Medium-voltage cable and method for manufacturing medium-voltage cable

Abstract

The present invention relates to the technical field of cables. Provided are a medium-voltage cable and a method for manufacturing the medium-voltage cable. The medium-voltage cable comprises a plurality of wire core units, the plurality of wire core units being stranded together to form a cable core structure; each wire core unit comprises: an insulated wire core; a metal shielding layer, covering the external part of the insulated wire core; and a semi-conductive adhesive layer, covering the external part of the metal shielding layer, the semi-conductive adhesive layer being formed by curing a semi-conductive adhesive. The medium-voltage cable of the present invention ensures electrical continuity of the metal shielding layer, and prevents harmful gas from flowing along braided gaps of the metal shielding layer, thereby effectively preventing harmful gas from leaking out of the cable, allowing medium-voltage cables to be widely used in offshore floating production storage and offloading units, and enhancing the applicability of medium-voltage cables.

Description

Medium voltage cable and method for manufacturing the same Technical Field

[0001] The present invention relates to the technical field of cables, and in particular to a medium voltage cable and a method for manufacturing the medium voltage cable. Background Art

[0002] Oil is the lifeblood of economic development, with global daily oil consumption reaching 80 million barrels. 60% of newly discovered oil and gas fields in the past decade are offshore, and it is estimated that 40% of future global oil and gas reserves will be concentrated in deepwater areas. Floating Production Storage and Offloading (FPSO) vessels are offshore floating production, storage, and offloading (FPSO) vessels that integrate production, storage, and offloading. These vessels involve oil processing, and hazardous gases can exist in unsafe areas. If conventional cables are used, these gases can spread through gaps in the cable core to safe areas, potentially endangering personnel.

[0003] Summary of the Invention

[0004] The present invention provides a medium voltage cable and a method for manufacturing the medium voltage cable, which are used to solve the defect in the prior art that conventional cables have gaps in their cores and harmful gases can be transmitted through the gaps in the cores.

[0005] The present invention provides a medium-voltage cable, comprising a plurality of core units, wherein the plurality of core units are twisted into a cable core structure, each of the core units comprising: an insulating core; a metal shielding layer covering the outside of the insulating core; and a semi-conductive adhesive layer covering the outside of the metal shielding layer, wherein the semi-conductive adhesive layer is formed by curing a semi-conductive adhesive. The medium-voltage cable is an airtight power cable with a rated voltage of 6 kV to 30 kV.

[0006] According to a medium voltage cable provided by the present invention, the semi-conductive adhesive consists of a first component and a second component, wherein the first component includes: 100 parts of methyl block room temperature vulcanized silicone rubber, 30-45 parts of ultrafine calcium carbonate, 6-10 parts of fumed silica, 3-5 parts of titanium dioxide, and 3-5 parts of graphene; the second component includes: 4-8 parts of tetraethyl orthosilicate, 2-4 parts of n-butyl borate, 2-4 parts of n-butyl titanate, a trace amount of octyltin dilaurate, and a trace amount of γ-aminopropyltriethoxysilane.

[0007] A medium voltage cable provided according to the present invention further includes a plurality of fillers, which are filled in the cable core structure and located between the plurality of core units, wherein the fillers are flat film, non-open mesh polypropylene ropes.

[0008] A medium voltage cable provided according to the present invention further includes a tape layer, wherein the tape layer is coated outside the cable core structure.

[0009] A medium voltage cable provided according to the present invention further includes an inner lining layer, which is coated outside the wrapping layer and is a low-smoke halogen-free polyolefin inner lining layer.

[0010] A medium voltage cable provided according to the present invention further includes an armor layer, wherein the armor layer is coated outside the inner lining layer.

[0011] A medium voltage cable provided by the present invention further includes an outer sheath layer, which is coated outside the armor layer and is a silane cross-linked low-smoke halogen-free outer sheath layer.

[0012] According to a medium voltage cable provided by the present invention, the insulated core includes: a conductor; a shielding layer covering the conductor; an insulating layer covering the shielding layer; and an insulating shielding layer covering the insulating layer.

[0013] According to the medium voltage cable provided by the present invention, the metal shielding layer is woven from tinned copper wires.

[0014] The present invention also provides a method for manufacturing the medium-voltage cable as described above, comprising: coating a semi-conductive adhesive on the outside of a metal shielding layer to form a semi-conductive adhesive layer, and wrapping the semi-conductive adhesive layer with an aluminum-plastic composite tape while coating, wherein the overlap rate of the aluminum-plastic composite tape is greater than or equal to 25%; after the semi-conductive adhesive layer is cured, removing the aluminum-plastic composite tape; and twisting a plurality of core units into a cable core structure.

[0015] Technical Effects

[0016] The medium-voltage cable provided by the present invention has the following beneficial effects compared with the prior art: by coating the outside of the metal shielding layer with semi-conductive glue, the electrical penetration of the metal shielding layer is ensured, and harmful gases are prevented from flowing along the braiding gaps of the metal shielding layer, effectively preventing the harmful gases from leaking out of the cable and posing a hidden danger to personnel safety. The medium-voltage cable can be widely used in offshore floating production storage and offloading units, thereby enhancing the applicability of the medium-voltage cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] FIG1 is a schematic structural diagram of a medium voltage cable provided by the present invention;

[0019] FIG2 is a flow chart of a method for manufacturing a medium voltage cable provided by the present invention;

[0020] Reference numerals:

[0021] 10: Insulated core; 11: Conductor; 12: Shielding layer; 13: Insulation layer; 14: Insulation shielding layer; 20: Metal shielding layer; 30: Semi-conductive adhesive layer; 40: Filler; 50: Taping layer; 60: Lining layer; 70: Armor layer; 80: Outer sheath layer. DETAILED DESCRIPTION

[0022] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0023] The features of the terms "first" and "second" in the description and claims of the present invention may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0024] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0025] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0026] The medium voltage cable and the method for manufacturing the medium voltage cable of the present invention will be described below with reference to FIG1 and FIG2 .

[0027] As shown in Figure 1, in an embodiment of the present invention, a medium-voltage cable includes multiple core units, which are twisted into a cable core structure. Each core unit includes an insulated core 10, a metal shielding layer 20, and a semi-conductive adhesive layer 30. The metal shielding layer 20 is coated on the exterior of the insulated core 10, and the semi-conductive adhesive layer 30 is coated on the exterior of the metal shielding layer 20. The semi-conductive adhesive layer 30 is formed by curing a semi-conductive adhesive.

[0028] It should be noted that the medium voltage cable referred to in the present invention is an airtight power cable with a rated voltage of 6kV to 30kV.

[0029] Specifically, the metal shielding layer 20 is woven with tinned copper wire with a nominal diameter of 0.2 mm and a weaving density of not less than 80%. After weaving, the metal shielding layer 20 is formed. Semi-conductive glue is coated on the outside of the metal shielding layer 20. After the semi-conductive glue is cured, a semi-conductive glue layer 30 is formed. The semi-conductive glue layer 30 has conductive properties and can ensure that the metal shielding layer 20 is electrically conductive. At the same time, the semi-conductive glue layer can fill the gaps generated by weaving to prevent harmful gases from diffusing along the gaps generated by weaving, posing a hidden danger to personnel safety.

[0030] The medium-voltage cable provided by the embodiment of the present invention, by coating a semi-conductive adhesive on the outside of the metal shielding layer, not only ensures the electrical penetration of the metal shielding layer, but also prevents harmful gases from flowing along the braiding gaps of the metal shielding layer, effectively preventing the harmful gases from leaking out of the cable and posing a hidden danger to personnel safety, so that the medium-voltage cable can be widely used in offshore floating production storage and offloading units, thereby enhancing the applicability of the medium-voltage cable.

[0031] Furthermore, in an embodiment of the present invention, the semi-conductive adhesive consists of a first component and a second component, wherein the first component includes: 100 parts of methyl block room temperature vulcanized silicone rubber, 30-45 parts of ultrafine calcium carbonate, 6-10 parts of fumed silica, 3-5 parts of titanium dioxide, and 3-5 parts of graphene; the second component includes: 4-8 parts of tetraethyl orthosilicate, 2-4 parts of n-butyl borate, 2-4 parts of n-butyl titanate, a trace amount of octyltin dilaurate, and a trace amount of γ-aminopropyltriethoxysilane.

[0032] Specifically, the semi-conductive adhesive consists of a first component and a second component. When in use, the first component and the second component are mixed and stirred evenly and then coated on the metal shielding layer 20. The semi-conductive adhesive can weld the gaps produced by the weaving of the metal shielding layer 20 to prevent the leakage of harmful gases, and at the same time has conductive properties.

[0033] The medium voltage cable provided by the embodiment of the present invention, by setting the semi-conductive adhesive as the above-mentioned component, not only has good conductivity, but also has a high temperature resistance level, with a long-term temperature resistance of 90°C, thereby enhancing the performance of the medium voltage cable and extending its service life.

[0034] As shown in Figure 1, in an embodiment of the present invention, the medium voltage cable further includes a plurality of fillers 40. The plurality of fillers 40 are filled in the cable core structure and located between the plurality of core units, wherein the fillers 40 are flat film, non-open mesh polypropylene ropes.

[0035] Specifically, in the prior art, filler 40 is often made of a fluffy material. When this material is filled within the cable core structure, tiny gaps exist within the fluffy material, allowing harmful gases to freely migrate along the cable's axial direction, posing a potential safety hazard to personnel. In this embodiment, filler 40 is made of a flat, ultra-thin, closed-mesh polypropylene rope. This allows the cable core structure to be tightly filled, ensuring the longitudinal airtightness of the medium-voltage cable core structure and preventing harmful gases from propagating along the axial direction of the cable to a safe area.

[0036] The medium-voltage cable provided in an embodiment of the present invention, by setting the filler as a flat film, non-mesh polypropylene rope, can fill the cable core structure tightly when the filler is filled into the cable core structure, thereby ensuring the longitudinal air tightness of the cable core structure, preventing harmful gases from flowing along the axial direction of the medium-voltage cable, and preventing harmful gases from leaking to a safe area and posing a hidden danger to personnel safety.

[0037] As shown in FIG. 1 , in an embodiment of the present invention, the medium voltage cable further includes a tape layer 50 , which is coated outside the cable core structure.

[0038] Specifically, multiple core units are twisted into a cable core structure. The interstices created during twisting are filled with flat, ultra-thin, non-opening polypropylene rope. A layer of non-woven fabric with a nominal thickness of 0.2 mm is wrapped around the cable core structure to form a tape layer 50. Furthermore, in this embodiment of the present invention, the overlap ratio of the tape layer 50 is 15%-20%. For example, for an 18 / 30kV 3×95 cable, the diameter after the tape layer 50 is wrapped is 70.6 mm.

[0039] As shown in FIG1 , in an embodiment of the present invention, the medium voltage cable further includes an inner lining layer 60 , which is coated on the outside of the wrapping layer 50 . The inner lining layer 60 is a low-smoke halogen-free polyolefin inner lining layer.

[0040] Specifically, the inner lining layer 60 is made of low-smoke halogen-free polyolefin material, such as 18 / 30kV 3×95 specification. The inner lining layer 60 has a nominal thickness of 1.8 mm and an outer diameter of 74.2 mm after extrusion.

[0041] As shown in FIG. 1 , in an embodiment of the present invention, the medium voltage cable further includes an armor layer 70 , which is coated on the outside of the inner lining layer 60 .

[0042] Specifically, the armor layer 70 is woven with tinned copper wires with a single wire diameter of 0.4 mm and a braiding density of not less than 80, for example, 18 / 30 kV 3×95 specifications, and an outer diameter after braiding of 75.8 mm.

[0043] As shown in FIG1 , in an embodiment of the present invention, the medium voltage cable further includes an outer sheath layer 80 , which is coated outside the armor layer 70 . The outer sheath layer 80 is a silane cross-linked low-smoke halogen-free outer sheath layer.

[0044] Specifically, when used in offshore floating production, storage and offloading (FPSO) vessels, these medium-voltage cables will be exposed to oily environments for extended periods, slowly corroding the outer sheath, thereby reducing the cable's service life. Conventional oil-resistant cables typically utilize radiation cross-linking to achieve this oil resistance. However, radiation cross-linking is limited by the cable's outer diameter and cannot be processed for cables exceeding 80mm. Consequently, the outer sheath of cables with larger diameters lacks oil resistance.

[0045] In this embodiment, the outer sheath layer 80 is extruded using silane cross-linked low-smoke halogen-free sheath material. For cables with a diameter greater than 80 mm, cross-linking can be completed in steam for 24 hours, so that the outer sheath layer 80 of the cable with a larger diameter also has oil resistance.

[0046] The medium voltage cable provided in the embodiment of the present invention has an outer sheath layer that is a silane cross-linked low-smoke halogen-free outer sheath layer, so that the outer sheath layer of the cable with a larger diameter also has oil resistance, thereby extending the service life of the medium voltage cable.

[0047] As shown in FIG1 , in an embodiment of the present invention, an insulated wire core 10 includes a conductor 11, a shielding layer 12, an insulating layer 13, and an insulating shielding layer 14. Shielding layer 12 is coated on the outside of conductor 11, insulating layer 13 is coated on the outside of shielding layer 11, and insulating shielding layer 14 is coated on the outside of insulating layer 13.

[0048] Specifically, in this embodiment, the conductor 11 is a tinned conductor, and multiple tinned conductor monofilaments are twisted into the conductor 11. For example, the cross-sectional area is 95mm 2 Conductor 11 is composed of 19 tinned monofilaments with an outer diameter of 2.52 mm, twisted in a 1+6+12 configuration. After twisting, conductor 11 has an outer diameter of 12.5 mm. A shielding layer 12, an insulating layer 13, and an insulating shielding layer 14 are extruded simultaneously on the outside of conductor 11 using a 150+100+60 three-layer co-extrusion continuous vulcanization line, forming an insulated core 10. Furthermore, for example, in the 18 / 30 kV 3×95 specification, the nominal thickness of shielding layer 12 is 0.8 mm, the nominal thickness of insulating layer 13 is 8.0 mm, and the nominal thickness of insulating shielding layer 14 is 0.8 mm. The outer diameter of insulated core 10 is 31.7 mm.

[0049] Furthermore, in an embodiment of the present invention, the shielding layer 12 may be made of a semi-conductive shielding material, the insulating layer 13 may be made of medium-voltage EPDM rubber, and the insulating shielding layer 14 may be made of a semi-conductive material.

[0050] As shown in FIG2 , an embodiment of the present invention further provides a method for manufacturing a medium voltage cable, which specifically includes the following steps:

[0051] Step 01: Coat the metal shielding layer 20 with semi-conductive adhesive to form a semi-conductive adhesive layer 30, and wrap the semi-conductive adhesive layer 30 with an aluminum-plastic composite tape while coating, wherein the overlap rate of the aluminum-plastic composite tape is greater than or equal to 25%; Step 02: After the semi-conductive adhesive layer 30 is cured, remove the aluminum-plastic composite tape; Step 03: Twist multiple core units into a cable core structure.

[0052] Specifically, a metal shield 20 made of tinned copper wire with a nominal diameter of 0.2 mm is braided over the insulated core 10, with a braiding density of no less than 80%. Semi-conductive adhesive is applied to the exterior of the metal shield 20, and aluminum-plastic composite tape is wrapped around it simultaneously, with an overlap rate of no less than 25%. Approximately 6 hours after coating, the semi-conductive adhesive cures, and the aluminum-plastic composite tape is removed. At this point, for example, the outer diameter of an 18 / 30 kV 3×95 core unit is 32.5 mm. Multiple core units are twisted into a cable core structure.

[0053] Furthermore, in this embodiment, the semi-conductive adhesive layer 30 has conductive properties, which can ensure electrical continuity of the metal shielding layer 20. At the same time, the semi-conductive adhesive layer can fill the gaps produced by weaving to prevent harmful gases from diffusing along the gaps produced by weaving and posing a hidden danger to personnel safety.

[0054] The manufacturing method of the medium-voltage cable provided by the embodiment of the present invention, by coating a semi-conductive glue on the outside of the metal shielding layer, not only ensures the electrical penetration of the metal shielding layer, but also prevents harmful gases from flowing along the braiding gaps of the metal shielding layer, effectively preventing the harmful gases from leaking out of the cable and posing a hidden danger to personnel safety, so that the medium-voltage cable can be widely used in offshore floating production storage and offloading units, thereby enhancing the applicability of the medium-voltage cable.

[0055] The following describes in detail the method for manufacturing a medium voltage cable provided by an embodiment of the present invention:

[0056] Multiple tinned conductor monofilaments are twisted into conductor 11. A shielding layer 12, an insulating layer 13, and an insulating shielding layer 14 are extruded simultaneously outside conductor 11 using a 150+100+60 three-layer co-extrusion continuous vulcanization production line in sequence to form an insulated core 10. A metal shielding layer 20 is braided with tinned copper wire with a nominal diameter of 0.2 mm, with a braiding density of not less than 80%. The metal shielding layer 20 is wrapped around the outside of the insulated core 10, and a semi-conductive adhesive is applied to the outside of the metal shielding layer 20. Simultaneously with the coating, an aluminum-plastic composite tape is wrapped around the metal shielding layer 20 with an overlap rate of not less than 25%. Approximately 6 hours after coating, the semi-conductive adhesive is cured, and the aluminum-plastic composite tape is removed. The multiple core units are twisted into a cable core structure.

[0057] Filler 40 is used in the gaps of the cable core structure. Filler 40 is made of flat film, ultra-thin, closed-mesh polypropylene rope. This ensures a tight core structure, ensuring longitudinal airtightness of the medium-voltage cable core and preventing harmful gases from propagating axially along the cable to safe areas. A layer of non-woven fabric with a nominal thickness of 0.2 mm is wrapped around the cable core structure to form a tape layer 50. An inner liner 60 of low-smoke, zero-halogen material is extruded over the tape layer 50. A braided armor layer 70 of tinned copper wire with a diameter of 0.4 mm is applied over the inner liner 60. An outer sheath 80 of silane-crosslinked, low-smoke, zero-halogen sheathing material is extruded over the armor layer 70.

[0058] Furthermore, the silane crosslinking process used to produce the outer jacket layer 80 places extremely high demands on processing technology. Pre-crosslinked char particles are generated during the production process. If these char particles remain in the screw and die and are not promptly expelled, they gradually accumulate and eventually form large, concentrated particles, forming large particles on the jacket surface and even causing holes. Research has shown that the primary cause of pre-crosslinking during extrusion is high extrusion temperature. Therefore, determining the minimum extrusion temperature at which the material can fully plasticize poses a challenge to silane crosslinking. After numerous trials and repeated adjustments to the process temperature, the optimal extrusion temperatures were determined to be: 145°C, 155°C, 160°C, 160°C, 165°C, 165°C, 165°C, 165°C, 165°C, 165°C, 165°C, 165°C, 165°C. To prevent the accumulation of small pre-crosslinked particles in the screw and die, a large, high-speed production machine is used. The screw speed is periodically increased during production, allowing the accumulated char in dead corners to be expelled under the thrust force, thus avoiding the formation of large char particles and holes.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A medium voltage cable, characterized in that: The cable core structure comprises a plurality of core units, wherein the plurality of core units are twisted into a cable core structure, and each core unit comprises: Insulated wire core; a metal shielding layer covering the outside of the insulating core; a semi-conductive adhesive layer, which is coated on the outside of the metal shielding layer, and the semi-conductive adhesive layer is formed by curing the semi-conductive adhesive; Wherein, the medium voltage cable is an airtight power cable with a rated voltage of 6kV to 30kV.

2. The medium voltage cable according to claim 1, characterized in that The semi-conductive adhesive consists of a first component and a second component, wherein the first component includes: 100 parts of methyl block room temperature vulcanized silicone rubber, 30-45 parts of ultrafine calcium carbonate, 6-10 parts of fumed silica, 3-5 parts of titanium dioxide, and 3-5 parts of graphene; The second component comprises: 4-8 parts of ethyl orthosilicate, 2-4 parts of n-butyl borate, 2-4 parts of n-butyl titanate, a trace amount of octyltin dilaurate, and a trace amount of gamma-aminopropyltriethoxysilane.

3. The medium voltage cable according to claim 1, characterized in that It also includes a plurality of fillers, which are filled in the cable core structure and located between the plurality of core units, wherein the fillers are flat films and non-open mesh polypropylene ropes.

4. The medium voltage cable according to claim 3, characterized in that It also includes a tape layer, which is coated outside the cable core structure.

5. The medium voltage cable according to claim 4, characterized in that It also includes an inner lining layer, which is coated on the outside of the wrapping layer and is a low-smoke halogen-free polyolefin inner lining layer.

6. The medium voltage cable according to claim 5, characterized in that It also includes an armor layer, which is coated outside the lining layer.

7. The medium voltage cable according to claim 6, characterized in that It also includes an outer sheath layer, which is coated outside the armor layer and is a silane cross-linked low-smoke halogen-free outer sheath layer.

8. The medium voltage cable according to claim 1, characterized in that The insulated core comprises: conductor; a shielding layer covering the conductor; an insulating layer, which covers the shielding layer; The insulating shielding layer is coated outside the insulating layer.

9. The medium voltage cable according to claim 1, characterized in that The metal shielding layer is woven from tinned copper wires.

10. A method for manufacturing a medium voltage cable according to claim 1, characterized in that: include: Coating a semi-conductive adhesive on the outside of the metal shielding layer to form a semi-conductive adhesive layer, and wrapping the semi-conductive adhesive layer with an aluminum-plastic composite tape at the same time, wherein the overlap rate of the aluminum-plastic composite tape is greater than or equal to 25%; After the semi-conductive adhesive layer is cured, removing the aluminum-plastic composite tape; Multiple core units are twisted into a cable core structure.

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