Profile wire conductor and a power cable
A profile wire conductor for an electric power cable has a central longitudinal axis and includes stranded individual profile wires arranged in concentric wire layers around the central longitudinal axis. The concentric wire layers include an inner wire layer of profile wires of a first type having a first radial cross sectional geometry, and an outermost wire layer of profile wires forming an outer surface of the profile wire conductor. At least one of the profile wires in the outermost wire layer is of a second type and has a second radial cross sectional geometry being different to the first radial cross sectional geometry. The profile wires of the second type form an indentation or protrusion in the outer surface of the profile wire conductor.
1 . A power cable comprising:
a profile wire conductor,
a semiconductive layer arranged around the profile wire conductor forming an interface between the profile wire conductor and the semiconductive layer, the profile wire conductor having a central longitudinal axis and comprising stranded individual profile wires arranged in concentric wire layers around the central longitudinal axis, the concentric wire layers including an inner wire layer of profile wires of a first type having a first radial cross sectional geometry, and an outermost wire layer of profile wires forming an outer surface of the profile wire conductor, at least one of the profile wires in the outermost wire layer being of a second type and having a second radial cross sectional geometry being different to the first radial cross sectional geometry, the profile wire of the second type forming an indentation or protrusion in the outer surface of the profile wire conductor, and
a conductor tape forming the interface between the profile wire conductor and the semiconductive layer, wherein the conductor tape is tightly arranged onto the profile wire conductor preserving the indentation or protrusion in the outer surface of the profile wire conductor,
wherein the interface is at least partly defined by the indentation or protrusion in the outer surface of the profile wire conductor, and
wherein the indentation or protrusion has an extension in the radial direction of between 0.5 mm and 3 mm, and/or wherein the indentation or protrusion has an extension in the circumferential direction of between 0.5 mm and 3 mm.
2 . The power cable according to claim 1 , wherein any radial cross section along the central longitudinal axis of the profile wire conductor comprises said indentation or protrusion in the outer surface of the profile wire conductor formed by the profile wires of the second type.
3 . The power cable according to claim 2 , wherein the stranded individual profile wires are helically laid along the central longitudinal axis, and wherein said indentation or protrusion in the outer surface of the profile wire conductor form at least one helically shaped protrusion or indentation following the lay of the profile wires of the outermost wire layer.
4 . The power cable according to claim 2 , wherein the first radial cross sectional geometry has the shape of an annulus sector, or of a trapezoid.
5 . The power cable according to claim 2 , wherein the second radial cross sectional geometry has the shape of a pentagon or a hexagon with two of its opposite sides being curved.
6 . The power cable according to claim 2 , wherein the first and second radial cross sectional geometries are non-congruent in shape and in size.
7 . The power cable according to claim 2 , wherein at least one of the profile wires in the outermost wire layer is of a third type and having a third radial cross sectional geometry being different to the second radial cross sectional geometry.
8 . The power cable according to claim 1 , wherein the stranded individual profile wires are helically laid along the central longitudinal axis, and wherein said indentation or protrusion in the outer surface of the profile wire conductor form at least one helically shaped protrusion or indentation following the lay of the profile wires of the outermost wire layer.
9 . The power cable according to claim 1 , wherein the first radial cross sectional geometry has the shape of an annulus sector, or of a trapezoid.
10 . The power cable according to claim 1 , wherein the second radial cross sectional geometry has the shape of a pentagon or a hexagon with two of its opposite sides being curved.
11 . The power cable according to claim 1 , wherein the first and second radial cross sectional geometries are non-congruent in shape and in size.
12 . The power cable according to claim 1 , wherein at least one of the profile wires in the outermost wire layer is of a third type and having a third radial cross sectional geometry being different to the second radial cross sectional geometry.
13 . The power cable according to claim 1 , wherein the semiconductive layer forms at least a part of an insulation system, and wherein the indentation or protrusion is designed to reduce shrink back of the insulation system.
14 . A method for producing at least a part of a power cable, the method comprising:
providing a plurality of profile wires of at least a first type having a first radial cross sectional geometry and of a second type having a second radial cross sectional geometry being different to the first radial cross sectional geometry;
stranding the plurality of profile wires in concentric wire layers around a central longitudinal axis to form a profile wire conductor having an inner wire layer of profile wires of the first type, and an outermost wire layer of profile wires forming an outer surface of the profile wire conductor in which at least one of the profile wires in the outermost wire layer is of the second type,
encasing the profile wire conductor with an insulation system comprising a semiconductive layer arranged around the profile wire conductor forming an interface between the profile wire conductor and the semiconductive layer,
wherein the profile wires of the second type form an indentation or protrusion in the outer surface of the profile wire conductor during the step of stranding the plurality of profile wires, the indentation or protrusion having an extension in the radial direction of between 0.5 mm and 3 mm and/or an extension in the circumferential direction of between 0.5 mm and 3 mm,
wherein the interface formed during the step of encasing the profile wire with the insulation system is at least partly defined by the indentation or protrusion in the outer surface of the profile wire conductor,
wherein the method further comprises tightly arranging a conductor tape onto the profile wire conductor while preserving the indentation or protrusion in the outer surface of the profile wire conductor, the conductor tape forming the interface between the profile wire conductor and the semiconductive layer.
15 . The method according to claim 14 , further comprising:
guiding a sub-portion of profile wires into a reshaping tool;
reshaping said sub-portion of profile wires in said reshaping tool to form profile wires of the second type.
16 . The method according to claim 14 , wherein the indentation or protrusion is designed to reduce shrink back of the insulation system.