Aluminum alloy energy-saving power cable

Abstract

The application belongs to the technical field of cables, and discloses an aluminum alloy energy-saving power cable, which solves the technical problem that the existing aluminum alloy power cable cannot simultaneously consider low line loss, high conductive energy-saving and fire safety performance. The power cable comprises, from inside to outside, a rare earth high-iron aluminum alloy tightly compressed stranded conductor, a nano conductive coating, an inner semiconductive shielding layer, a low dielectric loss crosslinked polyethylene insulating layer, an outer semiconductive shielding layer, a ceramicized silicone rubber fire-resistant layer and a low-smoke halogen-free flame-retardant sheath layer. Therefore, the application realizes full-link energy saving by four loss-reducing designs of the rare earth high-conductive aluminum alloy low-loss conductor, the nano coating for reducing interface resistance, the inner and outer shielding for suppressing discharge loss and the low dielectric loss crosslinked polyethylene for reducing dielectric polarization loss, thereby reducing power consumption of a power distribution system; and the ceramicized silicone rubber fire-resistant layer is provided to form a dense hard ceramic shell by rapid sintering when meeting high-temperature flame, so that the purpose of isolating flame, high temperature and smoke gas is achieved, thereby prolonging the fire-resistant power-on time.

Description

Technical Field

[0001] This invention belongs to the technical field of cables, and specifically relates to an aluminum alloy energy-saving power cable. Background Technology

[0002] Power cables are cables used to transmit and distribute electrical energy. They consist of a conductor, an insulation layer, a shielding layer, and a protective layer, and are widely used in urban underground power grids, power plants, and industrial and civil buildings.

[0003] Currently, the mainstream cables used in China's 0.6 / 1kV low-voltage power distribution systems are divided into two main categories: copper core cables and ordinary aluminum alloy cables, both of which have significant shortcomings. Copper-core power cables offer excellent conductivity and low loss, but their high raw material costs, large overall weight, and high labor and equipment costs for transportation and installation result in high investment costs for large-scale projects. Ordinary aluminum alloy conductors have insufficient conductivity and high DC resistance, leading to significant inherent line losses and serious energy waste. Traditional mica tape fire-resistant layers have poor interface contact and large air gaps, resulting in additional contact losses and further weakening energy-saving effects. Conventional insulation media have high losses, and the non-crosslinked structure has poor heat resistance, resulting in high operating temperature rise, low current carrying capacity, and excessive ineffective dissipation. Stranded aluminum alloy conductors have rough surfaces, concentrated electric fields, and severe partial discharge, generating discharge and heat losses. The lack of internal and external shielding leads to electric field distortion, uneven insulation stress, rapid aging during long-term operation, and increasing losses year by year. Ceramicized fire-resistant layers are mistakenly used as the main insulation, resulting in insufficient insulation performance, high leakage current, and a sharp increase in operating losses, posing safety hazards. The conductor-shield interface is not modified, resulting in high interface contact resistance and the inability to suppress additional interface losses, making it difficult to realize the overall energy-saving advantages. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned shortcomings in the prior art by providing an aluminum alloy energy-saving power cable, thereby solving the technical problem that existing aluminum alloy power cables cannot simultaneously achieve low line loss, high conductivity and energy saving, and fire resistance and safety performance.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: An energy-saving aluminum alloy power cable includes: Rare earth high-speed rail aluminum alloy tightly pressed stranded conductor; A nano-conductive coating is applied to the outer surface of the rare-earth high-speed rail aluminum alloy tightly stranded conductor. An inner semiconductive shielding layer covering the nano-conductive coating; A low-dielectric-loss cross-linked polyethylene insulation layer covering the inner semiconductive shielding layer; An outer semiconductive shielding layer covering the low dielectric loss cross-linked polyethylene insulation layer; A ceramicized silicone rubber fire-resistant layer covering the outer semiconductive shielding layer; A low-smoke, halogen-free flame-retardant sheath layer covering the ceramicized silicone rubber refractory layer.

[0006] Furthermore, the rare earth high-speed rail aluminum alloy compacted stranded conductor uses AA8030 or AA8176 series aluminum alloy matrix and adds 0.10 to 0.30 wt% rare earth elements. The compaction coefficient of the rare earth high-speed rail aluminum alloy compacted stranded conductor is ≥0.92 and the conductivity is ≥61.5% IACS.

[0007] Furthermore, the nano-conductive coating is any one of graphene-based conductive coating, carbon nanotube composite coating, or nano-silver composite conductive coating, and the thickness of the nano-conductive coating ranges from 3 to 5 μm.

[0008] Furthermore, the graphene-based conductive coating comprises, by weight parts: 70-75 parts of Mercury polyurethane matrix, 8-12 parts of single-layer graphene nanoparticles, 2-3 parts of dispersant, 1-2 parts of wetting and leveling agent, and the remainder being deionized water to make up to 100 parts.

[0009] Furthermore, the nano-conductive coating is a continuous, dense coating produced by a roll coating process.

[0010] Furthermore, the inner semiconductor shielding layer is a structural layer made of cross-linkable semiconducting shielding material, which is extruded and cross-linked simultaneously with the low dielectric loss cross-linked polyethylene insulation layer.

[0011] Furthermore, the dielectric loss tangent of the low-dielectric-loss cross-linked polyethylene insulation layer is tanδ≤0.0015.

[0012] Further, the low dielectric loss cross-linked polyethylene insulation layer comprises, by weight parts: 85-90 parts of low-density polyethylene, 6-10 parts of ethylene-α-olefin copolymer elastomer, 1.8-2.5 parts of organic peroxide cross-linking agent, 0.3-0.6 parts of compound antioxidant, 0.2-0.4 parts of aromatic amide voltage stabilizer, and 1.0-2.0 parts of nano-calcined kaolin.

[0013] Furthermore, the outer semiconductive shielding layer is a structural layer made of a cross-linkable semiconductive shielding material based on polyethylene and / or ethylene propylene rubber, and the volume resistivity of the outer semiconductive shielding layer is ≤100Ω·cm. The inner semiconductive shielding layer, the low dielectric loss cross-linked polyethylene insulation layer, and the outer semiconductive shielding layer are a three-layer co-extruded synchronous cross-linked structure.

[0014] The energy-saving aluminum alloy power cable provided by this invention has the following beneficial effects: 1. This invention achieves end-to-end energy saving through a quadruple loss reduction design: rare earth high-conductivity aluminum alloy low-loss conductor, nano-coating to reduce interface resistance, internal and external shielding to suppress discharge loss, and low dielectric loss cross-linked polyethylene to reduce dielectric polarization loss, thereby significantly saving the power consumption of the power distribution system. 2. By setting the ceramicized silicone rubber refractory layer, the ceramicized silicone rubber refractory layer can be quickly sintered to form a dense and hard ceramic shell when exposed to high temperature flames, thereby achieving the purpose of isolating flames, high temperature and flue gas, and extending the refractory electrical conduction time; 3. By leveling the interface of the inner and outer double-layer semi-conductive shielding layer and the nano-conductive coating through electric field equalization, low loss and long-term stability, there is no partial discharge and no air gap polarization loss, so that the parameters of the power cable provided by the present invention do not drift during long-term operation, thereby ensuring that the energy-saving effect does not decrease with the service life. 4. By setting a low dielectric loss cross-linked polyethylene insulation layer, the power cable provided by the present invention can increase the current carrying capacity under the same cross-section, and the temperature rise is lower under the same load, thus further reducing heat loss. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the aluminum alloy energy-saving power cable provided in Embodiment 1 of the present invention.

[0016] The attached diagram shows the markings and corresponding component names: 1-Rare earth high-speed rail aluminum alloy tightly stranded conductor, 2-Nano conductive coating, 3-Inner semi-conductive shielding layer, 4-Low dielectric loss cross-linked polyethylene insulation layer, 5-Outer semi-conductive shielding layer, 6-Ceramicized silicone rubber fire-resistant layer, 7-Low smoke halogen-free flame-retardant sheath layer. Detailed Implementation

[0017] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0018] Example 1 This embodiment provides an energy-saving aluminum alloy power cable to solve the technical problem that existing aluminum alloy power cables cannot simultaneously achieve low line loss, high conductivity and energy saving, and fire resistance and safety performance. (Reference) Figure 1 The energy-saving aluminum alloy power cable comprises, from the inside out, a rare-earth high-speed rail aluminum alloy tightly stranded conductor 1, a nano-conductive coating 2, an inner semi-conductive shielding layer 3, a low-dielectric-loss cross-linked polyethylene insulation layer 4, an outer semi-conductive shielding layer 5, a ceramicized silicone rubber fire-resistant layer 6, and a low-smoke halogen-free flame-retardant sheath layer 7, wherein: The rare-earth high-speed rail aluminum alloy compacted stranded conductor 1 serves as the foundation for energy conservation. Optionally, the rare-earth high-speed rail aluminum alloy compacted stranded conductor 1 uses an AA8030 or AA8176 series aluminum alloy matrix, with the addition of 0.10–0.30 wt% rare earth elements to refine the grains, reduce grain boundary resistance, and improve conductivity consistency. The compaction coefficient of the rare-earth high-speed rail aluminum alloy compacted stranded conductor 1 is ≥0.92, resulting in a dense and gapless structure with a conductivity ≥61.5% IACS, significantly reducing the DC resistance at 20℃ and reducing the inherent Joule loss of the conductor from the source, laying the material foundation for energy conservation in the entire system. Optionally, the rare-earth high-speed rail aluminum alloy compacted stranded conductor 1 can be manufactured using a multi-stage mold progressive compaction and gradient low-temperature annealing process.

[0019] The nano-conductive coating 2 applied to the outer surface of the rare earth high-speed rail aluminum alloy tightly stranded conductor 1 is key to interface energy saving. Optionally, the nano-conductive coating 2 is any one of graphene-based conductive coating, carbon nanotube composite coating, or nano-silver composite conductive coating. The thickness of the nano-conductive coating 2 is 3-5 μm. In this way, by setting the nano-conductive coating 2, the stranding micro gaps of the rare earth high-speed rail aluminum alloy tightly stranded conductor 1 are filled, the surface roughness is smoothed, the interlayer interface contact resistance is significantly reduced, and the additional interface loss is suppressed. At the same time, it plays a role in the conductor's anti-oxidation and anti-corrosion, avoiding the increase in resistance and the gradual increase in loss due to long-term oxidation, and maintaining the energy-saving effect for a long time.

[0020] Optionally, the graphene-based conductive coating comprises, by weight parts: 70-75 parts of waterborne polyurethane matrix, 8-12 parts of single-layer graphene nanopowder, 2-3 parts of dispersant, 1-2 parts of wetting and leveling agent, with the balance being deionized water to make up to 100 parts. The graphene-based nano-conductive coating 2 has a dense conductive network, the lowest interfacial contact resistance, strong oxidation resistance, and no drift in long-term operation, thus enabling long-term energy saving.

[0021] Optionally, the carbon nanotube composite coating comprises, by weight, 72-76 parts of acrylic resin matrix, 6-9 parts of multi-walled carbon nanotubes, 3-5 parts of conductive carbon black, 2-3 parts of dispersant, 0.5-1 part of defoamer, with the remainder being deionized water to bring the total to 100 parts. In this way, the carbon nanotube composite coating has good suspension properties, is not prone to sedimentation, has excellent roller coating workability, moderate cost, and is suitable for large-scale mass production.

[0022] Optionally, the nano-silver composite conductive coating comprises, by weight, 68-72 parts of organosilicon modified resin, 5-7 parts of nano-silver powder (20-50nm), 4-6 parts of graphene, 1-1.5 parts of coupling agent, and the remainder is solvent to make up to 100 parts. In this way, the nano-silver composite conductive coating has the highest conductivity, the lowest temperature rise, and the best control of heavy-load long line loss, making it suitable for large cross-section, high-load energy-saving scenarios.

[0023] Optionally, online dip coating, roller coating, or ultrasonic spraying can be used for integrated molding, wherein: Roller coating process: The rare earth high-speed rail aluminum alloy tightly pressed stranded conductor 1 travels at a speed of 15-35 m / min; the upper and lower covering coating rollers carry the material at a uniform speed and evenly attach the rare earth high-speed rail aluminum alloy tightly pressed stranded conductor 1 to the surface; then it is dried by infrared drying at a temperature of 120-150℃ and a drying length of 2.5-4 m, forming a film in one step with a stable thickness of about 4 μm.

[0024] Online dip coating process: Rare earth high-speed rail aluminum alloy tightly stranded conductor 1 is vertically passed through the coating dip tank, and the dip coating dwell time is 0.5 to 1 second; the thickness is controlled by negative pressure uniform film; then it is dried in a gradient, which is suitable for large cross-section conductors.

[0025] Ultrasonic spraying process: ultrasonic atomization spraying, with a droplet size of 50-100nm and a spraying pressure of 0.2-0.3MPa; the film is uniform, ultra-thin and without accumulation, suitable for high-precision small cross-section cables, and has better electric field uniformity.

[0026] Optionally, the nano-conductive coating 2 is a continuous dense coating produced by a roll coating process.

[0027] The inner semiconductive shielding layer 3 is a structural layer made of cross-linkable semiconductive shielding material, which is extruded and cross-linked simultaneously with the low dielectric loss cross-linked polyethylene insulation layer 4. In this way, the inner semiconductive shielding layer 3 can uniformly shape the surface electric field of the rare earth high-iron aluminum alloy tightly compressed stranded conductor 1, fill the uneven interface of the rare earth high-iron aluminum alloy tightly compressed stranded conductor 1, eliminate micro air gaps, further suppress the additional power loss caused by partial discharge, and optimize the interlayer interface bonding state to reduce interface polarization loss.

[0028] The low-dielectric-loss cross-linked polyethylene insulation layer 4 is the core energy-saving layer, with a dielectric loss tangent of tanδ≤0.0015, which greatly reduces dielectric polarization loss under alternating electric fields, reduces the ineffective dissipation of electrical energy as heat, and achieves continuous energy saving during cable operation.

[0029] Optionally, the low-dielectric-loss cross-linked polyethylene insulation layer 4 comprises, by weight parts: matrix resin: 85-90 parts of low-density polyethylene, 6-10 parts of ethylene-α-olefin copolymer elastomer, 1.8-2.5 parts of organic peroxide cross-linking agent, low-dielectric-loss antioxidant: 0.3-0.6 parts of compounded antioxidant (optionally hindered phenol plus phosphite compound), 0.2-0.4 parts of aromatic amide voltage stabilizer, and inorganic low-dielectric-loss modified filler: 1.0-2.0 parts of nano-calcined kaolin.

[0030] The preferred method is a catenary continuous crosslinking production line or a vertical continuous crosslinking production line, with a crosslinking temperature of 250-350℃ and a crosslinking pressure of 1.0-3.0MPa to ensure uniform and stable crosslinking degree. The long-term allowable operating temperature of the crosslinked insulation layer can reach 90℃, and the current carrying capacity is significantly improved.

[0031] The outer semiconductive shielding layer 5 is a structural layer made of cross-linkable semiconductive shielding material based on polyethylene or ethylene propylene rubber, modified with superconducting carbon black, and the volume resistivity of the outer semiconductive shielding layer 5 is ≤100Ω·cm; the inner semiconductive shielding layer 3, the low dielectric loss cross-linked polyethylene insulation layer 4 and the outer semiconductive shielding layer 5 are three-layer co-extruded and synchronously cross-linked structures, which makes the interface tightly bonded without gaps. In this way, the electric field of the outer surface is uniformly insulated, the equipotential of the outer insulating layer is maintained, and surface discharge and surface leakage loss are suppressed; the structural integrity is stabilized under fire-resistant conditions, and additional losses caused by interface peeling at high temperatures are avoided.

[0032] The inner semiconductive shielding layer 3 and the outer semiconductive shielding layer 5 work together to form a complete semiconductive shielding structure. The inner semiconductive shielding layer 3 eliminates electric field spikes and microscopic air gaps on the conductor surface, while the outer semiconductive shielding layer 5 uniformly distributes the electric field on the outer surface of the insulating layer. The two semiconductive shielding layers are synchronously cross-linked and chemically bonded at the interface with the insulating layer, completely eliminating interlayer air gaps and controlling the partial discharge to within 5 pC. Partial discharge generates high-frequency pulse currents, consuming electrical energy and accelerating insulation aging; suppressing discharge directly reduces discharge loss.

[0033] The ceramicized silicone rubber fire-resistant layer 6 is specifically designed for fire resistance and does not affect energy-saving insulation. The thickness of the fire-resistant layer is controlled between 0.3 and 0.8 mm. When exposed to flames at temperatures of 750–950°C, the ceramicized silicone rubber fire-resistant layer 6 can rapidly sinter to form a dense, hard ceramic shell, isolating it from flames, high temperatures, and smoke, thus extending the fire-resistant electrical conduction time to at least 90 minutes. It should be noted that this fire-resistant layer is only for fire protection and cannot replace the low-dissipation cross-linked polyethylene insulation layer 4 as the main insulation. The ceramicized silicone rubber has a relatively high dielectric loss and low volume resistivity; replacing the low-dissipation cross-linked polyethylene insulation layer 4 would result in significant leakage current and polarization loss, increased temperature rise, complete loss of energy-saving effect, and inability to withstand a long-term operating voltage of 0.6 / 1kV, posing a safety hazard of insulation breakdown.

[0034] The low-smoke halogen-free flame-retardant sheath layer 7 is made of environmentally friendly low-smoke halogen-free flame-retardant polyolefin material, which has the functions of aging resistance, weather resistance, flame retardancy, corrosion resistance and mechanical protection. It protects the internal energy-saving and fire-resistant structure to ensure long-term stable operation and avoids performance degradation and increased loss caused by external environmental damage.

[0035] Example 2 This embodiment provides a 0.6 / 1kV fire-resistant aluminum alloy energy-saving power cable, the structure of which, from the inside out, consists of: rare earth high-speed iron aluminum alloy tightly stranded conductor 1, nano conductive coating 2, inner shielding layer, low dielectric loss cross-linked polyethylene energy-saving insulation layer, outer shielding layer, ceramicized silicone rubber fire-resistant layer 6, and low smoke halogen-free flame-retardant sheath layer 7.

[0036] The conductor uses an AA8030 series aluminum alloy substrate with 0.15wt% rare earth elements, and is treated with multi-stage mold progressive compaction and gradient low-temperature annealing processes, achieving a compaction coefficient of 0.93. The nano-conductive coating 2 is a graphene-based conductive coating, formed using a roll coating process, with a coating thickness of 4μm. The inner shielding layer is a cross-linkable semi-conductive shielding material. The insulation layer uses the low-dissipation cross-linked polyethylene formulation provided in Example 1, formed using a CCV catenary continuous cross-linking process, with a measured dielectric loss tangent tanδ of 0.0012. The outer shielding layer is a synchronously cross-linked semi-conductive shielding material. The ceramicized silicone rubber refractory layer 6 has a thickness of 0.5mm. The sheath layer is a low-smoke, halogen-free, flame-retardant polyolefin material.

[0037] The performance parameters of the cable provided in this embodiment, as tested, are as follows: DC resistance at 20℃ is 0.815 Ω·km, conductivity is 62.0% IACS, partial discharge is ≤5pC, fire resistance time is ≥90min, and line loss is 1.21%. Compared with ordinary aluminum alloy cables, the line loss is reduced by 3.64 percentage points, resulting in significant energy savings.

[0038] Example 3 This embodiment is basically the same as Embodiment 2, except that: the conductor compaction coefficient is increased to 0.94; the thickness of the ceramicized silicone rubber refractory layer 6 is reduced to 0.3mm; and the insulation layer is changed to VCV vertical continuous crosslinking process.

[0039] Testing showed that the cable in this embodiment still meets the 90-minute fire resistance requirement, and the dielectric loss tangent tanδ conforms to the design specifications, demonstrating stable energy-saving performance. This embodiment shows that even when the fire-resistant layer thickness is reduced to the lower limit and the cross-linking process is changed to VCV vertical production, the technical solution of this invention can still stably achieve its objectives. Furthermore, due to the thinner fire-resistant layer, the cable has a smaller outer diameter and lighter weight per unit length, making it suitable for compact installation scenarios and projects requiring lightweight construction.

[0040] Example 4 This embodiment is basically the same as Embodiment 2, except that: the conductor compression coefficient is increased to 0.96; and the thickness of the ceramicized silicone rubber refractory layer 6 is increased to 0.8 mm.

[0041] Testing showed that the cable of this embodiment has a fire resistance time of up to 95 minutes, exceeding the national standard requirement of 90 minutes, and possesses fire safety redundancy. Compared with ordinary aluminum alloy cables, the line loss of this embodiment is reduced by about 8%, and the current carrying capacity is increased by about 10%, achieving optimal energy-saving effect. This embodiment is particularly suitable for harsh operating conditions such as large cross-section, heavy load, long-distance power distribution, and uninterrupted power supply, demonstrating the technical advantages of this invention in high current carrying capacity, low loss, and long life.

[0042] Although specific embodiments of the invention have been described in detail with reference to the accompanying drawings, this should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by a person skilled in the art without inventive effort within the scope described in the claims still fall within the scope of protection of this patent.

Claims

1. An energy-saving aluminum alloy power cable, characterized in that, include: Rare earth high-speed rail aluminum alloy compacted stranded conductor (1); Nano-conductive coating (2) is applied to the outer surface of the rare earth high-speed rail aluminum alloy tightly stranded conductor (1); An inner semiconductive shielding layer (3) covering the nano-conductive coating (2); Low dielectric loss cross-linked polyethylene insulation layer (4) covering the inner semiconductive shielding layer (3); An outer semiconductive shielding layer (5) covering the low dielectric loss cross-linked polyethylene insulation layer (4); A ceramicized silicone rubber fire-resistant layer (6) covering the outer semiconductive shielding layer (5); The low-smoke halogen-free flame-retardant sheath layer (7) covering the ceramicized silicone rubber refractory layer (6).

2. The aluminum alloy energy-saving power cable according to claim 1, characterized in that, The rare earth high-speed rail aluminum alloy compacted stranded conductor (1) uses AA8030 or AA8176 series aluminum alloy matrix and adds 0.10 to 0.30 wt% rare earth elements; the compaction coefficient of the rare earth high-speed rail aluminum alloy compacted stranded conductor (1) is ≥0.92 and the conductivity is ≥61.5% IACS.

3. The aluminum alloy energy-saving power cable according to claim 1, characterized in that, The nano-conductive coating (2) is any one of graphene-based conductive coating, carbon nanotube composite coating or nano-silver composite conductive coating, and the thickness of the nano-conductive coating (2) is 3 to 5 μm.

4. The aluminum alloy energy-saving power cable according to claim 3, characterized in that, The graphene-based conductive coating comprises, by weight, 70-75 parts of waterborne polyurethane matrix, 8-12 parts of single-layer graphene nanoparticles, 2-3 parts of dispersant, 1-2 parts of wetting and leveling agent, with the remainder being deionized water to bring the total to 100 parts.

5. The aluminum alloy energy-saving power cable according to claim 4, characterized in that, The nano-conductive coating (2) is a continuous dense coating produced by a roll coating process.

6. The aluminum alloy energy-saving power cable according to claim 1, characterized in that, The inner semiconductive shielding layer (3) is a structural layer made of cross-linkable semiconductive shielding material, which is extruded and cross-linked synchronously with the low dielectric loss cross-linked polyethylene insulation layer (4).

7. The aluminum alloy energy-saving power cable according to claim 1, characterized in that, The dielectric loss tangent of the low dielectric loss cross-linked polyethylene insulation layer (4) is tanδ≤0.0015.

8. The aluminum alloy energy-saving power cable according to claim 7, characterized in that, The low dielectric loss cross-linked polyethylene insulation layer (4) comprises, by weight parts: 85-90 parts of low-density polyethylene, 6-10 parts of ethylene-α-olefin copolymer elastomer, 1.8-2.5 parts of organic peroxide cross-linking agent, 0.3-0.6 parts of compound antioxidant, 0.2-0.4 parts of aromatic amide voltage stabilizer, and 1.0-2.0 parts of nano-calcined kaolin.

9. The aluminum alloy energy-saving power cable according to claim 1, characterized in that, The outer semiconductive shielding layer (5) is a structural layer made of a cross-linkable semiconductive shielding material based on polyethylene or ethylene propylene rubber, and the volume resistivity of the outer semiconductive shielding layer (5) is ≤100Ω·cm. The inner semiconductive shielding layer (3), the low dielectric loss cross-linked polyethylene insulation layer (4), and the outer semiconductive shielding layer (5) are three-layer co-extruded and synchronously cross-linked structures.

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