Profile Wire Conductor and A Power Cable

Abstract

A profile wire conductor for an electric power cable, the profile wire conductor having a central longitudinal axis and including 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, wherein the profile wires of the second type forms an indentation or protrusion in the outer surface of the profile wire conductor.

Claims

1. A profile wire conductor for an electric power cable, 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, wherein the profile wire of the second type forms an indentation or protrusion in the outer surface of the profile wire conductor.

2. The profile wire conductor 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 profile wire conductor according to claim 1, wherein the stranded individual profile wires are helically layed 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 profile wire conductor according to claim 1, wherein the first radial cross sectional geometry has the shape of an annulus sector, or of a trapezoid.

5. The profile wire conductor 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.

6. The profile wire conductor according to claim 1, wherein the first and second radial cross sectional geometries are non-congruent in shape and in size.

7. The profile wire conductor 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.

8. The profile wire conductor according to claim 1, 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.

9. A power cable having a profile wire conductor with a central longitudinal axis and including 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, comprising a semiconductive layer arranged around the profile wire conductor forming an interface between the profile wire conductor and the semiconductive layer, the interface being at least partly defined by the indentation or protrusion in the outer surface of the profile wire conductor.

10. The power cable according to claim 9, comprising 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.

11. 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, 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.

12. The method according to claim 11, 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.

13. The method according to claim 11, further comprising: tightly arrange a conductor tape onto the profile wire conductor while preserving the indentation or protrusion in the outer surface of the profile wire conductor.

14. The method according to claim 10, further comprising: encasing the profile wire conductor with an insulation system.

15. The profile wire conductor according to claim 2, wherein the stranded individual profile wires are helically layed 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.

16. The profile wire conductor according to claim 2, wherein the first radial cross sectional geometry has the shape of an annulus sector, or of a trapezoid.

17. The profile wire conductor 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.

18. The profile wire conductor according to claim 2, wherein the first and second radial cross sectional geometries are non-congruent in shape and in size.

19. The profile wire conductor 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.

20. The profile wire conductor according to claim 2, 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.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The specific embodiments of the inventive concept will now be described, by way of example, with reference to the accompanying drawings, in which:

[0051] FIG. 1 schematically shows a radial cross section of a profile wire conductor of an example embodiment;

[0052] FIG. 2 is a perspective view of the profile wire conductor of FIG. 1, the profile wire conductor extending along a central longitudinal axis 200;

[0053] FIG. 3 schematically shows a radial cross section of a profile wire conductor of an alternative example embodiment;

[0054] FIGS. 4A, 4B and 4C are radial cross sectional views of profile wires of the first and second type;

[0055] FIG. 5 schematically shows a radial cross section of a profile wire conductor of yet an alternative example embodiment;

[0056] FIG. 6 schematically shows a radial cross section of a power cable comprising the profile wire conductor of FIGS. 1-2; and

[0057] FIG. 7 is a flow chart describing a method of producing at least a part of a power cable according to example embodiments.

DETAILED DESCRIPTION

[0058] The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplifying embodiments are shown. The inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like elements throughout the description.

[0059] FIGS. 1 and 2 show an example of a profile wire conductor 201. In FIG. 1, a radial cross section of the profile wire conductor 201 is shown, and in FIG. 2, a perspective view of at least a part of the profile wire conductor 201 extending along a central longitudinal axis 200 is shown. The radial cross section is a cross section in the radial direction r of the profile wire conductor 201, i.e. perpendicular to the central longitudinal axis 200, as indicated in FIG. 2. The profile wire conductor 201 may e.g. be defined by cylindrical coordinates (by a radial distance r, azimuth ? which is the angle along the circumferential direction, and an axial coordinated along the longitudinal axis 200).

[0060] The profile wire conductor 201 comprises stranded individual profile wires 210 arranged in concentric wire layers 220 around the central longitudinal axis 200. The concentric wire layers 220 comprises an outermost wire layer 222 of profile wires 212 forming an outer surface of the profile wire conductor 201. Moreover, the concentric wire layers 220 comprises an inner wire layer 224 arranged in the embodiment of FIGS. 1 and 2 as the second outermost wire layer of the concentric wire layers 220, and is hereafter referred to as a first inner wire layer 224.

[0061] The first inner wire layer 224 is formed of profile wires 214 of a first type having a first radial cross sectional geometry. As shown in FIGS. 1 and 2, all of the profile wires 214 in the first inner wire layer 224 have the same radial cross sectional geometry, both in shape and in size.

[0062] The profile wires 212 of the outermost wire layer 222 are of a second type having a second radial cross sectional geometry being different to the first radial cross sectional geometry. For example, and as shown in FIGS. 1 and 2, the shape of the second radial cross sectional geometry differs from the shape of the first radial cross sectional geometry, i.e. the profile wires 212, 214 of the first and second types have cross sectional geometries of non-congruent shapes.

[0063] In FIGS. 1 and 2, the profile wires 212 of the second type forms indentations 240 in the outer surface of the profile wire conductor 201. However, it should be mentioned that not all of the profile wires in the outermost wire layer 222 need to be of the second type. Instead, one, or at least one, of the profile wires 212 in the outermost wire layer 222 is of the second type, and thus form a corresponding indentation 240 in the outer surface of the profile wire conductor 201.

[0064] As shown in FIG. 2, the indentations 240 extends along the longitudinal axis 200 of the profile wire conductor 201. Thus, any radial cross section along the central longitudinal axis 200 of the profile wire conductor 201 comprises the indentations 240, or indentation 240, in the outer surface of the profile wire conductor 201 formed by the profile wires 212 of the second type. In more detail, the stranded profile wires 210 of the embodiment of FIG. 2 are helically layed along the central longitudinal axis 200, such that the indentations 240 in the outer surface of the profile wire conductor 201 form helically shaped indentations 240 following the lay of the profile wires 210 of the outermost wire layer 222.

[0065] By changing the radial cross sectional geometry of the second type of profile wires, the profile wires may instead of an indentation 240 form a protrusion 250 in the outer surface of the profile wire conductor 201, which is shown in the example embodiment of FIG. 3. Again, it should be mentioned that not all of the profile wires in the outermost wire layer 222 needs to be of the second type.

[0066] Typically, the indentation 240 or protrusion 250 has an extension in the radial direction r of between 0.5 mm and 3 mm, and/or the indentation 240 or protrusion 250 has an extension in the circumferential direction of between 0.5 mm and 3 mm.

[0067] In FIGS. 1 and 2, the profile wire conductor 201 comprises more than one inner wire layer. That is, the profile wire conductor 201 may comprise a plurality of inner wire layers 226 arranged concentrically inside of the outermost wire layer 222. Typically, all profile wires in one specific inner wire layer have the same radial cross sectional geometry, with the same shape and size. Moreover, as seen in FIGS. 1 and 2, the radial cross sectional geometry of the profile wires in different inner wire layers 226 are congruent in shape but not in size. Thus, in the embodiment of FIGS. 1 and 2, in which the profile wire conductor 201 comprises a plurality of inner wire layers 226, all inner wire layers 226 are formed by profile wires of the same radial cross sectional shape. As seen in FIGS. 1 and 2, the profile wire conductor 201 comprises a centre wire 218 having a circular radial cross sectional shape. Thus, the plurality of inner wire layers 226 are arranged in between the centre wire 218 and the outermost wire layer 222. All of the inner wire layers 226 of the profile wire conductor 201 are profile wire layers 226.

[0068] FIG. 4A is a radial cross sectional view of a profile wire being an example of a profile wire 214 of the first inner wire layer 224. The profile wire is an example of the previously mentioned first type with the first radial cross sectional geometry 301. The first radial cross sectional geometry 301 has the shape of an annulus sector, or may be described as having the shape of a trapezoid, such as an isosceles trapezoid, in which two opposites sides (the bases) 301a, 301b of the trapezoid is curved along the circumferential direction of the profile wire conductor.

[0069] FIG. 4B is a radial cross sectional view of a profile wire being an example of a profile wire 212 of the outermost wire layer 222. The profile wire is an example of the previously mentioned second type with the second radial cross sectional geometry 302. The second radial cross sectional geometry has a shape deviating from that of an annulus sector (or trapezoid) as it comprises beveled edges, or cut-off corners, 302c at its outermost side (base) 302b. Stated differently, the intersections of the side (or base) 302b of the radial cross sectional geometry 302 facing outwards away from the center of the profile wire conductor, and the sides 302e, 302f of the radial cross sectional geometry 302 extending in the radial direction, are formed by beveled edges 302c. In other words, the second radial cross sectional geometry 302 has the shape of a hexagon with two of its opposite sides (or bases) 302a, 302b curved. Thus, the previously mentioned indentations 240 may be the result of the beveled edges 302c, as the profile wires 212 of the second type are arranged as the outermost wire layer 222. It should be noted that only one of the corners of the trapezoid may be cut-off (i.e. only comprising one of the beveled edges 302c), resulting in a radial cross sectional geometry with the shape of a pentagon with two of its opposite sides (or bases) 302a, 302b curved.

[0070] FIG. 4C is a radial cross sectional view of a profile wire being an example of a profile wire 212 of the outermost wire layer 222. The radial cross sectional geometry 303 of the profile wire is the same as that of the profile wire of FIG. 4B, except of that instead of beveled edges 302c, the corresponding position of the radial cross sectional geometry 303 of the profile wire comprises pointy corners 303c. Thus, the previously mentioned protrusions 250 of FIG. 3 may be the result of the pointy corners 303c, as the profile wires 212 of the second type are arranged as the outermost wire layer 222.

[0071] Thus, as apparent from comparing FIG. 4A with FIG. 4B or FIG. 4C, the first and second radial cross sectional geometries may be non-congruent in shape. According to one example, 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. Such example profile wire conductor 201 is shown in FIG. 5. The profile wire conductor 201 is the same as the profile wire conductor 201 shown in FIGS. 1 and 2, except for the profile wires 212a, 212b of the outermost wire layer 222. The profile wires 212a, 212b in the outermost wire layer 222 of the profile wire conductor 201 comprises profile wires 212a of a second type and profile wires 212b of a third type. Thus, the profile wires 212a, 212b in the outermost wire layer 222 of the profile wire conductor 201 may have different radial cross sectional geometries, with regards to shape and/or size. The profile wires 212a of the second type has a second radial cross sectional geometry being different to the first radial cross sectional geometry of the first type of profile wires 214 (the profile wires 214 of the first type being the same as for the profile wire conductor 201 of FIGS. 1 and 2), typically by that the size of the second radial cross sectional geometry is larger than the size of the first radial cross sectional geometry (the shape of the first and second radial cross sectional geometry may however be the same in the example embodiment). In the example profile wire conductor 201 of FIG. 5, the profile wires 212b of the third type have the same radial cross sectional shape (the annulus sector or trapezoid as previously described) but a radial cross sectional geometry of a larger size compared to the profile wires 212a of a second type. Thus, the profile wires 212b of the third type extends further in the radial direction r than the profile wires 212a of the second type and thereby forms indentation 240 in the outer surface of the profile wire conductor 201. As shown in the example of FIG. 5, every other the profile wires 212a, 212b in the outermost wire layer 222 is of the second type, and every other of the profile wires 212a, 212b in the outermost wire layer 222 is of the third type. Thus, profile wires 212a of the second type may be neighbouring to profile wires 212b of the third type.

[0072] FIG. 6 show an example of a power cable 1 comprising the profile wire conductor 201 previously described. In FIG. 6, a radial cross section of the power cable 1 is shown.

[0073] The power cable 1 comprises an insulation system 2 arranged around the profile wire conductor 201. The insulation system 2 comprises a semiconductive layer 3 forming an interface 5 between the profile wire conductor 201 and the insulation system 2. The interface 5 is at least partly defined by the indentations 240 (or protrusions 250 as shown in the embodiment of FIG. 3) in the outer surface of the profile wire conductor 201.

[0074] Thus, the insulation system 2 may comprise a semiconductive layer (or semiconducting conductor shield) 3 arranged closest to the profile wire conductor 201. As shown in FIG. 6, the insulation system 2 may further comprise an insulation layer (an electrically insulation layer) 9, arranged in contact with, and outside of, the semiconductive layer 3. Optionally, the insulation system 2 further comprises a semiconductive layer (or semiconductive insulation shield) 11 arranged in contact with, and outside of, the insulation layer 9. Thus, the semiconducting conductor shield 3 may be referred to as a first semiconductive layer 3 and semiconductive insulation shield 11 may be referred to as a second semiconductive layer 11. Optionally, the insulation system further comprises one or more outer layers arranged outside of the second semiconductive layer, such as e.g. a metallic shield and a sheath (not shown).

[0075] The semiconductive layer(s) 3, 11 and/or the insulation layer 9 may comprise a thermosetting polymer. The thermosetting polymer may for example be XLPE, crosslinked ethylene propylene diene monomer rubber (EPDM), or crosslinked ethylene propylene rubber (EPR). The semiconductive layer(s) 3, 11 typically comprises an electric conductive compound such as e.g. carbon black.

[0076] According to one embodiment, the semiconductive layer(s) 3, ii and/or the insulation layer 9 is/are thermoplastic, i.e. is/are formed of a thermoplastic composition comprising e.g. polypropylene and LDPE or LLDPE.

[0077] The insulation system 2 interacts with the indentations 240 (or protrusions 250 as shown in the embodiment of FIG. 3) in the outer surface of the profile wire conductor 201 formed by the profile wires 212 of the second type. As the semiconductive layer (or semiconducting conductor shield) 3 is arranged closest to the profile wire conductor 201, the semiconductive layer 3 interacts with the indentations 240 (or protrusions 250 as shown in the embodiment of FIG. 3) in the outer surface of the profile wire conductor 201. Hereby, friction forces and/or tortional forces between the profile wire conductor 201 and the insulation system 2 is increased to reduce axial shrinkage forces. In other words, the geometry of the outer surface of the profile wire conductor 201 reduce the shrink back of the insulation system 2 arranged around the profile wire conductor 201.

[0078] The power cable 3 may comprise a conductor tape 7 forming the interface 5 between the profile wire conductor 201 and the insulation system 2, or in more detail, between the semiconductive layer (or semiconducting conductor shield) 3 and the profile wire conductor 201. Thus, the conductor tape 7 is preferably tightly arranged onto the profile wire conductor 201 to preserve the indentations 240 in the outer surface of the profile wire conductor 201.

[0079] A method of producing at least a part of a power cable, such as the profile wire conductor 201, 201 of FIGS. 1-5, or a power cable 1 of FIG. 6, will now be described with reference to the flow chart of FIG. 7.

[0080] In a first step, S10, a plurality of profile wires is provided. The profile wires are 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. Examples of the first and second types of profile wires were exemplified in FIGS. 1-6.

[0081] In a second step, S20, the plurality of profile wires is stranded 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.

[0082] The profile wires of the second type form an indentation or protrusion in the outer surface of the profile wire conductor during the step S20 of stranding the plurality of profile wires. The thereby formed profile wire conductor may for example be the profile wire conductor 201 as in FIGS. 1-4. The profile wire conductor is thus an example of at least a part of a power cable produced by the method of the inventive concept.

[0083] In a first optional sub-step S5, being performed prior to the first step S10, or as a sub-step of the first step S10, a sub-portion of profile wires is guided into a reshaping tool. In a second optional sub-step S7, being performed subsequently to the first optional sub-step S5, the sub-portion of profile wires is reshaped in the reshaping tool to form profile wires of the second type. For example, the reshaping tool comprises a knife which cuts the sub-portion of the profile wires into the desired radial cross sectional shape. Thus, profile wires of the second type are provided in an efficient manner.

[0084] In an optional step S30, performed subsequent to the stranding step S20, a conductor tape is tightly arranged onto the profile wire conductor while preserving the indentation or protrusion in the outer surface of the profile wire conductor.

[0085] In an optional step S40, performed subsequent to the stranding step S20, and potentially subsequent to step S30, the profile wire conductor is encased with an insulation system. The thereby formed profile wire conductor and the insulation system may for example be the power cable 1 as in FIG. 6, or at least forming a part of such power cable. The insulation system typically comprises at least one semiconductive layer, or semiconducting conductor shield.

[0086] The inventive concept has mainly been described above with reference to a few examples. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended claims.