fig. 4. This passage increases in length with respect to the are as the arc is driven farther and farther i-nto the chute, the chute being constructed so that, at the entrance thereof, the passage 33, see Fig. 6, is relatively short, and which increases in length while traversing the chute. In Fig. 5, the passage 33 is shown as longer than the passage 33 of Fig. 6 but shorter than the passage 33 of Fig. 4. Furthermore, in accordance with my invention, the interleaving barriers or ridges 36 and 31 are gradually and progressively thickened vfrom the inner edge of arc chute 2i to the outer edge thereof to effect a gradual squeezing of the arc along its whole length, thereby forcing the arc into more intimate contact with the arc chute, consequently i-ncreasing the heat transfer and aiding the interruption thereof. The arrangement is preferably such that the product of the length and the width of the arc path at the entrance of the arc chute is substantially equal to this product at the exhaust extremity of the arc chute.

The operation of my improved circuit-interrupting device will now be described with refer-y 1ence to Fig. l. When relative movement between contactsril and I2 is produced, an arc is drawn increasing its lengthand, consequently,'also the arc resistance.,y The are also coming in contactv with gas-'emitting 'material- 2 3 causes gas to be evolved whichids .theblowout coil' Il in forcing the arc intof the entrance: passage, Fig. 6, of arc chutes 2 The arcalsojciirig into intimate contact-wlthfthepcrtions 23', 24', 2,5', and 26 formed of gasevolvingmaterial produces a fluid under relatively highpre'ssure which exhausts through 'theiarc chutes 2i as a fluid blast forcing the arcwithJit. As the arc moves through thevarc ;,chutes;2|;; which. are serially arranged witli'respectf to fthe arc, the' arc path continuouslylengthensv in view of the radially extending ribs or iins 36 and 31, providing a zigzag path transverse to thenormal direction of arc expansion. Since the ribs 36 and 31 are gradually thickened toward the outer circumference of the arcuate-shaped arc chutes 2i, the cross section of the arc path is'gradu'ally decreased and the arc is squeezed 'vinto more and more intimate contact with the arc chutes sofas to be cooled and, consequently, extinguished in a very short space of time.

Although my invention also inherently ernbodies the unbalanced magnetic interaction of the magnetic forces on the arc so as to force the dwindles down to zero at the inner edge of arc arc against the portions of the are chute, this reature is broadly claimed in the above-mentioned yBoehne patent.

It shouldbe understood that my invention is not limited`to the specific construction and arrangement herein illustrated and that changes and modifications may occur to those skilled in the art without departing from the spirit and scope of my invention. I, therefore, aim in the appended claims to cover all such changes and modications. f

What I claim as new and desire to secure by Letters Patent of the United States is:

l. In an electric arc-extinguishing apparatus comprising an insulating arc chute into which the arc to be interrupted is directed yhaving side walls disposed in closely spaced parallel relationship so as to form a narrow arc space therebetween, saidwalls on the sides facing each other having thereon in projecting relation interleaving ridges extending substantially transversel'y of the pathof said arc, the ridges of one wall being spaced with respect to the interleaving ridges of said other wall and said ridges being so shaped anddisposed as to provide for the arc a continuously lengthening path between said side walls which is zigzag transversely to the normal direction of arc expansion, said ridges being progressively thickened in the direction of arc expansion to effect a gradual squeezing of the arc along its whole length to force it into more intimate contact withsaid arc chute to cool the same rapidly. f y y 2. In an electric circuit-interrupting device, the combination of an insulating arc chute into which the arc to be interruptedis adapted to be directed having side walls disposed in closely spaced parallel relationshipy so as to form a narrow arc space therebetween, said walls on the sides facing each other having-thereon a plurality of ribs, said ribs being so shaped and disposed and so interleaved with each other as to provide for the arc a continuously lengthening path between said side walls which is zigzag transversely to the normal direction of arcy expension, the transverse spacing between said ribs decreasing in said direction of are expansion to eect a gradual squeezingof the arc to force vit into more intimate contact with said arc chute 4lio/'and means including gas evolving insulating material mounted adjacent the entrance to said arc chute so that when subjected to the heat of said arc gases are evolved which drive the are into said arc chute to extinguish the same.

3. In an electric circuit-interrupting device, the combination of an insulating are chute into which the arc to be interrupted is directed having side walls disposed in closed spaced parallel relationship so as to form a narrow are space therem between, said walls on the sides facing each other having thereon a plurality of saw-tooth shaped f ridges. said ridges being so disposed and so interleaved with each other as to provide for the arc a continuously' lengthening path between said side walls which is zigzag transversely to the normal direction of arer expansion, said sawtooth shaped ridges being progressively thiclb` ened in the direction of arc expansion to eiect a gradual squeezing of the arc thereby to increase the heat transfer to said arc chute.

4. In anelectric circuit interrupter including means between which an electric arc is adapted to be formed, an arc-extinguishing structure comprising a plurality of arc chutes alternately arranged between sections of gas-evolving insulating material and serially arranged with respect to said arc, magnetic means for forcing said arc into said arc chutes and against said gas-evolving insulating material, said arc chutes each comprising a pair of parallel plates having rib-like projections of insulating material, magnetic means for forcing said arc into said arc chutes, a gas-evolving insulating material being disposed adjacent the entrances to said arc chutes so that gas under pressure is produced when said arc acts on said gas-evolving material to aid said magnetic means in forcing said arc into said arc chutes, each oi said arc chutes comprising a pair of parallel plates having the adjacent faces thereof serrated,

the serrations being so disposed as to be interleaved with each other so as to provide a continuously lengthening path for said arc which is zigzag transversely to the normal direction of arc expansion.

6. In an electric circuit interrupter including means between which an electric arc is adapted to be formed, an arc-extinguishing structure comprising a plurality of arc chutes spaced from one another by sections of insulating material, magnetic means for forcing said arc into said arc chutes, said arc chutes each comprising a pair of parallel plates having the adjacent faces thereof serrated, the serrations being so disposed as to be interleaved with each other so as to provide a continuously lengthening path for said arc which is zigzag transversely to the normal direc tion of arc expansion, said serrations being progressively thickened in the direction of arc expansion to eilect a gradual squeezing of the arc thereby to increase the heat transfer to said arc chute.

7. In an electric circuit-interrupting device, the combination of an insulating arc chute into which the arc to be interrupted is adapted to be directed having side walls disposed in closely spacedrelationship so as to form a narrow arc space there between, said walls on the sides facing each other being so disposed as to provide for the arc a continuously lengthening path between said side walls,

the spacing be'tween said walls progressively decreasing in the direction of arc expansion to effect a gradual squeezing of the arc to force it progressively into more intimate contact with said arc chute and means including gas evolving insulating material mounted adjacent the entrance to said arc chute so that when subjected to the heat of said arc gases are evolved which drive the arc into said arc chute to extinguish the same.

8. In an electric circuit-interrupting device, the

combination of an insulating arc chute into which the arc to be interrupted is directed having side walls disposed in closely spaced relationship so as to form a narrow arc space therebetween, said walls on the sides facing each other being so disposed as to provide for the arc a continuously lengthening path between said side walls, the spacing between said walls progressively decreasing in the direction of arc expansion to ei'iect a gradual squeezing of the arc to force it progressively into more intimate contact with saidv arc chute, the product of the length and the width of the arc space between said side walls at the exhaust extremity of said chute being of substantially the same order as the product of the length and the width of the arc space at the entrance to said arc chute.

9. In an electric circuit interrupter including means between which an electric arc is adapted to be formed, an arc-extinguishing structure comprising an arc chute arranged between sections of gas-evolving insulating material, and means for moving said arc to the entrance of said arc chute and into active proximity to said gasevolving insulating material so that gases are evolved therefrom which drive the arc into said arc chute to interrupt the same.

l0. In an electric circuit interrupter including means between which an electric arc is adapted to be formed, an arc-extinguishing structure oomprising a plurality of arc chutes alternately positioned between sections oi gas-evolving insulating material, and means for moving said arc to the entrance of said arc chute and into active proximity to said gas-evolving insulating material so that gases are evolved therefrom which drive the arc into said arc chutes to interrupt the same.

1l. In an electric circuit interrupter including means between which an electric arc is adapted to be formed, a circular blow-out means, an arcextinguishing structure comprising a plurality of arc chutes arranged in an arcuate form about said circular blow-out means which is common t all ot said arc chutes, a plurality of sections of gas-evolving insulating material alternately arranged with said arc chutes around said circular blow-out means, means i'or moving said arc to the entrance of said arc chute and into active proximity to said gas-evolving insulating material so that the gases evolved are exhausted through said chute to drive said arc into said chute for arc-extinguishing purposes.

12. In an electric circuit interrupter including means between which an electric arc is adapted to be formed, an arc extinguishing structure comprising an arc chute constructed chieily of refractory material but including a minor amount of gas evolving insulating material located in the regionof the entrance to said arc chute, and means for moving said arc to the entrance of said arc chute and into active proximity to said gas evolving insulating material so that gases are evolved therefrom to assist in driving said arc into said chute to extinguish the same.

OLIVER C.

Images