US2945912A - High voltage insulator - Google Patents

High voltage insulator Download PDF

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Publication number
US2945912A
US2945912A US436656A US43665654A US2945912A US 2945912 A US2945912 A US 2945912A US 436656 A US436656 A US 436656A US 43665654 A US43665654 A US 43665654A US 2945912 A US2945912 A US 2945912A
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US
United States
Prior art keywords
resin
insulator
insulating
insulation
high voltage
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US436656A
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English (en)
Inventor
Imhof Alfred
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Moser Glaser and Co AG
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Moser Glaser and Co AG
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Filing date
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Application filed by Moser Glaser and Co AG filed Critical Moser Glaser and Co AG
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Publication of US2945912A publication Critical patent/US2945912A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/28—Coils; Windings; Conductive connections
    • H01F27/32—Insulating of coils, windings, or parts thereof
    • H01F27/327—Encapsulating or impregnating
    • 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
    • H01B17/26—Lead-in insulators; Lead-through insulators
    • H01B17/28—Capacitor type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F38/00—Adaptations of transformers or inductances for specific applications or functions
    • H01F38/20—Instruments transformers
    • H01F38/22—Instruments transformers for single phase AC
    • H01F38/28—Current transformers
    • H01F38/30—Constructions
    • 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
    • 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
    • Y10S174/10—Bushing with current transformers

Definitions

  • the present invention relates to high voltage insulators consisting at least partly of synthetic resins and a method for manufacturing same, and more particularly to high voltage insulators for electrical apparatuses such as transformers, coup-ling condensers, dry rectifiers, and the like.
  • An embedding insulation by means of cast resins may prove diflicult, particularly in connection with very high voltages of the electrodes to be insulated.
  • the casting of large objects is dilficult owing to the contract-ion of the resin due to hardening and subsequent cooling, and owing to the thermal expansion due to fluctuations of the operating temperature. If the thermal expansion of the resin exceeds that of the metal forming the electrodes, the resin is likely to crack and break.
  • the dissipation factor (tan 6) of the known embedding casting resins is so high at the high operating voltages that it is sometimes difficult to avoid thermal break-down of the resin.
  • insulators consisting of a wound web of fabric are easily damaged. If the webs of fabric are impregnated with a liquid such as oil they have to be protected against the loss of the liquid by being placed inside a container where they may gradually absorb moisture from the liquid.
  • suitably chosen insulators consisting of wound webs of fabric have great advantages such as extremely high breakdown voltages, a low tan 6 and a high elasticity, so that they are very suitable for the embedding of field controlling coverings, wire coils, and the like.
  • the invention overcomes the disadvantages set forth hereinabove in a simple manner by providing a combined high voltage insulating covering comprising a dielectric series connection of at least one layer of a wound web of insulating fabric and a layer of casting resin enclosing the same which is at least partly under electrical stress.
  • the embedding resin forms at least the outermost layer,
  • connection combines essentially the advantages of the two dielectrics without their disadvantages.
  • the casting resin must not be porous, and since 1t has to take up a portion of the total voltage drop, it must have a dielectrically good quality.
  • such casting resins are suitable which are obtained by a poly-reaction such as a polymerization of polyaddition, from starting materials which are liquid atroom temperature or increased temperatures, particularly from castable materials which harden without splitting off any volatile components.
  • the wound insulating webs or bands consist preferably of a porous dielectric such as paper, impregnated with an insulating liquid.
  • the specific dielectrtic resistance thereof should be as large as possible, which is accomphshed by'usmg impregnating liquids having a small dielectrtic constant, such as mineral oils having a dielectric constant of 2.3 to 2.5, or liquid fiuorinated hydrocarbons, e.g. tri-perfluoro-butyl-t-amine having a dielectric con stant of 1.86.
  • laminated paper insulators have a dielectric strength which may be much higher than that of a layer of compressed gas having the same dimensions, provided that a certain ratio of the pressure to the thickness of the layer is maintained- Pai-' tieularly advantageous is the thus obtainable high shock voltage strength which, independently of the pressure and the thickness of the layer, is higher than that of the corresponding gaseous dielectric.
  • the dielectric strength of the laminated paper dielectric is further improved by permeating the paper web with a "gas or a mixture of gases.
  • Suitable gases are, for instance, gaseous halogens either by themselves or as components of a gas mixture.
  • gases such as compressed air, nitrogen, carbon dioxide under normal or elevated pressure, inert gases, or mixtures of air and gases containing chlorine and/or fluorine, furthermore chlorophenyl indane with. or without pressure. Gas pressures from 1 to approximately 25 atmospheres may be used.
  • the gas permeated paper band may be obtained by placing first the insulating bandage, then casting and hardening through the synthetic resin layer under vacuum whereupon the apparatus is filled with the .gas or gas mixture.
  • the gas. may be supplied, for instance, by means of a valve arranged in the wall ofthe cast resin, said valve being connected with a container containing the gas under pressure; ifdesired, the valve may be plugged by casting resin after the apparatus has been filled with gas.
  • the filling with compressed gas may be accomplished, for instance, by means of a small rubber plate cast into the resin wall; for filling the evacuated apparatus, said rubber plate is perforated by a hollow needle connected to a container of compressed gas. Later the perforation together with the rubber plate can be closed by casting thereinto the same resin as used for the wall.
  • the bandage is of advantage to wind the bandage as a first step, then to place the element in a casting mold, and thereafter to pour the resinous raw material into the mold. After hardening of the resinous enclosing body, the bandaged insulation is dried under vacuum; for this purpose, openings may be provided, if required, in the resinous body. Then the impregnating step is carried out.
  • insulating liquids which are incombustible or at least as heat resistant as the cast ing resin itself.
  • Such liquids are, for instance, certain fluoroethers, fluoro-amines, and fluoro-silicones.
  • I use preferably liquid materials having a boiling point as high as possible, preferably exceeding C., such as tri-perfluorohexyl-tamine or tri-perfluorobutyl-t--amine.
  • the wound insulation consists preferably of 'a heat resistant material, for instance asbestos band or glass fiber band. This is particularly to be recommended when such insulators are provided with wire turns or windings which are heated by the operating current.
  • the wound insulation may'consist also of nonporous thermoplastic materials such as polystyrene, polyethylene, tetrafiuoroethylene and fiuorochloroethylene polymers, polyvinyl chloride, polyvinylidene chloride, and others.
  • nonporous thermoplastic materials such as polystyrene, polyethylene, tetrafiuoroethylene and fiuorochloroethylene polymers, polyvinyl chloride, polyvinylidene chloride, and others.
  • non-porous foils may be wetted with a liquid dielectric so that they do not enclose any air between the turns after the winding thereof, erg. polystyrene may be wetted withmineral oil.
  • Another insulating material suitable for windings which offers advantages in certain cases, is a flexible band rich in mica, consisting e.g. of superimposed layers of mica splittings assembled with thin coatings of insulating binder between each layer.
  • insulators according to the invention may be applied with advantage also in cases where a field control by conductive inserts, or an arrangement of wire turns such as those met in primary windings of voltage transformers, is desired.
  • Conductive inserts for instance in the shape of metal cfoils, may be readily wrapped in during the winding of the insulating bandage. Normally the ends of the controlling insert are arranged inside the wound insulating web (for instance paper web).
  • Laminated insulators present on the one hand the advantage that their electric strength perpendicularly to the laminated layers is very high; on the other hand, however, they have the disadvantage that the electric strength in the direction of the laminated layers is much smaller. At the border of such capacitive control inserts steep field gradients occur, particularly in the direction of the laminated layers. According to the invention this disadvantage is overcome in a simple manner by embedding the ends of the control inserts in the enveloping layer of casting resin. 'I his affords also the possibility to provide the ends with a bulge diminishing the field gradient; the bulge is embedded into the casting resin. r
  • the insulation according to the invention is furthermore applicable to condenser leads having one end under oil, the control inserts of which reach as far as the outer surface lying under oil, and which follow one another in radial direction so closely that a high voltage gradient is tolerated.
  • Such a fine control may be accomplished according to the invention by maintaining the control inserts in the correct mutual position by the wound dielectric and leading them up to the surface through the enveloping layer of casting resin.
  • the latter extends advantageously in axial direction of the leading-in insulators only as far as required by the field strength.
  • the wire turns may be preferably located in a free space left between the wound insulation and the enveloping insulation consisting of cast resin.
  • Elongated bodies particularly elongated leading-in insulators may be subject to the difliculty that the resin cover breaks due to the shrinkage at the hardening and cooling thereof.
  • a weak spot advantageously designed as a groove is provided according to the invention in a Zone in which the resin cover is subject to a relatively slight electrical stress 50 that the resin cover splits in 'said Zone when,
  • the insulator is cooled. Then the joint is again cemented in a separate operation by casting resin.
  • Fig. l is a sectional elevation of a first embodiment of the invention in form of a current transformer for high voltages
  • Fig. 2 is a sectional elevation of a second embodiment of the invention with a current transformer of similar design
  • Fig. 3 is a sectional elevation of a third embodiment of the invention showing a current transformer the pri mary of which is formed by a rod;
  • Fig. 4 is an elevation, partly in section, of an elongated leading-in rod current transformer with two secondary windings;
  • Fig. 5 is a section, on an enlarged scale, of the upper end of the transformer shown in Fig. 4;
  • Fig. 6 is a sectional elevation of a modification of the embodiment shown in Fig. 3.
  • a magnetic annular core 1 is penetrated by a tube 3 containing the primary windings (not shown) and being provided with a tubular extension or stem 2 which contains the current leads (not shown) connected to the primary winding (not shown).
  • the secondary winding 4 surrounds the core 1.
  • the primary winding (not shown) is wrapped by the insulating paper band 5 extending partly also over the stem 2.
  • This part of the insulating paper band includes potential control inserts 6 arranged coaxially with the stem 2 and having lower terminations 7.
  • the insulating paper band 5 is arranged inside the insulation 8 consisting of a cast resin and provided with weather protecting sheaths 9, for instance consisting of porcelain, and with a cover piece 10.
  • the insulation 8 of cast resin is provided with a grounded conductive outer layer 11 extending substantially over the lower part of the insulation'8 carrying the core 1.
  • a hollow iron core 101 is passed through by a primary conductor 102 shaped as a rod and surrounded by the secondary winding 104 which leads to the terminals such as 113.
  • the paper insulation r105 encloses part-of the rod-like primary conductor 102.
  • the resinous body 108 enclosing the whole structure except the ends of the primary conductor 102 is electrically stressed only at the two conical end portions thereof.
  • the secondary winding 104 wound on the magnetic core 101 is in direct contact with the mid portion of the paper insulation 105.
  • An expanding body 114 for instance a helical spring, is arranged between the one end face of the paper insulation 105 and the resin body 108. If the magnetic core 101 is provided with, or replaced by, a grounded part, the apparatus described hereinbefore may be used as a high voltage leading-in insulator.
  • the high voltage current conductor 15 is closely surrounded over part of its length by an impregnated paper insulation 16 provided with 'condenser control insets 17.
  • the paper insulation 16 is enclosed in its middle portion by a metal tube 18, and at the ends thereof by a synthetic resin insulation 19 cast thereon.
  • the metal tube 18 is surrounded by ferromagnetic cores 20, 21, carrying, respectively, the secondary windings 22 and 23 of the current transformers.
  • a plate 24 serves for attaching the cores and the secondaries of the transformer to the metal tube 18.
  • the part of the metal 18 surrounded by the cast resin 19 is provided at the outside thereof with grooves 25 improving the mechanical connection and the sealing of the parts 18 and 19.
  • the two measures for increasing the electrical strength may be applied in combination, thus achieving a further increase of the electrical strength.
  • Fig. 6 of the drawings showing a rodshaped current transformer in section
  • the ferromagnetic annular core 26 is surrounded by the secondary winding 27 which leads to the terminals such as 28.
  • the high voltage current rod or bar 29 penetrates the core 26 and is insulated against the same by the wound paper insulation 30 permeated by gas and surrounded by the synthetic resin body 31 enclosing also the core 26 carrying the secondary winding 27.
  • a valve 32 arranged in the wall of the synthetic resin body 31 serves for conducting the gas to the wound paper insulation 30.
  • a multiple insulation for a high voltage current conductor comprising an oil impregnated insulating fibrous web surrounding said conductor, a metal sleeve enclosing part of said web, and a sleeve consisting substantially of a casting resin, said resin sleeve enclosing said metal sleeve and said insulating web projecting from said metal sleeve and being integrally united with said metal sleeve and web.
  • An insulator as claimed in claim 1 including a cushion of resilient material provided in an area being under a low electrical stress.
  • a multiple insulation for a high voltage current conductor comprising an insulating fibrous web surrounding a rod conductor, said web being impregnated with a dielectric, and a sleeve consisting substantially of a casting resin, said resin sleeve enclosing, and being integrally united with, said insulating web and extending beyond said web into intimate contact with said conductor.
  • a method of manufacturing a high voltage insulator comprising the steps of making a bandaged insulator, casting an insulator consisting of synthetic resin around said bandaged insulator, providing a weak zone in said cast insulator, hardening said cast insulator, allowing said weak zone to break under the influence of contracting stresses, closing said break, and impregnating said bandaged insulator with a fluid insulator.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Insulating Of Coils (AREA)
  • Transformers For Measuring Instruments (AREA)
US436656A 1953-06-15 1954-06-14 High voltage insulator Expired - Lifetime US2945912A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH1107933X 1953-06-15

Publications (1)

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US2945912A true US2945912A (en) 1960-07-19

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US436656A Expired - Lifetime US2945912A (en) 1953-06-15 1954-06-14 High voltage insulator

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US (1) US2945912A (da)
DK (1) DK87140C (da)
FR (1) FR1107933A (da)
GB (1) GB766905A (da)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3222625A (en) * 1960-12-29 1965-12-07 Acec Resinous-type terminal-bushing construction with encapsulated current transformer
US3386059A (en) * 1965-10-21 1968-05-28 Sigma Instruments Inc Power line coupling device
US3437967A (en) * 1966-04-29 1969-04-08 Bernard Jean Josse Linear induction system feeding a low voltage current
DE3507509A1 (de) * 1979-03-12 1986-09-04 Interpace Corp. (n.d.Ges.d.Staates Delaware), Purchase, N.Y. Hochspannungsfestes bauteil und verfahren zu seiner herstellung
USD342936S (en) 1992-04-09 1994-01-04 Cooper Power Systems, Inc. Angled bushing
US5504419A (en) * 1992-04-03 1996-04-02 Moser-Glaser & Co. Ag Rod-core current transformer
US20170047721A1 (en) * 2014-05-12 2017-02-16 Siemens Aktiengesellschaft High-Voltage Bushing

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2630253A1 (fr) * 1988-04-19 1989-10-20 Alsthom Procede d'amelioration de la tenue au feu d'un bobinage de transformateur electrique sec
FR2630578B1 (fr) * 1988-04-22 1990-07-27 France Transfo Sa Transformateur sec enrobe a comportement au feu ameliore et procede de preparation de sa resine d'enrobage

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1759419A (en) * 1926-03-02 1930-05-20 American Brown Boveri Electric Condenser bushing
US2086078A (en) * 1933-06-20 1937-07-06 Haefely Emil High tension electric insulating bushings of the condenser type
US2209894A (en) * 1935-01-01 1940-07-30 Int Standard Electric Corp Method of and means for terminating electric cables
US2272615A (en) * 1937-10-26 1942-02-10 Int Standard Electric Corp Electric cable
US2287201A (en) * 1937-11-24 1942-06-23 Int Standard Electric Corp Electrical stress grading device
FR888061A (fr) * 1942-03-06 1943-12-02 Comp Generale Electricite Perfectionnements à la construction des bornes de traversées et boîtes d'extrémité de câble du type condensateur
FR1032118A (fr) * 1950-03-20 1953-06-30 Oerlikon Maschf Transformateur de mesure
US2651670A (en) * 1951-04-13 1953-09-08 Gen Electric High-voltage pothead with stress distributing means

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1759419A (en) * 1926-03-02 1930-05-20 American Brown Boveri Electric Condenser bushing
US2086078A (en) * 1933-06-20 1937-07-06 Haefely Emil High tension electric insulating bushings of the condenser type
US2209894A (en) * 1935-01-01 1940-07-30 Int Standard Electric Corp Method of and means for terminating electric cables
US2272615A (en) * 1937-10-26 1942-02-10 Int Standard Electric Corp Electric cable
US2287201A (en) * 1937-11-24 1942-06-23 Int Standard Electric Corp Electrical stress grading device
FR888061A (fr) * 1942-03-06 1943-12-02 Comp Generale Electricite Perfectionnements à la construction des bornes de traversées et boîtes d'extrémité de câble du type condensateur
FR1032118A (fr) * 1950-03-20 1953-06-30 Oerlikon Maschf Transformateur de mesure
US2651670A (en) * 1951-04-13 1953-09-08 Gen Electric High-voltage pothead with stress distributing means

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3222625A (en) * 1960-12-29 1965-12-07 Acec Resinous-type terminal-bushing construction with encapsulated current transformer
US3386059A (en) * 1965-10-21 1968-05-28 Sigma Instruments Inc Power line coupling device
US3437967A (en) * 1966-04-29 1969-04-08 Bernard Jean Josse Linear induction system feeding a low voltage current
DE3507509A1 (de) * 1979-03-12 1986-09-04 Interpace Corp. (n.d.Ges.d.Staates Delaware), Purchase, N.Y. Hochspannungsfestes bauteil und verfahren zu seiner herstellung
US5504419A (en) * 1992-04-03 1996-04-02 Moser-Glaser & Co. Ag Rod-core current transformer
USD342936S (en) 1992-04-09 1994-01-04 Cooper Power Systems, Inc. Angled bushing
US20170047721A1 (en) * 2014-05-12 2017-02-16 Siemens Aktiengesellschaft High-Voltage Bushing
US10014676B2 (en) * 2014-05-12 2018-07-03 Siemens Aktiengesellschaft High-voltage bushing

Also Published As

Publication number Publication date
FR1107933A (fr) 1956-01-06
DK87140C (da) 1959-04-13
GB766905A (en) 1957-01-30

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