US3164706A

US3164706A - Mechanical operating means for fluidblast circuit interrupter

Info

Publication number: US3164706A
Application number: US149951A
Authority: US
Inventors: Frederick B Johnson
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1961-11-03
Filing date: 1961-11-03
Publication date: 1965-01-05
Anticipated expiration: 1982-01-05
Also published as: GB972059A; JPS4033942Y1; FR1337744A; BE624218A

Description

Jan. 5, 1965 F. B. JOHNSON 3,164,706

MECHANICAL OPERATING MEANS FOR FLUID-BLAST CIRCUIT INTERRUPTER Filed Nov. 3, 1961 3 Sheets-Sheet 1 Fig. l.

5 2 M Frederick Bwildhnson Jan. 5, 1965 F. B. JOHNSON 3 MECHANICAL OPERATING MEANS FOR FLUID-BLAST CIRCUIT INTERRUPTER Filed Nov. 5, 1961 3 Sheet s-Sheet 3 44 S W c a M 8 R5 A mm F R E D m IL Y C O 3 2 c wtza 525 a 205:. A B C 5 5 5 .m a. m F. F. 4 F 2 m 6 6 7 2 7 2 6 2 7 2 a a 2 m 2 Fig.7.

QLA, H,

United States Patent ()fiti ce 3,164,706 Patented Jan. 5, 1965 3,164,706 MECHANICAL OPERATING MEANS FOR FLUID- BLAST CIRCUIT INTERRUPTER Frederick 13. Johnson, Pleasant Hills, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Nov. 3, .1961, Ser. No. 149,951 Claims. (Cl. 200-148) This invention relates to fluid-blast circuit interrupters in general, and, more particularly, to piston-type arcextinguishing structures for circuit interruptcrs of the fluid-blast type.

In United States Patent 2,913,559, issued November 17, 1959, to Charles F. Cromer, and assigned to the assignee of the instant application, there is disclosed and claimed a hydraulically-actuated fluid-blast circuit interrupter of the type in which the puffer structure compresses fluid to cause the ejection of the same out through an orifice and into intimate engagement with the established arc. In the pufler structure of the aforesaid patent, both the piston and the operating cylinder moved in opposite directions to quickly compress the fluid volume Within the operating cylinder to provide a considerable pressure difference across the orifice.

It is a general object of the present application to retain the general principles of operation of the puifer structure, as taught in the aforesaid patent, but providing a simplified and highly effective mechanical linkage interconnecting the movable contact rod and one of the movable operating elements of the puffer structure.

A more specific object of the present invention is to provide an improved operating linkage for a puifer-type fluid-blast circuit interrupter in which the rate of travel of one of the operating elements of the puffer structure may be controlled in a desired manner.

Still a further object of the present invention is the provision of an improved fluid-blast putter-type circuit interruplter utilizing a fluid-exhaust orifice, in which the mechanism interconnecting the two move able parts of the puffer structure is of a simple construction, may be easily adjusted and requires a minimum of space.

, Briefly, the present invention is concerned with the provision of an improved puffer structure in whch a pivotallymounted operating lever is linked to both the movable contact rod and to one of the movable elements of the puffer structure. The contact rod not only responds to the opening and closing movement of the movable contact, but also is linked to the other movable part of the piston structure so that during the opening operation of the interrupter, the two movable parts of the piston structure are moved toward each other in opposite directions to very quickly compress the compressible volume enclosed in the movable operating cylinder of the puffer device.

During the opening operation, the movable contact rod may move either the operating cylinder or the orifice structure, and the pivotally-mounted operating lever, actuated by the contact rod, causes the actuation of the other moveable part of the puffer structure, namely the interiorly disposed piston or the movement of the surrounding operating cylinder. As a result, compression of the fluid within the operating cylinder is quickly achieved, thereby causing a high-pressure flow of fluid through the orifice structure of the pullier device bringing about rapid extinction of the established arc.

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

FIGURE 1 is an end elevational View of a three-phase fluid-blast circuit interrupter of the puffer-type embodying principles of the present invention;

FIG. 2 is a side elevational view of the three-phase circuit interrupter of FIG. 1;

FIG. 3 is an enlarged cross-sectional view taken through one of the three interruptingassemblies of the circuit interrupter of FIGS. 1 and 2, illustrating the interconnecting linkage, and the parts being shown at an intermediate point n the opening operation;

FIG. 3A is a sectional view taken along the line I-I of FIG. 3;

FIG. 4 is an enlarged detailed view of the operating linkage of the puffer structure;

FIG. 5 is a graph indicating different pivot locations to obtain different travel curves of the piston;

FIGS. 5A, 5B and 5C diagrammatically represent different pivot locations indicated by the graph of FIG. 5;

FIG. 6 illustrates a modified form of the invention indicating how the parts may be interchangeable while retaining the simplified linkage; and, I

FIG. 7 is a sectional view taken substantially along the line VIIVII of FIG. 4.

Referring to the drawings, and more particularly to FIG. 1 thereof, the reference numeral 1 generally designates a three-phase fluid-blast circuit interrupter. As shown, the circuit interrupter 1 includes three interrupting assemblies A, B, C, each of which controls one of the phases. The interrupting assemblies A, B, C are supported up in the air upon a suitable supporting framework 2 by uprights 4. Braces 5 and 6 extend transversely between the uprights 4 and maintain a rigid structure. A mechanism compartment 7 is provided enclosing a suitable operating mcchanism, which may be of the pneumatic or solenoid actuated type. Briefly, the mechanism, disposed within the mechanism compartment 7 functions to cause closing of the contact structure 8 (FIG. 3) and simultaneously charge a pluralty of accelerating compression springs, not shown. During the openingoperation, the mechanism is unl atched, permitting therebythe accelerating compression springs to effect the clock-wise rotation of an operating shaft 9, causing thereby separation between the relatively stationary contact 10 and the movable contact 11 in each pole-assembly A, B, C.

Each pole-unit A, B or C includes a housing structure generally designated by the reference numeral 12. As shown, the housing structure comprises a pair of oppositely extending insulating cylinders 12 and an intervening grounded metallic support cylinder 12b. A suitable gas under pressure, such as sulfur hexafluoride SP gas, may be contained within the housing 12. Current transformers 3 may be provided, as shown.

It will be observed with reference to FIG. 1, that the rotatable crank-shaft 9 extends through a tube 13 extending transversely of the pole-units A, B, C, and is connected to each of the pole-unit assemblies by a bifurcated drive lever 14, the configuration of which is more readily apparent from an inspection of FIG. 3A of the drawings. The furcations 15, 16 of the bifurcated drive lever 14 make pivotal connection to pivot pins 17 extending laterally from links 18, in turn pivotally connected, as at 19, to trunnions extending later-ally of a movable pufier cylinder 20.

Also movable within the puffer cylinder 20 is a movable piston 21 pivotally connected, as at 22, to a floating link 23, the right-hand end of which is pivotally connected, as at 24, to a rotatable operating lever 25. The rotatable operating lever 25 is pivotally mounted intermediate its ends on stationary trunnion pins 26 (FIG. 7).

'The upper arm 27 of the rotatable operating lever 25 is pivotally connected, as at 28, to a floating link 29, in turn connected, as at 30, to a boss portion 31 of the movable contact rod 32.

As shown in FIG. 3, the right-hand end of the movable contact rod 32 is engaged by flexible fingers 33 which, in

' two parts.

turn, are electrically connected to the right-hand terminal plate 34 of each pole-unit assembly A, B, C.

With further reference to FIG. 3, it will be noted that the relatively stationary contact is supported, as by a threaded engagement 35, to a terminal plate 3-5. Consequently, in the closed-circuit position of the device, not shown, the electrical circuit therethrough includes line connection L left-hand terminal plate 36, relatively stationary contact 10, movable contact 11, movable contact guide rod 32, flexible fingers 33 to terminal plate 34 and hence to the other line connection L As well known by those skilled in the art, puffer devices utilized in conjunction with the contact structures of circuit interrupters are effective to cause a blast of arcextinguishing fluid, such as compressed gas, oil, etc. adjacent the established arc to quickly effect the extinction thereof. In the circuit interrupter 1, such as illustrated in FIGS. 1 and 2 of the drawings, employing for example, sulfur hexafluoride (SP gas as the arc-extinguishing medium, the relative movement between the operating cylinder 2G and the piston 21 causes compression of the sulfur hexafluoride gas within the region 37 of the puffer structure 38; This gas is ejected out through an orifice 39 toward the are established between the movable and relatively

stationary contacts

11, 10, respectively.

Circuit interrupters using conventional puffer structures have several fundamental limitations including the following:

(1) The amount of gas that can be moved through the orifice is limited to that trapped inside the cylinder at the start of a movement.

(2) The stored energy of the opening springs is expended in acceleration of the moving contacts to the open position, movement of the gas through the interrupter, movement of the cylinder structure to the open position and movement of the operating linkage to the open position. Only the first two of these are useful functions, the latter two being necessary evils that should be minimized.

(3) Rate of gas flow, neglecting compression, bears a linear relation to contact motion and may not be at the most efiicient rate as far as effective circuit interruption is concerned.

(4) To increase the amount or rate of gas flow requires a larger cylinder, or more travel plus increased acceleration of the initial cylinder. Either expedient requires increased acceleration forces which must be provided by the breaker closing mechanism.

With attention being directed to FIG. 3 of the drawings, it will be noted that the putfer structure 33 increases the amount of gas flow without increasing the size of the cylinder or the length of the stroke. This is done by dividing the stationary piston and guide assembly into As shown in FIG. 3, the left-hand part becomes a movable piston 21 which is caused to move in a direction opposite to that of the moving cylinder 2 thereby increasing the relative movement of the two, and correspondingly increasing the amount of gas blown through the interrupter. The right-hand part of this assembly 41 remains stationary and serves the function of guiding movement of the cylinder and contact assembly.

FIG. 4 shows a suggested linkage for driving the movable piston 21. It consists of an operating lever 25 pivoted at an intermediate point 2-6 to the stationary guide assembly 41, and two

links

23, 29, one pivoted to each end of the lever 25. The link 29 at the upper end is connected to the conductor bar 32 which is part of a moving contact assembly and moves with it. The bottom floating link 23 is connected to the piston 21 and imparts motion to it in a direction opposite to that of the contact motion. It is obvious that other linkage mechanisms might be used to produce this desired counter-movement between the moving cylinder 20 and the moving piston 21.

A further improvement that may be obtained with this structure is now described. In an interrupter of the type described, gas flow through the contacts and orifice before contact separation does little to help in the interruption. Therefore, it is desirable, if possible, to increase the gas flow after contact separation and to minimize it as much as possible before. It is particularly advantageous to augment the gas flow after the contacts 16, 11 have achieved enough separation to obtain circuit interruption. The linkage described lends itself to achieving this goal for that portion of gas flow caused by the piston 21 by relocating the pin centers and the length of the two arms of the operating lever. FIGS. 5A, 5B and 5C show, schematically, three such lever-arm arrangements; and the piston travel curves that will be obtained with each plotted as a function of the main cylinder travel in the graph of FIG. 5. Curve A shows an essentially linear relationship between the two travels which is obtained when the three pin centers are in line with each other. Curve B shows an increased rate of travel in the latter part of the travel, and curve C shows that it is even possible to obtain reversed travel of the movable piston 21 at the start with a maximum rate at the full open position. It should be remembered that these travels and accompanying gas flow will be superimposed on the moving cylinder travel and flow, which will always be a straight-line function, neglecting gas compression.

It is recognized that this mechanism requires the movement of additional parts as compared to the conventional design. However, the weight of these parts would be appreciably less than that of a larger cylinder that would give comparable gas movement. Also with the same size piston 21, the increased gas flow is obtained without the necessity of increased acceleration of all other moving parts as would be required if the longer stroke method were used. The net result is increased gas flow with relatively little increase in required accelerating forces.

FIG. 6 illustrates a modification of the puffer structure 38 in which the parts are interchanged. It will be noted that here the operating cylinder 20a is connected by a cylinder head 43 to a boss portion 44, which is linked, as at 45, to a floating link 46. The right-hand end of the floating link 46 is pivotally connected, as at 47, to the operating lever 25a. The upper end of the operating lever 25a is pivotally connected, as at 49, to a floating link 50, the latter pivotally connected, as at 51, to a boss portion 52 of the movable contact rod 32a. eration is the same as in the FIG. 3 arrangement, namely the operating cylinder 20a and the orifice structure 39a moving in opposite directions to quickly effect compression of the compressible gas disposed within the region 37 of the puffer device 38.

From the foregoing decription, it will be apparent that there is provided a simplified type of mechanical linkage involving little space and effecting interconnection between the

movable contact rod

32, 32a with one of the movable elements of the puffer device 38. The

movable contact rod

32, 32a is connected to the other movable part of the puffer device 38 so that during the opening operation the two movable parts of the puffer device move in opposite directions to quickly effect fluid compression within the space 37. The result of such rapid compression is a considerable differential pressure drop through the orifice 39, 39a to eject compressed fluid under high pressure into the are 40 established between the relatively stationary and

movable contacts

10, 11.

It will be noted that the operating arrangement for the puffer device may be readily adapted to conventional type puffer structures with little addition of parts and causes their more efficient operation. In addition, the utilization of the rapid operating puffer structure enables the effectiveness of the circuit interrupter 1 to be increased, particularly on linecharging interruptions or capacitor switching.

Although there has been illustrated and described specific structures, it is to be clearly understood that the same were merely for the purpose of illustration, and that changes and modifications may readily be made therein The method of op by those skilled in the art Without departing from the spirit and scope of the invention.

I claim as my invention:

1. A circuit interrupter of the fluid-blast type including a relatively stationary contact, a movable contact separable from the relatively stationary contact to establish an arc, a movable contact rod having said movable contact aflixed thereto, operating means for eiieoting opening and closing movement of the movable contact rod for effecting corresponding contact separation and contact reengagement, puffer means for compressing fluid to effect arc extinction including a movable cylinder part and a movable piston part, the movable piston part being movable Within the movable cylinder part for the compression of an arc-extinguishing fluid therein, a mechanical linkage including a pivotally mounted operating lever mechanically interconnecting said movable contact rod with one of said movable parts, said movable contact rod being secured to the other of said movable parts, whereby said two movable parts will move in opposite directions to very rapidly decrease the compressible volume within the movable cylinder during the opening operation of the interrupter.

2. The combination in a puffer-type fluid-blast circuit interrupter of contact means for establishing an arc, puffer means including an orifice for effecting extinction of said are by a blast of compressed arc-extinguishing fluid, the puffer means also including a movable piston part movable within a movable cylinder part for the compression of volume therein, said orifice secured to and movable with one of said movable parts, the contact means including a relatively stationary contact and a movable cooperable contact movable with a movable contact rod, mechanical linkage means including a pivotally mounted operating lever interconnecting said movable contact rod with one of said movable parts, means connecting the movable contact rod to the other movable part, whereby said movable parts of the putter means move in opposite directions to very rapidly compress fluid within the movable cylinder part for an arc-extinguishing blast of gas through said orifice.

3. A circuit interrupter of the fluid-blast type including a relatively stationary contact, a movable contact separable from the relatively stationary contact to establish an arc, a movable contact rod having said movable contact ailixed thereto, operating means for effecting opening and closing movement of the movable contact rod for effecting corresponding contact separation and contact reengagement, pufier means for compressing fluid to effect arc extinction including a movable cylinder part and a movable piston part, the movable piston part being movable within the movable cylinder part for the compression of an arc-extinguishing fluid therein, a mechanical linkage mechanically interconnecting said movable contact rod with one of said movable parts, said movable contact rod being secured to the other of said movable parts, said mechanical linkage including a rotatable operating lever fulcrumed about a stationary pivot, whereby said two movable parts will move in opposite directions to very rapidly decrease the compressible volume within the movable cylinder during the opening operation of the interrupter.

4. The combination according to claim 1, wherein the pufier means includes relatively stationary support means, and the pivotally-mounted operating lever is fulcrumed adjacent its mid-point on said support means.

5. A circuit interrupter of the fluid-blast type including a relatively stationary contact, a movable contact carrying an orifice structure and operating cylinder, a relatively stationary guide cylinder over which said operat ing cylinder slides and having an internallydocated stationary fulcrum support means, said movable contact having a rod-like extension extending axially through said guide cylinder, operating means secured to the outer side of said operating cylinder to cause the opening and closing movement thereof, a movable piston disposed internally of said operating cylinder and cooperable therewith to compressfiuid within the operating cylinder and force the same out through the orifice structure against the arc to extinguish the same, a reversing-movement operating lever fulcrumed adjacent its mid-point to said stationary fulcrum support means, link means connecting the opposite ends of said operating lever both to said movable piston and to said rod-like contact extension, whereby opening movement of the operating cylinder as efi'ected by said operating means causes opposite movement of the operating cylinder and movable piston to rapidly compress the fiuid within the operating cylinder.

References Eited in the file of this patent UNITED STATES PATENTS 2,781,435 Heilmann et a1. Feb. 12, 1957 2,913,559 Cromer Nov. 17, 1959 3,002,129 Mueller Sept. 26, 1961 FOREIGN PATENTS 811,554 France Ian. 18, 1937 663,423 Germany Aug. 5, 1938

Claims

1. A CIRCUIT INTERRUPTER OF THE FLUID-BLAST TYPE INCLUDING A RELATIVELY STATIONARY CONTACT, A MOVABLE CONTACT SEPARABLE FROM THE RELATIVELY STATIONARY CONTACT TO ESTABLSH AN ARC, A MOVABLE CONTACT ROD HAVING SAID MOVABLE CONTACT AFFIXED THERETO, OPERATING MEANS FOR EFFECTING OPENING AND CLOSING MOVEMENT OF THE MOVABLE CONTACT ROD FOR EFFECTING CORRESPONDING CONTACT SEPARATION AND CONTACT REENGAGEMENT, PUFFER MEANS FOR COMPRESSING FLUID TO EFFECT ARC EXTINCTION INCLUDING A MOVABLE CYLINDER PART AND A MOVABLE PISTON PART, THE MOVABLE PISTON PART BEING MOVABLE WITHIN THE MOVABLE CYLINDER PART FOR THE COMPRES-