Cord for high voltage overhead electrical lines, with high thermal limit and with 3 load-bearing cables

Description

[0001] The present invention relates to a cord for overhead electrical lines; the cord is suitable in particular for extreme environmental conditions (cold, ice and wind) and extreme installation conditions (large level differences). Cords of the indicated type are known to be currently produced in the form of a load-bearing cable, usually of steel, which supports wires of conductor material, usually of aluminium or its alloys.

[0002] However these traditional cords (because of the intrinsic characteristics of the steel load-bearing cable) present a considerable weight per unit of length and a high average coefficient of thermal expansion.

[0003] EP1821318 describes a cord for high voltage overhead electrical lines comprising a core about which at least one ring of quoins and/or conductors of circular cross-section and electrically conductive material are wrapped, the core consisting of at least three load-bearing cables twisted together, which are each formed from a plurality of twisted-together wires formed of composite hybrid carbon/glass fibre material.

[0004] The object of the present invention is to provide cords for electrical lines by which the stated technical drawbacks of the known art are eliminated.

[0005] This and other objects are attained according to the present invention by a cord in accordance with the technical teachings of the accompanying claims.

[0006] Further characteristics and advantages of the invention will be more apparent from the description of a preferred but non-exclusive embodiment of the invention, illustrated by way of non-limiting in the single figure, which represents a cross-section through the cord.

[0007] The cord 1 presents a core 2 about which one, two or more rings of electrically conductive quoins 3 are wrapped. The electrically conductive quoins are twisted together about the core in known manner. In alternative embodiments they can be formed of aluminium wires of circular cross-section.

[0008] They are preferably formed of Al-Zr alloy, however other materials which can be equally used include annealed aluminium and Al-Mg alloy.

[0009] In the figure the core is formed of three load-bearing cables 4 resting against each other and twisted together.

[0010] Each cable 4 is formed from a plurality of wires 5 also twisted together and made of composite material of hybrid carbon/glass fibres. The wires 5 are covered with a first sheath 6 of aluminium (or other material, for example aluminium zirconium or Al-Mg alloy) hot-extruded directly onto the wires 5.

[0011] In the described embodiment, each cable comprises seven wires. Such a wire number enables the cable to externally assume a nearly circular cross-section, which facilitates extrusion of the first sheath 6. However any number of wires can evidently be used.

[0012] Advantageously, before extruding the sheath, the composite material wires are covered with special infill 7 (preferably silicone or bi-component material with programmed crosslinking) and are then wrapped in a special tape (advantageously of Nomex) which maintains the infill 7 in position during the operations involved in extruding the sheath 6.

[0013] The infill 7 is advantageously of very viscous bi-component silicone grease. It is crosslinking and tends to solidify in a programmable manner (in the present text, "programmable" means a material the crosslinking rate of which can be decided previously, for example 3 minutes - 24 hours).

[0014] The use of the infill 7 can also be avoided by extruding the sheath 6 about the wires such that the aluminium also penetrates into the stellate areas.

[0015] Twisted together with the load-bearing cables 4 there are also provided at least three tubular filler elements of aluminium (or formed of flat/compact wires). These are internally hollow, i.e. they considerably reduce the weight of the cord compared with the use of solid filler elements. If it is wished to further increase the ultimate tensile strength, the tubular filler elements can be upgraded by a core of composite hybrid carbon/glass wires.

[0016] In concluding the description of the figure, it should be noted that the load-bearing cables 4 and the filler elements 8 are surrounded by and maintained in position by a second aluminium sheath 9 formed from a C-shaped element, inside which the cables and the filler elements are housed and which is then welded longitudinally.

[0017] Welding is preferably by TIG welding, but laser or microplasma welding could also be used.

[0018] The second sheath 9 could be replaced by a binding of electrically conductive material, or alternatively this electrically conductive material could be extruded about the cables and filler elements.

[0019] As can be seen from the aforesaid figure the three load-bearing cables, when viewed in cross-section, are positioned at the vertices of an equilateral triangle, as are also the filler elements.

[0020] In an alternative embodiment the aforedescribed cord has seven bearing cables 4, and six filler elements 8, but in other embodiments a different number of bearing cables and filler elements can be provided.

[0021] The aforedescribed cord has advantageously a high thermal limit (up to 150 °C) and is preferably of low mass (less than 4 kg/m).

[0022] The maximum external diameter is preferably about 50 mm, enabling the corona effect to be reduced to a minimum. Given the vast conductive surface formed by the double series of quoins, by the second sheath, the first sheath and by the tubular filler elements, the cord presents high current capacities with consequent low resistance.

[0023] The core of carbon and glass fibre based composite material results in low deformations at high loads. The intrinsic characteristics of the cord make it particularly suitable for installation on high voltage overhead lines under extreme climatic conditions (wind and ice up to 60 mm thick) by virtue of its very high ultimate tensile strength.

[0024] By way of example, it can be installed over level differences of 300 m with spans of about 1000 metres.

Claims

1. A cord (1) for high voltage overhead electrical lines comprising a core about which at least one ring of quoins and/or conductors of circular cross-section and electrically conductive material are wrapped, the core consisting of at least three load-bearing cables (4) twisted together, which are each formed from a plurality of twisted-together wires (5) formed of composite hybrid carbon/glass fibre material, characterized in that the load-bearing cables (4) are covered by a hot-extruded first sheath (6) of aluminium or its alloys, at least three filler elements (8) of aluminium or its alloys being twisted together with said load-bearing cables (4), said load-bearing cables (4) and said filler elements being surrounded by a second aluminium sheath or by a binding of aluminium or its alloys, about which the quoins are wrapped.

2. A cord as claimed in the preceding claim, wherein infill is provided between the wires and the first sheath to fill at least the stellate areas defined by the wires.

3. A cord as claimed in the preceding claim, wherein before extruding the first sheath, said infill is maintained in position by a tape preferably of Nomex, wrapped about the cables.

4. A cord as claimed in one or more of the preceding claims, wherein said infill comprises silicone grease and/or bi-component material crosslinkable in a programmable manner.

5. A cord as claimed in one or more of the preceding claims, wherein said twisted-together load-bearing cables are three in number which, when viewed in cross-section are positioned at the vertices of an equilateral triangle, said filler elements being three in number, also twisted together and disposed at the vertices of an equilateral triangle.

6. A cord as claimed in one or more of the preceding claims, wherein each load-bearing cable comprises seven wires of composite hybrid carbon/glass material.

7. A cord as claimed in one or more of the preceding claims, wherein each filler element is formed from an internally hollow tubular element.

8. A cord as claimed in the preceding claim, wherein a core of composite hybrid carbon/glass material is present in the cavity of each tubular element.

9. A cord as claimed in one or more of the preceding claims, wherein said second sheath is welded longitudinally and/or is replaced by a binding of conductive material tape.

10. A cord as claimed in one or more of the preceding claims, wherein said first sheath and/or said second sheath and/or said filler elements are formed of annealed aluminium, Al-Zr alloy or Al-Mg alloy.

Ansprüche

1. Seil (1) für Hochspannungs-Freileitungen, umfassend einen Kern, um den mindestens ein Ring von Keilen und/oder Leiter mit kreisförmigem Querschnitt und aus elektrisch leitendem Werkstoff eingehüllt sind, wobei der Kern aus mindestens drei zusammengedrehten Tragseilen (4) besteht, die jeweils von einem Mehrzahl von zusammengedrehten Adern (5) gebildet sind, wobei die Adern von gemischtem hybrid Kohlen/Glas Fasermaterial gebildet sind, dadurch gekennzeichnet, dass die Tragseilen (4) durch einen ersten heissextrudierten Mantel (6) aus Aluminium oder dessen Legierungen umhüllt sind, wobei mindestens drei Füllungselemente (8) aus Aluminium oder dessen Legierungen mit den genannten Tragseilen (4) zusammengedreht sind, wobei die genannten Tragseilen (4) und die genannte Füllungselemente durch einen zweiten Aluminium-Mantel oder durch eine Anbindung von Aluminium oder dessen Legierungen umhüllt sind, um dem die Keilen eingehüllt sind.

2. Seil nach dem vorhergehenden Anspruch, worin die Füllung zwischen den Adern und dem ersten Mantel vorhanden ist, um mindestens die von den Adern bestimmten Sternregionen zu füllen.

3. Seil nach dem vorhergehenden Anspruch, worin vor dem Extrudieren des ersten Mantels die genannte Füllung durch einem Band vorzugsweise Nomex in ihrer Position um den Seilen gehalten wird.

4. Seil nach einem oder mehreren der vorhergehenden Ansprüche, worin die genannte Füllung Silikonfett und/oder in einer programmierbaren Art vernetztebaren Bikomponentenwerkstoff umfasst.

5. Seil nach einem oder mehreren der vorhergehenden Ansprüche, worin die genannten zusammengedrehten Tragseilen in einer Menge von drei sind und, in Querschnitt gesehen, in den Eckpunkten eines gleichseitigen Dreieckes liegen, wobei die Füllungselemente auch in einer Menge von drei sind, auch zusammengedreht sind und auch in den Eckpunkten eines gleichseitigen Dreieckes liegen.

6. Seil nach einem oder mehreren der vorhergehenden Ansprüche, worin jeder Tragseil sieben Adern aus gemischtem hybrid Kohlen/Glas Material umfasst.

7. Seil nach einem oder mehreren der vorhergehenden Ansprüche, worin jedes Füllungselement von einem innerlich hohlen rohrförmigen Element gebildet ist.

8. Seil nach dem vorhergehenden Anspruch, worin ein Kern aus gemischtem hybrid Kohlen/Glas Material in der Vertiefung jedes rohrförmigen Elements vorhanden ist.

9. Seil nach einem oder mehreren der vorhergehenden Ansprüche, worin der genannte zweite Mantel der Länge nach geschweißt ist und/oder durch eine Anbindung eines leitenden Bands ersetzt ist.

10. Seil nach einem oder mehreren der vorhergehenden Ansprüche, worin der genannte Mantel und/oder der genannte Mantel und/oder die genannten Füllungselemente aus geglühtem Aluminium, Al-Zr-Legierung oder Al-Mg-Legierung gebildet sind.

Revendications

1. Corde (1) pour lignes électriques aériennes à haute tension électrique, comprenant un noyau autour duquel au moins un anneau de cales et/ou des conducteurs de section transversale circulaire et de matériau électriquement conducteur sont enveloppés, le noyau étant constitué d'au moins trois câbles porteurs (4) torsadés ensemble, chacun formé d'une pluralité de fils (5) torsadés ensemble, formés de matériau composite hybride de carbone/fibre de verre, caractérisé en ce que les câbles porteurs (4) sont couverts d'une première gaine extrudée à chaud (6) d'aluminium ou de ses alliages, d'au moins trois éléments de charge (8) d'aluminium ou de ses alliages torsadées ensemble avec lesdits câbles porteurs (4), lesdits câbles porteurs (4) et lesdits éléments de charge étant entourés d'une seconde gaine d'aluminium ou d'une liaison d'aluminium ou de ses alliages, autour de laquelle les cales sont enveloppées.

2. Corde selon la revendication précédente, où un remplissage est pourvu entre les fils et la première gaine pour remplir au moins les régions en étoile définies par les fils.

3. Corde selon la revendication précédente, où, avant d'extruder la première gaine, ledit remplissage est maintenu dans sa position par une bande, préférablement de Nomex, enveloppée autour des câbles.

4. Corde selon une ou plusieurs des revendications précédentes, où ledit remplissage comprend de la graisse de silicone et/ou un matériau à deux composants réticulable de manière programmable.

5. Corde selon une ou plusieurs des revendications précédentes, où lesdits câbles porteurs torsadés ensemble sont au nombre de trois et, lorsque visualisés en section transversale, sont disposés aux sommets d'un triangle équilatéral, lesdits éléments de charge étant au nombre de trois, eux aussi torsadés ensemble et disposés aux sommets d'un triangle équilatéral.

6. Corde selon une ou plusieurs des revendications précédentes, où chaque câble porteur comprend sept fils de matériau composite hybride carbone/fibre de verre.

7. Corde selon une ou plusieurs des revendications précédentes, où chaque élément de charge est formé par un élément tubulaire vide à son intérieur.

8. Corde selon la revendication précédente, où un noyau de matériau composite hybride carbone/fibre de verre est présent dans la cavité de chaque élément tubulaire.

9. Corde selon une ou plusieurs des revendications précédentes, où ladite seconde gaine est soudée longitudinalement et/ou est remplacée par une liaison d'une bande de matériau conducteur.

10. Corde selon une ou plusieurs des revendications précédentes, où ladite première gaine et/ou ladite seconde gaine et/ou lesdits éléments de charge sont formés en aluminium recuit, alliage de Al-Zr ou alliage de Al-Mg.

Drawing