US2419434A - Electric circuit interrupter - Google Patents

Description

April 22, l947- f G. L. BARCUS ETAL 2,419,434

ELECTRIC CIRCUIT ITERRUPTER Filed April 24, 1945 Figl.

Patented Apr. 22, 1947 UNITED STATES PATENT OFFICE ELECTRIC CIRCUIT INTERRUPTER George L. Barcus, Drexel Hill, and Alexander C. Boisseau, Lansdowne, Pa., assignors to General Electric Company, a corporation of New York Application April 24, 1945, Serial No. 590,014

(Cl. ZOO- 148) Claims.

Our invention relates to electric circuit interrupters, and more particularly to electric circuit interrupters employing a blast of gas such as air or other fluid to extinguish the arc drawn between the separable contacts.

Gas blast circuit breakers which have been extensively used in recent years generally are of two kinds, the so-called cross blast breaker and the axial blast breaker. The cross blast breaker is typified by the disclosure of United States Letters Patent 2,284,842, Prince et al., assigned to the same assignee as the present application, while the axial blast breaker is typied by Rankin Patent 2,306,186, granted December 22, 1942, and assigned to the same assignee as the present application. The axial blast breaker lends itself very well for high voltage outdoor application, but the current limit of an axial blast breaker is relatively low compared to that of a cross gas blast breaker. It would be desirable to provide a gas blast circuit breaker with the high current interrupting ability of the cross gas blast breaker and the high voltage capacity of an axial blast breaker.

Accordingly, it is an object of our invention to provide a new and improved fluid blast circuit interrupter of the gas blast type.

It is another object of our invention to provide a high voltage gas blast circuit breaker oi the cross gas blast type in which better voltage insulation by virtue of long creepage paths is provided, than prior arrangements used heretofore and yet wherein much higher currents may be interrupted than in high voltage circuit breakers used heretofore.

It is another object of our invention to provide a new and improved arc extinguishing structure for a iiuid or gas blast circuit interrupter.

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

vFor a better understanding of our invention reference may be had to the accompanying drawing in which Fig. 1 is an elevational view of an electric circuit interrupter embodying our invention; Fig. 2 is a sectional view of the circuit interrupter taken on line 2-2 of Fig. 1 but omit-A ting the supporting structure for the arc extinguishing unit; Fig. 3 is a sectional view taken on line 3--3 of Fig. 2 of the portion of a circuit interrupter adjacent the relatively movable contacts but showing the contacts in the open position; Fig. 4 is a sectional view taken on line 4-4 of Fig. 3 assuming that Fig. 3 is complete; Fig. 5 is a sectional view taken on line 5-5 of Fig. 3; Fig. 6 is a sectional View taken on line 6-6 of Fig. 3, and Fig. 7 is a perspective view of a portion of one of the insulating tubes used in our invention to illustrate a modiiication of our invention.

Referring now to Fig. 1 of the drawing, there is illustrated an electric circuit breaker generally indicated at I comprising an are extinguishing 0r circuit interrupting unit generally indicated at 2. It will be understood that our invention is applicable either to a single phase or a polyphase circuit breaker and the number of arc extinguishing units 2 will be determined by how many phase conductors the circuit breaker controls. Each interrupting unit 2 includes a pair of relatively separable arcing contacts 3 and 4, best shown in Figs. 2 and 3. Each set of arcing or interrupting contacts is serially connected with a set of isolating contacts comprising the movable contact arm 5 which engages with a stationary contact 6.

The interrupting unit 2 is supported from a framework generally indicated at l by a tripod arrangement of insulators designated at 8. Isolating contact arm 5 is pivotally mounted on a horizontal pivot 9 which is suitably supported from interrupting unit 2 and arm 5 is preierably gear driven from a rotatable insulator I0. Stationary contact 6 is also supported on a suitable insulator II from framework l and is electrically connected to a line terminal I2. .The other line terminal of the circuit interrupter I is indicated at I3 on the drawing.

Suspended from the supporting framework 1 is a tank I4 adapted to contain a source of iluid under pressure, such as air or other gas. This tank, or source of air, is connected to interrupting unit 2 through an insulated conduit I5 and the flow is controlled by a suitable blast valve (not shown). The means for rotating insulator I0, and consequently operating isolating arm 5, is also not shown but may comprise a suitable ilud motor. If desired, the general arrangement of circuit breaker I may be like that disclosed in copending Boisseau et al. application, Serial No. 565,834, filed November 30, 1944, and assigned to the same assignee as the present application.

Our invention is particularly concerned with interrupting unit 2 which preferably comprises an insulating chamber I6 of generally cylindrical configuration, formed of a material which will withstand the weather such as porcelain or the like. Cylindrical chamber I6 is suitably supported on a base I'I which in turn is supported by the tripod arrangement of insulators 8. Mounted within chamber I6 are relatively movable or separable interrupting contacts 3 and 4. Contact 4 is generally indicated as a stationary contact and is fastened by a suitable means indicated at I8 to cylinder I3 with a portion thereof extending outside of cylinder I8 and electrically connected by conductor I9 to disconnecting or isolating arm 5. Contact 3, when in engagement with contact 4 as shown in Fig. 2, extends entirely across arcing chamber IS and is movable in a path substantially perpendicular to the axis of chamber IB whereupon the arc drawn between relatively separable contacts 3 and 4 extends in a direction substantially perpendicular to the axis of chamber I6.

In order to produce relative separation or contacts 3 and 4 we have provided a fluid motor generally indicated at 26 comprising a cylinder 2| and a piston 22 reciprocal therein. Cylinder 2i is supported from chamber IE exteriorly thereof and the axis oi cylinder 2l intersects the axis of chamber i3 at substantially a right angle. Piston 22 is connected to movable contact 3 and is provided with a fairly long skirt so as to guide movable contact 3 in its movement in arcing chamber I3. Preferably movable contact 3 is biased to the closed position in engagement with stationary contact 4 as indicated in Fig. 2, by means of a compression spring 23. In the open position of the arcing contacts 3 and i piston 22 assumes the dotted position shown in Fig. 2. When fluid under pressure is admitted to arcing chamber I6 through conduit I5, it is admitted in a direction substantially parallel to the axis oi chamber I6 and perpendicular to the arc drawn between contacts 3 and 4. For this reason the term cross blast appropriately applies to this breaker'. When fluid under pressure is admitted to arcing chamber IG, it is also admitted to cylinder 2l of iluid motor 23 with the consequent relative separation of interrupting contacts 3 and 4.

In well known forms of cross blast circuit breakers employed heretofore an arc chute was usually provided including partitions or baiiie members which were arranged with their transverse edges closely adjacent to the arc drawn and generally perpendicular thereto. This arrangement has been found very satisfactory for interrupting currents of high value. However, in the constructions used heretofore the arc chute usually comprised a box-like structure with various walls joined together in a suitable manner. To make a fairly gas-tight structure, complicated machine grooving of the chute walls as well as sealing and tie bolting was required.

In accordance with our invention we provide an arc-extinguishing structure comprising a plurality of tubes of gas evolving insulating material 24, 25 and 23. |These tubes of insulating material have varied diameters so that they may be disposed in spaced concentric relationship or, in other words, nested together. The diameters are such that when the axes of the tubes 24, 25 and 2B coincide a cylindrical opening or space is defined between each adjacent pair of tubes. Preferably these tubes 24, 25 and 25 are formed from a gas evolving, insulating material such as horn fiber, methyl methacrylate, cr the like.

In order that the arc extinguishing structure comprising tubes E4, 25 and 25 may extend some istance below interrupting contacts 3 and 4, the walls of the tubes adjacent fluid motor 2li-are vlndrical chamber IS and tube largest diameter of the tubes. ibstantially semi-cylindrical spacer memare disposed between tubes 24 and 25, the smallest substantially semi-cylindrical spacer members are disposed between tubes 2t: nylr "fj u aal. Lu.

SSD C ci the same insulating material as and 23 and extend below interrupt the same distance as tubes Preferably they extend above con- :l a short distance which may be distance which they extend below contacts. The spacer members 33, 34 and 'he tubes 212, and E6 are suitably joined egs or cement into a unitary assembly whicl. may be supported in arcing chamber I 6 any suitable manner.

oi the and spacer members described above a plurality or nozzles 33, 3l and 38 are defined in the ieV -hand portion oi the structure as viewed in rig. 6 on the upper side of interrupting contacts Similarly, a plurality of c and 4. slot-like exhaust nozzles 33, 4G and 4I are defined in the right-hand portion of the interrupting structure of Fig. 6 on the upper side of interrupting contacts 3 and 4. On the lower side of contacts 3 and slot- like entrance nozzles 42, 43 and 44 are provided only on the right-hand portion ci' the interrupting structure as is clearly evident from o. Above the exhaust nozzles through 4I, inclusive, the arc gases are free to move through the cylindrical spaces defined by tubes 24, 25 and 23 and arcing chamber I6 and these gases will be cooled by intimate contact with the conning walls which extract heat from the arc by virtue of the surface vaporization that s set up by the arc heat. Preferably the tubes extend upwardly a considerable distance in the direction toward which the gases exhaust to cool the exhaust gases.

The cylindrical arc extinguishing structure described above is very well suited to withstand high internal pressures and it is apparent that very long creepage paths are provided thereby providing excellent voltage insulation so that the circuit breaker is adapted for higher voltage applications, while at the same time being capable of interrupting very high currents.

In cross blast arc chutes for electric circuit breakers employing a plurality of partitions or barriers, it is known that the arc erosion and gas generation is most severe at the barriers nearest to the point of contact separation or, in other words, nearest to the stationary contact in the construcion described above. It is apparent that with the arc extinguishing structure which we have disclosed, the cylindrical exhaust spaces are most extensive nearest the stationary contact where most needed and become successively less extensive within the smaller diameter inner tube 26 where the arcing 'eb These spacer members are prefer-Y be observed that with the arrangement feet appreciably diminishes. It is obvious then, that our construction inherently takes care of the known condition of maximum arc erosion and gas generation at the point of contact separation.

In order to prevent rain or snow from entering the upper end of arcing chamber i6 which is open to atmosphere, a suitable hood 45 is preferably provided. It should also be understood that to prevent flame emission from space 4E within tube 26 and the concentric cylindrical exhaust spaces designated at 41, 4% and 49 in Fig. 3, that any well known muffler arrangement may be utilized. Such muiller arrangements are disclosed in Bauerschmidt Patent 2,216,583, Linde Patent 2,272,214 or Rankin Patent 2,272,224, all assigned to the same assignee as the present application.

We have found that very excelient interrupting operation is obtained with a symmetrically constructed arc extinguishing structure in which the tubes such as 24, 25 and 26 are provided with diametrically opposed notches. Cin Fig. 7 we have illustrated in a perspective View a portion of a tube 58 which corresponds to the tube 24 described above. This tube is provided with J- shaped notches l and 52 which are identical and diametrically opposed. Such a symmetrical design has an advantage in that, as was mentioned above, the erosion occurs primarily near the stationary contact. Consequently, after an arc extinguishing structure has been eroded to the extent that it requires replacement, it can be restored to its original operating condition for all practical purposes merely by rotating it 180 in chamber I6.

When a blast of fluid such as air under pressure is supplied to chamber I relative separation of contacts 3 and 4 is caused and an arc is drawn therebetween. The blast of fluid under pressure causes successive portions of the arc to be looped in the slot-like passages or nozzles 36 through 4l, inclusive, from which the arc products fan out into the narrow cylindrical spaces 41, 48 and 49 between the concentric tubes which project above the substantially solid nested portion, clearly obvious from Fig. 4, and the gases evolved of the walls of the tubes will aid in rapidly extinguishing the arc.

While We have shown and described a particular embodiment of our invention, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from our invention in its broader aspects and We, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of our invention.

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

1. In a cross blast circuit interrupter, a chamber, a plurality of tubes of gas evolving insulating material of different diameters nested in said chamber to form spaces therebetween and having diametrically aligned openings in the walls thereof adjacent one end constituting a transverse arc passage therethrough, a contact in said chamber positioned adjacent the outer tube wall at one end of said passage, a cooperating contact reciprocable within said passage for drawing an arc therein, means for causing a longitudinal flow of pressure gas through said spaces from the end of said nested tubes adjacent said contacts to effect an arc extinguishing blast across said passage, and means for channeling said longitudinal flow of gas within said spaces through a plurality of slot-like nozzles for a short length of said tubes in the local region of said transverse arc passage.

2. In a cross blast circuit interrupter, a chamber, a plurality of tubes of gas evolving insulating material of different diameters nested in said chamber to form spaces therebetween and having diametrically aligned openings in the walls thereof adjacent one end constituting a transverse arc passage therethrough, each space having a larger volume than the adjacent inner space, a contact in said chamber positioned adjacent the outer tube wall at one end of said passage, a cooperating contact reciprocable within said passage for drawing an arc therein, means for causing a longitudinal iiow or" pressure gas through said spaces from the end of said nested tubes adjacent said contacts to effect a plurality of arc extinguishing blasts across said passage, and means for restricting for a short portion of the total length of said tubes in the local region of said transverse arc passage said longitudinal flow of gas through certain of said spaces to slotlike nozzles which are in communication with said transverse arc passage.

3. In a cross blast circuit interrupter, a chamber, a plurality of tubes of gas evolving insulating material of different diameters concentrically nested in said chamber to form spaces therebetween and having diametrically aligned openings in the walls thereof adjacent one end constituting a transverse arc passage therethrough, said aligned openings on one side of the common axis of said tubes being aligned holes and on the opposite side being aligned notches in the adjacent ends of the tubes, a contact in said chamber positioned adjacent the outer tube wall at the end of said passage adjacent said aligned holes, a cooperating contact movable through said passage for drawing an arc therein, means for causing a longitudinal now of pressure gas through said spaces from the end of said nested tubes adjacent said contacts to eifect a plurality of arc extinguishing blasts across said passage, means for restricting for a short portion of the total length or said tubes in the local region of said transverse arc passage the longitudinal flow of gas through said spaces to slot-like nozzles in communication with said transverse arc passage, and a fluid motor for moving said cooperating contact out of engagement with said stationary contact, said motor being in gas communication with said aligned notches and the adjacent slot-like passages.

4. In a cross blast circuit interrupter, a chamber, a, plurality of tubes of gas evolving insulating material of different diameters concentrically nested in said chamber to form spaces therebetween and having diametrically aligned openings in the walls thereof adjacent one end constituting a transverse arc passage therethrough, each space having a larger volume than 'the adjacent inner space, said aligned openings on one side of the common axis of said tubes being larger than those on the opposite side, a contact in said chamber positioned Aadjacent the outer tube wall at the end of said passage adjacent the smaller aligned openings, a cooperating contact movable through said passage for drawing an arc therein, means for causing a longitudinal flow of pressure gas through said spaces from the end of said nested tubes adjacent said contacts to effect a plurality of arc extinguishing blasts across said passage, means for restricting for a short portion of the total length of said tubes in the local region of said transverse arc passage the longitudinal ow of gas through said spaces to slot-like nozzles in communication with said transverse arc passage, and a fluid motor for moving said cooperating Contact out of engagement With said stationary Contact, said motor being in gas communication with said larger aligned openings and the adjacent slotelike passages.

5. ln a cross blast circuit interrupter, a chambei', a plurality of tubes of gas evolving insulating materiali of different diameters concentrically nested in said chamber to form spaces therebetween and having diametrically aligned identical openings in the Walls thereof adjacent one end constituting a transverse arc passage therethrough, each space having a larger volume than the adjacent inner space, a Contact in said charm ber positioned adjacent the outer tube wall at one end of said passage, a cooperating Contact reciprocable within said passage for drawing an arc therein, means for causing a longitudinal ilow of pressure gas through said spaces from the end of said nested tubes adjacent said contacts to eiect a plurality of arc extinguishing blasts across said passage, means for restricting for a short portion of the total length of said tubes in the local region of said transverse arc passage the longitudinal iloW of gas through said spaces to slot-like nozzles in communication with said transverse arc passages, and a fluid motor for moving said cooperating Contact out of engagement with said stationary Contact, said motor being in gas communication with said slot-like nozzles on the side of the common axis of said tubes opposite from said stationary contact.

GEORGE L. BARCUS. ALEXANDER C. BOISSEAU.

REFERENCES CITED The following references are of record in the rile of this patent:

UNITED STATES PATENTS 20 N umber- Name Date 2,156,663 Cole May 2, 1939 2,253,196 Paul Aug. 19, 1941

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