A high strength high voltage cable and a method of manufacturing the same

Abstract

The embodiment of the application relates to the field of cable manufacturing, in particular to a high-strength high-voltage cable and a manufacturing method thereof, which comprises a steel core layer, a conductor layer, an inner semiconductive shielding layer, an insulation layer, an outer semiconductive shielding layer and a sheath layer arranged in sequence from inside to outside; the conductor layer is a layered split conductor, comprising an inner layer conductor and an outer layer conductor coaxially sleeved on the outer side of the inner layer conductor; the inner layer conductor comprises a plurality of first strands twisted around the steel core layer, and the first strands are tightly formed by copper single wires; the outer layer conductor comprises a plurality of second strands twisted on the outer side of the inner layer conductor, and the second strands are twisted by insulated copper single wires. The steel core is used as a framework to bear the cable tension; the double-layer strands of the inner layer bare copper and the outer layer enameled copper are used around the steel core to form the layered split conductor, thereby solving the problems of ultrahigh mechanical strength and low AC resistance loss under high-fall laying.

Description

Technical Field

[0001] This invention relates to the field of cable manufacturing technology, specifically a high-strength high-voltage cable and its manufacturing method. Background Technology

[0002] High-voltage cables are key equipment for long-distance, high-capacity power transmission, and their performance directly affects the reliability and economic operation of the power grid. When cables are laid and operated in environments with high elevation differences (such as mountainous areas), they must withstand multiple mechanical loads such as their own weight, traction tension, and environmental stress for a long time, which places stringent requirements on the mechanical strength, structural stability, and long-term operational reliability of the cables.

[0003] To address the issue of mechanical strength, existing technologies, drawing on the experience of overhead conductors, incorporate galvanized steel wires or ropes as load-bearing elements in the cable's center or between layers. However, in such composite structures, the interface between the steel core and conductor is rough, making it prone to relative slippage between the metals under bending and tensile cyclic stress, leading to structural loosening and conductor deformation. Simultaneously, the introduction of the steel core alters the cable's electromagnetic field distribution, easily exacerbating the proximity effect and resulting in an additional increase in AC resistance.

[0004] Adding galvanized steel wire or wire rope to the cable center or interlayer to form a steel core strand increases the cable cross-sectional diameter, necessitating consideration of the AC resistance of the large-section conductor. To address this, existing technologies typically divide the conductor into multiple mutually insulated strands. While this optimizes current distribution to some extent, traditionally segmented conductors are usually made of pure copper or aluminum alloy, which have poor tensile strength and differ from the tensile strength of the steel core. Under the immense tension of high-drop laying, the plastic deformation of the conductor strands and the steel core is not coordinated, causing strand damage. Furthermore, the altered contact pressure between the strands after deformation easily leads to increased contact resistance, intensified heating, and continuous deterioration of mechanical and electrical properties. Summary of the Invention

[0005] To address the technical problems described in the background section, this invention provides a high-strength high-voltage cable and its manufacturing method. A steel core serves as the mechanical framework, independently bearing the tension during cable laying and operation. Simultaneously, a double-layered conductor is constructed around the steel core, consisting of an inner layer of bare copper and an outer layer of enameled copper. This division of labor—"steel core bearing the load, conductor dedicated to electrical conductivity"—along with electromagnetic depth optimization, collaboratively solves the problems of ultra-high mechanical strength and low AC resistance loss under high-drop laying conditions.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention discloses a high-strength high-voltage cable, comprising, from the inside out, a steel core layer, a conductor layer, an inner semi-conductive shielding layer, an insulation layer, an outer semi-conductive shielding layer, and a sheath layer; The conductor layer is a layered segmented conductor, including an inner conductor and an outer conductor that is coaxially sleeved on the outside of the inner conductor; The inner conductor comprises multiple first strands twisted together around the steel core layer, the first strands being formed by pressing copper single wires together; The outer conductor includes multiple second strands twisted to the outside of the inner conductor, and the second strands are formed by twisting together insulated copper single wires.

[0007] Furthermore, when the outer surface of the steel core layer has an insulating layer, the first strand is formed by pressing together oxygen-free copper single wire; when the outer surface of the steel core layer does not have an insulating layer, the first strand is formed by pressing together insulated copper single wire; the insulated copper single wire includes enameled oxygen-free copper single wire or surface-oxidized oxygen-free copper single wire.

[0008] Furthermore, the first block is fan-shaped or "SZ" shaped, and the second block is "SZ" shaped.

[0009] Furthermore, the compaction coefficient of the inner conductor has a set range, and the compacted inner conductor is stranded around the steel core layer with a stranding pitch ratio of a set value.

[0010] Furthermore, the outer conductor is wrapped around the outer side of the inner conductor using an opposite twisting method, and after twisting, it is pressed and shaped by a compression mold to form a second strand.

[0011] Furthermore, the steel core layer is formed by stranding multiple galvanized steel wires or using solid steel bars. When the stranding method is counter-directional stranding, it is less likely to loosen, while co-directional stranding results in relatively low AC resistance.

[0012] Furthermore, the insulating layer is extruded onto the outside of the inner semiconductive shielding layer.

[0013] Furthermore, the sheath layer includes a metal sheath and an outer sheath, wherein the metal sheath is a corrugated aluminum sheath with a set thickness; and the outer sheath is a weather-resistant polyethylene.

[0014] Furthermore, an anti-corrosion layer is provided between the metal sheath and the outer sheath.

[0015] Furthermore, an external electrode is provided on the outer side of the outer sheath.

[0016] This invention also discloses a method for manufacturing a high-strength high-voltage cable, comprising the following steps: Multiple galvanized steel wires are twisted together to form a steel core layer; Copper single wires are compacted into multiple first strands and twisted around a steel core layer to form an inner conductor; insulated copper single wires are twisted into multiple second strands and twisted around the outside of the inner conductor to form an outer conductor. Through a three-layer co-extrusion process, an inner semiconductive shielding layer, an insulating layer, and an outer semiconductive shielding layer are co-extruded sequentially on the outside of the conductor layer. A metal sheath and an outer sheath are formed sequentially on the outside of the outer semiconductive shielding layer.

[0017] Compared with existing technologies, one or more of the above technical solutions have the following beneficial effects: 1. Constructing a "steel core load-bearing + layered conductivity" architecture. Placing the steel core layer at the core makes it the load-bearing skeleton, absorbing the laying tension and its own weight, thus solving the fundamental problem of conductor deformation or breakage due to stress during high-drop laying. Simultaneously, a layered conductor design is adopted, with an inner layer of enameled copper and an outer layer of oxygen-free copper (enameling is more effective on the inner layer than the outer layer; using enameling for both inner and outer layers would be even more effective, but less economical). This not only reduces AC resistance through physical separation but also utilizes the insulating properties of the outer enameled copper to suppress the skin effect and proximity effect. This achieves decoupling and synergy between mechanical strength and conductivity, reducing AC resistance while ensuring the cable's mechanical strength meets requirements, providing a core solution for high-drop, high-voltage power transmission that combines ultra-high reliability and high efficiency.

[0018] 2. The first and second strands are either fan-shaped or "SZ"-shaped, offering a variety of optimized combinations. Fan-shaped strands are easy to manufacture and structurally stable, making them suitable as the foundation support for the inner layer; "SZ"-shaped strands, with their arc-shaped cross-section, provide stronger structural fit and heat dissipation channels. When used as the outer conductor, they can improve the overall roundness of the stranding and the mechanical locking force, thus flexibly adapting to application scenarios with different performance focuses and process conditions.

[0019] 3. After the enameled oxygen-free copper single wires are stranded into shape, they are then stranded in opposite directions and pressed through a die. Before entering the sizing and pressing die, process adjustments are made to initially fix the relative positions between the enameled copper wires, and then the stranding and sizing die is used to achieve the final shape. This process can maximize the elimination of micro-gaps within the outer strands, ensure the stability of the current path, and optimize the insulation effect between the enameled wires. At the same time, hydraulic shaping makes the outer conductors form a tightly bonded whole, further improving the cable's structural retention and deformation resistance under bending and torsion conditions.

[0020] 4. The insulation layer is formed on the outside of the inner semiconductive shielding layer through an extrusion process, forming a continuous, uniform, and gapless insulation layer that smoothly transitions with the semiconductive shielding layer, eliminating the risk of electric field concentration and partial discharge at the interface. For the bending and vibration often associated with high-altitude laying, this integrally formed insulation system exhibits excellent tensile strength and deformation resistance, which is crucial for ensuring the long-term reliability of high-voltage insulation.

[0021] 5. The corrugated aluminum sheath provides excellent radial waterproof barrier, electromagnetic shielding, and resistance to mechanical shock. Its "corrugated" structure gives the cable superior longitudinal flexibility and resistance to bending fatigue. The outer weather-resistant polyethylene sheath is designed for outdoor environments, resisting UV aging, chemical corrosion, and physical friction. Together, they form the ultimate "rigid-flexible" protection system for harsh laying environments with high elevation differences. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an improper limitation of the invention.

[0023] Figure 1 This is a schematic diagram of the cross-sectional structure of a high-strength high-voltage cable provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the cross-sectional structure of a high-strength high-voltage cable provided in Embodiment 2 of the present invention.

[0024] In the diagram: 1. Galvanized steel core, 2. Conductor, 3. Conductor shield, 4. Insulation layer, 5. Insulation shield, 6. Buffer layer, 7. Metal sheath, 8. Anti-corrosion layer, 9. Outer sheath, 10. Outer electrode. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0027] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to the present invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0028] A strand is an independent conductive unit in a high-voltage, large-section cable conductor, consisting of multiple pre-compressed and stranded metal wires (such as copper or aluminum) with a specific geometric cross-sectional shape (such as fan-shaped or corrugated). Multiple strands are arranged circumferentially and twisted together to form a complete cable conductor. The strand is the core structural component for implementing "segmented conductor" technology.

[0029] When a large-section solid conductor is subjected to alternating current, the current is "squeezed" to the surface of the conductor due to the strong skin effect and proximity effect, resulting in insufficient utilization of the central area, a reduction in the effective conductive area, and a significant increase in AC resistance.

[0030] The strand structure creates multiple independent conductive paths through physical segmentation, so that the current is no longer concentrated on the outer surface of a single conductor, but is distributed to flow across the entire cross-section of each strand, greatly increasing the "effective surface area" available for current and forcing a more uniform current distribution.

[0031] The strands are usually separated by gaps or by insulating materials, which can cut off the path of large annular eddy currents. This weakens the eddy currents circulating between the strands induced by the alternating magnetic field inside the conductor, thereby reducing the additional eddy current losses caused by proximity effects.

[0032] The following embodiments illustrate a high-strength high-voltage cable and its manufacturing method. A steel core serves as the mechanical skeleton, independently bearing the tension during cable laying and operation. Simultaneously, a double-layered conductor is constructed around the steel core, consisting of an inner layer of bare copper and an outer layer of enameled copper. This division of labor—"steel core bearing the load, conductor dedicated to electrical conductivity"—along with electromagnetic depth optimization, collaboratively solves the problems of ultra-high mechanical strength and low AC resistance loss under high-drop laying conditions.

[0033] Example 1: A high-strength high-voltage cable includes, from the inside out, a steel core layer, a conductor layer, an inner semi-conductive shielding layer, an insulation layer 4, an outer semi-conductive shielding layer, a metal sheath 7, and an outer sheath 9. The conductor layer is a layered split conductor, including an inner conductor and an outer conductor connected by a coaxial cable. The outer conductor is stranded outside the inner conductor, and the inner conductor is stranded around the steel core layer. The inner conductor includes multiple first strands, which are oxygen-free copper strands. The outer conductor includes multiple second strands, which are enameled oxygen-free copper strands.

[0034] The shapes of the first and second strands can be the same or different. In this embodiment, as shown... Figure 1 As shown, the first strand is fan-shaped and the second strand is corrugated; the inner conductor consists of 6 fan-shaped oxygen-free copper strands twisted around the steel core layer, and the outer conductor consists of 12 corrugated enameled oxygen-free copper strands twisted outside the inner conductor.

[0035] The aforementioned cable structure overcomes the problem of force-electric interference in traditional composite conductors (such as steel-cored aluminum stranded wire), and achieves optimal structural configuration by physically and functionally decoupling and coordinating the steel core used to bear stress with the conductor that carries power transmission.

[0036] By differentiating the materials and shapes of the inner and outer conductors (inner bare copper / outer enameled copper; fan-shaped / corrugated combination), active guidance and optimization of the current path are achieved.

[0037] Combination Figure 1 The cable structure of this solution is described in detail.

[0038] Steel core layer: Ultra-high strength galvanized steel strands are used as the central load-bearing core to form galvanized steel core 1. The steel strands are made of 7-19 galvanized steel wires with a diameter of 1.2-2.0mm twisted in the same direction, with a twisting pitch ratio of 8-12 and a tensile strength ≥1800MPa, which meets the tensile bearing requirements under high drop. Conductor layer: Covering the outside of the steel core layer, it adopts a layered conductor structure, including an inner conductor layer and an outer conductor layer. Inner conductor: It consists of 6 fan-shaped strands twisted around the steel core layer. The strands are made of oxygen-free copper single wires that are tightly pressed together. The single wire diameter is 0.8-1.0mm and the compaction coefficient is ≥0.92. Semiconductor resistive water material is filled between the strands to reduce contact resistance. Outer conductor: It consists of 12 corrugated or "SZ" shaped strands twisted together on the outside of the inner conductor. The strands are made of enameled oxygen-free copper single wires. The insulation properties of the enameled layer are used to weaken the skin effect, thereby reducing the AC resistance by 10%-15%. The conductor layer employs a combination of "SZ" shaped and fan-shaped strands, incorporating water-blocking filling between the strands and a stranding shaping process. The corrugated shape provides better mechanical fitting and heat dissipation channels, while precision stranding ensures extremely low contact resistance and high structural stability.

[0039] The inner conductors are close to the steel core, and the strands are tightly packed together, causing current to "repel" each other to the outside of adjacent strands. Therefore, the core requirement is to ensure high efficiency and low loss of conductivity within the strands. Thus, oxygen-free copper, with the highest conductivity, is used, employing a high compaction factor (≥0.92) to carry the main current in this area with minimal DC resistance and good internal thermal conductivity. This maximizes conductivity and heat dissipation, rather than prioritizing electromagnetic isolation within the strands.

[0040] The outer conductor is located in the region where the skin effect and proximity effect are most severe. Current is strongly pushed towards the outer surface, and the current distribution between the outer conductors is easily disrupted, generating additional eddy current losses. However, the outer conductor uses enameled copper strands with an extremely thin enamel film, which has minimal impact on DC resistance and heat dissipation. Yet, its insulation properties force the current to form an independent, optimized path within each outer conductor, disrupting harmful current coupling and circulation between the outer conductors. Transforming the outer conductor from a "loss-prone area" into a "high-efficiency conductive layer" directly contributes to reducing AC resistance by 10%-15%.

[0041] In this scheme, the strands of the inner conductor and the strands of the outer conductor can be the same or different; When using the combination of "inner fan-shaped + outer SZ-shaped", the fan-shaped strands of the inner conductor can easily compress multiple single wires into a high-density, regularly shaped block, which can tightly wrap around the circular steel core, forming a stable first-layer support structure. It is simple to manufacture and has high reliability.

[0042] The outer conductor uses corrugated strands, and the arc shape of the SZ strands ideally fits the circumference already formed by the inner fan-shaped blocks, resulting in a large contact area and extremely high overall roundness after stranding. Based on the mechanical principle similar to an arch bridge, the corrugated strands can "lock" against each other, making them less prone to loosening when the cable is bent or twisted, thus achieving optimal structural stability. At the same time, the grooves between the corrugations provide space for thermal expansion and may form tiny airflow channels, which is beneficial for conductor heat dissipation.

[0043] Shielding layer: Includes an inner semiconductive shielding layer and an outer semiconductive shielding layer. The inner semiconductive shielding layer is extruded onto the outside of the conductor layer, serving as conductor shielding 3, with a thickness of 0.8-1.2 mm. The outer semiconductive shielding layer is extruded onto the outside of the insulation layer, serving as insulation shielding 5, with a thickness of 0.8-1.2 mm. Both are made of cross-linked polyethylene-based semiconductive material with a volume resistivity ≤100Ω. m Insulation layer 4: Made of ultra-clean cross-linked polyethylene (XLPE) material, it is extruded onto the outside of the inner semi-conductive shielding layer through a three-layer co-extrusion process. The thickness is designed according to the cable voltage level (16-19mm for 110kV and 24-27mm for 220kV), and has excellent corona resistance and tensile strength. Sheath layer: includes metal sheath 7 and outer sheath 9. Metal sheath 7 is made of corrugated aluminum extrusion with a thickness of 2.0-2.8mm, providing waterproof and mechanical protection. Outer sheath 9 is made of weather-resistant polyethylene (PE) material with added UV and tear-resistant additives, with a thickness of 4.0-5.0mm, suitable for environmental stress in high-drop laying. A corrosion-resistant layer 8 is provided between the metal sheath 7 and the outer sheath 9, providing electrochemical isolation and corrosion protection. The corrugated aluminum sheath, serving as the metal sheath 7, may be damaged during installation and operation due to impacts or deformation, allowing moisture or electrolytes from the environment to come into contact with it. The corrosion-resistant layer (usually an extruded polyethylene or polyolefin coating, or a wrapped composite water-blocking tape) effectively prevents direct contact between moisture and the aluminum sheath, preventing electrochemical corrosion and thus protecting the mechanical integrity and sealing of the metal sheath, extending cable life.

[0044] An external electrode 10 is provided on the outer side of the outer sheath 9. For high-voltage cables, when there are local defects in the main insulation, a weak leakage current or partial discharge will occur. The external electrode 10 (usually a semi-conductive layer or conductive strip) and the metal sheath 7 together form a capacitance / current detection circuit. Grounding the external electrode at the cable line terminal or joint can effectively discharge the induced current or fault current on the surface of the outer sheath, ensuring the safety of personnel and equipment. Furthermore, by monitoring the current or signal between the external electrode 10 and the metal sheath 7, online monitoring of the cable insulation status and fault early warning can be achieved.

[0045] The manufacturing method of the above-mentioned cable is as follows: Steel core preparation: Galvanized steel wire is stranded in the same direction using a stranding machine to form a steel core. The stranding pitch is controlled to be 8-12 times the steel diameter, and the stranding tension is kept stable at 800-1000N to ensure the roundness and tensile strength of the steel core. Conductor layer fabrication: Inner conductor: Oxygen-free copper single wire is compressed into fan-shaped strands through a compression press in multiple passes, with the compression coefficient controlled at 0.92-0.95. Then, it is stranded around the steel core layer with a stranding pitch ratio of 10-14.

[0046] Outer conductor: Enamelled oxygen-free copper single wires are stranded into corrugated strands and wrapped around the outer side of the inner conductor using a unidirectional stranding method. The stranding pitch ratio is 12-16. After stranding, the conductor is pressed and shaped by a compaction mold to eliminate air gaps between strands and reduce contact resistance. Extrusion of shielding and insulation layers: A three-layer co-extrusion equipment is used to extrude the inner semiconductive shielding layer, XLPE insulation layer and outer semiconductive shielding layer in sequence. The extrusion temperature is controlled at 180-200℃, and the traction speed is matched with the extrusion speed to ensure that the eccentricity of the insulation layer is ≤5%. Metal sheath and outer sheath forming: A corrugated aluminum sheath is extruded on the outside of the shielding layer using an aluminum extrusion machine, followed by the extrusion of a PE outer sheath. The extrusion temperature of the outer sheath is 160-180℃. After cooling, online inspection is carried out to ensure that the sheath is free of pinholes and cracks.

[0047] This solution is introduced using a 110kV high-voltage cable with a high drop as an example.

[0048] Steel core preparation: 19 galvanized steel wires with a diameter of 1.5 mm are selected and twisted together in the same direction with a pitch ratio of 10 to form a steel core with a diameter of 12 mm and a tensile strength of 1900 MPa. Conductor layer fabrication: Inner conductor: Oxygen-free copper single wire with a diameter of 0.9mm is tightly compressed into 6 fan-shaped strands (compression coefficient 0.93), which are twisted around the steel core with a pitch ratio of 12. Outer conductor: 0.8mm diameter enameled oxygen-free copper single wire, stranded into 12 corrugated strands, stranded on the outside of the inner conductor with a pitch ratio of 14, and pressed and shaped by a hydraulic device, with a total conductor cross-section of 2000mm². Extrusion of shielding and insulating layers: The inner semiconductive shielding layer (1.2mm thick), the XLPE insulating layer (16mm thick), and the outer semiconductive shielding layer (1.2mm thick) are extruded sequentially using a three-layer co-extrusion equipment. Sheath layer forming: Extruded corrugated aluminum sleeve (2.3mm thick) as metal sheath, then extruded PE outer sheath (4.5mm thick). The outer sheath is added with anti-UV additives, and the weather resistance level reaches UV3. Example 2: This embodiment is explained using a 220kV high-voltage cable with a high drop as an example. Steel core preparation: 19 galvanized steel wires with a diameter of 2.0 mm are selected and twisted in opposite directions with a pitch ratio of 8 to form a steel core with a diameter of 15 mm and a tensile strength of 2000 MPa. Conductor layer fabrication: Inner conductor: Oxygen-free copper single wire with a diameter of 1.0mm is tightly compressed into 6 fan-shaped strands (compression coefficient 0.95), which are twisted around the steel core with a pitch ratio of 10. Outer conductor: Enameled oxygen-free copper single wire with a diameter of 0.9mm is used, which is stranded into 12 corrugated strands, twisted and compacted with a pitch ratio of 12, and the total cross-section of the conductor is 2500mm². Extrusion of shielding and insulating layers: inner semiconductive shielding layer thickness 1.2mm, XLPE insulating layer thickness 24mm, outer semiconductive shielding layer thickness 1.2mm. Sheath layer molding: Corrugated aluminum sleeve thickness 2.8mm, PE outer sheath thickness 5.0mm, with added tear-resistant additives, elongation at break ≥400%. Example 3: The high-strength high-voltage cable proposed in this embodiment has the following cross-sectional structure: Figure 2 As shown, the difference from Embodiment 1 is that the shape of the strands constituting the outer conductor is different. The strands corresponding to both the inner and outer conductors are fan-shaped, and there are six of them in each layer. The strands of the inner conductor are also made of oxygen-free copper, and the strands of the outer conductor are also made of enameled oxygen-free copper.

[0049] Inner conductor: It consists of 6 fan-shaped strands twisted around the steel core layer. The strands are made of oxygen-free copper single wires that are tightly compressed. The single wire diameter is 0.8-1.0mm and the compression coefficient is ≥0.92. Outer conductor: It consists of 6 sector-shaped strands twisted together on the outside of the inner conductor. The strands are made of enameled oxygen-free copper single wires. The insulation properties of the enameled layer are used to weaken the skin effect, thereby reducing the AC resistance by 10%-15%. The combination of "inner sector + outer sector" is a choice made to simplify the process and control costs. It achieves the basic function of segmenting conductors and reduces AC resistance. However, after the sector blocks are twisted together, the contact is mainly line contact between planes or between a plane and an arc surface, which is not as strong as the surface contact of corrugated blocks, and its resistance to loosening is slightly weaker. Furthermore, after multiple sector blocks are twisted together, the outer surface is an approximately circular shape composed of multiple small planar segments, which is not as smooth as corrugated blocks, and the gap with the subsequent shielding layer may be slightly larger. It is generally suitable for scenarios where mechanical stability requirements are not extremely stringent and cost control is a significant concern.

[0050] It is understood that, in addition to the strand shapes proposed in Embodiment 1 and Embodiment 3, corrugated strands can also be used in both the inner and outer conductors. For example, the inner conductor is made of 6 corrugated oxygen-free copper strands twisted around the steel core layer, and the outer conductor is made of 6 corrugated enameled oxygen-free copper strands twisted outside the inner conductor.

[0051] When using the above combination of "inner corrugated + outer corrugated", the overall structural stability, roundness, and heat dissipation potential are maximized. The interlocking of inner and outer layers is more ideal. However, the process of pressing the inner corrugated strands and covering the circular steel core is slightly more complex than that of the fan-shaped structure, and it requires higher precision in mold making and stranding. It is theoretically an ideal structure.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-strength high-voltage cable, characterized in that, It includes, from the inside out, a steel core layer, a conductor layer, an inner semiconductive shielding layer, an insulating layer, an outer semiconductive shielding layer, and a sheath layer; The conductor layer is a layered segmented conductor, including an inner conductor and an outer conductor coaxially sleeved on the outside of the inner conductor. The inner conductor comprises multiple first strands twisted together around the steel core layer, the first strands being formed by pressing copper single wires together. The outer conductor includes multiple second strands twisted to the outside of the inner conductor, the second strands being formed by twisting together insulated copper single wires.

2. The high-strength high-voltage cable as described in claim 1, characterized in that, When the outer surface of the steel core layer has an insulating layer, the first strand is formed by pressing together oxygen-free copper single wire; when the outer surface of the steel core layer does not have an insulating layer, the first strand is formed by pressing together insulated copper single wire; the insulated copper single wire includes enameled oxygen-free copper single wire or surface-oxidized oxygen-free copper single wire.

3. A high-strength high-voltage cable as described in claim 1, characterized in that, The first strip is fan-shaped or "SZ" shaped, and the second strip is "SZ" shaped.

4. A high-strength high-voltage cable as described in claim 1, characterized in that, The compaction coefficient of the inner conductor has a set range, and the compacted inner conductor is stranded around the steel core layer with a stranding pitch ratio of a set value.

5. A high-strength high-voltage cable as described in claim 1, characterized in that, The outer conductor is wrapped around the outer side of the inner conductor by an opposite twisting method. After twisting, it is pressed and shaped by a pressing mold to form a second strand.

6. A high-strength high-voltage cable as described in claim 1, characterized in that, The steel core layer is formed by twisting together multiple galvanized steel wires or by using solid steel bars.

7. A high-strength high-voltage cable as described in claim 1, characterized in that, The insulating layer is extruded onto the outside of the inner semiconductive shielding layer.

8. A high-strength high-voltage cable as described in claim 1, characterized in that, The sheath layer includes a metal sheath and an outer sheath. The metal sheath is a corrugated aluminum sheath with a set thickness. The outer sheath is weather-resistant polyethylene. An anti-corrosion layer is provided between the metal sheath and the outer sheath.

9. A high-strength high-voltage cable as described in claim 7, characterized in that, An external electrode is provided on the outer side of the outer sheath.

10. A method for manufacturing the high-strength high-voltage cable according to any one of claims 1-9, characterized in that, Includes the following steps: Multiple galvanized steel wires are twisted together to form a steel core layer; Copper single wires are compacted into multiple first strands and twisted around a steel core layer to form an inner conductor; insulated copper single wires are twisted into multiple second strands and twisted around the outside of the inner conductor to form an outer conductor. Through a three-layer co-extrusion process, an inner semiconductive shielding layer, an insulating layer, and an outer semiconductive shielding layer are co-extruded sequentially on the outside of the conductor layer. A metal sheath and an outer sheath are formed sequentially on the outside of the outer semiconductive shielding layer.

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