WO2012159221A1 - Electrical cable and application of this cable - Google Patents

Electrical cable and application of this cable Download PDF

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Publication number
WO2012159221A1
WO2012159221A1 PCT/CH2012/000111 CH2012000111W WO2012159221A1 WO 2012159221 A1 WO2012159221 A1 WO 2012159221A1 CH 2012000111 W CH2012000111 W CH 2012000111W WO 2012159221 A1 WO2012159221 A1 WO 2012159221A1
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WO
WIPO (PCT)
Prior art keywords
cable
insulating material
outer sheath
primary layer
single primary
Prior art date
Application number
PCT/CH2012/000111
Other languages
French (fr)
Inventor
Mario Colpa
Eric SPECHT
Hervé DE FRANCESCHI
Original Assignee
Bacab S.A.
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 Bacab S.A. filed Critical Bacab S.A.
Publication of WO2012159221A1 publication Critical patent/WO2012159221A1/en

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Classifications

    • 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
    • H01B13/22—Sheathing; Armouring; Screening; Applying other protective layers
    • H01B13/24—Sheathing; Armouring; Screening; Applying other protective layers by extrusion
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B9/00—Power cables
    • H01B9/02—Power cables with screens or conductive layers, e.g. for avoiding large potential gradients
    • H01B9/027—Power cables with screens or conductive layers, e.g. for avoiding large potential gradients composed of semi-conducting layers
    • 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
    • H01B7/30—Insulated conductors or cables characterised by their form with arrangements for reducing conductor losses when carrying alternating current, e.g. due to skin effect

Definitions

  • the present invention relates to an AC electrical cable having high voltages, especially voltages greater than 2KV and / or working at high temperatures, especially at temperatures of the order of 260 ° C, and / or used in an environment specific, especially aeronautical, said cable being arranged to push the boundary conditions of the corona partial discharge effect and comprising at least one central conductive core and at least one outer sheath made of an insulating material and surrounding said central conductive core.
  • the invention also relates to the application of this cable for heating liquid, semi-liquid or gaseous substances by Joule effect.
  • the technical problem of the corona partial discharge effect in the field of electrical energy transport in the form of an alternating current is well known. It arises in particular in a resistance heating application that uses the skin effect, commonly called “skin effect", which consists of heating pipes, in particular pipeline type pipes that convey products from oil drilling, liquid mineral substances such as sulfur or chemicals or the like which have the characteristic of being heavy, dense or viscous charged in substance with high density and whose pumping is difficult when they are at relatively low temperature, or even impossible in case solidification of the product.
  • Pipelines can also carry gas and the heat input can maintain this gas temperature and significantly reduce condensation. The temperature is maintained at values up to 180 ° C depending on the product to be maintained, the cable to work up to about 260 ° C.
  • This temperature maintenance can in particular be obtained through the skin effect and radiation, the heat being obtained by Joule effect.
  • an AC power cable into a tube and electrically connected to the cable at the other end of this tube.
  • the current flowing through the cable returns through the tube, the latter remaining on the inner surface of the tube.
  • the dissipated heat heats the tube which transfers the heat to the products conveyed and generates the rise in temperature of the liquids by Joule effect.
  • This tube is secured to the pipe or the pipeline by welding and / or bandage.
  • British Publication GB 1 459 579 discloses a heat generating conduit using the skin effect produced by an alternating current.
  • This conduit is made of a ferromagnetic material and contains an insulated cable that passes through it, this cable being provided with a screen layer to prevent a corona discharge. It is proven and recognized that the addition of this metal screen complicates the engineering of the so-called "skin effect" system and also complicates its installation.
  • British Patent GB 1.080.778 discloses a method of manufacturing a cable 5 for the same type of application, comprising a conductive central core having an outer sheath polyethylene and a polyolefin intermediate layer loaded with carbon black, these coaxial layers being produced by coextrusion. These materials have the essential defect not to stand at high temperatures, especially at temperatures of the order of 180 to 260 ° C such as those provided in the context of the invention.
  • US Pat. No. 3,660,592 also discloses an electrical cable having a central conductor insulated by a peripheral coating, these two elements being separated by a semiconductor fiuorocarbon resin layer containing from 0.5 to 75% graphite.
  • a resin layer is complex to achieve and the resin is not a thermoplastic is difficult to recycle, which has an extremely negative influence on the manufacturing cost.
  • US Pat. No. 5,532,375 discloses an electrical cable for exploiting the skin effect, which cable has a complex structure with a TFE semiconductor layer disposed between the conductor and the insulator. Its manufacturing cost is high and the temperatures targeted by the applications of the cable of the invention can not be reached.
  • the corona effect is well known and heating cables using the skin effect are usually used for temperatures not exceeding 120 ° C. Nevertheless, for many industrial applications, it would be advantageous to be able to raise this value and to go up to temperatures of the order of 260 ° C.
  • the usual cables do not make it possible to reach these temperatures, because of the risks related to the corona effect, without requiring important precautions consisting in significantly increasing the thickness of the layer of insulating material.
  • the thickness of the insulation is about 0.2mm.
  • the thickness of the insulation should be increased to about 0.8mm, resulting in a significant increase in the weight of the cable, which is a considerable drawback in the field of aeronautics.
  • the present invention proposes to overcome all of the disadvantages mentioned above by providing a cable to reduce the limits of the corona effect, without substantially increasing the weight and cost of manufacturing the cable while improving performance and the applications of this cable.
  • the cable according to the invention as defined in the preamble and characterized in that a single primary layer of a semiconductor material is interposed coaxially between said at least one conductive core and said at least one outer sheath. of corresponding insulating material, said single primary layer being extruded on said at least one conductive core.
  • said central conductive core is advantageously constituted by a set of multi-stranded metal wires, this assembly being surrounded by said outer sheath of insulating material and said single primary layer of semiconductor material being interposed coaxially between said set of multi-stranded metal wires and said outer sheath of insulating material.
  • the cable comprises a plurality of juxtaposed conductive wires, the central conducting core of each conducting wire being surrounded by a single primary layer of semiconductor material, itself surrounded by an outer sheath. of insulating material, said plurality of son being housed in a holding sheath surrounded by a metal screen, this assembly being enclosed in an insulating outer sheath.
  • Said single primary layer of semiconductor material is preferably made of a fluorinated thermoplastic polymer mixed with carbon black and said outer sheath of insulating material is made of a fluorinated thermoplastic polymer facilitating its manufacture by extrusion and recycling.
  • the cable according to the invention is disposed inside a duct for the purpose of heating by skin effect, and it is pulled inside said duct and fed at one end by a source of energy. electric supplying an alternating current.
  • the wires of the other end of the cable are short-circuited.
  • FIG. 1 represents a cross-sectional view of a particular embodiment of the cable according to the invention
  • FIG. 2 is a longitudinal sectional view of the cable represented by FIG. 1
  • FIG. 3 is a transverse view of a second embodiment of the cable according to the invention
  • FIG. 4 is a longitudinal sectional view of the cable represented by FIG.
  • the cable 10 comprises a conductive core 1 composed of a set of multi-strand wires 12, preferably made of copper coated with a layer of tin, silver or nickel based on aluminum alloy. copper, bronze or aluminum, and an outer sheath of insulating material 13 surrounding the conductive core 11.
  • This outer sheath 13 is made of a synthetic material such as a fluorinated thermoplastic polymer, and its thickness is calculated to ensure the safety of the cable. and its close environment.
  • the cable 10 further comprises a single primary layer 14 of a semiconductor material, interposed between the conductive core 11 and the outer sheath of insulating material 13.
  • the single primary layer 14 is advantageously made of an insulating material to which a specified percentage of carbon black has been added and obtained by extrusion.
  • the semiconductor material may be a fluorine polymer loaded with carbon powder.
  • This single semiconductor primary layer 14 has the effect of eliminating, or at least repelling, the critical conditions where the corona effect could occur on a cable not having this primary layer. Its embodiment by extrusion makes it possible to reduce the thickness of the outer insulating sheath 13 and consequently to substantially reduce the weight of the insulating material on cables intended for aeronautics, for example.
  • the longitudinal sectional view of FIG. 2 shows, in particular, the difference in thickness of the outer insulating sheath 13 and of the semiconducting primary layer 14.
  • the thickness of the latter should be more than doubled.
  • the solution of the invention solves the problem of the corona effect on AC power cables working under conditions where the risk exists.
  • the heating function of a duct conveying viscous products whose fluidity is increased by raising the temperature can also be solved by the principle of the skin effect generated by means of the cable 10 pulled directly inside this duct and powered by a source of electrical energy delivering an alternating current.
  • FIGS. 3 and 4 show another embodiment of a cable 20 used for heating ducts carrying liquid products, in particular filled or highly viscous liquids, the fluidity of which can be increased by raising their temperature in order to be able to use water pumps. circulation.
  • These heating ducts are used for petrochemical applications, for the transport of sulfur, ethylene, heavy hydrocarbons, etc.
  • the cable 20 shown which can be very long and in particular to a length of fifty kilometers, includes for example three insulated conductor wires 21, 22 and 23.
  • These three conductive wires 21, 22 and 23 are each composed of a conductive core 30 consisting of at least one multi-strand wire, this conductive core being surrounded by a single primary layer 31 made of a semiconductor material, this layer 31 being surrounded by an outer sheath of insulating material 32.
  • the three conductive wires 21 , 22 and 23 are arranged side by side and can be housed in a holding sheath 33 surrounded by a metal screen 34 which is itself enclosed in a sheath 35 made of an electrically insulating material.
  • the son 21, 22, 23 are connected by one of their ends to a voltage source Alternatively 24 and short-circuited by their other end opposite the current source 24, said ends being directly connected to each other or assembled by a star coupling in case of three-phase power supply.
  • said cable is disposed inside a conduit 40 for the purpose of heating by skin effect.
  • said cable is pulled inside said duct and supplied by an electric power source 24 delivering an alternating current, as shown in FIG.
  • the present invention is not limited to the embodiments described, but may undergo various modifications or variations. Practical achievements can be adapted to the intended applications.
  • the materials employed can also be varied according to these applications, in particular the synthetic materials used to produce the outer insulating sheath may be different depending on the intended use of the cable of the invention. It is the same materials used to make the semiconductor layer.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Organic Insulating Materials (AREA)

Abstract

The invention relates to an electrical cable (10) for AC current having high voltages greater than 2 KV and/or working at high temperatures of the order of 260°C, and/or used in a specific environment, in particular aeronautical. This cable (10) is designed to push back the limit conditions of the corona effect. For this purpose, it comprises a conducting core (11) and an outer insulating sheath (13) surrounding the conducting core (11) as well as a single semiconducting primary layer (14) interposed between this conducting core (11) and the insulating outer sheath (13). The single semiconducting primary layer (14) is extruded and made of fluoropolymer filled with carbon black.

Description

CABLE ELECTRIQUE ET APPLICATION DE CE CABLE  ELECTRIC CABLE AND APPLICATION OF THIS CABLE
Domaine technique Technical area
La présente invention concerne un câble électrique pour courant alternatif ayant des tensions élevées, notamment des tensions supérieures à 2KV et/ou travaillant à des températures élevées, notamment à des températures de l'ordre de 260°C, et/ou utilisé dans un environnement spécifique, notamment aéronautique, ledit câble étant agencé pour repousser les conditions limites de l'effet de décharge partielle corona et comportant au moins une âme conductrice centrale et au moins une gaine extérieure réalisée en un matériau isolant et entourant ladite âme conductrice centrale.  The present invention relates to an AC electrical cable having high voltages, especially voltages greater than 2KV and / or working at high temperatures, especially at temperatures of the order of 260 ° C, and / or used in an environment specific, especially aeronautical, said cable being arranged to push the boundary conditions of the corona partial discharge effect and comprising at least one central conductive core and at least one outer sheath made of an insulating material and surrounding said central conductive core.
L'invention concerne également l'application de ce câble pour le chauffage de substances liquides, semi-liquides ou gazeuses par effet Joule. The invention also relates to the application of this cable for heating liquid, semi-liquid or gaseous substances by Joule effect.
Technique antérieure Prior art
Le problème technique posé par l'effet de décharge partielle corona dans le domaine du transport d'énergie électrique sous la forme d'un courant alternatif est bien connu. Il se pose en particulier dans une application de chauffage par résistance qui utilise l'effet de peau, couramment appelé "skin effect", qui consiste à chauffer des conduites, en particulier des conduites du type pipeline qui véhiculent des produits issus de forages pétroliers, des substances minérales liquides comme le soufre ou des produits chimiques ou similaires qui ont la caractéristique d'être lourds, denses ou visqueux chargés en substance de forte densité et dont le pompage est difficile lorsqu'ils sont à relativement basse température, voire impossible en cas de solidification du produit. Les pipelines peuvent également véhiculer du gaz et l'apport de chaleur permet de maintenir ce gaz en température et de réduire très sensiblement la condensation. Le maintien de la température se fait à des valeurs pouvant aller jusqu'à 180°C en fonction du produit à maintenir, le câble devant travailler jusqu'à environ 260°C. Ce maintien en température, ou ce chauffage, peut notamment être obtenu grâce à l'effet de peau et par rayonnement, la chaleur étant obtenue par effet Joule. Dans ce but on insère un câble électrique alimenté en tension alternative dans un tube et on connecte électriquement le câble à l'autre extrémité de ce tube. Le courant partant par le câble retourne par le tube, celui-ci restant sur la surface intérieure du tube. La chaleur dissipée chauffe le tube qui transfère la chaleur aux produits véhiculés et génère la montée en température des liquides par ^ffet Joule. Ce tube est solidarisé à la conduite ou au pipeline par soudage et/ou bandage. The technical problem of the corona partial discharge effect in the field of electrical energy transport in the form of an alternating current is well known. It arises in particular in a resistance heating application that uses the skin effect, commonly called "skin effect", which consists of heating pipes, in particular pipeline type pipes that convey products from oil drilling, liquid mineral substances such as sulfur or chemicals or the like which have the characteristic of being heavy, dense or viscous charged in substance with high density and whose pumping is difficult when they are at relatively low temperature, or even impossible in case solidification of the product. Pipelines can also carry gas and the heat input can maintain this gas temperature and significantly reduce condensation. The temperature is maintained at values up to 180 ° C depending on the product to be maintained, the cable to work up to about 260 ° C. This temperature maintenance, or this heating, can in particular be obtained through the skin effect and radiation, the heat being obtained by Joule effect. For this purpose is inserted an AC power cable into a tube and electrically connected to the cable at the other end of this tube. The current flowing through the cable returns through the tube, the latter remaining on the inner surface of the tube. The dissipated heat heats the tube which transfers the heat to the products conveyed and generates the rise in temperature of the liquids by Joule effect. This tube is secured to the pipe or the pipeline by welding and / or bandage.
Malheureusement l'effet corona perturbe fréquemment les objectifs recherchés en créant des courts-circuits ou des décharges dues à l'ionisation de l'air susceptibles de détruire, voire traverser localement la couche d'isolation. Pour éviter ces inconvénients on est amené à augmenter l'épaisseur de la couche de matériau isolant, ce qui augmente le coût, la section et le poids du câble électrique. Une autre solution consiste à augmenter le ratio de câble sur le pipeline, mais ceci engendre aussi des surcoûts importants. Unfortunately the corona effect frequently disturbs the desired objectives by creating short circuits or discharges due to the ionization of the air likely to destroy or even cross the insulation layer locally. To avoid these disadvantages it is necessary to increase the thickness of the layer of insulating material, which increases the cost, the section and the weight of the electric cable. Another solution is to increase the cable ratio on the pipeline, but this also generates significant additional costs.
On connaît des publications antérieures qui proposent des solutions susceptibles de prévenir ces inconvénients pour ce type d'application relative au chauffage par effet de peau. La publication britannique GB 1 459 579 décrit un conduit générateur de chaleur utilisant l'effet de peau produit par un courant alternatif. Ce conduit est réalisé en un matériau ferromagnétique et contient un câble isolé qui le traverse, ce câble étant pourvu d'une couche écran pour éviter une décharge de corona. Il est avéré et reconnu que l'ajout de cet écran métallique complique l'ingénierie du système dit "skin effect" et complique également son installation. Prior publications are known which propose solutions which can prevent these disadvantages for this type of application relating to heating by skin effect. British Publication GB 1 459 579 discloses a heat generating conduit using the skin effect produced by an alternating current. This conduit is made of a ferromagnetic material and contains an insulated cable that passes through it, this cable being provided with a screen layer to prevent a corona discharge. It is proven and recognized that the addition of this metal screen complicates the engineering of the so-called "skin effect" system and also complicates its installation.
D'autres conduits générateurs de chaleur sont décrits par les brevets américains US 3,293,407 et US 3,515,837, qui sont conçus de telle manière que, lorsqu'un courant alternatif traverse le conducteur, un courant alternatif correspondant circule exclusivement à travers la peau intérieure du conduit ferromagnétique en générant de la chaleur, alors que pratiquement la tension au niveau du périmètre extérieur du tube est voisine de zéro. Other heat generating conduits are described by US Pat. Nos. 3,293,407 and 3,515,837, which are designed in such a way that, when an alternating current passes through the conductor, a corresponding alternating current flows exclusively through the inner skin of the ferromagnetic conduit. in generating heat, while virtually the voltage at the outer perimeter of the tube is close to zero.
Le brevet britannique GB 1.080.778 décrit un procédé de fabrication d'un câble 5 destiné à ce même type d'application, comportant un noyau central conducteur ayant une gaine extérieure en polyéthylène et une couche intermédiaire en polyoléfine chargée de noir de carbone, ces couches coaxiales étant produites par co-extrusion. Ces matériaux ont comme défaut essentiel de ne pas tenir aux températures élevées, notamment aux températures de l'ordre de 180 à 260°C î o telles que celles prévues dans le cadre l'invention. British Patent GB 1.080.778 discloses a method of manufacturing a cable 5 for the same type of application, comprising a conductive central core having an outer sheath polyethylene and a polyolefin intermediate layer loaded with carbon black, these coaxial layers being produced by coextrusion. These materials have the essential defect not to stand at high temperatures, especially at temperatures of the order of 180 to 260 ° C such as those provided in the context of the invention.
Le brevet américain US 3.660.592 décrit également un câble électrique ayant un conducteur central isolé par un revêtement périphérique, ces deux éléments étant séparés par une couche de résine de fiuorocarbone semi-conductrice contenant 15 de 0,5 à 75% de graphite. Une telle couche en résine est complexe à réaliser et la résine n'étant pas un thermoplastique est difficile à recycler, ce qui a une influence extrêmement négative sur le coût de fabrication. US Pat. No. 3,660,592 also discloses an electrical cable having a central conductor insulated by a peripheral coating, these two elements being separated by a semiconductor fiuorocarbon resin layer containing from 0.5 to 75% graphite. Such a resin layer is complex to achieve and the resin is not a thermoplastic is difficult to recycle, which has an extremely negative influence on the manufacturing cost.
Le brevet américain US 5.532.375 décrit un câble électrique en vue de 0 l'exploitation de l'effet de peau, ce câble ayant une structure complexe avec une couche semi-conductrice en TFE disposée entre le conducteur et l'isolant. Son coût de fabrication est élevé et les températures visées par les applications du câble de l'invention ne peuvent pas être atteintes. 5 L'effet corona est bien connu et les câbles de chauffage utilisant l'effet de peau sont habituellement utilisés pour des températures ne dépassant pas 120°C. Néanmoins, pour de nombreuses applications industrielles, il serait avantageux de pouvoir élever cette valeur et d'aller jusqu'à des températures de l'ordre de 260°C. Les câbles habituels ne permettent pas d'atteindre ces températures, à cause des0 risques liés à l'effet corona, sans nécessiter des précautions importantes consistant à augmenter de façon importante l'épaisseur de la couche de matériau isolant. Les tensions de travail habituelles sont limitées à 2KV, parce que l'effet co-ona augmente considérablement avec l'élévation de la tension de travail. Or, pour de très nombreuses applications, travailler à des tensions égales ou supérieures à 5 3,5KV et pouvant atteindre 5KV sans risquer le court-circuit par effet corona constitue une amélioration considérable de performances. US Pat. No. 5,532,375 discloses an electrical cable for exploiting the skin effect, which cable has a complex structure with a TFE semiconductor layer disposed between the conductor and the insulator. Its manufacturing cost is high and the temperatures targeted by the applications of the cable of the invention can not be reached. The corona effect is well known and heating cables using the skin effect are usually used for temperatures not exceeding 120 ° C. Nevertheless, for many industrial applications, it would be advantageous to be able to raise this value and to go up to temperatures of the order of 260 ° C. The usual cables do not make it possible to reach these temperatures, because of the risks related to the corona effect, without requiring important precautions consisting in significantly increasing the thickness of the layer of insulating material. The usual working voltages are limited to 2KV, because the co-ona effect increases considerably with the raising of the working voltage. However, for many applications, working at voltages equal to or greater than 3.5KV and up to 5KV without risking corona short circuit is a considerable improvement in performance.
Un autre problème se pose dans le domaine de l'aéronautique. Sachant que l'effet corona augmente à la fois avec l'élévation de la tension de travail et avec î o l'altitude, la tension habituellement utilisée dans les avions de lignes est de 115V pour réduire les risques de court-circuit par effet corona. L'objectif de certaines compagnies de porter la tension de travail à 230V passe par une augmentation conséquente de l'épaisseur de la gaine de matériau isolant, ce qui augmente de façon significative le poids des câbles. Pour un câble travaillant à la tension deAnother problem arises in the field of aeronautics. Knowing that the corona effect increases with both the elevation of the working voltage and with the altitude, the voltage usually used in the airliners is 115V to reduce the risk of short circuit by corona . The goal of some companies to increase the working voltage to 230V is to significantly increase the thickness of the insulating sheath, which significantly increases the weight of the cables. For a cable working at the voltage of
15 115V l'épaisseur de l'isolant est d'environ 0.2mm. Pour un câble travaillant à la tension de 230V l'épaisseur de l'isolant devrait être augmentée à environ 0.8mm, d'où une augmentation importante du poids du câble, ce qui constitue un inconvénient considérable dans le domaine de l'aéronautique. 0 Exposé de l'invention 115V the thickness of the insulation is about 0.2mm. For a cable working at the voltage of 230V the thickness of the insulation should be increased to about 0.8mm, resulting in a significant increase in the weight of the cable, which is a considerable drawback in the field of aeronautics. 0 Presentation of the invention
La présente invention se propose de pallier l'ensemble des inconvénients mentionnés ci-dessus en réalisant un câble permettant de reculer les limites de l'effet corona, sans augmenter de manière substantielle le poids et le coût de fabrication du câble tout en améliorant les performances et les applications de ce5 câble.  The present invention proposes to overcome all of the disadvantages mentioned above by providing a cable to reduce the limits of the corona effect, without substantially increasing the weight and cost of manufacturing the cable while improving performance and the applications of this cable.
Ce but est atteint par le câble selon l'invention tel que défini en préambule et caractérisé en ce qu'une couche primaire unique d'un matériau semi-conducteur est interposée coaxialement entre ladite au moins une âme conductrice et ladite0 au moins une gaine extérieure en matériau isolant correspondante, ladite couche primaire unique étant extrudée sur ladite au moins une âme conductrice. Selon un mode de réalisation, ladite âme conductrice centrale est avantageusement constituée d'un ensemble de fils métalliques multibrins, cet ensemble étant entouré de ladite gaine extérieure en matériau isolant et ladite couche primaire unique de matériau semi-conducteur étant interposée coaxialement entre ledit ensemble de fils métalliques multibrins et ladite gaine extérieure en matériau isolant. This object is achieved by the cable according to the invention as defined in the preamble and characterized in that a single primary layer of a semiconductor material is interposed coaxially between said at least one conductive core and said at least one outer sheath. of corresponding insulating material, said single primary layer being extruded on said at least one conductive core. According to one embodiment, said central conductive core is advantageously constituted by a set of multi-stranded metal wires, this assembly being surrounded by said outer sheath of insulating material and said single primary layer of semiconductor material being interposed coaxially between said set of multi-stranded metal wires and said outer sheath of insulating material.
Selon un autre mode de réalisation particulier, le câble comporte une pluralité de fils conducteurs juxtaposés, l'âme conductrice centrale de chaque fil conducteur étant entourée d'une couche primaire unique de matériau semi-conducteur, elle- même entourée d'une gaine extérieure en matériau isolant, ladite pluralité de fils étant logée dans une gaine de maintien entourée d'un écran métallique, cet ensemble étant enserré dans un fourreau extérieur isolant. Ladite couche primaire unique de matériau semi-conducteur est de préférence réalisée en un polymère thermoplastique fluoré mélangé à du noir de carbone et ladite gaine extérieure en matériau isolant est réalisée en un polymère thermoplastique fluoré facilitant sa fabrication par extrusion et son recyclage Dans le cadre d'une application particulière le câble selon l'invention est disposé à l'intérieur d'un conduit en vue du chauffage par effet de peau, et il est tiré à l'intérieur dudit conduit et alimenté à une extrémité par une source d'énergie électrique délivrant un courant alternatif. Dans le cadre de cette application, les fils conducteurs de l'autre extrémité du câble sont mis en court-circuit. According to another particular embodiment, the cable comprises a plurality of juxtaposed conductive wires, the central conducting core of each conducting wire being surrounded by a single primary layer of semiconductor material, itself surrounded by an outer sheath. of insulating material, said plurality of son being housed in a holding sheath surrounded by a metal screen, this assembly being enclosed in an insulating outer sheath. Said single primary layer of semiconductor material is preferably made of a fluorinated thermoplastic polymer mixed with carbon black and said outer sheath of insulating material is made of a fluorinated thermoplastic polymer facilitating its manufacture by extrusion and recycling. In a particular application, the cable according to the invention is disposed inside a duct for the purpose of heating by skin effect, and it is pulled inside said duct and fed at one end by a source of energy. electric supplying an alternating current. As part of this application, the wires of the other end of the cable are short-circuited.
Description sommaire des dessins Brief description of the drawings
La présente invention et ses principaux avantages apparaîtront mieux dans la description de différents modes de réalisation, en référence aux dessins annexés, dans lesquels: la figure 1 représente une vue en coupe transversale d'une forme de réalisation particulière du câble selon l'invention, la figure 2 est une vue en coupe longitudinale du câble représenté par la figure 1 , la figure 3 est une vue transversale d'une seconde forme de réalisation du câble selon l'invention, et la figure 4 est une vue en coupe longitudinale du câble représenté par la figure 3. The present invention and its main advantages will become more apparent in the description of various embodiments, with reference to the accompanying drawings, in which: FIG. 1 represents a cross-sectional view of a particular embodiment of the cable according to the invention, FIG. 2 is a longitudinal sectional view of the cable represented by FIG. 1, FIG. 3 is a transverse view of a second embodiment of the cable according to the invention, and FIG. 4 is a longitudinal sectional view of the cable represented by FIG.
Meilleures manières de réaliser l'invention Best ways to achieve the invention
En référence à la figure 1 , le câble 10, tel que représenté comporte une âme conductrice 1 composée d'un ensemble de fils multibrins 12, de préférence en cuivre revêtu d'une couche en étain, argent ou nickel à base d'alliage de cuivre, bronze ou aluminium, et une gaine extérieure en matériau isolant 13 entourant l'âme conductrice 11. Cette gaine extérieure 13 est réalisée en un matériau synthétique tel qu'un polymère thermoplastique fluoré, et son épaisseur est calculée pour assurer la sécurité du câble et de son environnement proche. Pour résoudre le problème de l'effet corona évoqué ci-dessus, le câble 10 comporte en outre une couche primaire unique 14 d'un matériau semi-conducteur, interposé entre l'âme conductrice 11 et la gaine extérieure en matériau isolant 13. Cette couche primaire unique 14 est avantageusement réalisée en un matériau isolant auquel on a ajouté un pourcentage déterminé de noir de carbone et obtenue par extrusion. A titre d'exemple préférentiel le matériau semi- conducteur peut être un polymère de fluor chargé en poudre de carbone. Cette couche primaire semi-conductrice unique 14 a pour effet de supprimer, ou du moins de repousser, les conditions critiques où l'effet corona pourrait se produire sur un câble ne comportant pas cette couche primaire. Son mode de réalisation par extrusion permet de réduire l'épaisseur de la gaine isolante extérieure 13 et par conséquent de réduire de façon substantielle le poids de la matière isolante sur des câbles destinés à l'aéronautique par exemple. La vue en coupe longitudinale de la figure 2 montre en particulier la différence d'épaisseur de gaine isolante extérieure 13 et de la couche primaire semi- conductrice 14. Pour obtenir une protection aussi efficace que celle qu'apporte la solution de l'invention avec un câble classique ne comportant que l'âme conductrice et la gaine isolante extérieure, l'épaisseur de cette dernière devrait être plus que doublée. La solution de l'invention résout le problème de l'effet corona sur des câbles d'alimentation en courant alternatif travaillant dans des conditions où le risque existe. La fonction de chauffage d'un conduit véhiculant des produits visqueux dont la fluidité est augmentée en élevant la température peut également être résolue par le principe de l'effet dé peau généré au moyen du câble 10 tiré directement à l'intérieur de ce conduit et alimenté par une source d'énergie électrique délivrant un courant alternatif. With reference to FIG. 1, the cable 10, as represented, comprises a conductive core 1 composed of a set of multi-strand wires 12, preferably made of copper coated with a layer of tin, silver or nickel based on aluminum alloy. copper, bronze or aluminum, and an outer sheath of insulating material 13 surrounding the conductive core 11. This outer sheath 13 is made of a synthetic material such as a fluorinated thermoplastic polymer, and its thickness is calculated to ensure the safety of the cable. and its close environment. To solve the problem of the corona effect mentioned above, the cable 10 further comprises a single primary layer 14 of a semiconductor material, interposed between the conductive core 11 and the outer sheath of insulating material 13. single primary layer 14 is advantageously made of an insulating material to which a specified percentage of carbon black has been added and obtained by extrusion. As a preferred example, the semiconductor material may be a fluorine polymer loaded with carbon powder. This single semiconductor primary layer 14 has the effect of eliminating, or at least repelling, the critical conditions where the corona effect could occur on a cable not having this primary layer. Its embodiment by extrusion makes it possible to reduce the thickness of the outer insulating sheath 13 and consequently to substantially reduce the weight of the insulating material on cables intended for aeronautics, for example. The longitudinal sectional view of FIG. 2 shows, in particular, the difference in thickness of the outer insulating sheath 13 and of the semiconducting primary layer 14. In order to obtain as effective protection as that provided by the solution of the invention with a conventional cable having only the conductive core and the outer insulating sheath, the thickness of the latter should be more than doubled. The solution of the invention solves the problem of the corona effect on AC power cables working under conditions where the risk exists. The heating function of a duct conveying viscous products whose fluidity is increased by raising the temperature can also be solved by the principle of the skin effect generated by means of the cable 10 pulled directly inside this duct and powered by a source of electrical energy delivering an alternating current.
Les figures 3 et 4 représentent une autre forme de réalisation d'un câble 20 utilisé pour le chauffage de conduits véhiculant des produits liquides, notamment des liquides chargés ou très visqueux dont on peut augmenter la fluidité en élevant leur température pour pouvoir utiliser des pompes de circulation. Ces conduits chauffants sont utilisés pour des applications en pétrochimie, pour le transport de soufre, d'éthylène, d'hydrocarbures lourds etc. FIGS. 3 and 4 show another embodiment of a cable 20 used for heating ducts carrying liquid products, in particular filled or highly viscous liquids, the fluidity of which can be increased by raising their temperature in order to be able to use water pumps. circulation. These heating ducts are used for petrochemical applications, for the transport of sulfur, ethylene, heavy hydrocarbons, etc.
Le câble 20 représenté, qui peut être très long et notamment atteindre une longueur de cinquante kilomètres, regroupe par exemple trois fils conducteurs isolés 21 , 22 et 23. Ces trois fils conducteurs 21 , 22 et 23 sont composés chacun d'une âme conductrice 30 constituée d'au moins un fil multibrins, cette âme conductrice étant entourée d'une couche primaire unique 31 faite d'un matériau semi-conducteur, cette couche 31 étant entourée d'une gaine extérieure en matériau isolant 32. Les trois fils conducteurs 21 , 22 et 23 sont disposés côte à côte et peuvent être logés dans une gaine de maintien 33 entourée d'un écran métallique 34 qui est lui-même enserré dans une gaine 35 faite d'un matériau électriquement isolant. Afin d'assurer le chauffage par effet Joule d'un conduit 40 à chauffer (représenté schématiquement) dans lequel ce type de câble 20 est placé, les fils conducteurs 21 , 22, 23 sont connectés par une de leurs extrémités à une source de tension 5 alternative 24 et mis en court circuit par leur autre extrémité opposée à la source de courant 24, lesdites extrémités étant directement reliées entre elles ou assemblées par un couplage étoile en cas d'alimentation triphasée. The cable 20 shown, which can be very long and in particular to a length of fifty kilometers, includes for example three insulated conductor wires 21, 22 and 23. These three conductive wires 21, 22 and 23 are each composed of a conductive core 30 consisting of at least one multi-strand wire, this conductive core being surrounded by a single primary layer 31 made of a semiconductor material, this layer 31 being surrounded by an outer sheath of insulating material 32. The three conductive wires 21 , 22 and 23 are arranged side by side and can be housed in a holding sheath 33 surrounded by a metal screen 34 which is itself enclosed in a sheath 35 made of an electrically insulating material. In order to ensure heating by Joule effect of a pipe 40 to be heated (shown schematically) in which this type of cable 20 is placed, the son 21, 22, 23 are connected by one of their ends to a voltage source Alternatively 24 and short-circuited by their other end opposite the current source 24, said ends being directly connected to each other or assembled by a star coupling in case of three-phase power supply.
Dans le cadre d'une application du câble électrique 20, ledit câble est disposé à î o l'intérieur d'un conduit 40 en vue du chauffage par effet de peau. A cet effet il est tiré à l'intérieur dudit conduit et alimenté par une source d'énergie électrique 24 délivrant un courant alternatif, comme le montre la figure 3. In the context of an application of the electric cable 20, said cable is disposed inside a conduit 40 for the purpose of heating by skin effect. For this purpose it is pulled inside said duct and supplied by an electric power source 24 delivering an alternating current, as shown in FIG.
Il est utilisé pour le chauffage par effet Joule d'un fluide visqueux circulant dans 15 ledit conduit, et les fils conducteurs 21 , 22, 23 de l'autre extrémité du câble sont mis en court-circuit. It is used for Joule heating of a viscous fluid circulating in said conduit, and the conductive wires 21, 22, 23 of the other end of the cable are short-circuited.
La présente invention n'est pas limitée aux formes de réalisation décrites, mais peut subir différentes modifications ou variantes. Les réalisations pratiques0 peuvent être adaptées aux applications prévues. Les matériaux employés peuvent également être diversifiés selon ces applications, notamment les matières synthétiques utilisées pour réaliser la gaine isolante extérieure peuvent être différentes selon l'utilisation prévue du câble de l'invention. Il en est de même des matériaux utilisés pour réaliser la couche semi-conductrice.The present invention is not limited to the embodiments described, but may undergo various modifications or variations. Practical achievements can be adapted to the intended applications. The materials employed can also be varied according to these applications, in particular the synthetic materials used to produce the outer insulating sheath may be different depending on the intended use of the cable of the invention. It is the same materials used to make the semiconductor layer.
5 5

Claims

REVENDICATIONS
1. Câble électrique (10; 20) pour courant alternatif ayant des tensions élevées, notamment des tensions supérieures à 2KV et/ou travaillant à des températures élevées, notamment à des températures de l'ordre de 260°C, et/ou utilisé dans un environnement spécifique, notamment aéronautique, ledit câble étant agencé pour repousser les conditions limites de l'effet de décharge partielle corona et comportant au moins une âme conductrice centrale (11 ; 30) et au moins une gaine extérieure (13; 32) réalisée en un matériau isolant et entourant ladite au moins une âme conductrice centrale ( 1 ; 30), caractérisé en ce qu'une couche primaire unique (14; 31) d'un matériau semi-conducteur est interposée coaxialement entre ladite au moins une âme conductrice (11 ; 30) et ladite au moins une gaine extérieure en matériau isolant (13; 32) correspondante, ladite couche primaire unique (14, 31) étant extrudée sur ladite au moins une âme conductrice . An AC power cable (10; 20) having high voltages, especially voltages above 2KV and / or working at elevated temperatures, especially at temperatures of the order of 260 ° C, and / or used in a specific environment, especially aeronautical, said cable being arranged to push back the boundary conditions of the corona partial discharge effect and comprising at least one central conducting core (11; 30) and at least one outer sheath (13; an insulating material surrounding said at least one central conducting core (1; 30), characterized in that a single primary layer (14; 31) of a semiconductor material is coaxially interposed between said at least one conductive core ( 11; 30) and said at least one outer sheath of corresponding insulating material (13; 32), said single primary layer (14, 31) being extruded onto said at least one conductive core.
2. Câble électrique (10) selon la revendication 1 , caractérisé en ce que ladite âme conductrice centrale (11) est constituée d'un ensemble de fils métalliques multibrins, cet ensemble étant entouré de ladite gaine extérieure en matériau isolant (13) et ladite couche primaire unique (14) de matériau semi-conducteur étant interposée coaxialement entre ledit ensemble de fils métalliques multibrins et ladite gaine extérieure en matériau isolant. 2. Electrical cable (10) according to claim 1, characterized in that said central conductive core (11) consists of a set of multi-stranded metal son, this assembly being surrounded by said outer sheath of insulating material (13) and said single primary layer (14) of semiconductor material being interposed coaxially between said set of stranded metal wires and said outer sheath of insulating material.
3. Câble électrique (20) selon la revendication 1 , caractérisé en ce qu'il comporte une pluralité de fils conducteurs juxtaposés (21 , 22, 23), l'âme conductrice centrale (30) de chaque fil conducteur étant entourée d'une couche primaire unique de matériau semi-conducteur (31), elle-même entourée d'une gaine extérieure en matériau isolant (32), ladite pluralité de fils étant logée dans une gaine de maintien (33) entourée d'un écran métallique (34), cet ensemble étant enserré dans un fourreau extérieur isolant (35). 3. Electrical cable (20) according to claim 1, characterized in that it comprises a plurality of juxtaposed conductive son (21, 22, 23), the central conductive core (30) of each conductive wire being surrounded by a single primary layer of semiconductor material (31), itself surrounded by an outer sheath of insulating material (32), said plurality of wires being housed in a holding sheath (33) surrounded by a metal screen (34) ), this assembly being enclosed in an outer insulating sleeve (35).
4. Câble électrique (10; 20) selon la revendication 1 , caractérisé en ce que ladite couche primaire unique de matériau semi-conducteur (14; 31) est réalisée en un polymère thermoplastique fluoré mélangé à du noir de carbone. The electrical cable (10; 20) according to claim 1, characterized in that said single primary layer of semiconductor material (14; 31) is made of fluorinated thermoplastic polymer mixed with carbon black.
5. Câble électrique (10; 20) selon la revendication 1 , caractérisé en ce que ladite gaine extérieure en matériau isolant (13; 32) est réalisée en un polymère thermoplastique fluoré. 5. Electrical cable (10; 20) according to claim 1, characterized in that said outer sheath of insulating material (13; 32) is made of a fluorinated thermoplastic polymer.
6. Application du câble électrique (20) selon l'une quelconque des revendications précédentes pour chauffer des substances liquides, semi-liquides ou gazeuses par effet Joule, caractérisé en ce que ledit câble est disposé à l'intérieur d'un conduit véhiculant un fluide en vue de son chauffage par effet de peau, et en ce qu'il est alimenté par une source d'énergie électrique délivrant un courant alternatif disposée à une extrémité dudit câble. 6. Application of the electric cable (20) according to any one of the preceding claims for heating liquid, semi-liquid or gaseous substances by Joule effect, characterized in that said cable is disposed inside a conduit carrying a fluid for its heating by skin effect, and in that it is fed by a source of electrical energy delivering an alternating current disposed at one end of said cable.
7. Application du câble électrique (20) selon la revendication 6, caractérisé en ce que les fils conducteurs (21 , 22, 23) de l'autre extrémité du câble sont mis en court-circuit. 7. Application of the electric cable (20) according to claim 6, characterized in that the conductive son (21, 22, 23) of the other end of the cable are short-circuited.
PCT/CH2012/000111 2011-05-20 2012-05-16 Electrical cable and application of this cable WO2012159221A1 (en)

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