A large cross-sectional area segmented conductor power cable

Abstract

This utility model discloses a large-section segmented conductor power cable, relating to the field of power transmission technology. It includes, from the inside out, a segmented conductor, a conductor shielding layer, an insulation layer, an insulation shielding layer, a buffer layer, a metal sheath, an anti-corrosion coating, and an outer sheath. The segmented conductor adopts a five-segment structure with specific sector height, sector width, single-wire diameter, and number of wires. The conductor shielding layer, insulation layer, and insulation shielding layer are integrally formed by three-layer co-extrusion, and each layer, as well as the subsequent buffer layer, metal sheath, anti-corrosion coating, and outer sheath, have a clearly optimized thickness range. This utility model, through a specific layered physical structure design, effectively solves the technical problems of difficult roundness control and interface defects in ultra-large cross-section segmented conductors, providing a high-voltage power cable with excellent electrical performance, comprehensive mechanical protection, and reliable long-term operation.

Description

Technical Field

[0001] This utility model relates to the field of power cable technology, specifically to a large cross-sectional area split conductor power cable suitable for high voltage levels, and particularly to a cross-linked polyethylene insulated power cable with a conductor cross-sectional area in the range of 2900mm² to 3500mm². Background Technology

[0002] With the rapid development of the national economy and the continuous growth of electricity demand, the requirements for the capacity and reliability of transmission lines are increasing, driving the development of power cables towards larger cross-sections and higher voltage levels. However, when transmitting alternating current, large-section conductors exhibit significant skin and proximity effects, causing their current-carrying capacity to not increase linearly with the increase of cross-sectional area. To overcome this problem, standards stipulate that cables of 66kV and above with a cross-sectional area of ​​800mm² or more must adopt a split conductor structure.

[0003] Currently, the maximum cross-sectional area of ​​split conductors specified in the national standard GB / T3956-2008 is 2500 mm². With technological advancements, there is a need to manufacture split conductors with cross-sections of 3000 mm² or even larger to meet the demands of power grid upgrades. However, the design and manufacturing of such ultra-large cross-section conductors face numerous challenges: First, the national standard lacks key parameter standards for 3000 mm² conductors, such as DC resistance and single-wire specifications, leaving design without a basis; second, controlling conductor roundness is extremely difficult, and roundness directly affects the smoothness of the interface between the inner shielding layer and the insulation layer, as well as the insulation eccentricity, which is crucial for ensuring the long-term reliability of the cable; third, during the production process, the large outer diameter and weight of the conductor can easily lead to strand misalignment and serpentine bending, and cause fatal defects such as interface protrusions and shielding nodules during insulation extrusion, severely restricting product quality and production stability.

[0004] Therefore, there is an urgent need for a large-section segmented conductor power cable with optimized structure, high roundness, and good manufacturability to solve the above-mentioned technical bottlenecks. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a large cross-sectional area split conductor power cable with stable structure, high roundness, and excellent interface performance.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A large-section split conductor power cable includes, from the inside out: a split conductor, the split conductor comprising a filling unit and a plurality of sector-shaped strands separated by a release paper, the filling unit filling the sector-shaped strands; a conductor shielding layer covering the outside of the split conductor; an insulation layer covering the outside of the conductor shielding layer; an insulation shielding layer covering the outside of the insulation layer; a buffer layer wrapped around the outside of the insulation shielding layer; a metal sheath covering the outside of the buffer layer; the metal sheath is further provided with an asphalt anti-corrosion coating; and an outer sheath covering the outside of the anti-corrosion coating; the conductor shielding layer, the insulation layer, and the insulation shielding layer are formed into an integral structure by a three-layer co-extrusion process.

[0007] Furthermore, the segmented conductor comprises multiple sector-shaped strands, and insulating paper is provided between each sector-shaped strand and on the outside of the outermost strand.

[0008] Preferably, the number of the fan-shaped strands is five, forming a five-segment conductor structure. Each fan-shaped strand has a height of 29.4±0.1mm and a width of 37.5±0.2mm.

[0009] Preferably, the filling unit is formed by twisting together several metal monofilaments. Each fan-shaped strand is formed by twisting together several metal monofilaments, the diameter of which is 3.05±0.1mm, and the number of monofilaments in each strand is 90-105.

[0010] Preferably, the equivalent cross-sectional area of ​​the split conductor of the cable is 2900-3500 mm², and more preferably 3000 mm².

[0011] Preferably, the conductor shielding layer tightly covers the outside of the segmented conductor, and its total thickness is between 1.8 and 4.0 mm. The conductor shielding layer is composed of a semiconducting strip first wrapped around the surface of the conductor and a semiconducting layer extruded onto its surface, wherein the thickness of the extruded semiconducting layer is between 1.3 mm and 3.3 mm. This layer is used to uniformly distribute the electric field on the conductor surface and prevent partial discharge.

[0012] Preferably, the insulation layer covers the outside of the conductor shielding layer, and its thickness is between 21.0 and 31.0 mm, with the specific thickness adjusted according to the voltage rating (220 kV to 750 kV) of the cable design. This insulation layer is made of ultra-pure cross-linked polyethylene (XLPE) material and is a key component of the cable that can withstand operating voltage and various overvoltages.

[0013] Preferably, the insulating shielding layer covers the outside of the main insulating layer and has a thickness of 1.2-1.8 mm. This layer works together with the conductor shielding layer to ensure a uniform electric field distribution inside and outside the main insulating layer and to prevent surface discharge.

[0014] Preferably, the buffer layer is wrapped around the outside of the insulating shielding layer, and its thickness is 6.0-7.0 mm. The buffer layer consists of an inner semi-conductive buffer strip and an outer semi-conductive water-resistant strip, which serves to buffer thermal expansion, maintain good electrical contact, and prevent water from flowing longitudinally.

[0015] Preferably, the metal sheath is a welded corrugated aluminum sheath that covers the outside of the buffer layer, with a thickness of 2.8-3.5 mm. This metal sheath serves as a radial waterproof and moisture-proof barrier, and provides mechanical protection and short-circuit current conduction capability.

[0016] Preferably, the outer sheath covers the outside of the anti-corrosion coating; the thickness of the anti-corrosion coating is 0.1-0.3 mm; the outer sheath includes an inner non-metallic sheath and an outer conductive sheath; the non-metallic sheath is extruded from polyvinyl chloride (PVC) or polyethylene (PE) material, with a thickness of 5.0-6.5 mm, serving as physical protection and insulation; the conductive sheath is a graphite layer or an extruded conductive layer, with a thickness of 0.1-0.3 mm, used to achieve reliable grounding of the cable's metal layer and for the outer sheath withstand voltage test.

[0017] The beneficial effects of this utility model are as follows: Structural Innovation: This utility model clearly proposes specific structural parameters for the 3000mm² ultra-large cross-section segmented conductor (such as strand height, strand width, single wire diameter and number) as well as the precise thickness range of each insulation layer and protective layer from the conductor shielding layer to the outer sheath, providing a clear structural standard for the design and production of this specification of cable.

[0018] Excellent roundness and stability: The optimized five-segment conductor structure design ensures that the segmented conductors have extremely high roundness, effectively improving the electric field distribution, reducing the risk of insulation eccentricity, and enhancing the electrical performance and long-term operational reliability of the product.

[0019] Comprehensive Protection System: This utility model cable constructs a multi-layered protection system: a three-layer co-extruded structure of inner shielding / insulation / outer shielding ensures core insulation performance; a buffer layer compensates for thermal expansion and achieves longitudinal water resistance; a corrugated aluminum sheath and an asphalt anti-corrosion coating together form a robust radial waterproof, moisture-proof, and corrosion-resistant barrier; and a double-layered outer sheath provides final physical protection and electrical safety assurance. This progressively layered structural design enables the cable to adapt to harsh operating environments. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the cross-sectional structure of the large cross-sectional area segmented conductor power cable described in this utility model.

[0022] In the diagram: 1. Segmented conductor; 1.1. Filling unit; 1.2. Sector-shaped strand; 2. Conductor shielding layer; 2.1. Semiconducting strip; 2.2. Semiconducting layer; 3. Insulating layer; 4. Insulating shielding layer; 5. Buffer layer; 5.1. Conductive buffer strip; 5.2. Semiconducting resistive water strip; 6. Metal sheath; 7. Anti-corrosion coating; 8. Outer sheath; 8.1. Inner sheath; 8.2. Conductive sheath. Detailed Implementation

[0023] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0024] Many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0025] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that excludes other embodiments.

[0026] Reference Figure 1 This utility model provides a large cross-sectional area split conductor power cable. This embodiment uses a cross-linked polyethylene insulated power cable suitable for 220kV voltage level and with an equivalent conductor cross-sectional area of ​​3000mm² as an example for detailed description.

[0027] The power cable consists of, from the inside out, a split conductor 1, a conductor shielding layer 2, an insulation layer 3, an insulation shielding layer 4, a buffer layer 5, a metal sheath 6, an anti-corrosion coating 7, and an outer sheath 8.

[0028] Segmented Conductor: As the conductive core of the cable, a five-segmented conductor structure is adopted. This segmented conductor 1 includes a filling unit 1.1 and five sector-shaped strands 1.2. The filling unit is composed of several oxygen-free copper monofilaments twisted together. Each sector-shaped strand is also made of oxygen-free copper, with a height of 29.4 mm and a width of 37.5 mm. The monofilaments used in each sector-shaped strand have a diameter of 3.05 mm, and there are 91 monofilaments in total. Corrugated paper is used as insulating paper between the sector-shaped strands and on the outermost strand. The equivalent calculated cross-sectional area of ​​this segmented conductor 1 is 3000 mm².

[0029] Conductor shielding layer: This layer is tightly wrapped around the outside of the segmented conductor using a three-layer co-extrusion process. The total thickness of this layer is 2.5 mm, and it consists of a semi-conductive strip 2.1 initially placed on the surface of the segmented conductor and a semi-conductive layer 2.2 extruded onto its surface. The thickness of the extruded semi-conductive layer is 1.8 mm. The conductor shielding layer smoothly covers the conductor, serving to uniformly distribute the electric field on the conductor surface and prevent partial discharge and corona discharge caused by electric field concentration.

[0030] Insulation layer: Covering the outside of the conductor shielding layer, its thickness is 26.0mm. This insulation layer is made of ultra-pure cross-linked polyethylene (XLPE) material and is the most critical insulation part of the cable to withstand 220kV operating voltage and various overvoltages (such as lightning overvoltage), and can withstand an operating temperature of 90°C for a long time.

[0031] Insulating shielding layer: Covering the outside of the insulating layer, forming an integral structure with the conductor shielding layer and the insulating layer, its thickness is 1.5mm. This layer is made of semi-conductive material and is used to homogenize the electric field distribution on the outer surface of the insulating layer. It works in conjunction with the conductor shielding layer to ensure that the electric field inside and outside the main insulating layer is uniform, while eliminating the risk of surface discharge caused by gaps between it and the subsequent metal layers.

[0032] Buffer layer: Wrapped around the outside of the insulating shield, with a thickness of 6.5mm. This buffer layer consists of an inner semi-conductive buffer strip 5.1 and an outer semi-conductive water-resistant strip 5.2. Its main functions include: compensating for expansion or contraction caused by thermal stress during cable operation, maintaining good electrical contact between the insulating shield and the metal sheath, and using the semi-conductive water-resistant strip to achieve longitudinal water-blocking function of the cable, preventing moisture from spreading along the cable axis.

[0033] Metal sheath: Covering the outside of the buffer layer, this embodiment uses a welded corrugated aluminum sheath with a thickness of 3.0mm. This metal sheath is the core barrier for radial waterproofing and moisture protection of the cable, effectively preventing moisture and humidity from penetrating the internal insulation system; at the same time, it provides excellent mechanical protection, resisting mechanical stresses such as external pressure and compression, and acts as a metal shielding layer to conduct short-circuit current in the system.

[0034] Anti-corrosion coating: Applied to the outside of the metal sheath, this embodiment uses an asphalt coating. This asphalt anti-corrosion coating can effectively prevent the metal sheath from being subjected to chemical and electrochemical corrosion in complex laying environments (such as direct burial, tunnels, etc.), thus extending the service life of the cable.

[0035] Outer sheath: Covering the outside of the anti-corrosion coating. The outer sheath includes a non-metallic inner sheath 8.1 and an outer conductive sheath 8.2. The inner non-metallic sheath is extruded from flame-retardant polyethylene (PE) material with a thickness of 5.5 mm. Its main function is to provide final physical protection against chemical corrosion, abrasion, and impact from the external environment, and to ensure insulation between the metal sheath and the ground. The outer conductive sheath is a semi-conductive polyethylene layer with a thickness of 0.2 mm. Its function is to achieve reliable grounding of the cable's metal sheath and facilitate DC withstand voltage testing of the outer sheath.

[0036] This invention, through specific structural design, material selection, and precise thickness matching of each layer, successfully manufactures a large cross-sectional area segmented conductor power cable with high roundness, excellent interface performance, and strong electrical reliability. It is particularly suitable for transmission lines with ultra-large cross-sections of 3000mm² and high voltage levels, effectively solving technical problems such as difficulty in roundness control and numerous production defects.

[0037] It should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of the technical solution of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A large cross-section segmented conductor power cable, characterized by, It includes, from the inside out, a segmented conductor, which includes a filling unit and a plurality of sector-shaped strands, the strands being separated by a release paper, and the filling unit filling the sector-shaped strands; A conductor shielding layer is used to cover the outside of the segmented conductor. An insulating layer covers the outside of the conductor shielding layer; an insulating shielding layer covers the outside of the insulating layer. A buffer layer is wrapped around the outside of the insulating shielding layer; a metal sheath is covered over the outside of the buffer layer; an asphalt anti-corrosion coating is also provided on the outside of the metal sheath; an outer sheath is covered over the anti-corrosion coating; the conductor shielding layer, the insulating layer, and the insulating shielding layer are an integral structure.

2. The power cable according to claim 1, characterized in that, The number of fan-shaped segments is five, and the height of each fan-shaped segment is 29.4±0.1mm, and the width of each fan-shaped segment is 37.5±0.2mm.

3. The power cable according to claim 2, characterized in that, The filling unit is made of several metal monofilaments twisted together. The diameter of the monofilament in each fan-shaped strand is 3.05±0.1mm, and the number of monofilaments is 90-105.

4. The power cable according to any one of claims 1-3, characterized in that The cross-sectional area of ​​the cable is 2900-3500 mm².

5. The power cable according to claim 1, characterized in that, The conductor shielding layer has a thickness of 1.8-4.0 mm and is composed of a semiconductive strip on the surface of the segmented conductor and a semiconductive layer on its surface, the thickness of which is 1.3-3.3 mm.

6. The power cable according to claim 1, characterized in that, The thickness of the insulating layer is 21.0-31.0 mm.

7. The power cable according to claim 1, characterized in that, The thickness of the insulating shielding layer is 1.2-1.8 mm.

8. The power cable according to claim 1, characterized in that, The buffer layer is 6.0-7.0 mm thick and consists of an inner semi-conductive buffer strip and an outer semi-conductive resistive water strip.

9. The power cable according to claim 1, characterized in that, The metal sheath is a welded corrugated aluminum sheath with a thickness of 2.8-3.5 mm.

10. The power cable according to claim 1, characterized in that, The outer sheath includes an inner sheath and an outer conductive sheath, wherein the thickness of the inner sheath is 5.0-6.5 mm and the thickness of the conductive sheath is 0.1-0.3 mm.

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