GB2184592A - Low voltage electric cable - Google Patents

Low voltage electric cable Download PDF

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Publication number
GB2184592A
GB2184592A GB08630236A GB8630236A GB2184592A GB 2184592 A GB2184592 A GB 2184592A GB 08630236 A GB08630236 A GB 08630236A GB 8630236 A GB8630236 A GB 8630236A GB 2184592 A GB2184592 A GB 2184592A
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GB
United Kingdom
Prior art keywords
extruded
electric cable
ofthe
extruded insulation
cross
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.)
Withdrawn
Application number
GB08630236A
Other versions
GB8630236D0 (en
Inventor
Francisco Antonio Granadillo
Alessandro Secco
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.)
Pirelli and C SpA
Original Assignee
Pirelli Cavi SpA
Cavi Pirelli SpA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Pirelli Cavi SpA, Cavi Pirelli SpA filed Critical Pirelli Cavi SpA
Publication of GB8630236D0 publication Critical patent/GB8630236D0/en
Publication of GB2184592A publication Critical patent/GB2184592A/en
Withdrawn legal-status Critical Current

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Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/18Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
    • H01B3/30Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
    • H01B3/301Macromolecular compounds obtained by reactions forming a linkage containing sulfur with or without nitrogen, oxygen or carbon in the main chain of the macromolecule, not provided for in group H01B3/302
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/18Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
    • H01B3/30Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
    • H01B3/303Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups H01B3/38 or H01B3/302
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/18Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
    • H01B3/30Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
    • H01B3/42Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes polyesters; polyethers; polyacetals
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/18Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
    • H01B3/30Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
    • H01B3/44Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins
    • H01B3/443Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins from vinylhalogenides or other halogenoethylenic compounds
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00Insulated conductors or cables characterised by their form
    • H01B7/17Protection against damage caused by external factors, e.g. sheaths or armouring
    • H01B7/29Protection against damage caused by extremes of temperature or by flame
    • H01B7/292Protection against damage caused by extremes of temperature or by flame using material resistant to heat

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  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Insulating Materials (AREA)
  • Insulated Conductors (AREA)

Abstract

A low voltage electric cable comprises a conductor surrounded by at least one extruded insulation layer 2 and an insulating varnish coating 3 around one or more of the extruded insulation layers. The extruded layer may be polyvinylidene fluoride, cross-linked copolyethylene-tetrafluoroethylene or polysulphone. The varnish coating may be polyester, polyamide, polyimide or polyester-imide. Two extruded insulation layers may be provided with or without an interposed coating of varnish (Figs. 2&3). The coating and the layer may be cross-linked by irradiation at the same or different times. <IMAGE>

Description

SPECIFICATION Low voltage electric cable This invention is concerned with low voltage electric cables which are intended for use under severe service conditions, in particular at high temperatures orin aircraft or special plants orthe like.
Electric cablesforsuch use generally comprise a conductor and one or more extruded polymeric i sulation layers having a high melting temperature andvervgood mechanical characteristics. Such cablesshould have, in addition to very good mechanical properties at high temperatures, good resistance to thermal ageing, that is resistance to the premature thermal degradation ofthe polymeric insulation.
In known cables of this kind, good mechanical properties at high temperatures are obtained by irradiating the extruded insulation layer or layers which comprise such polymers as ethylene-tetrafluoroethylene (ETFE) copolymer and various crosslinking agents, with high radiation dosages, such as 30 Mrad or more. However, this procedure-using a high radiation dose has a negativeeffectonthermal ageing resistance which, on the contrary is improved with lower radiation doses, for example 5-10 Mrad.
These two requirements are, therefore, conflicting and current practice is to use an intermediate radiation dosage that provides a more or less satisfactory compromise between the two requirements without allowing the optimum value of either propertyto be obtained.
We have now developed an improved low voltage cable in which the mechanical properties at high temperatures and the thermal ageing resistance are not interdependent and in which the extruded insulation layer or layers islare cross-linked at low radiation dosages or even not cross-linked at all without imapairing the cable performance at high service temperatures.
According to the present invention, there is provided a low voltage electric cable which comprises a conductor surrounded by at least one extruded insulation layer and an insulating varnish coating around one or more ofthe extruded insulation layers.
Suitable polymers forforming the extruded insulation are, forexample, fluorinated polymers, such as ethylene-tetrafluoroethylene copolymer available, for example, as'Tefzel" (Trade Mark) from du Pont, polyviny[idene fluoride, and aromatic polymers, such as polyesterlimides, polysulphones, and polyester/ sulphones,which polymers may be cross-linked or non-cross-linked.
Suitable polymersforforming the insulating varnish are. for example, polyimides, polyester imides, polyamides, and polyesters.
Thethickness ofthe insulating varnish coating is preferably from Sto 30%, more preferably from 10 to 1 50. ofthe thickness of the underlying extruded layer or layers or ofthe total thickness ofthe extruded [ayers. The insulating varnish coating is applied to the cable by means of an enamelling bath containing a solution ofthe varnish polymer, which is preferably cross-linkable, in a suitable solvent.
Forthe better understanding ofthe invention, preferrred embodiments thereofwill now be de scribe, by way of example, with reference to the accompanying drawings, in which: Figure lisa cross-section of a first embodiment of electriccable according to the invention, Figure 2 is a cross-section of a second embodiment, and Figure 3 is a cross-section of a third embodiment.
Referring to Figure 1, the electric cable comprises a metallicconductor 1,forexample of copper, sur- rounded by an extruded insulation layer 2 formed ,for example of EFTE copolymer cross-linked by irradiation, and a polyamidevarnish layer 5 applied by enamelling around the extruded insulation.
In the embodiment shown in Figure 2, a conductor 11 is surrounded by two extruded insulation layers 12 and 13, around which the varnish layer 15 is provided.
This embodiment is particularly suitable for providing a cable resistantto a notch propagation test.
Anotherembodimentwhich has been shown to be particularly resistant to notch propagation is that shown in Figure 3 in which the two extruded insulation layers 22 and 23 are not applied adjacent each other, but with the interposition ofthe insulating varnish coating 25. More particularly, a conductor 21 is surrounded by the extruded insulation layer 22 on which the coating 25 is applied by enamelling. After drying, the solvent and cross-linking the polymer, the insulating layer 23 is extruded on the coating 25.
The thickness ofthe insulating varnish layer (5, 15 or 25) is from Sand 30% and more preferably from 10 and 15% ofthe thickness ofthe extruded insulation layer or layers (2,12,13,22 and 23).The material forming the extruded insulation layers 2, 12,13,22 and 23 may be cross-linked or not, and the two layers 12, 13 and 22,23 may be cross-linked by irradiation at the same time or at different times.
The protectivevarnish coating may be formed as follows. A bath of a solution ofthe varnish polymer in a suitable solvent, such as N-methyl pyrrolidone, is prepared, the solution suitably containing from 4to 10% by weight ofthe polymer. The conductor already coated with at least one extruded insulation layer, is passedthroughthe bath and then through a die having a diameterwhich determinesthe coating thickness, and is then passed into a horizontal or vertical oven where drying of the solvent and crosslinking ofthevarnish polymer takes place.
In orderthatthe invention may be more fully understood,the following examples are given by way ofillustration; Examples E, F, H, Land N are in accordance with the invention and Examples A-D, G, I and Mare not in accordance with the invention and are given for the purpose of comparison.
Inthese Examples, samples of cableweresubmitted to accelerated ageing tests in which a length of cable is folded toform U over a mandrel, loaded with equal weights at its ends and maintained in an oven at 300"C for seven hours. The sample is then allowed to cool and is completely wound on the mandrel, first in one sense and then in the opposite sense, is then emersed in water and finally a 3kV voltage test is applied to it.
Failure ofthe sample in thevoltagetest may be dueto deformation of the insulation on the mandrel at 300"C owing to inadequate cross-linking orto damage to the insulation during the cold winding operation owing to excessive cross-linking. Excessive cross-linking causes the insulation to become brittle and thus impairs the ageing resistance of the insulation.
The cable samples all contained a 19 AWG tinned copper conductor. The insulation on the conductor was as follows: Examples A and B Example A had ETFE extruded insulation which was 0.25 mm thick and which had been cross-linked with a radiation dose of 30 Mrad. Example B was the same exceptthatcross-linking had been effected with a dose of 15 Mrad.
Examples CandD Examples C and D had two ETFE extruded insulation layers with atotal thickness of 0.25 mm which had been cross-linked with 30 and 15 Mrad, respectively.
Examples Eand F Examples E and F had extruded and cross-linked insulation corresponding to that of Examples B and D, respectively, and a polyimide varnish coating of 15 microns thickness. These two examples had structures corresponding tothose of Figure 1 and Figure 2, respectively.
Examples GandH Example G had polyvinylidenefluoride (PVDF) extruded insulation irradiated with 10 Mrad and Example H had the same PVDF extruded insulation and a varnish coating as in Examples E and F on top of it.
Examples land L Examples land L had polysulphoneextruded insulation 0.20mm thick which was cross-linked with a 30 Mrad irradiation dose and Example L had a varnish coating as described in Examples E and F30 microns thick on the polysulphone insulation.
Examples M and N Example M had non-cross-linked EFTE extruded insulation 0.25mm thick; Example N had the same and additionally a varnish coating as described in Exam ples E and F 15 micronsthick.
The constitution of the cables and the results obtained are summarised in the following table.
Example Insulation Cross- Varnish Result Insulation Thickness linking Thickness Dosage (mm) Mrad ( m) A) ETFE 0.25 30 - Fail 1) B)ETFE 0.25 15 - Fail2) C) ETFE 0.15inn.+ 0.10 out 30 - Fail 1) D)ETFE 0.15 inn.+ 0.10 out. 15 - Fail 2) E)ETFE 0.25 15 15 Pass F) ETFE 0.15 inn.+ 0.10Out. 15 15 Pass G)PVDF 0.25 10 - Fail 2) H)PVDF 0.25 10 15 Pass I)POLY- 0.20 30 - Fail 2) SULPHONE L) POLY- 0.20 30 30 Pass SULPHONE M)ETFE 0.25 - - Fail 2) N)ETFE 0.25 - 15 Pass Notes: inn. = inner layer out. = outer layer 1) = Failure because of embrittlement of insulation.
2) = Failure because of deformation ofthe insualation on the mandrel.
These results showthatthe insulating varnish coating provides the cable with thermal resistance so thatthe degree of cross-linking imparted to the extruded insulation can be chosen so as to obtain a good ageing resistance.
The varnish coating can be formed bya simple enamelling procedure and does not require the use of special or complicated equipment or plant and does not therefore have a negative effect on the productiv in/ or cost of the product.

Claims (8)

1. A low voltage electric cable which comprises a conductor surrounded by at least one extruded insulation layer and an insulating varnish coating around one or more ofthe extruded insulation layers.
2. An electric cable according to claim 1, in which the thickness ofthe insulating varnish coating is from Sto 30% ofthe thickness ofthe underlying extruded layer or layers.
3. An electric cable according to claim 1, which comprises a first extruded insulation layer around the conductor, an insulating varnish coating around the first extruded layer, and a second extruded insulation layer around the varnish coating.
4. An electriccable according to claim 3, in which the thickness ofthe insulating varnish coating is from 5 to 30% ofthe total thickness of the extruded layers.
5. An electric cable according to any of claims 1 to 4, in which the extruded insulation layers comprise a thermoplastic polymer.
6. An electric cable according to any of claims 1 to 4, in which the extruded insulation layer(s) comprise a cross-linked polymer.
7. An electric cable according to any of claims 1 to 6, in which the insulating varnish comprises a polyimide, a polyester/imide, a polyamide, or a polyester.
8. Alowvoltage electric cable substantially as herein described in any of Examples E, F, H, Land N.
GB08630236A 1985-12-20 1986-12-18 Low voltage electric cable Withdrawn GB2184592A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IT23314/85A IT1186156B (en) 1985-12-20 1985-12-20 ELECTRIC CABLE FOR LOW VOLTAGE

Publications (2)

Publication Number Publication Date
GB8630236D0 GB8630236D0 (en) 1987-01-28
GB2184592A true GB2184592A (en) 1987-06-24

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ID=11205981

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08630236A Withdrawn GB2184592A (en) 1985-12-20 1986-12-18 Low voltage electric cable

Country Status (7)

Country Link
JP (1) JPS62177808A (en)
BR (1) BR8606136A (en)
DE (1) DE3643381A1 (en)
ES (1) ES2002560A6 (en)
FR (1) FR2592206A1 (en)
GB (1) GB2184592A (en)
IT (1) IT1186156B (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1989000759A1 (en) * 1987-07-10 1989-01-26 Raychem Limited Wire
FR2712115A1 (en) * 1993-11-05 1995-05-12 Filotex Sa Screened cable, having a low level of noise and a high service temperature
WO2001018824A1 (en) * 1999-09-07 2001-03-15 Judd Wire, Inc. Dual layer system suitable for use as electrical insulation for wires and other conductors
EP2378612B1 (en) * 2010-04-15 2016-03-30 Hirschmann Automotive GmbH Coating of a lead frame with a plastic material with high shrinkage rate

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19644870A1 (en) * 1995-10-30 1997-05-07 Felten & Guilleaume Energie Electrical cable laid e.g. in grooves without spring back
JP2009245667A (en) * 2008-03-28 2009-10-22 Furukawa Electric Co Ltd:The Insulated wire and its manufacturing method

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3832231A (en) * 1972-08-21 1974-08-27 Gen Electric Method of rendering chlorosulfonated polyethylene rubber resistant to adherence of dirt,and the dirt resisting products thereof
GB2021304A (en) * 1978-04-19 1979-11-28 Haveg Industries Inc Insulation system for conductors
US4227042A (en) * 1978-12-07 1980-10-07 Western Electric Inc. Telephone cords
EP0056510A1 (en) * 1981-01-21 1982-07-28 Champlain Cable Corporation Insulation system for wire and cable

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3832231A (en) * 1972-08-21 1974-08-27 Gen Electric Method of rendering chlorosulfonated polyethylene rubber resistant to adherence of dirt,and the dirt resisting products thereof
GB2021304A (en) * 1978-04-19 1979-11-28 Haveg Industries Inc Insulation system for conductors
US4227042A (en) * 1978-12-07 1980-10-07 Western Electric Inc. Telephone cords
EP0056510A1 (en) * 1981-01-21 1982-07-28 Champlain Cable Corporation Insulation system for wire and cable

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1989000759A1 (en) * 1987-07-10 1989-01-26 Raychem Limited Wire
FR2712115A1 (en) * 1993-11-05 1995-05-12 Filotex Sa Screened cable, having a low level of noise and a high service temperature
WO2001018824A1 (en) * 1999-09-07 2001-03-15 Judd Wire, Inc. Dual layer system suitable for use as electrical insulation for wires and other conductors
EP2378612B1 (en) * 2010-04-15 2016-03-30 Hirschmann Automotive GmbH Coating of a lead frame with a plastic material with high shrinkage rate

Also Published As

Publication number Publication date
IT1186156B (en) 1987-11-18
ES2002560A6 (en) 1988-08-16
DE3643381A1 (en) 1987-07-02
IT8523314A0 (en) 1985-12-20
BR8606136A (en) 1987-09-22
FR2592206A1 (en) 1987-06-26
JPS62177808A (en) 1987-08-04
GB8630236D0 (en) 1987-01-28

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