US3214549A - Fluid-blast piston arrangement and contact structure for circuit interrupters - Google Patents

Description

Oct. 26, 1965 R. E. FRIEDRICH 3,214,549

FLUID-BLAST PISTON ARRANGEMENT AND CONTACT STRUCTURE FOR CIRCUIT INTERRUPTERS Filed May 2, 1962 s Sheets-Sheet 1 IRELATIVELY 5 HIGH 2 PRESSURE GAS Fig. I.

' lNVENTOR Robert E. Friedrich ATTOR N EY Oct. 26, 1965 R. E. FRIEDRICH 3,214,549

FLUID-BLAST PISTON ARRANGEMENT AND CONTACT STRUCTURE FOR CIRCUIT INTERRUPTERS Filed May 2, 1962 5 Sheets-Sheet 2 a a l I L I Fig.2.

Oct. 26, 1965 R E. FRIEDRICH 3,214,549

FLUID-BLAST PI STON ARRANGEMENT AND CONTACT STRUCTURE FOR CIRCUIT INTERRUPTERS Filed May 2, 1962 5 Sheets-Sheet 3 Fig.4.

9 4 4 a H m 1 n S 9w .m 3 e T h MS T N 5 O C Oct. 26, 1965 R. E. FRIEDRICH FLUID-BLAST PISTON ARRANGEMENT AND STRUCTURE FOR CIRCUIT INTERRUPTERS Filed May 2, 1962 Fig.5.

Oct. 26, 1965 R. E. FRIEDRICH 3,214,549

FLUID-BLAST PISTON ARRANGEMENT AND CONTACT STRUCTURE FOR CIRCUIT INTERRUPTERS 5 Sheets-Sheet 5 Filed May 2, 1962 Fig.6.

United States Patent 3,214,549 FLUID BLAST PISTON ARRANGEMENT AND CONTACT STRUCTURE FOR CIR- CUIT INTERRUPTERS Robert E. Friedrich, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania I Filed May 2, 1962, Ser. No. 191,957

Claims. (Cl. 200-148) This invention relates to circuit interrupters in general, and, more particularly, to circuit interrupters of the type in which an arc-extinguishing fluid, such as a liquid or a gas, is injected into the arcing space during the opening operation to effect are extinction.

A general object of the present invention is to provide an improved simplified-type of circuit interrupter in which highly-effective arc-extinguishing action is obtained without the reliance of an external high-pressure fluid source.

A more detailed object of the present invention is the provision of an improved circuit interrupter of the selfgenerated fluid-pressure type in which biasing means, such as a compression spring, is employed to actuate a suitable piston, or puffer structure to inject a blast of fluid, such as gas, under pressure into the arc to effect the extinction thereof.

In United States Patent 2,933,575, issued April 19, 1960, to Benjamin P. Baker, and assigned to the asignee of the instant application, there .is disclosed and claimed a circuit interrupter of the puffer type, in which a piston is secured to, and movable with the movable contact structure and actuated by a biasing means, such as a compression spring. In the aforesaid patent, a conducting crossbar, bridging a pair of serially-related units, is effective to charge the compression springs associated with the two interrupting units during the closing stroke, and also to effect contact-engaging movement. During the opening operation, the cross-bar moves downwardly, being actuated vertically by an insulating lift rod, and permits the biasing springs to actuate the aforesaid piston structures to inject an arc-extinguishing gas' into the drawn arcs established within the interrupting units.

It is a further object of the present invention to improve upon the puifer structure of the aforesaid Baker patent rendering it more effective, and, in addition, adapting the same to the use of a shunting resistor for lowering the rate of rise of the recovery-voltage transient.

Still a further object of the present invention is the provision of an improved puffer-type circuit interrupter in which the blast of arc-extinguishing fluid, such as a gas, is ejected not only toward the established arc, but also through the movable tubular contact and toward the isolating gap to assist thereby in the interruption of the residual-current are, when a shunting resistance is employed.

additional object of the invention is to provide an improved contact structure for a fluid-blast circuit interrupter.

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

FIGURE 1 is a vertical sectional view taken through a three-phase, three-pole circuit interrupter embodying the principles of the present invention, the contact structure being illustrated in the closed-circuit position;

FIG. 2 is a vertical sectional view taken substantially along the line II-II of FIG. 1;

FIG. 3 is an enlarged vertical sectional view taken through one of the improved puffer-type interrupting units of the present invention, the contact structure being illustrated in the closed-circuit position;

3,214,549 Patented Oct. 26, 1965 FIG. 4 is a view similar to that of FIG. 3, but illustrating the dispositon of the several parts at an intermediate point in the opening operation;

FIG. 5 is a top plan view of the breaker unit of FIG. 1 illustrating, in plan, the interrupter and resistor locations; and,

FIG. 6 is a vertical sectional view taken through a modified-type of interrupting unit, the several parts being shown at an intermediate point in the opening operation.

Referring to the drawings, and more particularly to FIG. 1 thereof, the reference numeral 1 generally designates a three-phase, three-pole fluid-type circuit interrupter; Although the arc-extinguishing fluid, for purposes of illustration, is assumed to be gas in the particular example shown, nevertheless it will be apparent to those skilled in the art that certain aspects of the present invention are applicable to other types of fluid-blast circuit interrupters utilizing different arc-extinguishing fluids than gas, for instance liquid, such as oil. The term fluid as employed in the appended claims is intended to cover any arc-extinguishing fluid, such as gases, liquids, vapors and sprays.

As shown in FIG. 5, the circuit interrupter 1 includes three pole-units A, B and C disposed within a single tank structure 2. Each pole-unit A, B, or C includes a pair of serially-related arc-extinguishing units 3 electrically interconnected by a conducting bridging member 4, actuated vertically, in a reciprocal manner, by an insulating liftrod 5. The upper end of each of the three lift-rods 5 is mechanically interconnected to a horizontally reciprocally movable operating rod 6 (FIG. 2) which is actuated by a suitable mechanism, not shown, disposed within a mechanism compartment 7 From the foregoing description, it will be apparent that during the opening operation suitablemechanism, disposed within the mechanism compartment 7, is effective to transmit motion through the operating rod 6, and, by suitable connecting mechanism effect downward opening movement of the several lift-rods 5 and consequent downward simultaneous opening movement of the three crossbars 4.

As illustrated in FIGS. 1 and 2 of,the drawings, preferably the arc-extinguishing units 3 are threadedly secured and fixedly clamped to the interior ends of terminal bushings 8, 9, 10, 11 and 12, 13 extending upwardly through an upper tank cover portion 14 and fixedly secured there'- to. Preferably current transformers 15 are employed for measuring the current flow'through thecircuit interrupter 1 and for relaying functions, as well known by those skilled in the art.

With reference to FIGS. 3 and 4 of the drawings, which more clearly illustrate the operation of the circuit-interrupting unit 3, it will be apparent that each unit 3 includes a tubular vented stationary contact structure 16 cooperable with a movable tubular contact 17.

As shown, the stationary contact 16 has an upper enlarged portion 16a, and a lower relatively-reduced portion 16b. In addition, venting openings are provided in the upper portion of the enlargement 16a so that the stationary contact 16 is freely vented.

The movable tubular contact 17 includes an annular outer set or cluster of relatively long circumferentiallydisposed flexible main contact fingers 17a and an annular inner set or cluster of relatively short circumferentiallydisposed flexible arcing fingers 17b. As shown, the main contact fingers 17a engage the external surface of the enlarged portion 16a, whereas the relatively short arcing fingers 17b engage the reduced portion 16b of the stationary contact 16. The arrangement functions to separate the movable main contact fingers 17a from the enlarged portion 16a prior to separation of the movable arcing finger 16b from the lower reduced neck portion 16b of the stationary contact 16 so that the arc is established adjacent the lower extremity 16d of the stationary contact, the purpose for which will be more apparent hereinafter;

The movable contact 17 has fixedly secured thereto, and movable therewith, an annular conducting piston portion 18 reciprocally movable within an operating cylinder 19, and biased downwardly in an opening direction by-a battery of compression springs 20. As shown, the conducting piston portion 18 supports the two sets of movable flexible arcing fingers 17a, 17b.

The compression springs 20 seat at their upper ends against a relatively fixed apertured partition plate 21, and seat at their lower ends against a spring plate 22 secured to, and movable with the lower extremity 170 of the movable tubularcontact 17.

As shown in FIG. 3, the conducting cross-bar 4 abuts the lower side 22a-of the spring plate 22 and forces the same upwardly, thereby charging the battery of compression springs 20 and effecting contact engagement between the movable tubular contact structure 17 and the rela- 'tively stationary contacts 16. A suitable flange portion 23 of" the cylinder 19 provides a stop, and serves the function of halting the downward opening travel of the movable spring plate 22, permitting thereby the separation between thecontact portions 4a of the conducting cross-bar 4*andthe lower surface 22a of the spring plate 22. The dottedlines 25 in FIGS. 1 and 2 illustrate the open-circuitposition of the conducting cross-bar 4.

Preferably, the apertured partition plate 21 is at least 'partly formedof a suitable conducting material, and not 'only effects a guiding function, but also serves to transmit current from a shunting impedance means 26, such as a resistor unit- 27, electrically interconnecting the partition plate 21 with the relatively stationary contact structure 16. As a result, during the opening operation, the downward opening movement of the movable tubular contact 17 Y away from the tubular ventedstationary contact 16 draws an are 28 (FIG. 4), which is shunted by the impedance means 26. Aswell known by those skilled in the art, the shunting impedance means 26 facilitates the interruption-ofthe main current arc 28 (FIG. 4) and forces the current through the interrupter unit 3 to pass through the resistor unit 27, thereby decreasing the magnitude of the current and also improving the power factor.

The residual-current are 29 (FIG. 6) is established between the end 4a of the conducting cross-bar 4 and the lower surface 22a ofthe spring plate 22, constituting thereby relatively separable disconnecting contacts. This are 29 is easily interrupted since it is of small amperage, and the current and voltage are substantially in phase.

During the closing operation, the operating mechanism disposed. within the'mechanism compartment 7 is effective to cause horizontalmovement of the operating rod .6 and, consequently, upward closing travel'of'the several lift-rods 5, thereby eifectingclosing of the contact structures 16, 17 and simultaneously causing charging of the several compression springsZO;

It will be noted that particularly effective gas-flow conditions exist during the opening operation by the gas flow passing upwardly through the tubular relatively stationary contact 16 and out throughvent openings. 16c associated therewith. The gas-flow conditions are indicated by the .arrows30 in FIG. 4 of the drawings.

With reference to FIG. of the drawings, it will be observed that particularly advantageous locations of the interrupting units 3 and resistor columns 27 are obtained by the illustrated construction. The result is compactness in size and a minimum lateral dimension of the severalparts. Where a suitable high-dielectric-strength arc-extinguishing gas, such as sulfur-hexafluoride (SP gas, isemployed, the spacing between the high-voltage parts and the grounded tank structure 2 may be a minimum. Moreover, it will be noted that dropping of a lower portion 2a of the tank 2' from the upper cover portion 14 thereof permits a ready inspection of the several units. By disposing the three pole-units A, B and C within a single tank structure 2 foundation space, required for the circuit interrupter 1, is thereby minimized.

FIG. 6 illustrates a modification of the invention in which the movable tubular contact 31 is vented throughout its entire length. As a result, during the opening operation, as illustrated in FIG. 6, the gas flow may pass downwardly through the lower vent opening 32 and facilitate extinction of the residual current arc 29. This has the advantage of utilizing the generated gas under pressure for two functions, first interrupting the main current are 23, as indicated by the arrows 34, and secondly, causing a downward flow of gas, as indicatedbythe arrows 35, toward the residual-current are 29, which is, therefore, more quickly interrupted.

It will be noted that again the movable contact structure 31 has a set of' circumferentially-disposed main contact fingers 31a, and, in addition, an outer longer set of arcing contact fingers 31b. In this embodiment of the invention the relatively stationary. contact structure 33 has straight wall portions, and the movable main and arcing sets of fingers 31a, 31b are reversed in location,- with respect to FIG. 3, so that the movable arcing fingers 3112 will separate last from the stationary contact 33. The arc, as before, will be drawnat the lower extremity 33a of the stationary contact 33 with at least part of the exhaust gas passing through the stationary tubular contact 33 in the manner illustrated by the arrows 34..

Although the invention has been described in connec tion with a suitable arc-extinguishing gas, such as sulfurhexafluoride (SP gas, provided within the space 36 within the tank structure 2,,it is to be clearly understood that other arc-extinguishing mediums may be employed. For example, the circuit'interrupter 1 may be utilized with a suitable arc-extinguishing liquid, such as circuitbreaker oil, instead of the described gas.. In this case;

the annular piston 18 would function to inject a blastof arc-extinguishing oil under pressure into the main cur.- rent are 28 and thereby effect the rapi-dextinction thereof. As will be obvious, the use of a gas, such as sulfurhexafluoride (SP gas, instead of oil results in'a lighter construction for the circuit interrupter with less Weight thereby imposed upon the framework 37 of the circuit interrupter 1.

The invention is particularly adapted for a mediumrange interrupting capacity of say, for example, 5000 mva. at voltages up to and including. 161 kv; It will be obvious, that by a suitable dimensioning of the parts, higher powers may be interrupted.

Although there have 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 by those skilled in the art, without departing from the spirit and scope of the invention.

I claim as my invention:

1. A fluid blast circuit interrupter including a grounded tank structure, a pair of terminal bushings extending into said grounded tank structure and carrying a pair of arcextinguishing units at their interior ends, a conducting cross-bar for electrically interconnecting the units, each arc-extinguishing unit including a. relatively stationary contact and a cooperable movable contact tubular throughout its entire length, a relatively stationaryapertured partition plate having at least a conducting portion, impedance means electrically interconnecting the conducting portion of said apertured partition plate with said relatively stationary contact, an annular piston see cured to and movable with said movable contact, the relatively stationary and movable contacts cooperating to establish a main current arc, the end of the cross-bar cooperating with the movable contact to establish a resi: dual-current arc, biasing means for biasing the movable contact toward the open position and said annular piston in a fluid-injecting direction, and said piston forcing fluid longitudinally through the tubular movable contact into the two arcing regions, whereby the fluid blast is injected toward the residual-current are as well as toward the main-current arc.

2. The combination in a three-phase three-pole fluidblast circuit interrupter of a single tank structure, three pairs of terminal bushings extending into the tank structure, the tank structure being grounded, six arc-extinguishing units secured to the interior ends of the three pairs of terminal bushings, three pairs of cross-bars, operating means for simultaneously effecting the opening and closing movement of the three cross-bars, each arcextinguishing unit including relatively separable contacts each having a tubular portion, one of said relatively separable contacts carrying an annular piston member and being movable, said one movable contact being tubular throughout its entire length, spring means for biasing the annular piston member and said one relatively movable contact in a downward opening direction, impedance means electrically interconnecting the other of the relatively separable contacts with an external side surface of the first said relatively separable contacts to facilitate the interruption of the main-current arcs, separation of the ends of the conducting cross-bars from said one separable contacts drawing residual-current arcs at the lower ends of each of the arc-extinguishing units, and the movement of each annular piston member in the opening direction causing a flow of arc-extinguishing fluid to pass through the respective movable contact to flow toward the residual-current are as well as toward the main current arc.

3. A fluid-blast circuit interrupter including a relatively stationary tubular contact having an exhaust opening therethrough, cooperable movable contact structure including a relatively long set of circumferentially-disposed flexible arcing contact fingers and an inwardly disposed shorter set of circumferentially-disposed flexible main contact fingers, conducting movable piston means carrying said two sets of contact fingers, the two sets of contact fingers engaging conductively the external sides of said relatively stationary tubular contact, the arrangement functioning to separate the main contact fingers first and then subsequently the arcing contact fingers from the relatively stationary tubular contact, a rearwardly-disposed conducting tubular contact tube having inlet openings in the side wall thereof, means defining an operating cylinder within which said movable piston means moves, fluid injected by said piston means entering said inlet openings and into the arcing region, and at least a portion of said injected fluid exhausting through said exhaust opening in the relatively stationary tubular contact.

4. A fluid-blast circuit interrupter including a relatively stationary tubular contact freely vented and having an exhaust opening therethrough, said relatively stationary contact having a tubular enlarged portion and a smaller tubular end portion, cooperable movable contact structure including a relatively long annular cluster of circumferentially-disposed flexible main contact fingers and an inwardly disposed annular cluster of circumferentially-disposed flexible shorter arcing contact fingers, conducting movable piston means carrying said two clusters of contact fingers, the two sets of contact fingers engaging conductively the external sides of said relatively stationary tubular contact on the two different diameter portions thereof, the arrangement functioning to separate the main contact fingers first and then subsequently the arcing contact fingers from the relatively stationary tubular contact, a rearwardly-disposed conducting tubular contact tube having inlet openings in the side wall thereof, means defining an operating cylinder within which said movable piston means moves, fluid injected by said piston means entering said inlet openings and into the arcing region, and at least a portion of said injected fluid exhausting through said freely vented exhaust opening in the relatively stationary tubular contact.

5. A fluid-blast circuit interrupter including an arcextinguishing unit, said arc-extinguishing unit including a relatively stationary contact and a cooperable movable contact separable to establish a main-current arc, said movable contact being tubular throughout its entire length, impedance means electrically shunting said contacts, means defining an operating cylinder, said movable contact carrying an annular piston therewith, the movable tubular contact having side openings, biasing means for biasing the movable contact toward the open position and said annular piston in a fluid-injecting direction within the operating cylinder, a conducting operating member making separable contact with said movable contact and cooperablc therewith to establish a residual-current arc, and the fluid blast being injected toward the residualcurrent are as well as toward the main current are.

References Cited by the Examiner UNITED STATES PATENTS 1,336,069 4/20 Conrad 200- 2,032,241 2/36 Whitehead 200166 2,037,544 4/36 Seaman 200-166 2,459,599 1/49 Strom 200148 2,757,261 7/56 Lingal et al. 200-448 2,786,922 3/57 Stumpfhaus 200-466 2,933,575 4/60 Baker 200-148 KATHLEEN H. CLAFFY, Primary Examiner. BERNARD A. GILHEANY, Examiner.

Claims (1)

1. A FLUID BLAST CIRCUIT INTERRUPTER INCLUDING A GROUNDED TANK STRUCTURE, A PAIR OF TERMINAL BUSHINGS EXTENDING INTO SAID GROUNDED TANK STRUCTURE AND CARRYING A PAIR OF ARCEXTINGUISHING UNITS AT THEIR INTERIOR ENDS, A CONDUCTING CROSS-BAR FOR ELECTRICALLY INTERCONNECTING THE UNITS, EACH ARC-EXTINGUISHING UNIT INCLUDING A RELATIVELY STATIONARY CONTACT AND A COOPERABLE MOVABLE CONTACT TUBULAR THROUGHOUT ITS ENTIRE LENGTH, A RELATIVELY STATIONARY APERTURED PARTITION PLATE HAVING AT LEAST A CONDUCTING PORTION, IMPEDANCE MEANS ELECTRICALLY INTERCONNECTING THE CONDUCTING PORTION OF SAID APERTURED PARTITION PLATE WITH SAID RELATIVELY STATIONARY CONTACT, AN ANNULAR PISTON SECURED TO AND MOVABLE WITH SAID MOVABLE CONTACT, THE RELATIVELY STATIONARY AND MOVABLE CONTACTS COOPERATING TO ESTABLISH A MAIN CURRENT ARC, THE END OF THE CROSS-BAR COOPERATING WITH THE MOVABLE CONTACT TO ESTABLISH A RESIDUAL-CURRENT ARC, BIASING MEANS FOR BIASING THE MOVABLE CONTACT TOWARD THE OPEN POSITION AND SAID ANNULAR PISTON IN A FLUID-INJECTING DIRECTION, AND SAID PISTON FORCING FLUID LONGITUDINALLY THROUGH THE TUBULAR MOVABLE CONTACT INTO THE TWO ARCING REGIONS, WHEREBY THE FLUID BLAST IS INJECTED TOWARD THE RESIDUAL-CURRENT ARC AS WELL AS TOWARD THE MAIN-CURRENT ARC.

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