US3170027A - Treated cellulosic insulation and electrical apparatus embodying the same - Google Patents

Treated cellulosic insulation and electrical apparatus embodying the same Download PDF

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Publication number
US3170027A
US3170027A US164113A US16411362A US3170027A US 3170027 A US3170027 A US 3170027A US 164113 A US164113 A US 164113A US 16411362 A US16411362 A US 16411362A US 3170027 A US3170027 A US 3170027A
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United States
Prior art keywords
cellulosic
insulation
paper
electrical
treated
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Expired - Lifetime
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US164113A
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English (en)
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James G Ford
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Westinghouse Electric Corp
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Westinghouse Electric Corp
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Publication date
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Priority to US164113A priority Critical patent/US3170027A/en
Priority to DEW33575A priority patent/DE1300825B/de
Priority to CH1506662A priority patent/CH433468A/de
Priority to JP5866462A priority patent/JPS4021178B1/ja
Application granted granted Critical
Publication of US3170027A publication Critical patent/US3170027A/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
    • H01F27/323—Insulation between winding turns, between winding layers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
    • H01B3/185—Substances or derivates of cellulose

Definitions

  • the present invention relates to cellulosic insulation which is particularly adapted for use in electrical apparatus.
  • the invention further relates to cellulosic insulation characterized by greatly improved electrical insulating properties and thermal stability.
  • the invention relates to the improved cellulosic electrical insulation and to electrical apparatus insulated therewith.
  • Cellulosic materials such as paper, cotton cloth, cotton tape, pressboard and wood have long been employed in the electrical industry as insulation for various components of electrical apparatus. Such materials represent a desirable source of electrical insulation from the standpoint of their economic advantages over other available types of insulation. Moreover, cellulosic insulation possesses adequtae physical properties and satisfactory initial dielectric strength.
  • FIG. 2 is a graph plotting dielectric strength retention ofstabilized and unstabilized kraft paper aged in trans former oil at 150 C.
  • FIG. 3 is a view in perspective, partly in section, of a transformer core insulated with the novel cellulosic insulation of the invention.
  • nitrile compounds having the general formula X-R-CN wherein R is a member of the group consisting of alkyl, alkoxy, alkoxy alkane, aromatic, or substituted aromatic substituents, and X is a member of the group consisting of H and CN.
  • Particularly desirable nitriles are those whose substituents are hydrophilic so that they are soluble in water and relatively insoluble in oil. Dinitriles are exceptionally desirable compounds for this purpose.
  • Representative members of this group of nitrogen-containing, i.e., cyano, compounds include butyl nitrile, octyl nitrile, isooctyl nitrile, adiponitrile, malo'nonitrile, isophthalonitrile, succinonitrile, p-aminobeuzonitrile, B-ethoxypropionitrile, andbenzylnitrile, as well as the simple substitution derivatives of these compounds for example, allrylv groups on the benzene ring of the aromatic compounds.
  • the power factor of treated cellulosic insulation immersed in liquid dielectrics is lower than that of a similar paper which has not been so treated, over a wide range of temperature aging test conditions. Further, material reductions in power factor occur when the liquid dielectric is oil containing oxidation inhibitors, such as alkylated phenols, for example, p-tertbutylphenol and dibutylparacresol, in amounts of 0.01% to 4% or more since the treated paper appears to be beneficially affected by the presence of such inhibitors.
  • oxidation inhibitors such as alkylated phenols, for example, p-tertbutylphenol and dibutylparacresol
  • the power factor of a refined petroleum oil (uninhibited) with kraft paper immersed therein was originally 0.008%, color 1 on the Lovibond scale, after one year at 95 C., the power factor was 0.29% and color was 5+.
  • the power factor 0.36% and color 5- after one year at 95 C.
  • the color was about 3 /2 and the power factor of the order of 0.1 to 0.05% after one year at 95 C.
  • the chemical compounds must be present in the cellulosic insulation in total amounts Within the range of from about 0.02% to about by weight based on the weight of the cellulosic material. Less than about 0.02% of one or more of the compounds does not impart to the cellulosic insulation any appreciable improvement in either electrical insulation or mechanical strength upon aging at elevated temperatures or upon exposure to elevated temperatures. The presence of more than about 10% of the compound is uneconomical and does not increase the degree of improvement beyond that obtained with 10%. Within this broader critical range, it is preferred to employ about 1% to about 5% by weight of nitrogen-containing compounds, these amounts having been found to impart a high degree of improvement in the electrical insulating and thermal stability properties of the cellulosic insulation.
  • the stabilizing compound and/or compounds must be present, in substantially uniform distribution, intimately present throughout the interstices of the fibers comprising the cellulosic insulation to obtain optimum benefits.
  • This requirement is readily met because of the fact that all of the members of the group of stabilizing compounds of the invention are readily water soluble and substantially oil insoluble.
  • the stabilizing compounds be closely associated at all times with the cellulose fibers to obtain the hereinbefore discussed benefits, particularly where the insulation is to be immersed in a liquid dielectric such as oil during use.
  • the stabilizing materials are merely suspended in the dielectric, an extended period of time elapses before the stabilizers permeate the cellulosic insulation and function at maximum effectiveness.
  • nitrile stabilizing compounds possess a suitable degree of solubility in water or water-alcohol mixture, they may be desirably applied in such solution to thoroughly permeate the cellulose insulation during its production.
  • incorporation of the compound or compounds may be readily carried out in the paper mill.
  • Paper is generally made on either a Fourdrinier machine or a cylinder type machine. In either method, the formed web of 'felted cellulosic fibers is transferred from the forming screen to a felt belt for drying.
  • the web is thereby carried through a dryer which consists of a number of steam heated rolls after which, if desired, it is passed between calender rolls to impart a particular surface finish or density, and finally it is rolled for storage and shipment. Also, generally, the dryer is split so that the paper web partially dries in the first portion thereof and is finished dried in the second portion. Between the two sections of heated rolls a tank is usually positioned for application of sizing materials to the paper.
  • the stabilizing compound or compounds in aqueous solution are present in and applied from the conventional sizing tank.
  • the partially dried paper is passed through the aqueous nitrile soltuion and, by suitably adjusting the concentration of the solution, it adsorbs a specified amount of stabilizing compound. After this treatment, the paper passes through the second portion of the dryer. The temperature of the drying rolls is determined so as to obtain of its original bursting strength.
  • the resulting dried paper contains the stabilizing compound uniformly and intimately distributed throughout the fiber interstices.
  • the water solubility of the stabilizing compound increases as the temperature of the Water increases, it may be desirable to heat the solution and saturate it so that the concentration of succinonitrile is high whereby on passing the paper therethroug-h a specified high pick-up of the compound is obtained.
  • temperatures of the order of about 6090 C. are adequate.
  • the numeral 10 represents the treated kraft paper which is wound around the individual coils and which is wound between the high and low voltage coils of the transformer.
  • the transformer coil comprises low voltage coils 14 and 16, as Well as high voltage coils 13, 2t) and 22., insulated by layer-to-layer application of the treated paper.
  • the low voltage coil 14 is insulated from the treated winding-towinding by insulation 24.
  • the electrical conductors employed may comprise enameled wire which resists softening at temperatures of up to 250 C.
  • Suitable enamels are epoxy resin enamels, polyester resin enamels such as isophthalate-glycol-maleate resins, silicone enamels and polyvinyl formal-phenolic resin enamels.
  • the enamels may be applied directly on copper wire or may be employed with asbestos or glass fiber wrapping or other fibrous materials.
  • a liquid I dielectric will fill the channels 26 and will, as well, completely permeate the paper insulation. Subsequent to being wound and assembled the entire assembly is vacuum treated to remove air and moisture from the paper and the coil is thereafter baked to eliminate fully any moisture.
  • the nitrile treated insulation of this invention enables the transformer construction to be more solid and tighter because the treated cellulosic spacers and other compo nents lose less than half the thickness loss on thermal aging exhibited by untreated pressboard, kraft paper and other cellulosic materials.
  • the paper, cloth or other cellulosic product may include small amounts of up to 5% of one or more additional heat and dielectric stabilizing materials such as melamine and dicyandiamide.
  • the cellulosic materials also may include resins or binders such as polyacrylamide resin and melamine-aldehyde resin.
  • An improved sheet cellulosic product adapted for use in electrical apparatus in combination with a fluid dielectric impregnant, the product comprising cellulosic fibers in sheet form, the sheet having uniformly distributed throughout its interstices from about 0.02% to about by weight based on the weight of the cellulosic fibers of a nitrile compound having the general formula wherein R is a member of the group consisting of alkyl, alkoxy, alkoxy alkane, aromatic, and substituted aromatic substituents, and X is a member of the group consisting of H and -CN.
  • improved electrical apparatus comprising, in combination, an electrical conductor winding provided with a hard, tough, flexible enamel coating which resists softening at temperatures up to about 250 C., cellulosic electrical insulation substantially around the winding, the improvement which comprises the provision of from 0.02% to 10% by weight, based on the total weight of the cellulosic electrical insulation of at least one nitrile compound having the general formula wherein R is a member of the group consisting of alkyl, alkoxy, alkoxy alkane, aromatic, and substituted aromatic substituents, and X is a member of the group consisting of H and --CN, said nitrile compound being uniformly distributed throughout the interstices within the cellulosic electrical insulation, and a liquid dielectric consisting essentially of a petroleum hydrocarbon oil surrounding at least part of said electrical conductor winding and substantially completely permeating said cellulosic electrical insulation.
  • a nitrile compound having the general formula X-R-CN wherein R is a member of the group consisting of alkyl, alkoxy, alkoxy alkane, aromatic, and substituted aromatic substituents, and X is a member of the group consisting of H and -CN.
  • improved electrical apparatus comprising, in combination, an electrical conductor winding provided with a hard, tough, fiem'ble enamel coating which resists softening at temperatures up to about 250 C., and cellulosic electrical insulation substantially around the winding, the improvement which comprises the inclusion of from 0.02% to 10% by weight, based on the total weight of the cellulosic electrical insulation of at least one nitrile compound having the general formula wherein R is a member of the group consisting of alkyl, alkoXy, alkoxy alkane, aromatic, and substituted aromatic substituents, and X is a member of the group consisting of H and CN, said nitrile compound being uniformly distributed throughout the interstices Within the cellulosic eiectrical insulation, and a liquid dielectric consisting essentially of chlorinated diphenyl surrounding at least part of said electrical conductor winding and substantially completely permeating said cellulosic electrical insulation.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Organic Insulating Materials (AREA)
  • Paper (AREA)
US164113A 1962-01-03 1962-01-03 Treated cellulosic insulation and electrical apparatus embodying the same Expired - Lifetime US3170027A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US164113A US3170027A (en) 1962-01-03 1962-01-03 Treated cellulosic insulation and electrical apparatus embodying the same
DEW33575A DE1300825B (de) 1962-01-03 1962-12-20 Stabilisierungsmittel fuer elektrisches Isoliermaterial
CH1506662A CH433468A (de) 1962-01-03 1962-12-21 Stabilisiertes Cellulosematerial
JP5866462A JPS4021178B1 (enExample) 1962-01-03 1962-12-24

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US164113A US3170027A (en) 1962-01-03 1962-01-03 Treated cellulosic insulation and electrical apparatus embodying the same

Publications (1)

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US3170027A true US3170027A (en) 1965-02-16

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US (1) US3170027A (enExample)
JP (1) JPS4021178B1 (enExample)
CH (1) CH433468A (enExample)
DE (1) DE1300825B (enExample)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3469219A (en) * 1966-06-16 1969-09-23 Westinghouse Electric Corp Thermally stabilized cellulose in electrical apparatus and method for making same
US3510346A (en) * 1966-10-21 1970-05-05 Westinghouse Electric Corp Thermally stable cellulose products
US3582985A (en) * 1969-02-12 1971-06-01 Allis Chalmers Mfg Co Method of improving strip paper for electrical insulation
US3622260A (en) * 1967-01-07 1971-11-23 Bayer Ag Process for improving the heat and acid resistance of cellulose-containing materials
US4196044A (en) * 1976-02-05 1980-04-01 Dennison Manufacturing Company Product and process for making a creped and calendered cellulosic electrical paper
US20050072540A1 (en) * 2003-09-12 2005-04-07 Ehv-Weidmann Industries Inc. System and method for creping electrical insulating paper
US20110030987A1 (en) * 2007-12-27 2011-02-10 Olof Hjortstam Electric Insulation Material, An Electric Device Comprising The Insulation Material And A Transformer

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6954520B2 (ja) * 2017-12-05 2021-10-27 株式会社ダイセル 点火器組立体、及びガス発生器

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2722561A (en) * 1949-09-03 1955-11-01 Westinghouse Electric Corp Heat stabilizing of cellulosic insulation in electrical apparatus
US2901813A (en) * 1953-10-20 1959-09-01 American Viscose Corp Textile material of regenerated cellulose containing a polyacrylamide

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2535690A (en) * 1947-08-02 1950-12-26 Gen Electric Fibrous dielectric compositions

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2722561A (en) * 1949-09-03 1955-11-01 Westinghouse Electric Corp Heat stabilizing of cellulosic insulation in electrical apparatus
US2901813A (en) * 1953-10-20 1959-09-01 American Viscose Corp Textile material of regenerated cellulose containing a polyacrylamide

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3469219A (en) * 1966-06-16 1969-09-23 Westinghouse Electric Corp Thermally stabilized cellulose in electrical apparatus and method for making same
US3510346A (en) * 1966-10-21 1970-05-05 Westinghouse Electric Corp Thermally stable cellulose products
US3622260A (en) * 1967-01-07 1971-11-23 Bayer Ag Process for improving the heat and acid resistance of cellulose-containing materials
US3582985A (en) * 1969-02-12 1971-06-01 Allis Chalmers Mfg Co Method of improving strip paper for electrical insulation
US4196044A (en) * 1976-02-05 1980-04-01 Dennison Manufacturing Company Product and process for making a creped and calendered cellulosic electrical paper
US20050072540A1 (en) * 2003-09-12 2005-04-07 Ehv-Weidmann Industries Inc. System and method for creping electrical insulating paper
US20110030987A1 (en) * 2007-12-27 2011-02-10 Olof Hjortstam Electric Insulation Material, An Electric Device Comprising The Insulation Material And A Transformer
US8178780B2 (en) * 2007-12-27 2012-05-15 Abb Research Ltd. Electric insulation material, an electric device comprising the insulation material and a transformer

Also Published As

Publication number Publication date
JPS4021178B1 (enExample) 1965-09-20
DE1300825B (de) 1969-08-07
CH433468A (de) 1967-04-15

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