United States Patent (11) 3,566,001 72 Inventor James R. McCloud Burbank, Calif. FOREIGN PATENTS 21 Appl. No. 852,534 685,663 l (1953 Great Britain...... 174/12(3) (22) Filed Aug. 25, 1969 Primary Examiner-Laramie E. Askin 45 Patented Feb. 23, 1971 Attorney-Ostrolenk, Faber, Gerb & Soffen 73) Assignee I-F-E Imperial Corporation Philadelphia, Pa. ABSTRACT: A hollow insulation column has a central con 54 GAS-FILLED BUSHING WITHSPRING BIAS ductor extending therethrough, and the insulation column is CLAMPNG AND INTERNAL FLEXBLE SHUNT filled with a high-pressure gas, such as hexafluoride, 4. Claims, 3 Drawing Figs. under greater than atmospheric pressure in order to provide (52) U.S.C...... 174/31, insulation between the central conductor and a centrally 174/12 disposed mounting flange in the bushing. One end of the cen (51) int. Cl...... H01b. 17126 tral conductor is connected to an end conductive plate of the (50 Field of Search...... 174/11.3, bushing through flexible shunts in order to permit dimensional changes between the central conductor and the insulation 12.3, 14.3, 15.3, 16.3, 18,31 bushing, due to temperature changes. The is held 56) References Cited clamped together by a spring biasing arrangement connected UNITED STATES PATENTS to the upper end of the bushing between a flange mounted on 2,623,919 12/1952 Bowers...... 174/12(3) the upper end of the conductive member within the bushing 2,853,538 9/1958 Frakes...... 174/12(.3) and a plate which is fastened directly to the upper conductive 3,331,918 7 11967 Sonnenberg et al...... 174/12(.3)X atmosphere.head of the bushing. There are only two seals to the external

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N . INVENTOR. SNNY //7/1/as a M2 CA2ZZO BY 677eazz14.4%e 2sea 2.2a:- 1222-223 3,566,001 2 GAS-FILLED BUSHING WITHSPRNG BAS CLAMPNG soft, sealing stop gaskets 21 and 22. The insulator bushing of AND INTERNAL FLEXBLE SHUNT FIG. 1 then contains a main elongated conductor 30 which is threaded into a conductive adapter 31 which is received by BRIEF DESCRIPTION OF INVENTION the conductive head plate 32. Electrical equipment within the 5 housing 15 which are to be connected to conductor 30 are This invention relates to insulation bushings of the type used connected thereto through a suitable threaded connection, for for bringing an electrical conductor into an enclosed housing, example, with the adapter 31. such as a gas-insulated circuitbreaker, and more particularly Note that the end of conductive tube 30 is provided with a relates to a novel gas-filled bushing which is held assembled by filter disc 33 which is contained between the threaded clamp virtue of a spring-biased connection and in which the central 10 ing discs 34 and 35 which are threaded into the interior of the conductor of the bushing is connected to the terminal head of end of tube 30 to filter gases used to purge the interior of the the bushing by flexible conductors, whereby only two seals are bushing. needed to the external atmosphere. Conductive plate 32 is also provided with an opening 36 THE PRIOR ART which is covered by a filter 37, as shown in FIG. 3, where filter 15 37 is held in place by screw 38 and gasket 39. This structure is Gas-filled bushings are well known for introducing high useful for removing condensed moisture from the inside of the voltage conductors into a housing, such as a gas-filled circuit bushing. interrupter. It is necessary to construct such bushings so that The outer end of the insulation bushing, as shown to the left at least the portion of the bushing extending beyond a sealed in FIG. 1, contains a well-contoured end conductive plate 41 housing will itself be sealed to prevent the leakage of gas 20 which may have a threaded terminal 42 extending therefrom therefrom. In the past, up to six seals were needed. In addition, so that convenient connection may be made to the bushing. it is necessary to permit relative expansion or dimensional Conductive member 41 is then sealed to the left-hand end of change between the central conductor of the bushing and the hollow insulator section 10 by a good pressure seal consisting exterior housing. To this end, a flexible bellows is of the hard, load-bearing compression gasket 43 and its rela commonly introduced between the interior diameter of the 25 tively soft, sealing stop gaskets 44 and 45. It will be noted that hollow insulation column and the central conductor where the the left-hand end of conductor 30 is spaced from conductive bellows forms a gastight seal to the insulation column and per member 41 so that the conductor 30 may expand and contract mits relative expansion and contraction of the central conduc at a different rate than insulator sections. 10 and 11, due to tor and the exterior insulator. The present invention 30 temperature change. eliminates the use of such bellows-type devices which are ex Electrical connection between conductive member 41 and pensive and are subject to failure. Devices of this type are the central conductor 30 and the means for holding the insula shown typically in the U.S. Pat. to Friedrich et al. No. tor assembled constitute the novel features of the present in 3,059,044. In particular, and in accordance with the inven vention. This equipment includes a spring-receiving disc 50 tion, the bellows of the prior art is replaced by a flexible shunt 35 and a conductive flange member 51 which is threaded onto extending directly from one end of the central conductor of the left-hand end of conductor 30. Flange member 51 is the bushing to the main conductive head of the insulator. The shown in plan view in FIG. 2. It will be noted that flange main conductive head is then sealed to the end of the insula member 51 has a threaded interior 52 which is threaded onto tion column by a novel spring clamping arrangement which the end of conductive tube 30 and then fixed in this position clamps together the entire insulation column. 40 by pin 53 which extends through a suitable opening in the up standing wall 54, shown as opening 55 in FIG. 2, to prevent BRIEF DESCRIPTION OF THE FIGS. subsequent rotation of the flange member 51 with respect to FIG. 1 is a partial cross-sectional diagram of an insulation conductor 30 after the bushing has been assembled. bushing constructed in accordance with the present invention. Electrical connection is made between conductive member FIG. 2 is a plan view of the flange member of FIG. 1 which is 45 40 and flange plate 51 and thus conductor 30 by means of connected to the upper end of the bushing conductor. flexible, conductive straps. These flexible, conductive straps FIG. 3 is an enlarged cross-sectional view of the filter ar may be packages of thin, copper sheets, for example, 25 layers rangement in the conductive headplate of FIG. 1. of copper sheets, each having a thickness of 0.010 inch. A typ ical flexible conductor of this type is shown in FIG. 1 as flexi DETALED DESCRIPTION OF THE PREFERRED 50 ble conductive member 60. A plurality of such flexible EMBODIMENT member will be distributed around the periphery of flange Referring first to FIG. 1, there is illustrated an insulation member 51, and, for example, either such conductive strips bushing which consists of two insulator columns 10 and 11 can be used, only one of which is shown in FIG. 1 for purposes which may be of any standard configuration and which are 55 of clarity. jointed in end-to-end relation through an annular mounting One end of the conductive members, such as conductive flange 12. The annular mounting flange 12 is of the standard member 60, is bolted to the interior of conductive member 41 type and contains numerous bolt hole openings, such as bolt as by the bolt 61, while the other end envelopes around the ex holes 3 and i4, such that the insulator can be mounted to any terior of the flange as shown, and is disposed beneath a pres suitable enclosure such as the fragmentarily shown enclosure 60 sure washer 62. Note that conductive member 60 may have an i5 which could, for example, represent the sealed housing of a opening therethrough for passing a threaded insulated shank gas circuit interrupter. Thus, the entire section 11 will be im 63 which serves as a spring guide for the parallel springs 64 mersed within such an enclosure, which may also be gas-filled. and 65. One end of spring 64 and 65 bears on pressure washer Relatively hard, load-supporting gaskets 16 and 40 may, 62 in order to make good electrical contact between conduc therefore, be provided between the flange plates 12 and 32 65 tor 60 and flange 51. The other ends of springs 64 and 65 rest and insulator section 11 to protect the insulator from damage on insulated washers 100 which are carried on disc 50 as by coming into contact with these metal plates, since leakage shown. Note that parts 63,80 and 100 are insulated to prevent at this joint is allowable since both the interior of the tank 15 the various springs and bolts from carrying current and spark and the interior of the insulation column could both be filled ing to parts 50 and 51. with gas at the same pressure. 70 As mentioned above, a plurality of such assemblies are The insulation section 10, however, is positioned above the disposed about the flange member 51 where FIG. 2 illustrates exterior of the tank 15 so that an extremely effective seal must an opening 70 for threadably receiving threaded shank 63, be provided between the flange plate 12 and insulator 10. This with the entire assembly of springs 64, 65, shank 63 and con seal is shown in FIG, as consisting of a relatively hard, load ductor 61 being associated with this portion of the cross-sec supporting compression gasket 20 contained within suitable 75 tional view, 3,566,001 3 4. Seven similar assemblies will be similarly associated with a hollow, elongated insulator column; threaded openings 71 to 77, shown in FIG. 2, for receiving the b. an elongated conductor within said hollow, elongated in threaded shanks of the respective assemblies. sulator column and extending along the axis thereof; Spring-receiving disc 50 is then rigidly threaded into en c. first conductive member positioned at one end of said in gagement with conductive member 41 as by insulated bolts sulator column and rigidly connected to one end of said such as bolt 80, shown in FIG. 1. Note that bolt 80, along with elongated conductor; seven other bolts in the preferred embodiment of the inven d. a second conductive member positioned in fixed relation tion, will also pass through aligned openings in flange member to the other end of said insulator column and forming a 51, these openings being shown in FIG.2 as through-openings hermetic seal to said other end of said insulator column; 8 to 88. O said other end of said elongated conductor being spaced It will be observed that the springs, such as springs 64 and from said second conductive member; 65, will serve to hold the entire insulator bushing in mechani e. means making a flexible electrical connection between cal alignment, with the insulator sections 10 and 11 being in said second conductive member and the other end of said compression. That is, springs 64 and 65 are compression elongated conductor, and including a flange member con springs which urge members 50 and 51 away from one 15 nected to said other end of said elongated conductor and another. This has the effect of pressing conductive end mem flexible shunt means extending from said second conduc bers.41 and 3 toward one another, thereby applying forces tive member to said flange member; tending to hold the bushing assembled and applying pressure f means clamping said first and second conductive mem to the various seals throughout the assembly. At the same bers to said ends of said insulator including a pressure time, a strong pressure connection is made between flexible 20 plate fixed to said second conductive member and conductive strap 60 and the flange 51 to establish a good path disposed within the interior of said hollow insulator and for electrical current from conductive member 41 through the disposed on the side of said flange member opposite to flexible conductors to conductive flange 51 and thence said second conductive member, and a spring-biasing through conductor 30 to the adapter 31. . means connected between said flange member and pres It will be observed that if there should be dimensional 25 sure plate for biasing said flange member and pressure changes of conductor 30 with respect to the insulator housings plate away from one another; and 10 and 11, these dimensional changes will be easily absorbed g, a high dielectric gas undergreater than atmospheric pres by the flexible conductors, such as conductor 60, without sure filling the interior of said hollow insulator. danger of cracking, while a good pressure seal is maintained 2. The bushing of claim 1 which includes a mounting flange throughout the interior of the insulator for those portions of 30 extending from the outer surface of said insulator column. the insulator bushing which are above the housing 15. 3. The bushing of claim 2 wherein said hollow insulator con Although this invention has been described with respect to sists of first and second sections in end-to-end disposition; said particular embodiments, it should be understood that many mounting plate comprising an annular member interposed variations and modifications will now be obvious to those between the adjacentends of said first and second sections. skilled in the art, and, therefore, the scope of this invention is 35 4. The bushing of claim 2 which includes first and second limited not by the specific disclosure herein, but only by the seal ring means respectively sealing said second conductive appended claims. member to one end of said first section and sealing one surface claim: of said mounting plate to the opposite end of said first section. 1. A gas-filled bushing comprising, in combination: 40

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