摘要:
A cable having at least one electrical conductor and at least one extruded covering layer based on a thermoplastic polymer material in admixture with a dielectric liquid. The thermoplastic polymer material is selected from: (a) at least one propylene homopolymer or at least one copolymer of propylene with at least one olefin comonomer; (b) a mechanical mixture of at least one propylene homopolymer or copolymer (a) and (c) at least one elastomeric copolymer or ethylene with at least one aliphatic α-olefin, and optionally a polyene. The cable of the invention possesses good mechanical and electrical properties, including high dielectric strength, in particular enabling it to be used at high operating temperature.
摘要:
A cable having at least one electrical conductor and at least one extruded covering layer based on a thermoplastic polymer material in admixture with a dielectric liquid. The thermoplastic polymer material is selected from: (a) at least one propylene homopolymer or at least one copolymer of propylene with at least one olefin comonomer; (b) a mechanical mixture of at least one propylene homopolymer or copolymer (a) and (c) at least one elastomeric copolymer or ethylene with at least one aliphatic α-olefin, and optionally a polyene.
摘要:
A cable for use in a predetermined voltage class includes at least one conductor; at least one extruded insulating layer surrounding the conductor, the insulating layer being made from a non-crosslinked insulating material having at least one thermoplastic polymer and at least one dielectric liquid, the insulating layer having a thickness such as to provide a voltage gradient on the outer surface of the cable insulating layer not smaller than 1.0 kV/mm; and a protective element around the extruded insulating layer having a thickness and mechanical properties selected to provide a predetermined impact resistance capability, the protective element having at least one expanded polymeric layer, the thickness being sufficient to prevent detectable insulating layer damage upon impact of at least 25 J energy. The insulating layer thickness and the protective element thickness can be selected in combination to minimize the overall cable weight while preventing detectable insulating layer damage upon impact of at least 25 J energy.
摘要:
A process for manufacturing an electric cable. In particular, the process includes the steps of: a) feeding a conductor at a predetermined feeding speed; b) extruding a thermoplastic insulating layer in a position radially external to the conductor; c) cooling the extruded insulating layer; and d) forming a circumferentially closed metal shield around the extruded insulating layer. The process may be carried out continuously, i.e., the time occurring between the end of the cooling step and the beginning of the shield forming step is inversely proportional to the feeding speed of the conductor.
摘要:
A process for manufacturing an electric cable. In particular, the process includes the steps of: a) feeding a conductor at a predetermined feeding speed; b) extruding a thermoplastic insulating layer in a position radially external to the conductor; c) cooling the extruded insulating layer; and d) forming a circumferentially closed metal shield around the extruded insulating layer. The process according to the invention is carried out continuously, i.e., the time occurring between the end of the cooling step and the beginning of the shield forming step is inversely proportional to the feeding speed of the conductor.
摘要:
A cable for use in a predetermined voltage class includes at least one conductor; at least one extruded insulating layer surrounding the conductor, the insulating layer being made from a non-crosslinked insulating material having at least one thermoplastic polymer and at least one dielectric liquid, the insulating layer having a thickness such as to provide a voltage gradient on the outer surface of the cable insulating layer not smaller than 1.0 kV/mm; and a protective element around the extruded insulating layer having a thickness and mechanical properties selected to provide a predetermined impact resistance capability, the protective element having at least one expanded polymeric layer, the thickness being sufficient to prevent detectable insulating layer damage upon impact of at least 25 J energy. The insulating layer thickness and the protective element thickness can be selected in combination to minimize the overall cable weight while preventing detectable insulating layer damage upon impact of at least 25 J energy.
摘要:
A process for producing a cable, such as, for medium-tension or high-tension power transmission or distribution, having at least one coating layer made of a thermoplastic polymer material. The process includes at least the following steps: (a) extruding a thermoplastic material of at least one thermoplastic polymer and at least one dielectric liquid; (b) passing the thermoplastic material through at least one static mixer; and (c) depositing and shaping the thermoplastic material around a conductor belonging to the cable so as to obtain a layer of thermoplastic coating on the conductor.
摘要:
An electrical cable includes a conductor, an outer sheath, and a self-repairing material layer between the conductor and outer sheath. The self-repairing material layer is distributed around the conductor in a discontinuous manner. An anchor portion is formed between the conductor and the outer sheath.
摘要:
An electric cable for power transmission at low voltage has at least one conductor and an insulating coating surrounding the at least one conductor. The insulating coating has at least two insulating layers. In a radial direction from the inside toward the outside of the electrical cable, the insulating coating has at least one insulating layer made of a non-expanded polymeric material and at least one insulating layer made of an expanded polymeric material.
摘要:
A process for manufacturing a cable which includes a conductor; an inner semiconductive layer surrounding the conductor and having a thickness lower than or equal to 0.4 mm; and an insulating layer surrounding the inner semiconductive layer. The process includes the step of co-extruding the inner semiconductive layer and the insulating layer and includes: a) providing a first annular flow of inner semiconductive material and a second annular flow of insulating material; b) contacting the outer surface of the first annular flow and the inner surface of the second annular flow at an axial distance from the contacting point where the inner surface of the first annular flow contacts the conductor; c) selecting in combination the predetermined feeding speed and the contacting point as a function of the dynamic viscosity of the inner semiconductive material and of the insulating material, so that a ratio between the shear stress of the inner semiconductive layer at the radially inner wall of the extrusion die and the shear stress of the insulating layer at the radially outer wall of the extrusion die, in proximity of the contacting point, is about 0.5 to 4; and d) compression extruding the insulating layer and the inner semiconductive layer onto the conductor.