US3930112A - Mixed fluid impregnant for oil filled electric cables - Google Patents

Mixed fluid impregnant for oil filled electric cables Download PDF

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Publication number
US3930112A
US3930112A US558834A US55883475A US3930112A US 3930112 A US3930112 A US 3930112A US 558834 A US558834 A US 558834A US 55883475 A US55883475 A US 55883475A US 3930112 A US3930112 A US 3930112A
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US
United States
Prior art keywords
liquid
specific gravity
cable
water
mixture
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Expired - Lifetime
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US558834A
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English (en)
Inventor
Franco Pasini
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Pirelli and C SpA
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Pirelli SpA
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Assigned to SOCIETA' PIRELLI S.P.A., A COMPANY OF ITALY reassignment SOCIETA' PIRELLI S.P.A., A COMPANY OF ITALY ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: INDUSTRIE PIRELLI S.P.A.
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Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00—Insulated conductors or cables characterised by their form
    • H01B7/14—Submarine cables
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
    • H01B13/30—Drying; Impregnating
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B9/00—Power cables
    • H01B9/06—Gas-pressure cables; Oil-pressure cables; Cables for use in conduits under fluid pressure
    • H01B9/0611—Oil-pressure cables

Definitions

  • ABSTRACT An underwater electric power cable in which the normal liquid impregnant, such as alkylaryl derivatives, polybutenes, polyisobutylenes, mineral oils, etc. having a specific gravity less than the specific gravity of water, is mixed with a second liquid having a specific gravity higher than that of water in proportions which will provide a mixture having a specific gravity substantially equal to that of the water in which the cable is immersed.
  • the normal liquid impregnant such as alkylaryl derivatives, polybutenes, polyisobutylenes, mineral oils, etc. having a specific gravity less than the specific gravity of water
  • the second liquid is miscible with the first liquid, and has low dielectric losses, a low dielectric constant, a viscosity at least as low as that of the first liquid and a boiling point of at least 150C.
  • a halogenated hydrocarbon such as hexachlorobutadiene, is a preferred second liquid.
  • the present invention relates to an improvement in power cables of the type known as oil-filled cables.
  • oil-filled cables refers to cables having a composite insulation formed by paper and by a liquid dielectric and of the self-contained type.
  • said liquiddielectric can flow outwardly or inwardly with the expansion or contraction cycles which may happen due to the thermal variations of the cable, the solid insulation of the cable being thereby continuously and completely maintained in an impregnated condition.
  • impregnants are alkylbenzenes, the employment of which is known from Italian Pat. No. 594,475 which indicates that dodecylbenzene is particularly suitable as an impregnant for cables of the oil-filled type for high voltages.
  • Italian Pat. No. 809,256 discloses the use of alkylbenzenes other than dodecylbenzene, which are characterized by the fact of having, with respect to the latter, a considerably lower viscosity.
  • the same' patent suggests, as most appropriate alkylbenzenes, those having a viscosity ranging between 2 and centiStokes at C and a flash point in open cup (Marcusson) higher than 100C.
  • the extremely low viscosity of the latter impregnants permits the limiting of the size of the transient pressure variations and consequently, permits limiting in 'an appropriate manner, the service pressure in cables of long length, as, for example, those for submarine use.
  • the alkylbenzenes disclosed in said Italian patents have at 20C a specific gravity ranging, as an average, from 0.85 to 0.88 g/cm.
  • mineral oils are known, which, as a function of their chemical structure and of their mean molecular weight, have aspecific gravity at 20C which is generally between 0.85 and 0.90 g/cm.
  • the lead forming the cable sheath tends to collapse under the outer hydraulic pressure which is greater than the inner one, and this requires a compensatory increase of the inner service pressure of the cable.
  • the present invention has, as one object, the elimination of the hereinbefore-mentioned disadvantages by providing an oil-tilled cable in which the inner hydrostatic pressure is balanced as much as possible with respect to the pressure of the receiving ambient.
  • This object is achieved by adding to the usual fluid impregnant of the cable a liquid having a specific gravity signiflcantly higher than that of the water receiving the cable and in such a proportion as to bring the specific gravity of the fluid impregnant very near or even equal to the specific gravity of the water of said receiving ambient.
  • the liquid to be added to the fluid impregnant must be mixable, or miscible, with the latter and must have appropriate dielectric characteristics, in particular, low dielectric losses and a low dielectric constant. It must also have suitable physical characteristics, such as, a viscosity equal to or lower than that of the fluid impregnant to which it is added and has a reasonably high boiling point, preferably higher than C, to avoid evaporation thereof during degassing of the mixture.
  • the main object of the present invention is to provide improved underwater power cables, in particular, submarine cables intended for high voltages, which comprise natural or synthetic products as fluid impregnants, the fluid impregnant of the cable being mixed with a liquid dielectric which is miscible withthe impregnant and which has appropriate dielectric and physical characteristics.
  • the liquid dielectric has a specific gravity higher than the specific gravity of the water of the ambient intended to receive said cables, and is mixed with the fluid impregnant in such proportions as to bring the specific gravity of the mixture to a value near that of the specific gravity of the water of said ambient.
  • FIGURE illustrates, in longitudinal cross-section, a portion of a known type of submarine cable. Although one type of cable is illustrated, it will be understood that the invention may be used with cables of a construction different from the cable illustrated.
  • a hollow conductor 1 defines an oil duct 2.
  • insulation 3 formed by layers of paper which are impregnated with oil under pressure.
  • the insulation 3 is surrounded by a metal sheath 4 which in turn is surrounded by an elastomeric sheath 5.
  • the cable is protected .by a layer or layers 6 of a known type, such as frettage, armor, etc.
  • the oil duct 2 is filled with the oil mixture 7 of the invention and this mixture is also supplied to the insulaliquid dielectric is a halogenated hydrocarbon.
  • halogenated hydrocarbons are those which best meet the specific gravity and mixability-requirements necessary to carry the invention into effect.
  • chlorinated hydrocarbons are of particular interest, and among the latter, hexachlorobutadiene is surprisingly suitable and has the following characteristics:
  • a liquid-filled underwater, electric power cable comprising a conductor surrounded by insulation, said insulation being impregnated with a mixture of a first liquid having a predetermined viscosity, at predetermined boiling point, a specific gravity less than that of water, low dielectric losses and a low dielectric constant with a second liquid miscible with said first liquid, a viscosity at least as low as that of said first liquid, a boiling point at least as high as C, a specific gravity higher than that of water and dielectric losses and a dielectric constant respectively substantially at least as low as said dielectric losses and said dielectric constant of said first liquid, said first liquid being at least 50 percent by weight of the mixture and the weight of the second liquid being at least equal to the amount thereof required to provide a specific gravity of the mixture substantially equal to the specific gravity of water.
  • An electric power cable fluid impregnant comprising at least 50 percent by weight of a first liquid having a predetermined viscosity, a predetermined boiling point, a specific gravity less than that of water, low dielectric losses and a low dielectric constant mixed with a second liquid miscible with said first liquid, a boiling point at least as high as 150C, a specific gravity higher than that of water, and dielectric losses and'a dielectric constant respectively substantially at least as low as said dielectric losses and said dielectric constant of said first liquid, the weight percent of said second liquid being at least sufficient to provide a specific gravity for the mixture which is substantially equal to the specific gravity of water.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Insulated Conductors (AREA)
  • Organic Insulating Materials (AREA)
  • Lubricants (AREA)
  • Measuring Temperature Or Quantity Of Heat (AREA)
  • Ropes Or Cables (AREA)
  • Suspension Of Electric Lines Or Cables (AREA)
US558834A 1974-03-25 1975-03-17 Mixed fluid impregnant for oil filled electric cables Expired - Lifetime US3930112A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IT49591/74A IT1011139B (it) 1974-03-25 1974-03-25 Perfezionamento a cavi per energia

Publications (1)

Publication Number Publication Date
US3930112A true US3930112A (en) 1975-12-30

Family

ID=11271109

Family Applications (1)

Application Number Title Priority Date Filing Date
US558834A Expired - Lifetime US3930112A (en) 1974-03-25 1975-03-17 Mixed fluid impregnant for oil filled electric cables

Country Status (13)

Country Link
US (1) US3930112A (OSRAM)
JP (1) JPS5845121B2 (OSRAM)
AR (1) AR202340A1 (OSRAM)
BR (1) BR7500261A (OSRAM)
CA (1) CA1039941A (OSRAM)
DE (1) DE2511404C2 (OSRAM)
DK (1) DK38575A (OSRAM)
FR (1) FR2266265B1 (OSRAM)
GB (1) GB1449445A (OSRAM)
IT (1) IT1011139B (OSRAM)
NO (1) NO138819C (OSRAM)
SE (1) SE412484B (OSRAM)
ZA (1) ZA751857B (OSRAM)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2832861A1 (de) * 1977-07-29 1979-02-08 Pirelli Mittel zum impraegnieren der papierisolierung eines oelgefuellten elektrischen energiekabels
US4237334A (en) * 1977-08-06 1980-12-02 Showa Electric Wire & Cable Co., Ltd. Laminated insulating paper and oil-filled cable insulated thereby
DE3200954A1 (de) * 1981-01-16 1982-09-02 Società Cavi Pirelli S.p.A., 20123 Milano Mit einem isolierenden medium impraegniertes elektrisches stromkabel
CN110400659A (zh) * 2019-07-31 2019-11-01 福建礼恩科技有限公司 一种充油海底电缆的制备方法

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2468544A (en) * 1945-11-10 1949-04-26 Gen Electric Stabilized halogenated compositions and electrical devices
US3163705A (en) * 1959-08-21 1964-12-29 Anaconda Wire & Cable Co Oil insulated impregnant for high voltage electrical apparatus
US3588644A (en) * 1969-10-06 1971-06-28 Mc Graw Edison Co Electrical apparatus and stabilized dielectric therefor
US3668128A (en) * 1969-01-09 1972-06-06 British Insulated Callenders Electrical insulating oil, and to electrical apparatus incorporating them
US3673093A (en) * 1966-06-03 1972-06-27 Montedison Spa Liquid dielectric composition of alkyl benzene and an antioxidation stabilizer
US3740625A (en) * 1971-11-04 1973-06-19 Sprague Electric Co Electrical capacitors with ester impregnants
US3745432A (en) * 1972-04-28 1973-07-10 Monsanto Co Impregnated capacitor
US3878314A (en) * 1973-10-26 1975-04-15 Rte Corp Protective apparatus for underground high voltage electrical devices

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE973637C (de) * 1939-08-11 1960-04-21 Enfield Cables Ltd Papierisoliertes elektrisches Massekabel
DE909110C (de) * 1941-09-03 1954-04-12 Siemens Ag Isolieroel fuer elektrotechnische Zwecke, insbesondere fuer Transformatoren und Kondensatoren
DE1665324B2 (de) * 1965-11-17 1972-05-18 Industrie Pirelli S.P.A., Mailand (Italien) Verwendung von alkylbenzolen als impraegnieroel fuer hochspannungs-oelkabel
JPS594475A (ja) 1982-07-01 1984-01-11 井関農機株式会社 揺動式選別装置

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2468544A (en) * 1945-11-10 1949-04-26 Gen Electric Stabilized halogenated compositions and electrical devices
US3163705A (en) * 1959-08-21 1964-12-29 Anaconda Wire & Cable Co Oil insulated impregnant for high voltage electrical apparatus
US3673093A (en) * 1966-06-03 1972-06-27 Montedison Spa Liquid dielectric composition of alkyl benzene and an antioxidation stabilizer
US3668128A (en) * 1969-01-09 1972-06-06 British Insulated Callenders Electrical insulating oil, and to electrical apparatus incorporating them
US3588644A (en) * 1969-10-06 1971-06-28 Mc Graw Edison Co Electrical apparatus and stabilized dielectric therefor
US3740625A (en) * 1971-11-04 1973-06-19 Sprague Electric Co Electrical capacitors with ester impregnants
US3745432A (en) * 1972-04-28 1973-07-10 Monsanto Co Impregnated capacitor
US3878314A (en) * 1973-10-26 1975-04-15 Rte Corp Protective apparatus for underground high voltage electrical devices

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2832861A1 (de) * 1977-07-29 1979-02-08 Pirelli Mittel zum impraegnieren der papierisolierung eines oelgefuellten elektrischen energiekabels
US4225747A (en) * 1977-07-29 1980-09-30 Industrie Pirelli Societa Per Azioni Submarine electric power cables containing naphthalene based liquids
US4237334A (en) * 1977-08-06 1980-12-02 Showa Electric Wire & Cable Co., Ltd. Laminated insulating paper and oil-filled cable insulated thereby
DE3200954A1 (de) * 1981-01-16 1982-09-02 Società Cavi Pirelli S.p.A., 20123 Milano Mit einem isolierenden medium impraegniertes elektrisches stromkabel
US4556756A (en) * 1981-01-16 1985-12-03 Societa' Cavi Pirelli S.P.A. Electric power cable impregnated with insulating fluid
CN110400659A (zh) * 2019-07-31 2019-11-01 福建礼恩科技有限公司 一种充油海底电缆的制备方法

Also Published As

Publication number Publication date
BR7500261A (pt) 1975-12-23
GB1449445A (en) 1976-09-15
NO138819B (no) 1978-08-07
CA1039941A (en) 1978-10-10
JPS5845121B2 (ja) 1983-10-07
AR202340A1 (es) 1975-05-30
FR2266265B1 (OSRAM) 1977-04-15
SE7503400L (OSRAM) 1975-09-26
DE2511404A1 (de) 1975-10-02
JPS50132485A (OSRAM) 1975-10-20
IT1011139B (it) 1977-01-20
DE2511404C2 (de) 1984-03-15
NO138819C (no) 1978-11-15
AU7949675A (en) 1976-09-30
FR2266265A1 (OSRAM) 1975-10-24
SE412484B (sv) 1980-03-03
NO751000L (OSRAM) 1975-09-26
DK38575A (OSRAM) 1975-09-26
ZA751857B (en) 1976-02-25

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AS Assignment

Owner name: SOCIETA PIRELLI S.P.A., PIAZZALE CADORNA 5, 20123

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:INDUSTRIE PIRELLI S.P.A.;REEL/FRAME:003847/0084

Effective date: 19810101