Method of manufacturing power cable

Abstract

To provide a power cable and a method of manufacturing the power cable in which a mechanical support layer is expanded to cause the mechanical support layer to support a metallic water-blocking layer.SOLUTION: A method of manufacturing a power cable 1 includes: providing a conductor 5; providing an insulation system 7 including an inner semiconducting layer 9 arranged around the conductor, an insulation layer 11 arranged around the semiconducting layer, and an outer semiconducting layer 13 arranged around the insulation layer; providing an elastic mechanical support layer 15 around the outer semiconducting layer; compressing the mechanical support layer radially by means of a compression element; longitudinally welding opposing edges of a metallic sheet arranged radially outside the mechanical support layer so as to form a metallic water-blocking layer 17 radially separated from the mechanical support layer in the radially compressed state; and releasing the compression element from compressing the mechanical support layer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure generally relates to power cables.

Background Art

[0002] A power cable includes an electrical insulator that electrically insulates a conductor. In order to prevent moisture from entering this insulator, generally, a metallic Radial direction water barrier is required.

[0003] Conventionally, the metal used is lead, which is a soft, malleable, and extrudable metal. The lead moisture shield realizes a wall that is safe against water ingress, but has several drawbacks. For example, the lead moisture shield for use with high-voltage cables requires a fairly thick sheath thickness. As a result, the cable becomes very heavy. Furthermore, lead is a dangerous toxic substance for both the human body and the environment.

[0004] For example, as disclosed in EP2312591, EP3438993, and EP3786982, it is known to provide a power cable with a water barrier in the form of a copper metal sheath that is connected by welding longitudinal seams.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 2

Summary of the Invention

[0006] Before welding, a metal sheet may be wound around the electrical insulator. The OpposingThe edges are welded longitudinally at a distance of approximately 1 to 7 mm radially from the layer immediately below, so as not to damage that layer, thus forming a metal sheath.

[0007] After welding is performed, the metal sheath may be subjected to a diameter reduction process using rollers to reduce the distance between the sheath and the layer immediately below. However, most metals available for specific applications, such as copper, are harder and less workable than lead. Depending on the type of metal and the thickness of the metal material, performing diameter reduction can be extremely difficult or even impossible due to the force that must be applied by the rollers. Furthermore, performing diameter reduction increases the risk of buckling of the metal material, especially if the metal material is thin.

[0008] A general objective of this disclosure is to provide a power cable that solves or at least mitigates the problems of the prior art.

[0009] Accordingly, according to a first aspect of the present disclosure, a method for manufacturing a power cable, comprising: a) providing a conductor; b) providing an insulating system including an inner semiconducting layer disposed around the conductor, an insulating layer disposed around the inner semiconducting layer, and an outer semiconducting layer disposed around the insulating layer; c) providing an elastic mechanical support layer around the outer semiconducting layer; and d) compressing the mechanical support layer by a compression element. radial direction Compressing to and e) Mechanical support layer radial direction outside Distributed to The metal sheet that was placed Opposing The edges are welded in the longitudinal direction, radial direction From the mechanical support layer in a compressed state, radial direction A method is provided which includes forming a metallic waterproof layer with gaps between it and f) expanding the mechanical support layer by releasing the compression elements from the mechanical support layer so that the mechanical support layer can support the metallic waterproof layer.

[0010] The support provided by the mechanical support layer on the metallic waterproofing layer may be direct or indirect.

[0011] The mechanical support layer supports the metallic waterproof layer along its entire inner circumference.

[0012] The mechanical support layer, after expansion, is between the metallic waterproofing layer and the outer semiconducting layer. radial direction The space may be filled to a large or all extent. This may eliminate the need to reduce the diameter of the metallic waterproof sheath, or at least reduce the amount of diameter reduction required. However, in one example, the mechanical support layer radial direction inside to, Between the mechanical support layer and the outer semiconducting layer, and / or the mechanical support layer radial direction outside to, A layer of expandable tape may be provided between the mechanical support layer and the metallic waterproofing layer.

[0013] Due to the elasticity of the mechanical support layer, this mechanical support layer expands and contracts thermally in response to fluctuations in the magnitude of the current flowing through the conductor during the operation of the power cable, between the outer semiconducting layer and the metallic waterproofing layer. radial direction It can dynamically expand and contract to fill gaps / spaces. Therefore, the mechanical properties of the power cable, including the alignment of the conductor and insulation system, can be maintained during operation.

[0014] The mechanical support layer further prevents water from entering in the longitudinal direction.

[0015] The power cable may be a medium-voltage power cable or a high-voltage power cable. In this specification, medium voltage means a voltage in the range of 1kV to 72.5kV. In this specification, high voltage means a voltage exceeding 72.5kV.

[0016] The power cable may be a direct current (DC) power cable or an alternating current (AC) power cable. The AC power cable may be a single-phase or polyphase AC power cable. The DC power cable may include cores or poles of single-phase, two-phase, or three-phase or more DC power.

[0017] According to one embodiment, the compression element is radial direction outer Wrapped fastened cord or tape of the mechanical support layer.

[0018] According to one embodiment, this compression element contains a polymer material or is composed of a polymer material.

[0019] According to one embodiment, this polymer material is one of polypropylene, polyethylene, nylon, Nomex® (registered trademark), para-aramid, and biaxially oriented polyethylene terephthalate.

[0020] According to one embodiment, step f) requires heating the compression element to melt. Therefore, by heating, expansion can be intentionally caused.

[0021] According to one embodiment, step f) involves the decomposition of the compression element. Therefore, the expansion can be the result of the natural process of the decomposition of the compression element.

[0022] According to one embodiment, the compression element contains biodegradable materials such as cellulose-based fibers or polyhydroxyalkanoate (PHA).

[0023] According to one embodiment, the mechanical support layer includes a polymer foam or a polymer film layer, and gas-filled bubbles are provided between these polymer film layers.

[0024] The polymer film layer may include, for example, low-density polyethylene (LDPE).

[0025] This gas could be air, for example.

[0026] The polymer foam may include, for example, ethylene vinyl acetate (EVA) foam, low-density polyethylene (LDPE), or polystyrene foam, or may be composed of these.

[0027] According to one embodiment, the mechanical support layer is either an extruded layer or a tape wrapped around the insulating system.

[0028] According to one embodiment, the metallic waterproofing layer includes copper, aluminum, or stainless steel.

[0029] According to one embodiment, the power cable is a submarine power cable.

[0030] According to one embodiment, the mechanical support layer is semiconductive and provides an electrical connection between the outer semiconductive layer and the metallic waterproofing layer.

[0031] According to one embodiment, the metallic waterproofing layer is smooth, i.e., not corrugated.

[0032] A second aspect of this disclosure provides a power cable that can be obtained by the method of the first aspect.

[0033] In general, all terms used in the claims should be interpreted according to their ordinary meaning in the art unless expressly provided herein. Any reference to “a / an / the (element, device, component, means, etc.)” should be interpreted frankly as referring to at least one of such elements, devices, components, means, etc., unless expressly provided otherwise.

[0034] Next, with reference to the attached drawings, a specific embodiment of the inventive concept will be described as an example. [Brief explanation of the drawing]

[0035] [Figure 1] This diagram schematically shows a cross-sectional view of an example of a power cable. [Figure 2a] This diagram schematically shows cross-sections of the various steps involved in manufacturing a power cable. [Figure 2b] This diagram schematically shows cross-sections of the various steps involved in manufacturing a power cable. [Figure 2c] This diagram schematically shows cross-sections of the various steps involved in manufacturing a power cable. [Figure 2d] This diagram schematically shows cross-sections of the various steps involved in manufacturing a power cable. [Figure 3] Figure 1 is a flowchart illustrating the process of manufacturing power cables, such as the power cable shown in Figure 1. [Modes for carrying out the invention]

[0036] Next, the inventive concept will be described more fully below with reference to the accompanying drawings illustrating the exemplary embodiments. However, the inventive concept may be implemented in a number of different forms and should not be construed as being limited to the embodiments described herein. Rather, these embodiments are provided as examples so that this disclosure may be complete and comprehensive and so as to fully convey the scope of the inventive concept to those skilled in the art. Similar numbers refer to similar elements throughout this description.

[0037] Figure 1 shows a schematic cross-sectional view of an example of power cable 1.

[0038] The power cable 1 includes a power core 3a.

[0039] This power core 3a comprises a conductor 5. The conductor 5 may be, for example, a single wire, a stranded wire, or a stranded insulated wire. The conductor 5 is made of metal. The conductor 5 may include, for example, copper or aluminum.

[0040] The power core 3a is equipped with an isolation system 7.

[0041] The insulating system 7 comprises an inner semiconducting layer 9 positioned around the conductor 5. The inner semiconducting layer 9 may include, for example, a thermoplastic elastomer (TPE) based on cross-linked polyethylene (XLPE), polypropylene (PP), PP random copolymer, ethylene propylene diene monomer (EPDM) rubber, or ethylene propylene rubber (EPR), which is mixed with a semiconducting component such as carbon black to form a semiconducting polymer or semiconducting paper. The semiconducting polymer may be extruded.

[0042] The insulating system 7 comprises an insulating layer 11. The insulating layer 11 is positioned around the inner semiconducting layer 9. The insulating layer 11 may be in direct contact with the inner semiconducting layer 9. The insulating layer 11 may include, for example, XLPE, PP, PP random copolymer, EPDM rubber, or thermoplastic elastomer (TPE) based on EPR, or paper. The insulating layer 11 may be extruded.

[0043] The insulating system 7 comprises an outer semiconductive layer 13 positioned around the insulating layer 11. This outer semiconductive layer 13 may be in direct contact with the insulating layer 11. This outer semiconductive layer 13 may include a thermoplastic elastomer (TPE) based on XLPE, PP, PP random copolymer, EPDM rubber, or EPR, which is mixed with a semiconductive component such as carbon black to form a semiconductive polymer or semiconductive paper. The semiconductive polymer may be extruded.

[0044] The insulation system 7 may also be a triple extrusion-molded insulation system.

[0045] The power core 3 is surrounded by the outer semiconducting layer 13 radial direction outside Distributed to It is equipped with an elastic mechanical support layer 15.

[0046] For example, this mechanical support layer 15 may be semiconductive.

[0047] The mechanical support layer 15 may include, for example, a layer of polymer foam or polymer film, or be composed of these, with gas-filled bubbles between these polymer film layers.

[0048] If the mechanical support layer 15 contains or is composed of a polymer foam and is semiconductive, the polymer material forming the polymer foam may be mixed with a semiconductive component such as carbon black to form a semiconductive polymer foam.

[0049] If the mechanical support layer 15 includes or is composed of polymer film layers in which gas-filled bubbles are introduced between each polymer film layer, the polymer material forming this polymer film layer may be mixed with a semiconductive component such as carbon black to form a semiconductive polymer film layer.

[0050] During the manufacture of the power cable 1, compression elements such as cords or tapes are placed around the mechanical support layer 15. These compression elements are placed around the mechanical support layer 15. radial direction It is positioned to be compressed. During the manufacture of the power cable 1, the compression element in the later stages of manufacture releases the mechanical support layer 15 from being compressed. Thus the mechanical support layer 15 is radial direction It expands. After the mechanical support layer 15 expands, traces of the compression element may remain around the mechanical support layer 15. These traces may be found in the finished power cable 1 product.

[0051] The power core 3a includes a metallic waterproof layer 17. The metallic waterproof layer 17 is arranged concentrically with and around the mechanical support layer 15.

[0052] The mechanical support layer 15 is positioned between the outer semiconductive layer 13 and the metallic water-impermeable layer 17.

[0053] The mechanical support layer 15 mechanically supports the metallic waterproofing layer 17.

[0054] The mechanical support layer 15 may be, for example, an extruded layer, or it may be in the form of a tape wrapped around the insulating system 7.

[0055] The metallic waterproofing layer 15 may be provided with a metal sheath. This metal may be, for example, aluminum, an aluminum alloy, copper, a copper alloy, or stainless steel.

[0056] The power core 3a comprises a polymer layer 19 concentrically arranged around a metallic waterproof layer 17. This polymer layer 19 may include, for example, XLPE, PP, EPDM, or EPR.

[0057] The polymer layer 19 may also be semiconducting.

[0058] For example, the polymer layer 19 may be bonded to the metallic water-impermeable layer 17 by an adhesive. If the polymer layer 19 is semiconductive, the adhesive is semiconductive.

[0059] The polymer layer 19 may also be a polymer jacket.

[0060] The polymer layer 19 may be in direct contact with the outer surface of the metallic water-impermeable layer 17.

[0061] The polymer layer 19 may be extruded onto the metallic water-impermeable layer 17.

[0062] Power cable 1 has a polymer layer 19 radial direction outside Distributed to An outer layer 21 may be provided.

[0063] The outer layer 21 comprises a plurality of outer wires 23 arranged helically around the polymer layer 19. The outer layer 21 may also comprise outer wires 23 made from metals such as galvanized carbon steel, austenitic stainless steel, copper, or aluminum, and / or outer wires 23 made from synthetic materials such as aramid fibers within the jacket.

[0064] If at least a portion of the outer wire 23 is made of metal, the outer layer 21 may be covered with bitumen.

[0065] Figures 2a to 2d show exemplary manufacturing steps for producing power cable 1.

[0066] In the example shown in Figure 2a, the mechanical support layer 15 is provided around the outer semiconductive layer 13.

[0067] At this stage, the metallic waterproofing layer 17 has not yet been placed around the mechanical support layer 15.

[0068] The mechanical support layer 15 may be, for example, in the form of a tape wrapped around the insulating system 7, or it may be extruded onto the insulating system 7. The outer edges of the tape may be joined to each other, for example, by adhesive.

[0069] Figure 2a further shows that a compression element 16 is provided around the mechanical support layer 15. This compression element 16 is provided around the mechanical support layer 15 radial direction Compress it to [size].

[0070] The compression element 16 is, for example, tightly wound in a helical manner around the mechanical support layer 15, thereby almost completely compressing the mechanical support layer 15. radial direction A tape or cord that compresses the tape or cord may also be used.

[0071] A combination of a compressed mechanical support layer 15 and a compression element 16 radial direction The thickness of the mechanical support layer 15 in an uncompressed state radius It is preferable that the dimensions are substantially smaller than the directional dimensions. Combining the compressed mechanical support layer 15 and the compression element 16 radial direction The thickness is, for example, the thickness of the mechanical support layer 15 in an uncompressed state. radius It may be less than half the dimension in the direction.

[0072] The compression element 16 may include, for example, a polymer material having a melting point in the range of 100 to 400°C, or may be composed of such a polymer material. Examples of suitable polymer materials include polypropylene, polyethylene, nylon, Nomex®, para-aramid, and biaxially oriented polyethylene terephthalate.

[0073] In another example, the compression element 16 contains or is composed of a biodegradable material such as cellulose fibers, polyhydroxyalkanoates, or Bioska® material.

[0074] Figure 2b shows the situation when a metallic waterproof layer 17 is formed around the mechanical support layer 15, which is still being compressed by the compression element 16.

[0075] This metallic waterproof layer 17 was made by wrapping a metallic sheet around the compression element 16 at a position radially away from the compression element 16. Opposing The edges were welded in the longitudinal direction to form a weld seam 17a.

[0076] Figure 2c shows the structure obtained in Figure 2b when it undergoes heat treatment. This causes the compression element 16 to melt and decompose. Consequently, the mechanical support layer 15 may expand to its naturally expanded state.

[0077] Instead of heat treatment, the compression element 16 may decompose naturally if it is made from a suitable biodegradable material. In this case, external inducements such as heating may not be necessary to expand the mechanical support layer 15.

[0078] Figure 2d shows the state after the heat treatment is complete. In this example, the mechanical support layer 15 is in direct contact with the inner surface of the metallic waterproofing layer 17.

[0079] In one modified form, the metallic waterproofing layer 17 may undergo diameter reduction before and after heat treatment so that the mechanical support layer 15 can be reliably in direct contact with the inner surface of the metallic waterproofing layer 17.

[0080] Figure 3 is a flowchart illustrating the method for manufacturing power cable 1.

[0081] In step a), conductor 5 is provided.

[0082] In step b), an insulating system 7 is provided around the conductor 5. For example, the insulating system 7 may be provided around the conductor 5 in a triple extrusion process or a tape winding process.

[0083] In step c), a mechanical support layer 15 is provided around the semiconductive layer 13 on the outside of the insulating system 7.

[0084] The mechanical support layer 15 may be extruded onto the insulating system 7 in step c), or it may be folded or wrapped around the insulating system 7 in the form of a tape.

[0085] In step d), the mechanical support layer 15 is compressed by the compression element 16. radial direction It is compressed. The compression element 16 may, for example, be wrapped around the mechanical support layer 15 to compress the mechanical support layer 15.

[0086] In step e), the metallic sheet Opposing The edges are welded in the longitudinal direction to form a metallic waterproof layer 17 around the compression element 16.

[0087] In step f), the mechanical support layer 15 is compressed and then the compression element 16 is released, thereby the mechanical support layer 15 radial direction It expands.

[0088] Step f) may require, for example, heating the metallic waterproofing layer 17 by induction heating or a heating element. Thus, the compression element 16 is heated to soften or melt. This causes the compression element 16 to soften the metallic waterproofing layer 17. radial direction Supporting radial direction It expands.

[0089] If the compression element 16 contains or is composed of a biodegradable material, the compression element 16 will decompose over time, and the mechanical support layer 15 will decompose the metallic waterproof layer 17. radial direction Supporting radial direction This allows it to expand. Preferably, this biodegradable material should be chosen so that the compression element 16 decomposes quickly while the power cable 1 is still inside the factory.

[0090] The invention has been primarily described with reference to several examples. However, as will be readily apparent to those skilled in the art, other embodiments not disclosed herein are equally feasible within the scope of the invention as defined by the appended claims.

Claims

1. A method for manufacturing power cables, a) Providing a conductor (5), b) Providing an insulating system (7) including an inner semiconductive layer (9) arranged around the conductor (5), an insulating layer (11) arranged around the inner semiconductive layer (9), and an outer semiconductive layer (13) arranged around the insulating layer (11), c) Providing an elastic mechanical support layer (15) around the outer semiconductive layer (13), d) Compressing the mechanical support layer radially with the compression element (16), e) The opposing edges of a metallic sheet positioned radially outside the mechanical support layer are welded in the longitudinal direction to form a metallic watertight layer (17) that is radially spaced away from the mechanical support layer which is compressed in the radial direction, f) By releasing the compression element (16) from compressing the mechanical support layer (15), the mechanical support layer (15) is expanded so that the mechanical support layer (15) can support the metallic waterproof layer (17). Methods that include...

2. The method according to claim 1, wherein the compression element (16) is a cord or tape wound around the radially outward side of the mechanical support layer (15).

3. The method according to claim 1 or 2, wherein the compression element (16) includes or is composed of a polymer material.

4. The method according to claim 3, wherein the polymer material is one of polypropylene, polyethylene, nylon, Nomex®, paraaramid, and biaxially oriented polyethylene terephthalate.

5. The method according to claim 1 or 2, wherein step f) includes heating the compression element (16) so that it melts.

6. The method according to claim 1 or 2, wherein step f) includes decomposing the compression element (16).

7. The method according to claim 6, wherein the compression element comprises a cellulose fiber or a biodegradable material such as polyhydroxyalkanoate (PHA).

8. The method according to claim 1 or 2, wherein the mechanical support layer (15) includes a polymer foam or a polymer film layer, and gas-filled bubbles are provided between the polymer film layers.

9. The method according to claim 1 or 2, wherein the mechanical support layer (15) is an extruded layer or in the form of a tape wrapped around the insulating system (7).

10. The method according to claim 1 or 2, wherein the metallic waterproofing layer (17) comprises copper, aluminum, or stainless steel.

11. The method according to claim 1 or 2, wherein the power cable (1) is a submarine power cable.

12. The method according to claim 1 or 2, wherein the mechanical support layer (15) is semiconductive, providing an electrical connection between the outer semiconductive layer (13) and the metallic water-impermeable layer (17).

13. The method according to claim 1 or 2, wherein the metallic water-impermeable layer (17) is smooth.

14. A power cable (1) obtained by the method described in claim 1 or 2.

Images