US3214550A - Circuit interrupters with crossbars captively related to piston structures - Google Patents

Description

G. J. EASLEY 3,214,550

-BARS CAP'I'IVELY Oct. 26, 1965 CIRCUIT INTERRUPTERS WITH CROSS RELATED TO PISTON STRUCTURES 5 Sheets-Sheet 1 Filed May 2, 1962 INVENTOR Gi|ber1J.Eus|ey BY Em WORNEY G. J. EASLEY Oct. 26, 1965 CIRCUIT INTERRUPTERS WITH CROSS-BARS CAPTIVEL RELATED TO PISTON STRUCTURES 5 Sheets-Sheet 5 Filed May 2, 1962 Fig.3.

Oct. 26, 1965 G. J. EASLEY 3,214,550

CIRCUIT INTERRUPTERS WITH CROSS-BARS GAPTIVELY RELATED TO PISTON STRUCTURES 5 Sheets-Sheet 4 Filed May 2, 1962 Fig.4.

Oct. 26, 1965 CIRCUIT INTERRUPTE R Filed May 2, 1962 G J. EASLEY WITH CROSS-BARS CAPTIVELY RELATED TO PISTON STRUCTURES 5 Sheets-Sheet 5 Fig.5.

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United States Patent 3,214,550 CIRCUIT INTERRUPTERS WITH CROSS- BARS CAPTIVELY RELATED TO PISTON STRUCTURES Gilbert .1. Easley, Edgewood, Pa, assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed May 2, 1962, Ser. No. 191,959 3 Claims. (Cl. 200148) This invention relates to circuit interrupters in general and, more particularly, to circuit interrupters of the type which force a blast of arc-extinguishing fluid into the established arc to effect the interruption thereof.

A general object of the present invention is to provide an improved, compact, and highly-eflicient circuit interrupter which Will involve a minimum of guiding action, and which will also be effective over a Wide current range.

A more specific object of the present invention is to provide an improved tank-type circuit interrupter in which a pair of arc-extinguishing units are secured to the lower ends of terminal bushings extending into the tank structure, and in which the conducting cross-bar is fixedly secured to a pair of puffer structures associated with the two serially-related arc-extinguishing units.

A more specific object of the present invention is the provision of a three-pole single-tank-type of circuit interrupter of the gas-blast puffer-type, in which the three liftrods and cross-bars are simultaneously actuated by an operating mechanism, and which does not need any straight-line connecting mechanism, associated therewith.

Still a further object of the present invention is the provision of a gas-blast type of circuit interrupter of minimum vertical dimensions obtained by the attachment of the conducting cross-bar to the puffer structures themselves,

so that no isolating gap distance need be required in the fully open-circuit position of the interrupter.

Still a further object of the present invention is the provision of an improved puffer-type gas-blast circuit interrupter in which the energy of the cross-arm, lift-rod and operating linkage is not thrown away when the puffer structure tends to stall on high-value fault currents.

Still a further object of the present invention is the provision of a tank-type gas-blast circuit interrupter particularly of the puffer-type, in which a lateral metallic support may be secured to the lower ends of the two arcextinguishing units and thereby impose less cantilever load upon the supporting terminal bushings.

Yet a further object of the present invention is the provision of an improved puffer-type circuit interrupter in which the operating mechanism, associated with the crossbar, is used to assist the puffer springs over the entire opening stroke.

Still a further object of the present invention is the provision of an improved puffer-type circuit interrupter in which reliance may be placed upon a single shock absorber disposed within the mechanism cabinet, and as a result there is no necessity for associating a shock absorber with each puffer-type interrupter individually. Preferably, such a construction is obtained by a captive arrangement between the cross-bar and the movable puifer structures themselves.

In United States patent application filed May 2, 1962, Serial No. 191,957, by Robert E. Friedrich, and assigned to the assignee of the instant application, there is described and claimed a single grounded tank-type three-pole circuit interrupter, in which a pair of serially-related puffer structures are associated with each pole-unit of the interrupter. It is a further object of the present invention to improve upon the puffer-type interrupting structures of the aforesaid Friedrich application, rendering the breaker of minimum vertical height, eliminating guiding action to a considerable extent, and moreover utilizing the inertia and operating force of the mechanism to assist the puffer springs over the entire opening stroke.

Higher-voltage compressed-gas circuit interrupters of the sulfur-hexafluoride (SP gas type, such as set forth in United States patent application filed January 23, 1959, Serial No. 788,668, new United States Patent 3,057,983, issued October 9, 1962, to Russell N. Yeckley, Joseph Sucha and Benjamin P. Baker, and assigned to the assignee of the instant application, provide a double-pressure scheme for high interrupting capacity. The present invention is particularly concerned, according to one aspect, with a circuit interrupter in a single grounded tank made of metal, using puffer-type interrupters for moderate interrupting capacity, such, for example, as 5000 mva. at 115, 138 and 161 kv., but not necessarily limited to these ratings. The use of a single tank at a moderate pressure of say 45-60 p.s.i.g. results in a somewhat less costly breaker to build than a three-tank double-pressure breaker, such as the foregoing type, adapted for high interrupting capacity. By utilizing relatively low-pressure gas, no gas compressor or heater is necessitated, and there is no possibility of liquefaction of the gas.

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

FIG. 1 is a side elevational view of a tanktype threepole circuit interrupter embodying features of the present invention;

FIG. 2 is a top plan view of the circuit interrupter of FIG. 1;

FIG. 3 is a vertical sectional view taken through the tank-type circuit interrupter of FIG. 1 substantially along the line IIIIII of FIG. 2, and illustrating the disposition of the several parts in the closed-circuit position of the interrupter;

FIG. 4 is a vertical sectional view taken substantially along the line IVIV of FIG. 2, again the contact structure being illustrated in the closed-circuit position;

FIG. 5 is an enlarged vertical sectional view taken through one of the puffer-type arc-extinguishing units of the circuit interrupter of the invention, illustrating the disposition of the several parts at an intermediate point in the opening operation; and

FIG. 6 is a vertical sectional view taken through. a modified-type of circuit interrupter, the contact structure again being illustrated at an intermediate point in the opening operation.

Referring to the drawings, and more particularly to FIG. 1 thereof, the reference numeral 1 designates a tank-type three-phase circuit interrupter including a grounded tank structure 2 and pairs of serially-related terminal bushings 3, 4, 5, 6, 7, 8 for the three pole-units A, B, and C of the interrupter 1. As shown more clearly in FIG. 2 of the drawings, the terminal bushings extend through the upper portion 2a of the tank structure 2. The lower portion 212 of the tank structure 2 may be dropped downwardly for visual inspection of the interior of the tank 2, when the device is supported upon an upstanding frame support, not shown. For the larger ratings, of course, the tank structure 2 might rest itself upon a suitable foundation, as shown in FIG. 1, and access into the interior of the tank 2 obtained through a manhole 10, as indicated in FIG. 1. For the smaller-size ratings, not shown, the manhole 10 could be omitted, and reliance placed upon separation of a split-tank structure 2 itself.

Disposed adjacent one side of the tank structure 2 is an operating mechanism compartment 11, within which is situated any suitable operating mechanism, say a pneumatic mechanism, solenoid mechanism, or a hydraulic mechanism, as well known by those skilled in the art. Also disposed adjacent one side of the tank 2, as shown in FIG. 1, is a storage reservoir 13, which may be utilized for storage of a suitable arc-extinguishing fluid, such as sulfur hexafluoride (SF gas, for example, under pressure.

I By illustrating an embodiment of the present invention as utilized with an arc-extinguishing gas, such as sulfur hexafluoride (SF gas, it is not to be inferred thereby that the invention is restricted only to this particular gas, or, for that matter, to gases in general. It will be obvious to those skilled in the art that other arc-extinguishing fluids, such as liquids, say a circuit-interrupter oil, for example, may be employed instead of an arc-extinguishing gas. Merely for purposes of illustration is the present invention described as utilizing the highly-efiicient arcextinguishing gas sulfur hexafluoride (SP say at a pressure of 45-60 p.s.i.g. A suitable interconnection, which may include a reducing valve, permits the transmission of the gas under pressure from the storage reservoir tank 13 into the interior 14 of the tank structure 2. With reference to FIGS. 1 and 2, it will be observed that suitable current transformers 15 may encircle the terminal bushings and may have conduits 16, 17 associated therewith to accommodate the cable connections therefrom. Additionally, a transistorized potential device housing 18 may be associated with the other side of the tank 2 from the mechanism compartment 11 for relaying purposes, as Well understood by those skilled in the art.

FIG. 3 more clearly shows the arrangement of the serially-related arc-extinguishing units 20 disposed within the interior 14 of the tank structure 2. With reference to FIG. 4, showing the middle pole-unit B, taken in conjunction with FIG. 3, it will be observed that a pair of arc-extinguishing units 20 is associated with each poleunit A, B or C of the interrupter 1. Preferably, the interrupting units 20 are fixedly clamped, and secured to the interior ends of the pairs of terminal bushings. Also an insulating lift-rod 21 and a conducting cross-bar 22 are associated with each pole-unit, A, B or C of the interrupter 1. The arrangement is such that downward opening movement of each lift-rod 21 carries therewith the conducting cross-bar 22, to the ends of which are secured, in captive arrangement, the piston structures 24 (FIG. of the interrupting units 20. As a result, downward opening movement of the lift-rod 21 and cross-bar 22 carries therewith the piston structures 24 in captive relation, thereby assisting the puffer compression spring 26.

With further reference to FIG. 5 of the drawings, it will be observed that movable with the piston structure 24 is a movable contact structure 29, comprising a plurality of circumferentially-disposed flexible contact fingers 30 and an arc horn 31. The relatively movable contact structure 29 is cooperable with a post-type relatively-fixed contact 33, which is fixedly secured to a top metallic cover plate 34 of the unit 20, and extends downwardly coaxially thereof. Surrounding the relatively movable contact structure 29 and providing a cylindrical enclosure for the piston 24 is an insulating interrupter casing 36, having a plurality of vent openings 37 in the upper portion thereof.

It will be observed, however, that the lower portion of the casing 36 is enclosed, so that downward movement of the piston 24 within the casing 36, constituting an operating cylinder, will inject a quantity of arc-extinguishing fluid, in this particular instance sulfur-hexafluoride (SF gas, upwardly through one or more apertures 38 provided in the piston structure 24 and adjacent the drawn are 40 to quickly effect the extinction thereof. To assist in more effectively guiding of the fluid, preferably an insulating orifice structure 42 is utilized, of annular form, and having a lower threaded portion 43 thereof fixedly threadedly secured to an upstanding support collar 45 constituting an integral part of the piston 24.

The lower end of the insulating interrupting casing 36 is closed by a closure plate 46 having a downwardly extending tubular neck portion 47, which assists in guiding the piston rod 49 of the interrupter unit 20. It will be observed that the lower extremity of the piston rod 49 is fixedly secured, by any suitable fastening means, such as nuts 50, to the outer extremity 22a of the conducting cross-arm 22. As a result, the cross-arm 22 maintains constant contact with the piston rod 49 during the entire opening and closing stroke, and the upper ends 21a of the lift rods 21 may have a pivotal connection, as at 52, to bell-crank levers 53, as shown in FIG. 3. The plurality of bell-crank levers 53 may be pivotally supported, as at 54, to a suitable support bracket 55, extending downwardly from the cover portion 2a of the tank structure 2. The other arms 56 of the bell-cranks 53 may be pivotally connected, as at 57, to a generally horizontally-extending operating rod 58, which, in turn, is pivotally connected, as at 59, to a bell-crank lever 60. The shaft 61 of the bell-crank lever extends through a sealed gas-tight opening in the side of the bell-crank lever housing 62, and is pivotally connected, through another crank 63 outside lever housing 62, to a vertically-extending operating rod 64, which extends interiorly within the mechanism compartment 11 and is connected to the mechanism 65 provided therein.

From the foregoing description it will be apparent that upward movement of the vertical rod 64, secured to the operating mechanism 65 within mechanism compartment 11, will permit clockwise rotation of the bell-crank lever 60, and resulting rightward generally horizontally opening movement of the operating rod 58. Through the pivotal connections 57, the several bellcrank levers 53 will be rotated in a counterclockwise direction about pivots 54 to effect thereby downward opening movement of the several lift-rods 21. The downward movement of the several lift-rods 21 will force the pistons 24 downwardly, within the associated operating cylinders 36, and effect thereby arc extinction in the previously-described manner. This opening travel is assisted by the springs 26, associated with the individual interrupter units 20, and also by the tail spring 66 (FIG. 3) connected to operating rod 58.

During the closing operation, the operating mechanism 65, provided in the mechanism compartment 11, is effective to cause counter-clockwise rotation of the bell-crank lever 60 (FIG. 3). This action, in turn, causes leftward closing movement of the operating rod 58, and consequent clockwise rotation of the several bell-crank levers 53. The clockwise rotation of the several bell-crank levers 53 will, through the pivotal connections 52, cause upward closing movement of the several lift-rods 21 and consequent closing movement of the three cross-bars 22. The

ends 22a of each cross-bar 22 will force the piston structure 24 associated therewith upwardly, and will also effect reengagement of the contact structure 29, 33. As will be apparent, this closing motion compresses, or charges the individual interrupter springs 26 and also the tail spring 66. The interrupter 1 is then closed and latched in the closed position in readiness for a subsequent opening operation. The circuit interrupter 1 has a number of important advantages. First, the considerable kinetic energy (momentum) built up during the early part of the opening stroke in the moving parts (mass) such as the crossbar 22, lift rod 21, cranks 53 and 60, horizontal operating rod 58, vertical operating rod and operating mechanism parts inside compartment 11 (not shown), is eifective to assist the puffer structure 24 throughout the remainder of the opening stroke. Secondly, a disconnecting contact gap is eliminated which permits a shorter lift rod 21 stroke with resultant decreased mechanical effort (greater mechanical advantage), and also an overall reduction in vertical height of interrupter 1. Thirdly, a conducting support 27 may be provided between the lower ends of the interrupting units 20, when required. Fourthly, a

straight-line guide mechanism is not required at the upper ends of the lift rods 20, since the latter are guided by the interrupting units themselves. Fifthly, a single shock absorber 80 connected to the vertical operating rod 64 is suflicient where it may be serviced conveniently without draining tank 2 instead of an individual shock absorber on each interrupter 20.

FIG. 6 illustrates a modified-type of circuit-interrupting unit 71 in which the piston 24a is fixed, and the operating cylinder 36a is movable relative thereto. In the modified arrangement of FIG. 6, the piston rod 72 is fixedly secured to the movable closure plate 73 of the operating cylinder 36a. As before, the gas is compressed within the region 74 and forced upwardly out of apertures 75 provided in the movable closure plate 73. The orifice structure 42 directs the gas flow in the manner previously described.

For ensuring substantial equal division of voltage between the pairs of arc-extinguishing units 20, 65, preferably a capacitance voltage divider unit 76 is associated with each unit, and is electrically connected between the stationary and movable contact structure of the unit. The actual current carried by the capacitor voltage divider 76 is negligible, yet it has the desirable advantage of imposing substantially equal voltage stress upon each unit. The open-circuit position of the crossbars 22 is indicated by the dotted lines 77 in FIGS. 4 and 6.

With further reference to FIG. 6, it will be noted that the piston 24a is supported upon suitable legs 24b afiixed to the lower ends of insulating support rods 78, which are interleaved with extensions 36b of the cylinder 36a in order to provide a means for biasing a spring 26 between the two members. Preferably, an insulating bushing 80 is used around the cylinder stem 72, and also an insulating piston ring 81 is used to prevent passing current at these points and also to reduce friction. It is to be noted that the metallic cross-arm 22 is arranged so that it will pull, as well as push, the puffer cylinder 36a. Provision of an over-size hole 82 and a slight gap permits lateral alignment and prevents binding of the pulfers 36a.

In general, the construction and operation of'the interrupter 1 of the present invention is somewhat similar to that of conventional oil breakers, that is an interrupter 20, 65 is mounted on the lower end of each terminal bushing, and is operated by a bridging cross-arm 22 mounted upon an insulating lift rod 21. A simple crank 53 above each lift rod 21 is connected to a horizontal operating rod 58 so that a straight-line lever system is not required. The terminal bushings utilized may be either of the gas-insulated type, gas-encased condenser type, or oil-impregnated condenser type. It is desirable that breakers of this particular voltage rating, for example, 115 to 161 kv. use potential devices connected to the bushings. If straight gas-filled bushings are used, the potential devices are preferably of the transistor-amplified type, such as set forth in U.S. Patent 2,924,726. Encapsulated current transformers 15 are preferably mounted about the grounded portion of the bushings outside of the tank 2. The tank structure may be of the frame-mounted style with a split tank, or floor mounted with a manhole entrance 10 for the higher ratings.

It is desirable that the interrupting units be spaced equally about the center-line of the breaker so that the bridging metallic cross-arms 22 are of the same length for all three poles. The bushings are preferably mounted at the same angle, but the center pole bushings are set in somewhat closer to the tank center in order to obtain the uniform interrupter spacing desired. The horizontal operating rod 58 across the top of the breaker 1 is connected to the three pole-unit crank-levers 53 and is operated 'by the mechanism disposed within the mechanism compartment 11. As pointed out above, the bell crank 60 changes the vertical motion of the operating mechanism to horizontal motion in order to get the desired mechanical advantage as the breaker reaches the closed position. The only rotating seal need be a single gland seal on the center bearing of the bell-crank shaft 61. The tail spring 66 (FIG. 3) connected to the horizontal pull rod 58 supplements the springs 26 in the individual interrupter units 20, and provides some adjustment to control the opening speed of the breaker. Suitable shock absorber (FIG. 3) for cushioning the opening movement of the breaker would be connected to the vertical operating rod 64 and located in the operating mechanism cabinet 11. An important advantage of the present construction of the instant invention is that the arrangement operates a pair of puffer interrupters with a captive crossarm 22. The piston 24 may be movable as illustrated in FIG. 5, or stationary as illustrated in FIG. 6.

There are several advantages to be realized by making the conducting cross-arm 22 captive to the piston structures. A short stroke is possible, which permits best mechanical advantage for the operating mechanism. A considerably longer stroke would be necessitated if the cross-arm 22 parted, that is finger contacts with considerable overlap would be necessary because of the puffer stalling on high fault currents, and a substantial dielectric gap between the cross-arm and fingers would be required due to open-circuited capacitor voltage dividers. The kinetic energy of the cross-arm, lift-rod and operating linkage obtained by accelerating these parts early in the opening stroke is not thrown away when the puffer tends to stall on high fault currents. It is possible to use a metallic support 27 between the bottom of the interrupting units 20. This becomes somewhat important since the bushing cantilever load is greater than usual on this breaker due to greater-than-normal angle required to keep the tank small and cross-arms short, and also somewhat greater than usual contact load. A lift-rod guide is not required since the lift-rod 21 itself is guided by the captive cross-arm 22. Shock absorbers 80 to cushion the opening stroke may be located at one place, such as in the mechanism cabinet 11. If the cross-arm parted away from the movable contact structure 29, it would be necessary to use a shock absorber to cushion each puffer individually. Shock absorbers inside the tank are undesirable due to the possibility of oil leakage when the tank is evacuated prior to gas filling.

From the foregoing description it will be apparent that there is provided a novel puffer-type fluid-blast circuit interrupter of minimum dimensions, and in which control is achieved over the movable contact structure 29 during the entire opening and closing operation. The three poles A, B and C may advantageously be located in a single tank 2 and due to the guiding action afforded by the captive arrangement, a straight-line guiding mechanism is not necessitated at the upper ends of the lift rod 21.

Although there have been shown 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 circuit interrupter including a single grounded tank, three pairs of terminal bushings extending into the tank, an interrupting unit secured to the lower end of each terminal bushing, a relatively stationary contact associated with each interrupting unit, a cooperable movable contact, orifice-type gas-piston means for each unit including an operating-cylinder element and a piston element, said elements being movable relative to each other to compress gas, means securing the movable contact of each unit to one of said elements, spring means situated adjacent the bottom of each unit to bias the respective movable contact in an opening direction, a conducting cross-bar fixedly secured to the movable contact of each interrupting unit, an insulating lift rod disposed intermed-iate the units and actuating the conducting cross-bar,

an actuating bell-crank lever pivotally connected to the upper end of each of the three lift rods, a generally horizontally-extending operating rod pivotally connected to each of the bell-crank levers, and means for effecting generally longitudinal horizontal reciprocal opening and closing movement of the operating rod, and a single shock-absorbing system associated with the operating rod.

2. A circuit interrupter including a single grounded tank, three pairs of terminal bushings extending into the tank, an interrupting unit secured to the lower end of each terminal bushing, a relatively stationary contact associated with each interrupting unit, a cooperable movable contact, orifice-type piston means for each unit including an operating-cylinder element and a piston element, said elements being movable relative to each other to compress fluid, means securing the movable contact of each unit to one of said elements, a conducting cross-bar fixedly secured to the movable contact of each interrupting unit, an insulating lift rod disposed intermediate the units and actuating the conducting cross-bar, an actuating bellcrank lever pivotally connected to the upper end of each of the three lift rods, a generally horizontally-extending operating rod pivotally connected to each of the bellcrank levers, means for effecting generally longitudinal horizontal reciprocal opening and closing movement of the operating rod, and a single shock-absorbing system disposed externally of said grounded tank and associated with the operating rod.

3. A circiut interrupter including a single grounded tank, three pairs of terminal bushings extending into the tank, an interrupting unit secured to the lower end of each terminal bushing, a relatively stationary contact associated with each interrupting unit, a cooperable movable contact, orifice-type piston means for each unit 'in cluding an operating-cylinder element and a piston ele-l ment, said elements being movable relative to each other" to compress fluid, means securing the movable contact of each unit to one of said elements, a conducting crossbar fixedly secured to the movable contact of each in-' terrupting unit, an insulating lift rod disposed intermediate the units and actuating the conducting cross-bar, an actuating bell-crank lever pivotally connected to the upper end of each of the three lift rods, a generally hori zontally-extending operating rod pivotally connected to each of the bell-crank levers, means for effecting generally longitudinal horizontal reciprocal opening and closing movement of the operating rod, and three conducting braces extending between the three pairs ofinterrupting units in generally parallel relationship to the respective cross-bars associated therewith.

References Cited by the Examiner UNITED STATES PATENTS KATHLEEN H. CLAFFY, Primary Examiner.

BERNARD A. GILHEANY, Examiner.

Claims (1)

1. A CIRCUIT INTERRUPTER INCLUDING A SINGLE GROUNDED TANK, THREE PAIRS OF TERMINAL BUSHINGS EXTENDING INTO THE TANK, AN INTERRUPTING UNIT SECURED TO THE LOWER END OF EACH TERMINAL BUSHING, A RELATIVELY STATIONARY CONTACT ASSOCIATED WITH EACH INTERRUPTING UNIT, A COOPERABLE MOVABLE CONTACT, ORIFICE-TYPE GAS-PISTON MEANS FOR EACH UNIT INCLUDING AN OPERATING-CYLINDER ELEMENT AND A PISTON ELEMENT, SAID ELEMENTS BEING MOVABLE RELATIVE TO EACH OTHER TO COMPRESS GAS, MEANS SECURING THE MOVABLE CONTACT OF EACH UNIT TO ONE OF SAID ELEMENTS, SPRING MEANS SITUATED ADJACENT THE BOTTOM OF EACH UNIT TO BIAS THE RESPECTIVE MOVABLE CONTACT IN AN OPENING DIRECTION, A CONDUCTING CROSS-BAR FIXEDLY SECURED TO THE MOVABLE CONTACT OF EACH INTERRUPTING UNIT, AN INSULATING LIFT ROD DISPOSED INTERMEDIATE THE UNITS AND ACTUATING THE CONDUCTING CROSS-BAR, AN ACTUATING BELL-CRANK LEVER PIVOTALLY CONNECTED TO THE UPPER END OF EACH OF THE THREE LIFT RODS, A GENERALLY HORIZONTALLY-EXTENDING OPERATING ROD PIVOTALLY CONNECTED TO EACH OF THE BELL-CRANK LEVERS, AND MEANS FOR EFFECTING GENERALLY LONGITUDINAL HORIZONTAL RECIPROCAL OPENING AND CLOSING MOVEMENT OF THE OPERATING ROD, AND A SINGLE SHOCK-ABSORBING SYSTEM ASSOCIATED WITH THE OPERATING ROD.

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