GB2079521A - Overhead electrical cable - Google Patents

Overhead electrical cable Download PDF

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Publication number
GB2079521A
GB2079521A GB8119843A GB8119843A GB2079521A GB 2079521 A GB2079521 A GB 2079521A GB 8119843 A GB8119843 A GB 8119843A GB 8119843 A GB8119843 A GB 8119843A GB 2079521 A GB2079521 A GB 2079521A
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GB
United Kingdom
Prior art keywords
conductor
hlb
hydrophilic
hydrophilic material
polyoxyethyleneglycol
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.)
Granted
Application number
GB8119843A
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GB2079521B (en
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 GB2079521A publication Critical patent/GB2079521A/en
Application granted granted Critical
Publication of GB2079521B publication Critical patent/GB2079521B/en
Expired 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
    • H01B5/00Non-insulated conductors or conductive bodies characterised by their form
    • H01B5/16Non-insulated conductors or conductive bodies characterised by their form comprising conductive material in insulating or poorly conductive material, e.g. conductive rubber
    • 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
    • H01B7/28Protection against damage caused by moisture, corrosion, chemical attack or weather
    • H01B7/282Preventing penetration of fluid, e.g. water or humidity, into conductor or cable
    • H01B7/285Preventing penetration of fluid, e.g. water or humidity, into conductor or cable by completely or partially filling interstices in the cable
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02ATECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A30/00Adapting or protecting infrastructure or their operation
    • Y02A30/14Extreme weather resilient electric power supply systems, e.g. strengthening power lines or underground power cables

Abstract

A conductor for use as an overhead electrical cable comprises one or more wires 10 clad with a sheath 11 of plastics material which incorporates at least one electrically conductive material and at least one hydrophilic material. The sheath is thus rendered partially conductive and also hydrophilic, causing any water on the conductor to distribute uniformly as a thin film, thus promoting rapid evaporation and lessening the usual corona discharges and accompanying noise. The conductive material may be C black and the hydrophilic material an ester of a fatty acid e.g. sorbitan monostearate, or of a polyoxyethylene glycol or polyvinyl alcohol. The plastics material may comprise PVC or polyethylene together with dioctyl phthalate and other additives. <IMAGE>

Description

SPECIFICATION Overhead conductor The present invention relates to a conductor for use as an overhead line transmitting high voltage A.C. electricity.
Known overhead lines comprise bare conductors suspended between poles or pylons. These lines are generally used for transmitting A.C. electricity at high voltage (say 400-500kV). Each conductor has a diameter of several centimeters and may comprise a single metal element or, more frequently, several metal wires stranded together.
Along the bare conductor, corona discharges occur, involving ionisation of the air in contact with the bare surface of the current-carrying conductor. The magnitude of the discharge current is proportional to the electric field gradient prevailing around the conductor and hence to the applied voltage: for the case of 400-500kV mentioned above, the field gradient would be about 20kV/cm. One of the consequence of the corona discharges is the generation of noise. When the conductor is dry, the noise generation is quite limited and the effective disturbance caused is practically negligible. However, when the conductor is wet, the generated noise is much more intense and can cause notable disturbances which are irritating and annoying for passers-by and to local inhabitants.Thus, the conductance of moisture-carrying air is increased, so that the air ionises more readily and supports a higher intensity of discharge.
The noise manifests itself as a continuous background buzzing, accompanied by frequent peaks of higher intensity. A spectral analysis of the frequencies of this noise has shown the presence of a high frequency component in the audible and ultrasonic range and a low frequency component corresponding to the frequency of the electrical supply (for example 50 Hz), and the harmonics of these components. From these arise the probability of beat frequencies and hence of increases or decreases in the noise generated.
Suppression or at least considerable reduction of this noise is required, especially in view of the tendency to progressively increase the operating voltages. One solution might be to insulate the conductors themselves by covering them with a layer of insulating plastics material, for the purpose of eliminating the electrical contact between the current carrying conductor and the air, and thus to suppress the corona discharges. However, this solution would have various drawbacks. Firstly, in order to reduce to zero the electric field gradient around the conductor, the insulating plastics cladding would require a considerable thickness and would need to be covered with a semi- or partially-conductive shield electrically connected to earth. This would involve a substantial increase in weight of the overhead conductor, and a more complex construction.Also, the plastics material must possess certain chemico-physical characteristics, such as resistance to attack, in course of time, from atmospheric agents, and this implies a complex formulation for the plastics material. Moreover, there would be technical difficulties involved in ensuring that the insulating cladding or the semi-conductive shield would not become damaged at the joints of the conductors to the insuiators on the poles or pylons of the system of overhead lines. Such damage could give rise to dangerous discharges that could adversely affect the entire insulating cladding.
A second solution might comprise sand blasting the bare surfaces of the conductors to roughen those surfaces by the formation of microscopic indentations and protuberances-to some extent similar to the effects produced through natural ageing of the bare conductors exposed to the action of atmospheric agents. Test carried out on conductors that have been treated in this way have shown a certain reduction in the background noise, but also have shown a significant increase in the peaks of noise. Hence, this solution also has its drawbacks.
We have now devised a conductor for use as an overhead line wherein the noise generated, when the conductor is wet, is substantially reduced.
In accordance with the present invention, there is provided a conductor for use as an overhead line comprising one or more wires and clad with a sheath of plastics material which comprises at least one electrically conductive material and at least one hydrophilic material.
An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawing, the single Figure of which is a view of a conductor for use as an overhead line.
The drawing shows a conductor comprising a plurality of metal wires 10 stranded together and covered by a thin plastics material sheath 11. Instead of the plurality of wires 10, there might instead be a single metal element.
The plastics material sheath is only thin and, for example, may be between 1 and 3 mm thick.
We have surprisingly found that the noise generated with wetted conductors carrying high voltage A.C. electricity can be suppressed or at least substantially reduced by covering the conductors themselves with the thin plastics sheath, providing the plastics material is rendered semi- or partially-conductive by the incorporation of at least one conductive material, and that it is also rendered hydrophilic by the incorporation of at least one hydrophilic material.
In the following TABLE, there are given the compositions of some preferred Examples of sheath formulations. All the formulations comprise a plastics resin or resin-rubber base (P.V.C., polyethylene, etc., nitrile rubber, ethylene vinyl-acetate rubber etc.), various additives (antioxidants, plasticizers, lubricants etc.), and at least one conductive material and at least one hydrophilic material.
The conductive material-which is generally a carbon-black, permits the electrical field around the plastics cladding to be equal, or nearly equal, to the electrical field around the bare conductor. The quantity (in parts by weight) of said conductive material, or mixture of conductive materials, can vary, for example, from 5 to 40 parts by weight, per 100 parts by weight of the total formulation.
The hydrophilic materials used in the Examples given in the TABLE, are as follows: SORBITAN MONOSTEARATE (HLB = 4.7) MONOGLYCERIDES OF FATTY ACIDS (HLB = 2.8)/POLYOXYETHYLENEGLYCOL-LAURATE (HLB = 12.8) (MIXTURE 50/50, HLB = 5) SORBITAN MONOLAURATE (HLB = 8.6)/PHENOLiC ETHER of POLYOXYETHYLENEGLYCOL (HLB= 11) (MIXTURE 50/50, HLB= 10) ALKYLPHENYL-POLYOXYETHYLENEGLYCOL (HLB = 11) PO LYOXYETHYLEN EGLYCO L-MO N O LAU RATE (H LB = 14) POLYOXYETHYLEN EGLYCOL DISTEARATE (H LB = 16.4) POLYOXYETHYLENEGLYCOL-SORBlTAN MONOOLEATE (HLB = 15) OXYETHYLATED ALIPHATIC ALCOHOL (HLB = 17) POLYVINYL ALCOHOL For each hydrophilic material or mixture, there is indicated the value of the HLB (Hydrophile Lipophile-Balance), which data, as is known, express fundamental characteristics of surfactant materials.
The quantity in parts by weight, of said hydrophilic materials, when used alone, or mixed together, can vary for example from 1 to 10 parts by weight (per 100 parts by weight of the total formulation).
The hydrophilic material permits the water (which falls on the conductors as rain, or as a result of condensation of water vapour in the atmosphere) to become distributed in a homogeneous manner, as a thin film over the entire conductor surface.
Conductors in accordance with the present invention have been tested and it has been verified that the noise usually generated with a wet conductor is suppressed, or substantially reduced.
The tests were carried out in an "anechoic chamber' '-an acoustically insulated chamber in which conductor lengths were kept under electric tension, and in which it was possible to simulate the atmospheric conditions. It was also possible to measure the intensity of generated noise and to survey its frequency spectrum.
Among the examples shown in the given TABLE, the best results were obtained by the mixtures corresponding to the Examples No. 4 and 5.
In the conductors in accordance with the present invention, the hydrophilic character of the plastics sheath material causes the water to distribute into the form of a thin film over the entire surface of the conductor, and hence it is subjected to a rapid evaporation (sometimes favoured also by heat emanating from the conductor itself). The semi-conductive character of the plastics material enables the sheath to remain unstressed electrically and hence it is not liable to any rapid deterioration in its electrical properties.
COMPOSITIONS (parts by weight) MIXTURE NO.
1 2 3 4 5 6 7 8 9 10 11 12 PVC 38.5 38.5 38.5 38.5 38.5 38.5 38.5 38.5 38.5 38.5 - POLYETHYLENE - - - - - - - - - - 78 79 NITRILE RUBBER 9 9 9 9 9 9 9 9 9 - - ETHYLENE VINYL-ACETATE RUBBER - - - - - - - - - 9 - DIOCTYLPHTHALATE 29 29 29 29 29 29 29 29 29 29 - LEAD TRIBASIC-SULPHATE 3 3 3 3 3 3 3 3 3 3 - CALCIVM STEARATE 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 - BISPHENOL 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 - ANTIOXIDANT - - - - - - - - - - 1 1 CARBON-BLACK 11 12 13 14 15 13 15 16 17 14 16 16 SORBITAN-MONOSTEARATE (HLB = 4.7) 8 - - - - - - - - - - MONOGLYCERIDES OF FATTY ACIDS (HLB = 2.8)/POLYOXYETHYLENE GLYCOL LAURATE (HLB = 12.8) (MIXTURE 50/50, HLB = 5) - 7 - - - - - - - - - SORBITAN MONOLAURATE (HLB = 8.6)/PHENOLIC ETHER OF POLY ETHYLENEGLYCOL (HLB = 11) (MIXTURE 50/50, HLB = 10) - - 6 - - - - - - - - ALKYL-PHENYL-POLYOXYETHYLENE GLYCOL (HLB = 11) - - - 5 - - - - - 5 5 POLYOXYETHYLENEGLYCOL-MONO LAURATE (HLB = 14) - - - - 4 - - - - - - 4 POLYOXYETHYLENEGLYCOL DISTEARATE (HLB = 16.4) - - - - - 6 - - - - - POLYOXYETHYLENEGLYCOL SORBITAN MONOOLEATE (HLB = 15) - - - - - - 4 - - - - OXYETHYLATED ALIPHATIC ALCOHOL (HLB = 17) - - - - - - - 3 - - - POLYVINYL ALCOHOL - - - - - - - - 2 - - -

Claims (14)

1. A conductor for use as an overhead line comprising one or more wires and clad with a sheath of plastics material which comprises at least one electrically conductive material and at least one hydrophilic material.
2. A conductor as claimed in claim 1, in which said conductive material is carbon-black.
3. A conductor as claimed in claim 1 or 2, in which said plastics material comprises from 5 to 40 parts per 100 by weight of said conductive material.
4. A conductor as claimed in any preceding claim, in which said hydrophilic material is sorbitan-monostearate having a HLB = 4.7.
5. A conductor as claimed in any one of claims 1 to 3, in which a mixture of said hydrophilic material is used, which mixture has a HLB = 5 and comprises 50/50 parts by weight of monoglycerides of fatty acids having a HLB = 2.8 and polyoxyethyleneglycol laurate of HLB= 12.8.
6. A conductor as claimed in any one of claims 1 to 3, in which a mixture of hydrophilic materials is used, which mixture has a HLB = 10, and comprises 50/50 parts by weight of sorbitan monolaurate, having a HLB = 8.6, and of phenolic ether of polyoxyethyleneglycol having a HLB = 11.
7. A conductor as claimed in any one of claims 1 to 3, in which said hydrophilic material is alkylphenyl polyoxyethyleneglycol having a HLB = 11.
8. A conductor as claimed in any one of claims 1 to 3, in which said hydrophilic material is polyoxyethyleneglycol-monolaurate having a HLB = 14.
9. A conductor as claimed in any one of claims 1 to 3, in which said hydrophilic material is polyoxyethyleneglycol-distearate having a HLB = 16.4.
10. A conductor as claimed in any one of claims 1 to 3, in which said hydrophilic material is polyoxyethyleneglycol-sorbitan monooleate having a HLB = 1 5.
11. A conductor as claimed in any one of claims 1 to 3, in which said hydrophilic material is oxyethylated aliphatic alcohol having a HLB = 1 7.
1 2. A conductor as claimed in any one of claims 1 to 3, in which said hydrophilic material is polyvinyl alcohol.
1 3. A conductor as claimed in any one of claims 4 to 12, in which 100 parts by weight of said mixture comprises from 1 to 10 parts by weight of said hydrophilic material(s).
14. A conductor as claimed in any preceding claim, in which said sheath has a thickness of from 1 to 3 mm.
1 5. A conductor according to claim 1, wherein the sheath of plastics material has a composition in accordance with any of the Examples herein set out in the Table.
GB8119843A 1980-06-30 1981-06-26 Overhead electrical cable Expired GB2079521B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IT83634/80A IT1136539B (en) 1980-06-30 1980-06-30 PERFECTED AERIAL LINE CONDUCTOR

Publications (2)

Publication Number Publication Date
GB2079521A true GB2079521A (en) 1982-01-20
GB2079521B GB2079521B (en) 1984-04-18

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ID=11323451

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Application Number Title Priority Date Filing Date
GB8119843A Expired GB2079521B (en) 1980-06-30 1981-06-26 Overhead electrical cable

Country Status (13)

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JP (1) JPS5715308A (en)
AR (1) AR225084A1 (en)
AU (1) AU542216B2 (en)
BR (1) BR8104092A (en)
CA (1) CA1174307A (en)
DE (1) DE3125509A1 (en)
DK (1) DK147777C (en)
ES (1) ES503967A0 (en)
FR (1) FR2485792A1 (en)
GB (1) GB2079521B (en)
IT (1) IT1136539B (en)
NZ (1) NZ197412A (en)
SE (1) SE8103935L (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000008655A1 (en) * 1998-08-06 2000-02-17 Abb Ab An electric dc-cable with an insulation system comprising an extruded polyethylene composition and a method for manufacturing such cable
FR2990047A1 (en) * 2012-04-27 2013-11-01 Nexans High voltage electrical transmission cable comprises semiconductive polymeric element that surrounds electrically conductive element in cross section, reduces corona effect along cable and has constant thickness around conductive element
US9859038B2 (en) 2012-08-10 2018-01-02 General Cable Technologies Corporation Surface modified overhead conductor
US10726975B2 (en) 2015-07-21 2020-07-28 General Cable Technologies Corporation Electrical accessories for power transmission systems and methods for preparing such electrical accessories
US10957468B2 (en) 2013-02-26 2021-03-23 General Cable Technologies Corporation Coated overhead conductors and methods

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2874282B1 (en) 2004-08-12 2006-10-27 Electricite De France REDUCTION OF THE NOISE OF AERIAL LINES BY PLASTIC SHEATH
FR2874283B1 (en) * 2004-08-12 2006-12-15 Electricite De France REDUCTION OF AERIAL LINE NOISE BY TEXTILE COATING

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1465846A1 (en) * 1963-06-25 1969-03-27 Licentia Gmbh High-voltage overhead line cable with high electrical strength

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000008655A1 (en) * 1998-08-06 2000-02-17 Abb Ab An electric dc-cable with an insulation system comprising an extruded polyethylene composition and a method for manufacturing such cable
FR2990047A1 (en) * 2012-04-27 2013-11-01 Nexans High voltage electrical transmission cable comprises semiconductive polymeric element that surrounds electrically conductive element in cross section, reduces corona effect along cable and has constant thickness around conductive element
US9859038B2 (en) 2012-08-10 2018-01-02 General Cable Technologies Corporation Surface modified overhead conductor
US10586633B2 (en) 2012-08-10 2020-03-10 General Cable Technologies Corporation Surface modified overhead conductor
US10957468B2 (en) 2013-02-26 2021-03-23 General Cable Technologies Corporation Coated overhead conductors and methods
US10726975B2 (en) 2015-07-21 2020-07-28 General Cable Technologies Corporation Electrical accessories for power transmission systems and methods for preparing such electrical accessories

Also Published As

Publication number Publication date
AR225084A1 (en) 1982-02-15
ES8204556A1 (en) 1982-05-01
FR2485792A1 (en) 1981-12-31
CA1174307A (en) 1984-09-11
IT8083634A0 (en) 1980-06-30
DK147777B (en) 1984-12-03
SE8103935L (en) 1981-12-31
JPS5715308A (en) 1982-01-26
IT1136539B (en) 1986-08-27
DK280981A (en) 1981-12-31
BR8104092A (en) 1982-03-16
GB2079521B (en) 1984-04-18
DE3125509A1 (en) 1982-05-13
FR2485792B1 (en) 1984-04-20
DK147777C (en) 1985-05-20
AU542216B2 (en) 1985-02-14
NZ197412A (en) 1983-07-15
ES503967A0 (en) 1982-05-01
AU7142881A (en) 1982-01-07

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PCNP Patent ceased through non-payment of renewal fee