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EP-3738130-B1 - PROCESS FOR IMPREGNATING THERMAL ENERGY ABSORBING MATERIAL INTO THE STRUCTURE OF AN ELECTRIC CABLE, AND RESPECTIVE ELECTRIC CABLE

EP3738130B1EP 3738130 B1EP3738130 B1EP 3738130B1EP-3738130-B1

Inventors

  • HERRMANN PAIS DE SOUSA, Mário Emanuel
  • ALMEIDA LOURENÇO MARQUES TEIXEIRA, Maria Marcela
  • DA SILVA RIBEIRO, Paulo Renato
  • CURADO MATEUS CORREIA, Nuno André
  • SOUSA GOMES, CARLA FILIPA
  • MARQUES PEREIRO ROCHA, Nuno Miguel
  • TORRES TAVARES DA SILVA, Daniela
  • APARÍCIO VIEIRA, Tiago André

Dates

Publication Date
20260506
Application Date
20181022

Claims (12)

  1. A process for impregnating thermal energy absorbing material (12) into the structure of an electric cable (1), comprising the steps of: a) heating a bath of thermal energy absorbing material (12) at a temperature between 50 °C and 100 °C; b) immersing the substrate of the electrical cable (1) in the heated bath of thermal energy absorbing material (12); and c) passing through a dimensional rectification section (15) for fixing the thermal energy absorbing material (12) to the substrate; characterized by the immersion comprising passing the substrate of the electrical cable (1) though a set of impregnation rollers (17) submerged within the thermal energy absorbing material (12).
  2. Process according to claim 1, characterized in that the substrate is the shielding layer (6) of an electric cable (1).
  3. Process according to any of the preceding claims, characterized in that it comprises the further step of applying a strapping tape (9) for restraining the thermal energy absorbing material (12) when applied to the cavities of the shielding (6) or cavities of the corrugated metal tape or sheath (13) of the electric cable (1).
  4. Process according to any of the preceding claims, characterized in that the substrate is an impregnation tape (18).
  5. Electric cable (1) comprising a conductive core (2); a triple insulation layer, covering the conductive core (2), composed of two semiconductive layers (4), an inner and an outer semiconductor, and a layer of polymer insulation material (5) comprised in between, the triple insulation layer being enclosed by a shielding layer (6) comprised of metal wires (7), at least one semiconductive tape (3), and a metal tape or sheath (10); and a sheath of polymer material (11); said cable being characterized by comprising a thermal energy absorbing (12) material located in the cavities of the shielding layer (6) to increase the energy conveyance capacity of the cable (1) while maintaining its diameter.
  6. Electric cable (1) according to claim 6, characterized in that the metal tape or sheath (10) is corrugated.
  7. Electric cable (1) according to any of the preceding claims 6 or 7, characterized in that the thermal energy absorbing material (12) is of an organic base having an operating range between 50 °C and 85 °C.
  8. Electric cable (1) according to claim 8, characterized in that the thermal energy absorbing material (12) is a phase change material.
  9. Electric cable (1) according to any claims 8 or 9, characterized in that the thermal energy absorbing material (12) comprises a phase change material mixed with short chain hydrocarbons in amounts between 10% and 25% v/v.
  10. Electric cable (1) according to any of the preceding claims, characterized in that the thermal energy absorbing material (12) to be impregnated in the cavities of the shielding (6) - in empty spaces provided by the metal wires (7) or cavities provided by the corrugated metal tape or sheath (10) - comprises a mixture with thickeners in amounts between 25% and 50% v/v.
  11. Electric cable (1) according to claim 11, characterized in that the thickener is glass fiber.
  12. Electric cable (1) according to claim 11, characterized in that the thickener is pyrogenic silica.

Description

Technical Field The present application describes a process for impregnating thermal energy absorbing material into the structure of an electric cable, and respective electric cable. Summary According to the invention there is provided a process for impregnating thermal energy absorbing material into the structure of an electric cable as defined in claim 1 and an electric cable as defined in claim 5. Further developments of the invention are the subject of the dependent claims. The present application describes a process for impregnating thermal energy absorbing material into the structure of an electric cable. The process comprises the following steps: a) heating a bath of thermal energy absorbing material at a temperature between 50 °C and 100 °C;b) immersing a substrate in the bath of thermal energy absorbing material;c) passing through a dimensional rectification section for attaching the thermal energy absorbing material to the substrate. In one embodiment of the process, the substrate is the shielding layer of an electric cable. In another embodiment of the process, it comprises the further step of applying a strapping tape for restraining the thermal energy absorbing material when applied to the cavities of the shielding or cavities of the corrugated metal tape or sheath of an electric cable. In another embodiment of the process, the substrate is an impregnation tape. According to an aspect of the invention, in step b) the substrate passes through the bath of thermal energy absorbing material through a set of impregnation rollers. The present application further describes an electric cable comprising a conductive core, a triple insulation layer, composed of two semiconductive layers and a layer of polymer insulation material, a shielding layer comprised of metal wires, at least one or more semiconductive tapes, a metal tape or sheath, either corrugated or not, and a sheath of polymer material; this cable is characterized in that it comprises a thermal energy absorbing material introduced between at least one of the structural sections of the electric cable according to the impregnation process previously described. According to an aspect of the invention, the electric cable comprises a thermal energy absorbing material located in the cavities of the shielding layer to increase the energy conveyance capacity of the cable while maintaining its diameter. In a particular embodiment of the electric cable, the thermal energy absorbing material is of an organic base having an operating range between 50 °C and 85 °C. In a particular embodiment of the electric cable, the thermal energy absorbing material is a phase change material. In another particular embodiment of the electric cable, the thermal energy absorbing material comprises a phase change material mixed with short chain hydrocarbons in amounts between 10% and 25% v/v. In yet another particular embodiment of the electric cable, the thermal energy absorbing material to be impregnated in the cavities of the shielding - in empty spaces provided by the metal wires or cavities provided by the corrugated metal tape or sheath - is mixed with thickeners in amounts between 25% and 50% v/v. In yet another particular embodiment of the electric cable, the thickener is glass fiber. In yet another particular embodiment of the electric cable, the thickener is pyrogenic silica. Background art The latent concerns about the environment and the depletion of natural resources impose the demand for durable products and more efficient operation, issues that have greatly motivated the innovations in the energy sector. The conveyance of energy through high and very high voltage cables is conditioned by Joule-effect losses resulting from heat generation during the passage of electric current in the conductor, which limit the transmission distances since being proportional to the length of the installation. In addition to this limitation, insulated cables, mainly used in underground installations, for having polymer materials in its structure, make the maximum temperature attainable in the conductor a limiting factor for their dimensioning, such temperature being defined by the characteristics of said materials. This means that, despite having the capacity to convey higher currents, the conductor may not do so in the presence of these polymer materials that allow the correct and safe operation of the cable when buried, in order not to degrade said materials. In these cables, the conductor is the area of greater temperature generation (as a function of the current passing therethrough), which is dissipated by the subsequent layers. The inner semiconductor and crosslinked polyethylene insulation (XLPE), layers following the conductor, are those subject to higher temperatures. The maximum temperature the XLPE material can undergo, in steady state, is 90 °C, so that the integrity thereof is not compromised. As a result of this restriction of the insulation material, the cables co