US3059044A - Terminal-bushing constructions - Google Patents

Terminal-bushing constructions Download PDF

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Publication number
US3059044A
US3059044A US856775A US85677559A US3059044A US 3059044 A US3059044 A US 3059044A US 856775 A US856775 A US 856775A US 85677559 A US85677559 A US 85677559A US 3059044 A US3059044 A US 3059044A
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United States
Prior art keywords
gas
terminal
bushing
filled
assembly
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US856775A
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English (en)
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Robert E Friedrich
James H Frakes
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CBS Corp
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Westinghouse Electric Corp
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Priority to US856775A priority Critical patent/US3059044A/en
Priority to DEW28821A priority patent/DE1193568B/de
Priority to CH1278660A priority patent/CH388407A/de
Priority to FR845663A priority patent/FR1279539A/fr
Priority to JP5726560A priority patent/JPS3618582B1/ja
Priority to JP4726460A priority patent/JPS371397B1/ja
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Publication of US3059044A publication Critical patent/US3059044A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B17/00—Insulators or insulating bodies characterised by their form
    • H01B17/36—Insulators having evacuated or gas-filled spaces
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H33/00—High-tension or heavy-current switches with arc-extinguishing or arc-preventing means
    • H01H33/02—Details
    • H01H33/021—Use of solid insulating compounds resistant to the contacting fluid dielectrics and their decomposition products, e.g. to SF6
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H33/00—High-tension or heavy-current switches with arc-extinguishing or arc-preventing means
    • H01H33/02—Details
    • H01H33/53—Cases; Reservoirs, tanks, piping or valves, for arc-extinguishing fluid; Accessories therefor, e.g. safety arrangements, pressure relief devices
    • H01H33/56—Gas reservoirs
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S174/00—Electricity: conductors and insulators
    • Y10S174/01—Anti-tracking

Definitions

  • This invention relates to terminal-bushing constructions in general, and, more particularly, to a novel type of terminal bushing in which a dielectric gas is substituted for the usual liquid or solid dielectric.
  • a more specific object of the present invention is to provide an improved terminal bushing of the gas-filled type.
  • Another object of the present invention is to provide an improved terminal-bushing construction adaptable for use with gas-filled electrical apparatus, such as circuitinterrupting apparatus, transformer apparatus, or the like, in which the dielectric gas from the gas-filled electrical apparatus may also be utilized interiorly within the terminal bushing as a dielectric medium therein.
  • gas-filled electrical apparatus such as circuitinterrupting apparatus, transformer apparatus, or the like
  • Another object of the present invention is to provide an improved gas-filled terminal bushing in which novel means are provided to obtain a potential tap for the terminal bushing.
  • Still a further object of the present invention is to avoid the use of paper, oil, compounds etc., generally employed in terminal-bushing constructions, and to employ instead a suitable dielectric gas in a sealed construction, which, preferably, will be noninfiammable, and which will also be self-healing.
  • a further object of the present invention is to provide an improved gas-filled bushing with good electrical characteristics, which is simple of design, of economical construction, has desirable manufacturing features and which is light in weight.
  • Yet a further object of the present invention is to provide an improved sealing construction for a gas-filled terminal bushing.
  • Another object of the present invention is to provide an improved gasketed sealing construction, or a soldersealed sealing construction, suitable for long operational life, and which will require a minimum of maintenance.
  • Still another object of the present invention is to provide an improved gas-filled terminal bushing adaptable for various current and voltage ratings by suitable dimensioning of the several component parts.
  • Conventional terminal bushings generally use solid or liquid materials for the insulation to prevent electrical breakdown between the axially extending conductor and the ground flange.
  • the materials generally used are porcelain, paper, plastic, oil, etc. The processing, curing, forming and the manufacturing assembly of these materials are very difficult and costly.
  • the conventional terminal bushing requires a filling material between the solid insulation and the porcelain shell. A gauge is generally needed to determine the level of the filler, and a chamber is necessary to take care of the filler expansion, as required.
  • Solid insulation bushings are always subject to voids forming or to localized dielectric heating, which may cause permanent damage to the insulation.
  • the dielectric gas serves as the insulation medium between the internal conductor and the ground flange to prevent electrical breakdown.
  • a vacuum may be pulled upon the terminal bushing to remove the air, and the insulating gas may be pumped, or released into the terminal bushing from a high-pressure vessel, or the gas may be admitted from an adjacently associated gasfilled electrical apparatus.
  • the gas itself has an economical advantage over solid insulation material costs, and treating and manufacturing costs.
  • An ancillary object of the present invention is to provide an improved gas-filled terminal bushing which may be associated with gas-filled electrical apparatus, in which construction the terminal bushing is provided with gas from the gas-filled electrical apparatus, so that upon breakage of any portion of the terminal bushing, the alarm system provided for the gas-filled electrical apparatus will be actuated by the loss of gas pressure from the gas leaking through the bushing, and thereby permit the use of a singl-e alarm apparatus for two diiferent types of gasfilled apparatus, namely the gas-filled enclosure with its electrical apparatus and the associated gas-filled terminal bushing.
  • Still a further object of the present invention is to provide an improved gas-filled terminal bushing in which the communicating passage for filling the gas-filled terminal bushing is disposed at the upper end of the conducting stud, so that when a heavy dielectric gas, heavier than air, is employed, removal of the dielectric gas from the electrical apparatus will permit the heavy gas within the terminal bushing to remain in place unaffected by the withdrawal of the dielectric gas from the associated gas filled electrical apparatus.
  • the present invention has particular applicability when employed with gas-filled circuit interrupting structures of the type set forth in US. patent application filed January 23, 1959, Serial No. 788,668, by Russell N. Yeckley, Joseph Sucha and Benjamin P. Baker, and assigned to the assignee of the instant application.
  • a three-pole circuit-interrupting structure comprising metallic tanks filled with sulfur-hexafiuoride (SP gas, and this extinguishing gas serves not only as an interrupting gas, but also as a dielectric gas for insulating the high-voltage parts, disposed interiorly within the metallic tanks, from the grounded tanks.
  • SP gas sulfur-hexafiuoride
  • a more specific object of the present invention is to provide an improved surface-treating construction for the porcelain shell of a terminal bushing, which is immersed into a sulfur-hexafiuoride gas atmosphere which may be subjected to arcing.
  • FIGURE 1 is a perspective view of a three-pole, gasfilled, power circuit interrupter utilizing terminal bushings of the type proposed by the present invention
  • FIGS. 2A and 2B collectively illustrate a partial vertical sectional view taken through the improved terminal
  • FIG. 5 is a top plan view of the terminal bushing of I FIGS. 2A and 2B;
  • FIG. 6 is a considerably enlarged, vertical sectional, fragmentary view through the potential-tap assembly of the improved terminal bushing
  • FIG. 7 is a side elevational view of the potential-tap receptacle assembly associated with the potential-tap assembly of the bushing;
  • FIG. 8 is a fragmentary sectional illustration of the use of a filter cartridge associated with the lower end of the terminal bushing of FIG. 23;
  • FIGS. 9 and 10 fragmentarily illustrate, in section
  • FIG. 11 is a side elevational view of a potential-tap
  • the reference numeral 1 generally designates a high-voltage, high-power fluid-blast circuit interrupter, adaptable for the control of a three-phase transmission circuit, whose lines are indicated by the reference characters L L L L L L As noted in FIG. 1,
  • pole-units may generally be designated by the letters A, B and C.
  • the pole-units are identical in construction; consequently, a description of the operation of one pole-unit will suflice for an understanding of the operation of all the pole units.
  • a weatherproof enclosing tube 3 encloses an axially-movable operating rod, which mechanically interconnects the three-pole units A, B and C for simultaneous operation, so that there is no relaying difliculty.
  • An acceleratingspring housing 3a is disposed at the end of the stationary weatherproof tube 3, within which is disposed an opening accelerating spring, which biases the enclosed operating rod to the right, as viewed in FIG. 1.
  • a mechanism and gas-control housing 4 is disposed adjacent to the tank structure 2 of front pole-unit A, ,and not only houses a rather conventional pneumatic mechanism for effecting the axial motion of the enclosed operating shaft within tube 3, but also the housing 4 encloses the equipment employed for maintaining the dual-pressure, gas-supply system at the desired pressures.
  • Each of the tank structures 2 includes a generallyrhoriz'ontally extending, cylindrical tank portion 5, which has a pair of hinged closure caps 6 at its opposite ends.
  • the hinged closure caps, or heads 6, may be swung to an open position about their hinges, to permit the lateral withdrawal of an arc-extinguishing assemblage from the tank structure 2 during maintenance operations.
  • Each tank structure 2 is preferably supported by flange plates 8, which may be welded to longitudinally extending steel beams 10, which extend beneath all three poleunits A, B and C.
  • a crane may be employed to bodily lift the pair of steel beams 19, together with the several tank structures 2 and the housing 4, to permit the bodily placement of the circuit interrupter 1 upon a mounting slab of concrete, or the like, as well known by those skilled in the art.
  • FIG. 1 shows a pair of upstanding cylindrical steel positioning supports 11, disposed adjacent opposite ends of the centrally situated cylindrical tank portion 5, to permit the mounting of a pair of terminal bushings, gen- 4 erally designated by the reference numerals 12, 13, to the lower internal ends 12A (FIG. 2B) of which is detachably secured the longitudinally extending multi-break arc-extinguishing assemblage, to which reference has been previously made.
  • Through-type current transformers 14 encircle the terminal bushings 12, 13 of FIG. 1 to provide relaying protection, as is well known by those skilled in the art. There is suflicient clearance between the inner diameter of the current transformers 14 and the weather sheds 12B, 13B
  • the mechanism housing 4 has hinged doors 15, opened by handles 16.
  • the circuit interrupter 1 which is of the fluid-blast type, because of its light-weight and portability may be placed upon mounting slabs previously employed for oil circuit breakers of the tank-type for the same voltage and current rating.
  • the fluid-blast circuit interrupter 1 is of such unusually small size, compared to conventional fluid-blast circuit breakers of the prior art, that its dimensions enable the substitution of it for oil circuit breakers of the same rating.
  • the longitudinally extending, multi-break arc-extinguishing assemblage extends substantially coaxially along the center of the central cylindrical portion 5 of the tank structure 7.. Reference may be had to the aforesaid application for details of the multi-break arc-extinguishing assemblage, which is secured to the lower interior ends 12A, of the terminal bushings 12, 13 respectively.
  • the multi-break arc-extinguishing assemblage includes interrupting ability adaptable for the current and voltage rating shown, namely 230 kv., 15,000 mva.
  • the operating mechanism disposed within the mechanism cabinet 4 is such as to effect axial movement of the operating rod disposed within the enclosing tube 3, and, through suitable linkage, to effect opening of the contact structure associated with each of the arc-extinguishing assemblages, not shown, disposed coaxialiy along the central portions 5 of each tank structure 2.
  • the mechanism is operable to effect opening of the blast valve associated with a high-potential, gas-storage chamber, which constitutes one end of the arc-extinguishing assemblage.
  • the release of a blast of high-pressure gas from such storage chamber through blast tubes associated with the arc-exwhich the exhaust gas discharges, may be of a considerably lower pressure, say 30 p.s.i.
  • Suitable compressor equipment is provided within the mechanism compartment 4 to receive the low-pressure exhaust gas and to recompress it, forcing the recompressed high-pressure gas back into an auxiliary highpressure storage tank, not shown, which subsequently feeds such high-pressure gas back into the high-pressure high-voltage storage tank associated with each of the arc-extinguishing assemblages for each pole-unit.
  • auxiliary highpressure storage tank not shown
  • the gas disposed within the tank structures 2 is a suitable dielectric gas, which also has considerable arc-extinguishing ability.
  • a gas may be sulfur-hexafluoride gas (SP or selenium-hexafluoride gas (SeF or a mixture of one or both of such gases with air, carbon dioxide, helium, argon, or nitrogen.
  • SP sulfur-hexafluoride gas
  • SeF selenium-hexafluoride gas
  • Other gases conceivably may be employed providing they have the desired dielectric and arc-extinguishing characteristics.
  • the present invention is particularly concerned with the construction of the terminal-bushing structures 12, 13, and their constructional features constitute, partially, the subject matter of the present invention.
  • the gas filled terminal bushing 12 is of extremely simple construction, and also involves relatively few parts in comparison with conventional terminal bushings, which employ solid or liquid dielectric associated with the bushing.
  • a hollow tubular terminal lead 17 Threadedly secured, as at 18, to the lower interior end of the terminal lead 17, is a bottom terminalplate portion 19, provided with a gasket and supporting a lower porcelain shell, or enclosure 21. As shown, the lower porcelain shell 21 is provided with a plurality of sheds, or skirts 21A to increase the creepage distance axially along the terminal bushing 12.
  • the upper end of the lower porcelain shell 21 abuts a second gasket 22, which, in turn, is forced under pressure against a plate-like supporting flange 23 at ground potential.
  • a second gasket 22 Secured, as by welding, to the upper surface 24 of the grounded support flange 23 are a plurality, in this particular instance four, supporting arms 25, which serve to support, in an operative position, the through-type current transformers 14 shown in FIG. 1 of the drawings.
  • the laterally extending supporting arms 25 are provided with notches 26 to permit the transportation of the terminal bushing 12 by a sling carried by a suitable crane.
  • an upstanding cylindrical support 27 to the upper end of which is secured, as by welding, an outwardly extending flange ring 28.
  • the flange ring 28 is provided with a gasket 22 disposed within a suitable groove, and the gasket 2.? is arranged to be forced under pressure against the lower side or" the upper porcelain shell 30.
  • the upper porcelain shell is provided with petticoats, or skirts 123 to increase the creepage distance.
  • another gasket 31 Disposed at the upper end of the upper porcelain 30 is another gasket 31, which is disposed within a suitable groove provided in a cap bowl 32.
  • FIG. 3 which shows more clearly the construction of the upper cap-bowl assembly 33, and the detailed component parts of the sealing gasket 31, it will be observed that a plurality of compression springs 34 are utilized to exert compressive force through the porcelain shells 21, so and through the grounded flange assembly 35, comprising the flange rings 23, 28 and the upstanding cylindrical support 27.
  • the interior centrally-disposed terminal lead 1'7 is placed under tension, whereas the porcelain shells, 21, 30 maintain the gaskets 2G, 22, 29 and 31 under compressive force, ensuring thereby a fluid-tight sealed arrangement.
  • tubular terminal lead 17 is threadedly secured, as at 36, to a spring-seat and terminal assembly, generally designated by the reference numeral 37, and including a laterally extending flange-plate portion 38, against which the upper ends of the several compression springs 34 seat.
  • a spring-seat and terminal assembly generally designated by the reference numeral 37, and including a laterally extending flange-plate portion 38, against which the upper ends of the several compression springs 34 seat.
  • insulating bushings 34a are interposed between the upper ends of the springs 34 and the conducting plate portion 38.
  • a gas-communication hole 39 constituting a passage means, is provided in the terminal assembly 37, and permits the communication of gas from the region 4%) (FIG. 2B), interiorly of the gas-filled apparatus 1, upwardly through the open lower end 61 of the tubular terminal lead 17, into the interior 41 thereof, through the gascommunication hole 39 (FIG. 3), into the region 42, and downwardly past the flange portion 38 of terminal 37 and into the region 43 between the terminal lead 17 and the porcelain shells 21, 3t).
  • a plurality of removable spring bolts 45 are employed to effect preco-mpression of the compression springs 34 prior to the assembling of the bushing 12.
  • the spring-seat and terminal assembly 37 is assembled to the cap bowl 32 in a previous assembly operation.
  • the spring bolts 45 are employed, one for each compression spring 34, and the tightening of the spring bolts 45 ensures a predetermined precompression of the springs 34.
  • the terminal lead 17 is screwed to the lower terminal plate 19
  • lower porcelain shell 21 is mounted
  • central grounded flange assembly 35 is positioned into place, upper porcelain shell 30, and following cementing of the gaskets 31a- 310 (FIG.
  • the spring bolts 45 are unscrewed and are not employed as a further constructional part of the terminal bushing 12, as indicated in FIG. 2A of the drawings.
  • the spring bolts 45 are only utilized for the precompression of the springs 34.
  • a flexible sealed joint comprising a thin metallic diaphragm 47.
  • the outer peripheral edge 43 of the diaphragm 47 is sealed, as by solder 49 (FIG. 3), within a groove 50, provided at the upper peripheral edge 51 of the spring bowl 32.
  • the inner peripheral edge 52 of the diaphragm 47 is secured, as by a soldered connection 52a, to a sleeve 53, which is threaded, as at 54 to the upper threaded portion of the upper terminal assembly 37, as shown in FIG. 3.
  • a reinforcing soldered connection 53a is superimposed upon the threaded connection at 54 to ensure a long-lasting fluid-tight seal.
  • a plate-like back-up shield 56 is screwed, as at 57, onto the threaded end 55 of the terminal member 37. The back-up shield 56 ensures that the diaphragm 47 will not unduly expand during high-pressure conditions existing within the region 43 internally of the bushing structure 12.
  • the terminal bushing 12 may receive its gaseous dielectric from the gas-filled electrical apparatus 1, with which it is employed.
  • the terminal bushing 12 may be filled, through a plugged opening 58 provided at the lower end of the lower terminal 19, and a suitable plug 59 (FIG. 2B) may be employed, screwed into a lower threaded end 60 of the hollow terminal lead 17
  • the gas-filled terminal bushing 12 constitutes a separate piece of equipment, which may be pneumatically isolated from the equipment, with which it is associated. Loss of gas from the associated gas-filled apparatus will. not, under such circumstances, affect the integrity of the terminal bushing 12, since it is a totally sealed item.
  • one, or a plurality of plugged bushings 12 could be connected by a pipe connection 23a, through a valve 23b from atank of filling gas 44, as indicated in FIG. 2B.
  • the flange plate 23 may have a bored passage 23c registering with the pipe connection 23a. Branch connections 23d could lead to other similar gas-filled bushings 12.
  • a pressure gauge 9 may be employed to measure the pres sure internally of the bushing, as indicated in FIG. 2A.
  • the cartridge 63 includes a tubular enclosure, such as a tube 64, inserted as by a press fit or a threaded connection at 65 within the lower end of the terminal stud 17.
  • Activated alumina powder 62 may be maintained within the cartridge '63 by employing suitable end screens 66, closing the ends of the metallic tube 64.
  • the activated alurnina cartridge 63 has the additional advantage of absorbing any arced products of decomposition from the SP gas. As a result, only clean, filtered gas of high dielectric strength is permitted to enter into the interior 43 of the terminal bushing 12.
  • FIG. 3 also shows in greater detail the gasket sealing arrangement 31 of FIG. 2A, involving a pair of ringshaped O-gaskets 31a, 31b of resilient material, with a stop gasket 310.
  • the stop gasket 31c prevents the porcelain casing 30 from striking the lower metallic surface 32a of the spring bowl 32.
  • the two resilient O-gaskets 31a, 31b provide double protection, and the leak-detecting bore 67 enables the insertion of a leak detector to determine whether any gas has accumulated past the inner O-ring gasket 31a.
  • the leak-detecting bore 67 has a plug 68 associated therewith.
  • the leak-detecting bore construction is set forth and claimed in US. patent application, filed November 27, 1959, Serial No. 855,760, by Benjamin P. Baker, and assigned to the assignee of the instant application.
  • FIGS. 9 and 10 of the drawings For certain applications it may be desired to use a solder-sealed construction, such as illustrated in FIGS. 9 and 10 of the drawings.
  • an annular sealing ring 69 is employed, which is solder-sealed to the lower end of the porcelain casing 30.
  • the solder-sealed methods set forth in United States Patent 1,852,093 issued April 5, .1932, to Lloyd Smede and Errol B. Shand, and assigned to the assignee of the instant application, may be employed.
  • a flexible ring gasket 70 formed of neoprene, for example, may be employed for sealing, together with a stop gasket 71 to prevent actual contact of the porcelain casing 30 with the flange plate 28.
  • the solder-sealed connection 74 may be employed in conjunction with the lower end of the porcelain shell 30.
  • a metallic sealing ring 76 may be solder-sealed, as at 77, to the upper end of the porcelain casing '30.
  • the outer peripheral edge 78 of the sealing ring 76 may be solder-sealed as at 79 to the outside surface of the cap bowl 32.
  • a stop gasket 84 and a resilient O-ring 75 may be employed, as shown.
  • Packing 72 may be associated with the solder seal 79.
  • a potential-tap assembly is associated with the grounded flange assembly 35 of the terminal bushing 12.
  • a potential cylinder 89 composed of a suitable metallic material, such as aluminum, for instance, is provided interiorly within the cylindrical upstanding support 27.
  • the potential cylinder 89 is maintained in a proper position by a pair of insulating annular support members 90, 91, which are maintained in position by suitable machine screws 92.
  • the potential cylinder 89 is electrically isolated from the grounded supporting cylinder 27.
  • An electrical connection is made to the potential cylinder 89 interiorly of the bushing structure 12 by means of a compression spring 93, which may be formed of any suitable metallic material, such as stainless steel.
  • the contacting compression spring 93 is enclosed within a surrounding insulating tube 94, which is inserted into a bore 95 provided laterally in the ground flange ring 23.
  • a contact 96 Associated with the outer end of the compression spring 93 is a contact 96, which makes electrical connection with a potential-tap receptacle assembly, generally designated by the reference numeral 97, and including an interiorly disposed electrically insulated socket tap, not shown, which may be electrically connected with a potential tap ground plug 98 (FIG. 1 1), when it is not desired to use the potential-tap assembly 88.
  • the glaze would be omitted from the external surface of the lower, immersed shell 21, and the nontracking liquid coating 7, set forth below, applied.
  • the lower shell 21 is highly resistant to corrosive action of the arced SP gas, and has long operational life.
  • the activated alumina cartridge 63 will prevent the arced SF,- gas from adversely aifecting the inner surfaces of the bushing, so these surfaces have not been found to require a protective coating.
  • the applied coating is prepared according to theteachings set forth in United States patent application filed September 15, 1959, Serial No. 840,086, (now abandoned) by Jacob Chottiner, Ben Moreland and Byron V. McBride, entitled Electrically Insulating Coating Composition, and assigned to the assignee of the instant application.
  • liquid coating compositions which are suitable for use in accordance with this invention consist essentially of (A) from 4% to 36% by volume of at least one resinous polymeric epoxide, (B) from 4% to 36% by volume of a polyamide derived by reacting diethylene triamine with linolenic acid, (C) from 2% to 48% by volume of finely divided aluminum oxide trihydrate and (D) the balance solvent.
  • Part A Percent by weight Polymeric epoxide 33.3 Polyamide resin 33.3 Aluminum oxide trihydrate 33.3
  • Part B V Xylene 80 Cellosolve The composition is prepared by admixing equal parts by weight of Part A and Part B.
  • the novel terminal bushing 12 of the present invention consists mainly of three main parts, these being the terminal conductor 17, the shell enclosure, including the two porcelain shells Z1, and the interiorly disposed dielectric gas.
  • the hollow terminal lead 17 extends the full length of the terminal bushing 12. and serves a dual purpose. First, it is a mechanical member, and with the spring-cap construction 33 holds the terminal bushing together under continuous pressure, thereby maintaining constant pressure on the gasketed seals 20, 22, 29 and 31.
  • the terminal stud 17 provides an electrical voltage and current path through the terminal bushing 12.
  • the shell enclosure consists of the two end terminals 19, 37, the two porcelain weather casings 21, 30 and the mounting ground-flange assembly 35. Gaskets, solder and welded joints are used to make the shell enclosure gas-tight. It is very essential for the terminal bushing 12 to be tight and not to leak gas.
  • stop gaskets 31c, 71 are employed to prevent porcelain contact with metal, which could cause fracture to the vitreous porcelain.
  • the resilient gaskets 31a, 31b are confined in their grooves and are compressed to make the gas-tight seal. Soldersealed construction may, when desired, be employed, as shown in FIGS. 9 and 10.
  • a metallic collar 69 or 76 is soldered directly to the porcelain and then to the adjacent metal part.
  • This arrangement gives a hermetically-sealed joint with long service life. 7 v v
  • the dielectric gas fills the space 43- between the internal conductor 17 and the interior walls of the shell enclosure.
  • the gas may be used at atmospheric pressure, or at any pressure above atmospheric pressure,'a s desired, to get the best electrical characteristics.
  • Conventional bushings use solid or liquid materials for the insulation to prevent electrical breakdown between the conductor 17 and the ground-flange assembly. These materials are porcelain, paper, plastic, oil, etc. The processing, curing, forming and the manufacturing assembly of these materials are very diflicult and costly.
  • the conventional terminal bushing requires a filling material between the solid insulation and the porcelain shell. A gauge to determine the level of the filler is needed, and a chamber is necessary to take care of the filler expansion, which may result upon temperature cycling.
  • the dielectric gas serves as the 1Q insulation medium between the conductor 17 and the ground-flange assembly 35 to prevent electrical breakdown.
  • a vacuum is pulled upon the terminal bushing 12 to remove the air, and the insulating gas is pumped, or released from a high-pressure vessel into the terminal bushing 12 without any diflicult manufacturing operations. No processing, impregnating, curing, etc. are required, and the production-assembly time for the terminal bushing 12 is greatly reduced.
  • the gas itself also has quite an economical advantage over solid insulation material cost, and treating and manufacturing costs.
  • the terminal bushing of the present invention can be filled with gas pressure and completely sealed by usage of the plug 59, so as to be a self-sustained unit and operate as a separate piece of apparatus.
  • the terminal bushing 12 may also be used with an opening 61 (FIG. 2B) and be filled and operated from the same gas as used in the gas-filled apparatus, to which the bushing 12 may be applied.
  • the gas insulation is self-healing and does not require repairing or replacing damaged insulation. Gas does not form voids or have localized hot spots. Neither does the gas deteriorate with age nor develop progressive electrical puncture through the body, or creep over the surface as can occur on bushings with organic materials for the insulation. Gas has a favorable characteristic for ionizing around sharp or rough parts of the electrodes, and forms what is equivalent to a semiconducting smooth radius area that prevents further overstress, that may cause electrical failure or radio influence.
  • the proposed terminal bushing of the present invention has a ground-flange sleeve 27, which will take the regular bushing current transformer 14.
  • a potential tap can be used with the gas-filled bushing by taking a potential from a cylinder 89 inserted inside the flange sleeve 27 and insulated from the flange.
  • gas-filled bushing over the conventional bushings is the absence of paper, oil, compounds, etc., which support combustion in case of fire, and can be a considerable hazard to the electrical apparatus and operating conditions.
  • the materials for the proposed gas filled bushing 12 are preferably noninflammable.
  • the proposed gas-filled bushing offers a bushing with good electrical characteristics, simple of design, of very economical construction, having desirable manufacturing features and is very light in weight.
  • gas-filled terminal bushing of the present invention is not confined to use on gas-filled circuit-interrupting structure, but may also be employed on other types of apparatus, such as power transformers.
  • the power transformer is [gas-filled
  • the gas from the transformer may be employed to fill the terminal bushing 12, as was the case with the gas-filled circuit-interrupting apparatus of FIG. 1.
  • any sudden pressure arising within the tank structures 2 during interrupting conditions will not be transmitted immediately to the porcelain shells 21, 30, which might result in their fracture.
  • the small gas communication hole 39 permits only a gradual transmission of gas flow from the gas-filled apparatus 1 into the interior of the terminal bushing construction.
  • this loss of pressure would withdraw more gas from the tank structure 2 into the terminal bushing 12, and this process would trip the circuit-breaker alarm system.
  • the single alarm system for the circuit-interrupting structure 1 serves not only as an alarm for the tank structures 2, but also for the terminal bushings 12, 13 themselves.
  • the employment of a heavy gas, such as SP will permit the terminal bushing 12 to be removed from the gas-filled apparatus 2, or from a gas-filled power transformer apparatus, with which it may possibly be associated, and due to the heavy weight of the gas, the gas disposed within the interior 43 of the terminal bushing would not tend to fiow out of the terminal bushing 12 following its removal from the associated gas-filled apparatus. If the opening 39 were disposed at the lower end of the ter' rninal bushing 12, the heavy gas might leak out of the terminal bushing 12 following its removal from the gastilled apparatus.
  • the terminal bushing 12 may be removed from the gas-filled apparatus without fear of loss of the gas within the bushing, and entrance of contaminated air, possibly moistureladen.
  • any good dielectric gas may be employed, such as sulfur-hexafluoride (SP selenium hex-afluoride (SeF or mixtures of either one or both of said gases with nitrogen, air, argon, helium and carbon dioxide.
  • SP selenium hex-afluoride SeF or mixtures of either one or both of said gases with nitrogen, air, argon, helium and carbon dioxide.
  • CCI F octofluoropropane C F Freon 12
  • CSF trifluoromethyl sulfur pentafluoride
  • gas-filled electrical apparatus such as a circuit interrupting structure, transformer struc ture, or the like and a gas-filled terminal bushing associated with said gas-filled electrical apparatus of gas passage meansinterconnecting the gas-filled electrical apparatus and the gas-filled terminal bushing, whereby the gas-filled terminal bushing obtains its dielectric gas from the gas-filled electrical apparatus through said gas passage means, the conductor stud of the gas-filled terminal bushing lbeing tubular and constituting a part of said gas passage means, and a filter cartridge disposed within said tubular conductor stud to filter the gas entering the gas-filled terminal bushing.
  • gas-filled electrical apparatus such as a circuit interrupting structure, transformer struc ture, or the like
  • gas-filled terminal bushing associated with said gas-filled electrical apparatus of gas passage meansinterconnecting the gas-filled electrical apparatus and the gas-filled terminal bushing, whereby the gas-filled terminal bushing obtains its dielectric gas from the gas-filled electrical apparatus through said gas passage means, the conductor stud of the gas-filled terminal bushing
  • a gas-filled terminal bushing including a compression spring assembly disposed adjacent one end thereof, an elongated tubular gas conducting conductor stud secured to the compression spring assembly at one end thereof, a pair of surrounding insulating shells one of which engages said compression spring assembly in abutting fashion, a ground flange assembly interposed between the pair of insulating shells, a terminal plate assembly secured to the other end of said elongated tubular gas conducting conductor stud and engaging the other insulating shell in abutting fashion, said compression spring assembly including a spring plate flange portion having a restricted opening provided therein, which communicates with the space interiorly of the tubular gas conducting conductor stud, the other end of said restricted opening communicating with the space interiorly of the pair of insulating shells whereby gas may fill the interior of the terminal bushing for increasing the dielectric strength therein, and the compression spring assembly subjecting the tubular gas conducting conductor stud to tensile stress and the shells in flange assembly to compressive stress, and said dielectric gase
  • a gas-filled terminal bushing construction wherein a pair of insulating shells and an interposed ground flange assembly surround a bare axially extending conductor stud, characterized by the combination of a potential tap assembly including an electrically floating metallic potential cylinder disposed inside of the ground flange assembly yet spaced therefrom, said bare metallic potential cylinder being wholly disposed interiorly of the pair of shells and ground flange assembly, means for fixedly mounting said electrically floating metallic bare potential cylinder into a relatively fixed position comprising a pair of insulating annular support members, and means for securing said pair of insulating annular support members adjacent opposite ends of said interposed ground flange assembly.
  • gas-filled electrical apparatus such as circuit-interrupting structure, transformer structure, or the like including a tank filled with dielectric gas, a gas-filled terminal bushing extending through the wall of said tank and secured thereto, a tubular conductor stud extending axially through the gas-filled terminal bushing for carrying electrical current from exteriorly of said tank to the region interiorly thereof, gas-passage means inter-connecting the interior of said gas filled tank and the interior of the gas-filled terminal bushing whereby the gas-filled terminal bushing obtains its dielectric gas from the gas-filled electrical apparatus, and said tubular conductor stud being the sole communicating gas-passage means between the gas-fi1led electrical apparatus and the interior of the gas-filled terminal bushing.

Landscapes

  • Insulators (AREA)
  • Gas-Insulated Switchgears (AREA)
US856775A 1959-12-02 1959-12-02 Terminal-bushing constructions Expired - Lifetime US3059044A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
US856775A US3059044A (en) 1959-12-02 1959-12-02 Terminal-bushing constructions
DEW28821A DE1193568B (de) 1959-12-02 1960-10-31 Durchfuehrung fuer elektrische Geraete, insbesondere Leistungsschalter, die ein gas-foermiges Isoliermittel enthalten
CH1278660A CH388407A (de) 1959-12-02 1960-11-15 Elektrische Durchführung
FR845663A FR1279539A (fr) 1959-12-02 1960-12-01 Manchons de borne
JP5726560A JPS3618582B1 (US06582424-20030624-M00016.png) 1959-12-02 1960-12-02
JP4726460A JPS371397B1 (US06582424-20030624-M00016.png) 1959-12-02 1960-12-02

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US856775A US3059044A (en) 1959-12-02 1959-12-02 Terminal-bushing constructions

Publications (1)

Publication Number Publication Date
US3059044A true US3059044A (en) 1962-10-16

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US856775A Expired - Lifetime US3059044A (en) 1959-12-02 1959-12-02 Terminal-bushing constructions

Country Status (5)

Country Link
US (1) US3059044A (US06582424-20030624-M00016.png)
JP (2) JPS3618582B1 (US06582424-20030624-M00016.png)
CH (1) CH388407A (US06582424-20030624-M00016.png)
DE (1) DE1193568B (US06582424-20030624-M00016.png)
FR (1) FR1279539A (US06582424-20030624-M00016.png)

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3126439A (en) * 1964-03-24 High-voltage electrical insulating bushing
US3129310A (en) * 1961-06-01 1964-04-14 Westinghouse Electric Corp Potential-tap assembly for relatively high-voltage equipment
US3160701A (en) * 1960-11-14 1964-12-08 Westinghouse Electric Corp Electrical apparatus
US3178504A (en) * 1962-04-30 1965-04-13 Westinghouse Electric Corp Pressure-cap assembly for terminal bushings
US3178505A (en) * 1962-05-09 1965-04-13 Westinghouse Electric Corp Terminal-bushing construction
US3214546A (en) * 1961-10-12 1965-10-26 Westinghouse Electric Corp Compressed-gas circuit interrupters having improved arc-extinguishing means
US3529072A (en) * 1968-03-25 1970-09-15 Westinghouse Electric Corp High-mechanical-strength terminal bushing having bushing body portion fixedly supported by flangetube assembly and flexible casing support
US3674964A (en) * 1971-05-20 1972-07-04 Gen Electric High voltage electric circuit breaker with rapid response tripping means
US4052555A (en) * 1975-07-23 1977-10-04 Allied Chemical Corporation Gaseous dielectric compositions
US4071461A (en) * 1975-06-23 1978-01-31 Allied Chemical Corporation Gaseous dielectric mixtures for suppressing carbon formation
US4166798A (en) * 1978-08-21 1979-09-04 Allied Chemical Corporation Electrical device with fluorinated divalent sulfur dielectric gas
US4204084A (en) * 1978-06-26 1980-05-20 Allied Chemical Corporation Apparatus with dielectric gas mixtures in substantially uniform field
US4275260A (en) * 1979-09-04 1981-06-23 Electric Power Research Institute, Inc. Dielectric gas mixture containing trifluoronitromethane and/or trifluoromethanesulfonyl fluoride
WO1995022158A1 (en) * 1994-02-14 1995-08-17 Abb Power T & D Company Inc. High performance circuit breaker with independent pole operation linkage and conical composite bushings
US5576523A (en) * 1994-02-14 1996-11-19 Abb Power T&D Company, Inc. Independent pole operation linkage
US20090179011A1 (en) * 2008-01-10 2009-07-16 Thangavelu Asokan Ablative-based multiphase current interrupter
US20170287588A1 (en) * 2014-12-12 2017-10-05 Abb Schweiz Ag Apparatus for the generation, distribution and/or usage of electrical energy and component for such an apparatus
US20180247757A1 (en) * 2015-10-20 2018-08-30 Abb Schweiz Ag Dry type cast transformer with flexible connection terminal

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2622738B1 (fr) * 1987-11-04 1990-01-12 Alsthom Procede de mise en place d'un tamis moleculaire dans un appareil electrique tel qu'un disjoncteur et appareil ainsi equipe
FR2631153B1 (fr) * 1988-05-06 1991-03-15 Dervieux Sarl Ets Paul Dispositif de deroulage d'un cable electrique aerien a emmanchement rapide sur la tige de fixation de l'isolateur, et tige de fixation correspondante
FR2965120B1 (fr) 2010-09-22 2012-10-12 Areva T & D Sas Appareil de coupure d'un courant electrique de moyenne ou haute tension et son procede de fabrication

Citations (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1703409A (en) * 1921-03-02 1929-02-26 Products Prot Corp High-voltage terminal
US1788873A (en) * 1928-01-20 1931-01-13 Condit Electrical Mfg Corp Insulating bushing and electrostatic potential transformer
USRE18189E (en) * 1931-09-15 Means por supporting baffles in oil-filled bushings
US1983370A (en) * 1932-04-18 1934-12-04 Ohio Brass Co Bushing insulator
GB449842A (en) * 1934-06-30 1936-07-06 British Thomson Houston Co Ltd Improvements in and relating to bushing insulators for electric apparatus
US2082055A (en) * 1936-03-27 1937-06-01 Ohio Brass Co Bushing insulator
US2125089A (en) * 1936-10-09 1938-07-26 Westinghouse Electric & Mfg Co Bushing structure
US2160660A (en) * 1937-09-23 1939-05-30 Gen Electric High potential terminal
US2308022A (en) * 1940-07-19 1943-01-12 Westinghouse Electric & Mfg Co Insulating bushing
CH246358A (de) * 1941-12-08 1946-12-31 Secheron Atel Elektrische Vorrichtung mit einem unter innerem Überdruck stehenden Behälter, in welchem Hochspannung führende Teile der Vorrichtung untergebracht sind, und Verfahren zu deren Herstellung.
US2508184A (en) * 1946-02-01 1950-05-16 Westinghouse Electric Corp Bushing mounting structure
US2523082A (en) * 1946-11-30 1950-09-19 Gen Electric Surface coated electrical bushing
US2528934A (en) * 1949-04-29 1950-11-07 Shell Dev Adhesive composition containing a fluidized glycidyl ether and an amphoteric oxide
US2705223A (en) * 1952-03-11 1955-03-29 Gen Mills Inc Thermosetting resinous compositions from epoxy resins and polyamides derived from polymeric fat acids
GB791205A (en) * 1956-07-30 1958-02-26 Gen Electric Improvements relating to the insulation of electrical apparatus by a gaseous dielectric
US2853538A (en) * 1953-09-28 1958-09-23 Westinghouse Electric Corp Electrical bushings
US2859269A (en) * 1955-01-25 1958-11-04 Gen Electric High voltage bushing
US2889395A (en) * 1954-08-31 1959-06-02 Westinghouse Electric Corp Bushing for electrical apparatus
US2916723A (en) * 1955-08-31 1959-12-08 Gen Electric Low voltage outlet bushing
US2937359A (en) * 1956-05-31 1960-05-17 Gen Electric Power factor tap for high voltage bushing

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1852093A (en) * 1928-11-07 1932-04-05 Westinghouse Electric & Mfg Co Article of manufacture and process of making it
DE962992C (de) * 1942-05-10 1957-05-02 Hein Lehmann & Co Eisenkonstru Biegungsfeste Isolationsstelle
DE915355C (de) * 1944-04-29 1954-07-19 Siemens Ag Durchfuehrung fuer hohe Gleichspannungen
DE957314C (de) * 1952-09-07 1957-01-31 Dielektra Ag Gas- und fluessigkeitsdichte Befestigung eines Durchfuehrungsisolators in einer Gehaeusewand
US2933551A (en) * 1954-10-28 1960-04-19 Westinghouse Electric Corp Terminal-bushing with means for controlling magnetic heating

Patent Citations (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USRE18189E (en) * 1931-09-15 Means por supporting baffles in oil-filled bushings
US1703409A (en) * 1921-03-02 1929-02-26 Products Prot Corp High-voltage terminal
US1788873A (en) * 1928-01-20 1931-01-13 Condit Electrical Mfg Corp Insulating bushing and electrostatic potential transformer
US1983370A (en) * 1932-04-18 1934-12-04 Ohio Brass Co Bushing insulator
GB449842A (en) * 1934-06-30 1936-07-06 British Thomson Houston Co Ltd Improvements in and relating to bushing insulators for electric apparatus
US2082055A (en) * 1936-03-27 1937-06-01 Ohio Brass Co Bushing insulator
US2125089A (en) * 1936-10-09 1938-07-26 Westinghouse Electric & Mfg Co Bushing structure
US2160660A (en) * 1937-09-23 1939-05-30 Gen Electric High potential terminal
US2308022A (en) * 1940-07-19 1943-01-12 Westinghouse Electric & Mfg Co Insulating bushing
CH246358A (de) * 1941-12-08 1946-12-31 Secheron Atel Elektrische Vorrichtung mit einem unter innerem Überdruck stehenden Behälter, in welchem Hochspannung führende Teile der Vorrichtung untergebracht sind, und Verfahren zu deren Herstellung.
US2508184A (en) * 1946-02-01 1950-05-16 Westinghouse Electric Corp Bushing mounting structure
US2523082A (en) * 1946-11-30 1950-09-19 Gen Electric Surface coated electrical bushing
US2528934A (en) * 1949-04-29 1950-11-07 Shell Dev Adhesive composition containing a fluidized glycidyl ether and an amphoteric oxide
US2705223A (en) * 1952-03-11 1955-03-29 Gen Mills Inc Thermosetting resinous compositions from epoxy resins and polyamides derived from polymeric fat acids
US2853538A (en) * 1953-09-28 1958-09-23 Westinghouse Electric Corp Electrical bushings
US2889395A (en) * 1954-08-31 1959-06-02 Westinghouse Electric Corp Bushing for electrical apparatus
US2859269A (en) * 1955-01-25 1958-11-04 Gen Electric High voltage bushing
US2916723A (en) * 1955-08-31 1959-12-08 Gen Electric Low voltage outlet bushing
US2937359A (en) * 1956-05-31 1960-05-17 Gen Electric Power factor tap for high voltage bushing
GB791205A (en) * 1956-07-30 1958-02-26 Gen Electric Improvements relating to the insulation of electrical apparatus by a gaseous dielectric

Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3126439A (en) * 1964-03-24 High-voltage electrical insulating bushing
US3160701A (en) * 1960-11-14 1964-12-08 Westinghouse Electric Corp Electrical apparatus
US3129310A (en) * 1961-06-01 1964-04-14 Westinghouse Electric Corp Potential-tap assembly for relatively high-voltage equipment
US3214546A (en) * 1961-10-12 1965-10-26 Westinghouse Electric Corp Compressed-gas circuit interrupters having improved arc-extinguishing means
US3178504A (en) * 1962-04-30 1965-04-13 Westinghouse Electric Corp Pressure-cap assembly for terminal bushings
US3178505A (en) * 1962-05-09 1965-04-13 Westinghouse Electric Corp Terminal-bushing construction
US3529072A (en) * 1968-03-25 1970-09-15 Westinghouse Electric Corp High-mechanical-strength terminal bushing having bushing body portion fixedly supported by flangetube assembly and flexible casing support
US3674964A (en) * 1971-05-20 1972-07-04 Gen Electric High voltage electric circuit breaker with rapid response tripping means
US4071461A (en) * 1975-06-23 1978-01-31 Allied Chemical Corporation Gaseous dielectric mixtures for suppressing carbon formation
US4052555A (en) * 1975-07-23 1977-10-04 Allied Chemical Corporation Gaseous dielectric compositions
US4204084A (en) * 1978-06-26 1980-05-20 Allied Chemical Corporation Apparatus with dielectric gas mixtures in substantially uniform field
US4166798A (en) * 1978-08-21 1979-09-04 Allied Chemical Corporation Electrical device with fluorinated divalent sulfur dielectric gas
US4275260A (en) * 1979-09-04 1981-06-23 Electric Power Research Institute, Inc. Dielectric gas mixture containing trifluoronitromethane and/or trifluoromethanesulfonyl fluoride
WO1995022158A1 (en) * 1994-02-14 1995-08-17 Abb Power T & D Company Inc. High performance circuit breaker with independent pole operation linkage and conical composite bushings
US5569891A (en) * 1994-02-14 1996-10-29 Abb Power T&D Company, Inc. High performance circuit breaker with independent pole operation linkage and conical composite bushings
US5576523A (en) * 1994-02-14 1996-11-19 Abb Power T&D Company, Inc. Independent pole operation linkage
US20090179011A1 (en) * 2008-01-10 2009-07-16 Thangavelu Asokan Ablative-based multiphase current interrupter
US7875822B2 (en) * 2008-01-10 2011-01-25 General Electric Company Ablative-based multiphase current interrupter
US20170287588A1 (en) * 2014-12-12 2017-10-05 Abb Schweiz Ag Apparatus for the generation, distribution and/or usage of electrical energy and component for such an apparatus
US10818407B2 (en) * 2014-12-12 2020-10-27 Abb Schweiz Ag Apparatus for the generation, distribution and/or usage of electrical energy and component for such an apparatus
US20180247757A1 (en) * 2015-10-20 2018-08-30 Abb Schweiz Ag Dry type cast transformer with flexible connection terminal
US10755851B2 (en) * 2015-10-20 2020-08-25 Abb Power Grids Switzerland Ag Dry type cast transformer with flexible connection terminal

Also Published As

Publication number Publication date
DE1193568B (de) 1965-05-26
FR1279539A (fr) 1961-12-22
JPS371397B1 (US06582424-20030624-M00016.png) 1962-05-02
JPS3618582B1 (US06582424-20030624-M00016.png) 1961-10-06
CH388407A (de) 1965-02-28

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