US2667555A - Blast diffusing means for electric circuit breakers of the fluid-blast type - Google Patents

Description

fan. 26, 195% J. w. BEATTY ET AL Z,6@79555 BLAST DIFFUSING MEANS FOR ELECTRIC CIRCUIT BREAKERS OF THE FLUID-BLAST TYPE Filed May 21, 1952 2 Sheets-Sheet l Fl k. a g

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John W Beatt Haw-old N. Schneidev;

J. W. B TTY ET AL FFUSING ME FOR ELECTRIC CIRCUIT AKERS OF THE FLUID-BLAST TYPE Jan. 26, 1954 BLAST DI BRE -2 Sheets-Sheet 2 Filed May 21, 1952 w H stw om w t e P O o B o. n .s m ew v .m d e mm o /w r a H H b Patented Jan. 26, 1954 e I I UNITED STATES BLAST DIFFUSING MEANS FOR ELECTRIC CIRCUIT BREAKERS OF THE FLUID-BLAST Schneider, Springfield, Pa., assignors to General Electric Company,

York

Application May-2r; 1952, Serial No; 289,082

This invention relates to blast diffusing means for electric circuit breakers of the fluid blast type and more particularly to an arrangement wherein a blast diifuser is interposed in a fluid passage interconnecting the circuit breaker contacts and la v ve used to. entr th vflew .qtfltuid mm a r e such we re e vqir- T ,hi a e.s c r r u ib ea ers. of the gas blast type, especially where a long-stroke isolating blade coactswith a short-strokeinterrupting contact, it is frequently necessary because of the high voltage rating of the circuit breaker, to supply a blast ofgas thrqugh a long passage or arcing chamber'leading from the blast valve to the arcing zoneof the circuit breaker. Due to the fact that the connecting passage between the blast valve and the circuit breaker contacts is quite long and because pressure of the gas contained in the reservoir is rather high, of the order of'250 pounds per square inch, it has been observed that blast pressure oscillations and aberrations of substantial amplitude travel along the passage to the region of the arcing contacts and that such Wide variations produce corresponding fluctuations in insulating strength which can interfere with the proper functioning of the circuit interrupter by causing unpredictable voltage breakdowns or restrikes during the interrupting process, especially when performing capacitance switching.

A principal object of this invention is to provide means for substantially reducing pressure oscillations in the region of the arcing zone of the contacts of a fluid blast circuit breaker so as to preclude fortuitous failures of interruption of the breaker; v a

In accordance with the invention, blast diffusing means is interposed between the blast valve and the contacts of a fluid blast circuit breaker which means effectivelyreduces harmful irregular aberrations in' the pressure of the fluid in the region of the contacts. Such pressure diffusing; means generally may take the form of any honeycomb device such as a plurality of corrugated metallic layers interspersed with other layers of sheet metal so as to form a plurality of parallel passages through which the blast passes en route to the contacts of the circuit breaker to thereby produce a mixing through turbulence for effectively damping harmful oscillations in the fluid pressure such as are producedby the pressure wave front and'its ensuing reverberations.

For a better understanding of theinvention, reference may be had to the following description taken in conjunction with the drawing in which Fig. 1 represents schematically a circuit breaker of the gas blast type embodying the principles of the invention, in which Fig. 2 is an enlargedlcross-sectional. view alongathe line 2-4 of .1. andin. which;Eig...3. is'lan. enlargedlver-s a corporation of New' 2' v tical section of a portion of the structure shownin Fig. -1.

In the drawing the numeral 1 generally designates an interrupting unit comprising one pole of a gas blast circuit breaker. Th supply of pressure fluid to interrupting unit I is supplied; through blast valve}, whichis under the control of opening control valve 3, from a source-pf; fiuid pressure 4. Once the circuit controlled; by the breaker hasbeen interrupted by interrupter. unit I, a circuit isolatin operation of the breaker;

is accomplished due to operation of fluid-ach ated device 5 as will be more fullyexplained I Interrupterunit l comprises metallic enclos ing structure 6 which supports finger contacts l biased by spring means 8 into engagementwith tubular contact 9. Theenclosingstruc ture B supported by an insulating casing III which in turn is mounted uporrthe metallic base member II. The specific construction of the unit I is more fully described and is claimed in applica-.

tion Serial No..233,637-Beatty, filed June 26, 1951, and an interrupter o f th general type dis; closed in Fig. 1 is disclosed and broadly'claiined in application Serial No. 202,100 -Beatty, filed December 21, 1950, now Patent No. 2, 45,697,; issued July 14, 1953, both of which applications are assigned to the assignee of this invention.

The interrupting finger contacts 1 are separated tween these contacts. This supply of gas flows in the direction of the arrows to atmosphere and is supplied to the blast valve 2 from the air receiver 4 through the short conduit 12. The terminals of the breaker are indicated schematically by a line connected to member 6 and by another line whose arrow represents a sliding contact with. the movable isolating tubular contact 9.

Blast valve 2 the balanced-typeand com -1 prises a pair of disks l3mounted on-a' valve" spindle 15 on which is disposed a main operating piston 16 and a valve restraining piston; Li. The valve is biasedtoward the closed positionby spring means [4. A conduit I8 interconnects openingcontrol valve 3 with the enclosing struc ture [9 in which the main operating piston 16 is movable. As illustrated, opening control valve 3 is of the electromagnetically actuated type Opening control valve 3, as is well known, could be. responsive to an electric condition of the systern controlled. byv the breaker electric condition of thesystem controlled by the-breaker I :Valve 3 -also. could .be. manually actuated or,-of cou-rse, Y

could be both manually and automatically operable.

Full opening movement of blast valve 2 is accomplished when opening control valve 3 is opened. Opening of the opening control valve 3 supplies pressure fluid underneath the piston l6 and causes the valve 2 to move to its fully opened position. In this way a major blast is supplied to the interrupting unit I to separate the finger contacts I from the tubular contact 9 and to extinguish an are drawn between these contacts. When blast valve 2 is reclosed due to the closing of conrol valve 3 and to the action of spring M, the blast pressure in interrupter casing ID will decay so that the contacts I will return to the position illustrated due to the bias of their individual closing springs 8.

After interruption of an are drawn between the contacts I and 9, a suitable isolating gap is established before the blast of fluid is shut off. To this end the arrangement shown in the drawing is constructed so that the tubular contact 9 can be drawn downwardly, during, after or coincident with the interrupting or blasting operation. Isolating contact 9 is connected at its lower end to a vertical operating rod 29 of insulating material which is pinned at 2| to a switch lever 22 which in turn is pivoted at 23 to a guide link 24 mounted at fixed pivot 25. Operating crank 26 mounted for rotation about a fixed pivot 21 is pinned at 28 to the lever 22. Opening bias for contact 9 is supplied in the form of compressional spring 29 which biases a transversely disposed rod 30 toward the right. Rod 39 is pinned to bell crank 26 at 3|. Spring 29 normally is inefiective to separate isolating contact 9 from interrupting finger contacts 1 due to the toggle construction comprising links 32 and 33 which are pinned together at 34. Rod 30 is connected to link 33 through bell crank 35 pivotally mounted at the fixed pivot 36 and pinned at its upper extremity to rod 39 by pin 31 and at its lower end to link 33 by a pin 38. Link 32, which really is one member of a three-armed crank, is mounted on a fixed pivot 32a. With the toggle comprising links 32 and 33 in the overcenter position indicated, the bias of spring 29 is ineffective to separate the contacts. However, if the toggle is moved downwardly through dead center and beyond, the spring 29 then imparts a rapid opening movement to the contact 9 through its operating rod 29 and parts associated therewith. The lower position of rod 29 and of switch lever 22 are indicated by dotted lines and the full isolating stroke is indicated by the distance S. Opening movement of the parts is arrested when roller 3811 on bell crank 26 engages bufier or dashpot 38b.

For the purpose of breaking the toggle comprising links 32 and 33, the fluid-actuated device is arranged to respond to the opening of control valve 3 and the resulting operation of the blast valve fluid motor comprising piston IS in the cylinder structure l9, thus ensuring that the interrupting contacts are blown open and blasted prior to breaking the toggle whereby to initiate the isolating movement of contact 9.

Fluid-actuated device 5 is provided with an enclosing cylinder 39 and an opearting piston 40. Thus, when fluid pressure is supplied above piston 40, downward motion will be imparted thereto so as to break the toggle 32-33 whereupon spring 29 quickly opens the isolating contact 9.

Fluid pressure is supplied above the piston 49 by means of a conduit 4| which connects to the 4. enclosing structure l9. Blast valve spindle I5 is provided with an undercut portion 42 and fluid pressure is supplied from opening control valve 3 to the structure l9 through forked conduits l8 and 43. Thus, when opening control valve 3 is opened, fluid pressure in conduit l8 will cause the blast valve piston Hi to move upwardly. Responsive to such valve opening movement, fluid pressure supplied through conduit 43 passes through the structure I9 to the conduit 4| to operate piston 49 of fluid-actuated device 5 as a result of the undercut portion 42 of the spindle I5 establishing communication between conduits 43 and 4|. Thus, it is impossible to supply fluid to the device 5 to cause isolating movement of contact 9 unless the blast valve 2 has been opened. This particular interlocking arrangement is more fully disclosed and claimed in application Serial No. 233,542-Shores, filed June 26, 1951.

As already mentioned, a full breaker opening stroke is completed with the opening of the isolating contact 9; the cycle being terminated by the timed reclosing of the closing valve 3 as through the operation of an auxiliary switch actuated by some appropriate moving part during the downward stroke of the piston 49 of the pneumatic operator 5. Thus, pressure below the blast valve piston I6 is relieved through the atmospheric vent of the closing control valve 3 so that the blast valve 2 closes under the urge ofits spring l4, while pressure above the motor piston 49 is relieved, when the blast valve'closes, through the vent to atmosphere in the structure I!) adjacent the undercut portion 42 of the blast valve spindle, the opening spring 29 ensuring that a full opening stroke is attained by the isolating contact 9.

Since the finger contacts 1 return to the position indicated due to the action of biasing means 8 after the fluid blast is cut oil, closure of the breaker is accomplished by imparting upward movement to the contact 9. To this end, fluid pressure is supplied to the underside of piston 40 of device 5 to cause upward movement thereof and movement of the operating linkage against the bias of spring 29 to close the breaker. Fluid pressure is supplied to the lower portion of structure 39 by means of breaker closing control valve 44 which, as indicated schematically on the drawing, is of the electromagnetically operated type. Valve 44 is connected with cylinder 39 through a conduit 45a and is constructed so as to vent the lower portion of cylinder 39 to atmosphere when closed. Fluid pressure is supplied to valve 44 through suitable means such as the conduit 44a.

In order to prevent an arc from striking between contacts I and 9 as contact 9 approaches the closed position, it is desirable to supply a minor blast of gas to the contacts. blast is supplied by opening the valve 2 a partial distance only. In this way, the sup-ply'of pres-,

sure fluid in air receiver 4 is not needlessly wasted. For the purpose of imparting partial opening movement to blast valve 2, a fluid motor comprising piston 45 and a restraining means in the form of piston H are provided, such structure being disclosed and claimed in application Serial No. 244,064 by Harold N schneider and Reed M. Anderson which was filed on August 28, 1951, and which is assigned to the assignee of this inven tion. Fluid pressure is supplied to pistons l1 and 45 through conduits 46 and .41 from an auxiliary valve comprising undercut portion 48 of a slidable member 49 which is movable in accord- This minor ance with movement of piston 40. Fluid pressure is supplied to conduit lt from the lower portion of cylinder 30 through port 55 due to the establishment of communication between port 50 and conduit :35 as the undercut portion it of control member ii moves Fluid pressure s lied through conduit bears against surface of restraining piston ii and through conduit Lil is caused to bear against the lower surface of piston d which is of larger diameter than piston it. It will be observed that the travel E of piston s5 is less than the travel A of piston it. Thus, fluid pressure supplied below piston 5-5 will impart upward movement to valve stem 55 to force valve 2 to open partially. Valve 2, being provided with the two disks i3, is of the balanced type. Thus, the momentum of the parts, being sumcient to overcome the force of spring it, would cause the valve to open fully once it is partically opened by piston 45. To prevent such as occurrence, the piston H is arranged to exert a downward force on the valve spindle 55 so as to maintain the valve 2 in a partially opened position for producing a minor closing blast as determined by the position of piston 555 after that piston completes its upward. travel distance 3. l -urthermore, piston ll causes a slower opening of the valve than when the valve is opened by piston 65 during opening of the breaker.

In accordance with this invention, a blast diffuser structure 5i is mounted within the casing in between the blast valve 2 and the zone of arcing. Diffuser 5i includes a retainer structure 52 with a bell mouth portion 53 at the lower end thereof which is provided with six radiating web members 54. Similarly, six spider elements 55 radiate from the upper end of the retainer 52. Disposed about the retainer 52 and its web 54 and spider elements 55 is a sleeve member 55 which is secured to the base member l I by a threaded engagement. Between the radially extending webs 54 and the radially extending spider members 55 is wound a scroll structure comprising a fiat metal sheet 5? and a corrugated metallic element 55 to form a suitable foraminous structure.

The sleeve 55 is brazed to the spider elements 55 and to the web elements 54 so as to form a unitary removable unit 5!.

For the purpose of guiding the vertical reciprocatory motion of the isolating contact 9, an insulating ring 59 is secured within an appropriate groove formed within the inner periphery of the retainer 52. Preferably, the ring 59 is constructed of a hard, smooth, low friction material.

From Fig. 3 it will be observed that the diffuser unit 5! is screwed into a strong metallic member of the structure, shown in this instance as the blast valve housing flange, so that the sleeve 56 constitutes a reinforcing wall for taking at least a portion of the inwardly exerted pressure due to the split halves of the wedged clamping ring 60 which are secured in position by bolts GI and lugs 62, thereby to prevent distortion of the easing II).

For best results, the diffuser element 5| is disposed in a region which is between the blast valve and the interrupting contacts so as to provide a direct flow path from the downstream side of the diffuser to the interrupting contacts, 1. e., at a place where direct flow from the diffuser to the contacts is then possible without any material change in the direction of flow. Furthermore,

the diffuser should be disposed as close to the interrupting contacts as the voltage conditions permit.

Preferably then, the difiuser element 51 would be located toward the mid-section of the casing it? rather than, as indicated by the somewhat schematic Fig. 1, being secured directly to the blast valve casing i I.

In other words, when applying the diffuser of our invention to its best advantage to an actual so KV. high voltage interrupter which was successfully tested and is now operating in service, it was fastened directly to the metallic supporting structure which houses the fixed isolating contacts, via, at the upper flange of the structure 6 of the aforesaid application of Beatty Serial No. 202,100.

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

1. An electric circuit breaker of the fluid blast type comprising an insulating cylindrical casing, a pair of contacts disposed within said casing, said contacts being separable to draw an arc to be extinguished and one of said contacts being reciprocable within said casing, means including a blast valve for directing a blast of fluid to said contacts for extinguishing the are drawn therebetween upon separation thereof, and diffuser means disposed in the path of said blast for moderating the blast effect in a manner to eliminate harmful oscillations in the pressure of said fluid in the region of said contacts, said diffuser means comprising an annular cylindrical retainer having an inner and an outer wall, a foraminous mass disposed between said walls, and a narrow anti-friction ring captured in said inner wall for guiding said reciprocable contact.

2. An electric circuit breaker of the fluid blast type comprising a support, an insulating cylindrical casing, a securing means for clamping said casing to said support, a pair of contacts disposed within said casing, said contacts being separable to draw an arc to be extinguished and one of said contacts being reciprocable within said casing, means including a blast valve for directing a blast of fluid to said contacts for extinguishing the are drawn therebetween upon separation thereof, and diffuser means disposed in the path of said blast for moderating the blast efiect in a manner to eliminate harmful oscillations in the pressure of said fluid in the region of said contacts, said diffuser means comprising an annular cylindrical retainer having an inner and an outer cylindrical wall, a foraminous mass disposed between said walls, a narrow antifriction ring captured in said inner wall for guiding said reciprocable contact, and contractible means forming a portion of said securing means for compressibly sealing one end of said cylindrical casing to said outer cylindrical wall, said outer wall serving to reinforce said casing against the compressive action of said contractible means- JOHN w. BEATTY.

HAROLD N. SCHNEIDER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,298,838 Paxton Oct. 13, 1942 2,382,850 Bennett Aug. 14, 1945 2,552,358 Whitney et a1 M May 8, 1951 FOREIGN PATENTS Number Country Date 532,670 Germany Sept. 2, 1931

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