Insulated three-core aluminum plastic composite tape high-voltage land cable and manufacturing method thereof

Abstract

The application relates to the technical field of high-voltage cables, in particular to an insulated three-core aluminum-plastic composite tape high-voltage land cable and a manufacturing method thereof. The high-voltage land cable comprises three single-core cables and an armor layer; each single-core cable comprises an aluminum conductor, a three-layer co-extrusion insulation layer, a second semi-conductive water-blocking tape, a phase-dividing aluminum wire shielding layer, a second semi-conductive water-blocking tape, an aluminum-plastic composite tape longitudinal wrapping layer and a single-core semi-conductive outer sheath, the three-layer co-extrusion insulation layer comprises a conductor shielding layer, an XLPE insulation layer and an insulation shielding layer, the single-core semi-conductive outer sheath is wrapped outside the aluminum-plastic composite tape longitudinal wrapping layer and is in electrical communication with the aluminum-plastic composite tape longitudinal wrapping layer, the outer wall of the single-core semi-conductive outer sheath is in electrical communication with the armor layer after the three single-core cables are cabled, and the aluminum-plastic composite tape longitudinal wrapping layer, the single-core semi-conductive outer sheath and the armor layer constitute an equipotential grounding system. The application realizes the domestic application of the high-voltage cable, reduces power transmission loss and engineering cost, and meets the long-distance power transmission demand from a new energy power generation side to a booster station.

Description

Technical Field

[0001] This invention relates to the field of high-voltage cable technology, and particularly to an insulated three-core aluminum-plastic composite high-voltage land cable and its manufacturing method. Background Technology

[0002] With the expansion of new energy power plants such as wind power and photovoltaic power, traditional 35kV transmission lines, due to their high losses and insufficient capacity, are no longer suitable for the demand for long-distance, high-capacity power transmission. The industry is shifting towards 66kV voltage level solutions. Currently, 66kV and above high-voltage land cables generally adopt a single-core structure, meaning each phase is cabled separately, with three cores laid in parallel. While this solution meets basic insulation and mechanical protection requirements, it significantly increases material usage and the workload of installation. Furthermore, the metal shielding and armor layers generate sheath circulating currents, leading to additional energy losses and operating temperature rise, affecting current-carrying capacity and lifespan.

[0003] In existing technologies, the medium-voltage three-core structure is directly upgraded to 66kV. However, the aluminum-plastic composite strip of the medium-voltage structure only serves the function of water blocking and is not designed for the three-phase shielding layer potential balance under high-voltage conditions. When applied to 66kV, the potential imbalance between the shielding layers is aggravated, the circulating current loss is concentrated and the temperature rise exceeds the standard, which cannot meet the reliability requirements of long-distance power transmission over land.

[0004] While 66kV three-core submarine cables exist, employing corrugated aluminum sheaths and steel wire armor to achieve potential equalization and waterproofing, their transfer to land faces numerous challenges: Structural redundancy results in extreme weight, insufficient traction for conventional land-based laying equipment, and the cost of specialized machinery doubles; the corrugated aluminum sheath manufacturing process is complex and requires large quantities of materials, exceeding the affordability of new energy projects; submarine cables are designed for the high heat dissipation environment of seawater, while land soil resistivity varies and heat dissipation is poor, making it impossible to meet standards for sheath circulating temperature rise and grounding reliability. Furthermore, the conventional three-core corrugated aluminum-plastic composite tape structure has stringent requirements for cable roundness; failure to meet these standards can lead to defects such as wrinkles and missed adhesions in the longitudinal wrapping, resulting in waterproofing failure, reduced shielding reliability, and a low cable qualification rate. Summary of the Invention

[0005] To address the shortcomings and contradictions of existing technologies, the purpose of this invention is to provide a 66kV insulated three-core aluminum-plastic composite high-voltage land cable and its manufacturing method, solving the problems of grounding stability, molding reliability, and engineering economy of high-voltage three-core structures in long-distance land power transmission, realizing the domestic application of high-voltage cables, reducing transmission losses and engineering costs, and meeting the long-distance power transmission needs from the new energy power generation side to the booster station.

[0006] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions: In a first aspect, embodiments of the present invention disclose an insulated three-core aluminum-plastic composite tape high-voltage land cable, comprising three single-core cables and an armor layer; each single-core cable, from the inside out, comprises an aluminum conductor, a three-layer co-extruded insulation layer, a phase-separated aluminum wire shielding layer, a semi-conductive resistive water tape, an aluminum-plastic composite tape longitudinal sheath, and a single-core semi-conductive outer sheath; the three-layer co-extruded insulation layer, from the inside out, comprises a conductor shielding layer, an XLPE insulation layer, and an insulating shielding layer; the single-core semi-conductive outer sheath wraps around the outside of the aluminum-plastic composite tape longitudinal sheath and is electrically connected to the aluminum-plastic composite tape longitudinal sheath; after the three single-core cables are cabled, the outer wall of the single-core semi-conductive outer sheath is electrically connected to the armor layer; the aluminum-plastic composite tape longitudinal sheath, the single-core semi-conductive outer sheath, and the armor layer constitute a global equipotential grounding system, forcibly balancing the potential of the three-phase phase-separated shielding layer, and suppressing sheath circulation and temperature rise during long-distance laying on land.

[0007] Secondly, embodiments of the present invention also disclose a method for manufacturing an insulated three-core aluminum-plastic composite high-voltage land cable, comprising the following steps: Preparation of profiled compacted aluminum conductors; A conductor shielding layer, an XLPE insulation layer, and an insulation shielding layer are sequentially formed on the outside of the aluminum conductor using a three-layer co-extrusion process. After extrusion, the material is degassed. A first semiconducting resistive water strip is wrapped around the outside of the insulating shielding layer, a phase-separated aluminum wire shielding layer is prepared on the outside of the first semiconducting resistive water strip, and a second semiconducting resistive water strip is wrapped around the outside of the phase-separated aluminum wire shielding layer. Aluminum-plastic composite tape is independently wrapped longitudinally on a single wire core, and a single-core semi-conductive outer sheath is extruded simultaneously. Vacuum-assisted segmented cooling is used to bond the aluminum-plastic composite tape and the sheath together. Three single-core wires with single-core semi-conductive outer sheaths are bundled into a cable, and a cable wrapping tape is wrapped around the outside of the bundled cable cores. Armoring is applied to the outside of the cable wrapping tape, and an outer sheath is extruded on the outside of the armor layer.

[0008] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages: 1. In this invention, three single-core cables are integrated into a single cable, sharing the cabling wrapping tape, armor layer, and outer sheath. This avoids the material duplication caused by the separate outer sheaths and armor layers of the three independent cables in the single-core scheme, reducing material costs and laying workload. Secondly, by forming an equipotential grounding system through the longitudinal wrapping layer of aluminum-plastic composite tape, the single-core semi-conductive outer sheath, and the armor layer, potential balance is forcibly achieved between the three-phase shielding layers, eliminating potential differences and suppressing the generation of induced circulating current in the sheath. This solves the problems of circulating current loss and excessive temperature rise in long-distance laying of high-voltage three-core structures on land. Thirdly, by adopting a single-core independent longitudinal wrapping aluminum-plastic composite tape scheme, the forming precision of shielding and water-blocking functions is shifted from the cabling level to the single-core level. This avoids the problem of difficult roundness control in large-diameter cabling with a bundled structure, improving the cabling qualification rate and waterproof reliability. By employing an all-aluminum system consisting of aluminum conductors, aluminum wire shielding, and aluminum-plastic composite tape, the cable's weight is significantly reduced, making it compatible with conventional terrestrial laying equipment and eliminating the need for specialized submarine cable construction machinery. This solves the problems of excessive weight and cost associated with submarine cable structures. Therefore, this invention provides a three-core structure solution for 66kV high-voltage terrestrial cables that balances grounding stability, forming reliability, and engineering economy, effectively filling the technological gap in 66kV three-core high-voltage terrestrial cables.

[0009] 2. Discarding the prevailing notion in the field that high voltage requires metal sheathing for voltage equalization, this innovative semi-conductive sheath-steel tape armored full-area equipotential grounding system eliminates the need for a thick-walled, all-encompassing metal sheath. It achieves forced voltage equalization of the three-phase shielding layer solely through coupling between the low-cost semi-conductive sheath and the armor layer. Experimental results demonstrate that the sheath circulating current is reduced by 71.4% compared to medium-voltage structural upgrades, and the steady-state temperature rise is reduced by 50.5%. The voltage equalization effect is even superior to the three-core submarine cable solution. Furthermore, the material cost of the shielded voltage equalization system is more than 60% lower than that of the metal sheath solution, achieving high-performance voltage equalization at a low cost, exceeding conventional expectations in the field.

[0010] 3. By adopting a single-core independent longitudinally wrapped aluminum-plastic composite tape + synchronously extruded semi-conductive sheath, the forming precision of shielding and water-blocking functions is reduced from the "cable-forming level" to the "single-core level," fundamentally avoiding the problem of difficult roundness control in large-diameter cabling with a bundled structure. Trial production results show that the first-pass yield of cabling has increased from 72% in the industry bundled process to 97%, while eliminating the need for expensive bundled metal sheath production equipment. This achieves a balance between high reliability and low cost, a technical effect that cannot be obtained by those skilled in the art through conventional process adjustments.

[0011] 4. Lightweight all-aluminum system, suitable for large-scale onshore engineering applications: Utilizing an all-aluminum metal functional system with aluminum conductors, aluminum wire shielding, and aluminum-plastic composite tape, combined with steel tape armor replacing the steel wire armor of submarine cables, the weight per unit kilometer is reduced by 40.2% compared to a three-core submarine cable of the same voltage. It can be directly adapted to conventional onshore laying equipment, eliminating the need for specialized submarine cable construction machinery. Trial production cost verification shows that the manufacturing cost per unit kilometer is only 57.3% of that of a three-core submarine cable of the same voltage, and the overall engineering investment is reduced by more than 22% compared to a three-core parallel connection scheme. This makes the 66kV three-core high-voltage cable economically feasible for large-scale onshore renewable energy deployment for the first time.

[0012] Advantages of additional aspects of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In addition, the dimensions or spacing between the components are exaggerated to show the position of each component, and the schematic diagrams are for illustrative purposes only.

[0014] Figure 1 This is a schematic diagram of the overall layered structure of the 66kV three-core high-voltage land cable provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the single-core layered structure of a 66kV three-core high-voltage land cable provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the production process route provided in an embodiment of the present invention; In the diagram: 1. Aluminum conductor; 2. Conductor shielding layer; 3. XLPE insulation layer; 4. Insulation shielding layer; 5. First semiconducting resistive water tape; 6. Phase-separated aluminum wire shielding layer; 7. Second semiconducting resistive water tape; 8. Aluminum-plastic composite tape longitudinal wrapping layer; 9. Single-core semiconducting outer sheath; 10. Cable wrapping tape; 11. Steel tape armor layer; 12. Outer sheath. Detailed Implementation

[0015] To more clearly illustrate the technical solutions of the embodiments in this specification, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this specification. For those skilled in the art, these drawings can be applied to other similar scenarios without creative effort. Unless obvious from the linguistic context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0016] Generally speaking, the terms "comprising" and "including" only indicate that the steps and elements are explicitly identified, and these steps and elements do not constitute an exclusive list. The method or apparatus may also include other steps or elements.

[0017] In long-distance power transmission scenarios from the renewable energy generation side to the substation, three-phase AC power needs to be transmitted by three conductors carrying the current of each phase. Existing single-core solutions cable each of the three conductors independently, increasing the amount of redundant materials used for the outer sheath and armor layers, and causing sheath circulating current losses due to potential differences between the three phase shielding layers. For medium-voltage three-core structure upgrades, the lack of a dedicated potential balancing design means that directly upgrading to the 66kV high-voltage level will further amplify the potential imbalance problem in the three-phase shielding layers. For submarine cable three-core high-voltage structures, although potential balancing and waterproofing are achieved through a thick-walled, all-metal sheath, their structural redundancy and weight make them unsuitable for onshore engineering.

[0018] Therefore, there are two sets of irreconcilable core technological contradictions in the existing technology: First, the contradiction between performance and cost: If the medium-voltage phase-separated aluminum-plastic structure is directly upgraded to 66kV, the sheath circulating current will surge and the temperature rise will exceed the standard due to the imbalance of the three-phase shielding potential, which cannot meet the reliability of long-distance operation; if the corrugated aluminum sheath solution of submarine cable is adopted, although it can achieve voltage equalization, the structure is redundant, the weight is too large, and the cost is too high, which is completely beyond the economic affordability of land-based new energy projects.

[0019] Second, the contradiction between reliability and yield: the total outer diameter of the 66kV large cross-section insulated wire core after cabling exceeds 130mm and has extremely high rigidity. If the traditional all-inclusive aluminum-plastic process is used, it is difficult to control the roundness of the cabling. The aluminum-plastic wrinkles, missing adhesive, and waterproof failure occur frequently, and the industry's first-pass yield is only 72%. If the cabling processing precision is greatly improved, the tooling and process costs will increase exponentially, losing the value of engineering application.

[0020] Furthermore, a long-standing technical bias exists in this field: it is generally believed that 66kV and above high-voltage cables must use continuous metal sheaths (corrugated aluminum / lead sheaths) to achieve reliable shielding, voltage equalization, and radial waterproofing; the semi-conductive layer can only assist in equalizing the electric field and cannot be used as the main voltage equalization path. These contradictions and technical biases have collectively prevented the long-term implementation of low-cost, high-reliability 66kV three-core high-voltage terrestrial cables.

[0021] Based on this, this embodiment provides an insulated three-core aluminum-plastic composite high-voltage land cable, such as... Figure 1 , Figure 2As shown, the cable includes three single-core cables and an armor layer. Each single-core cable, from the inside out, includes an aluminum conductor 1, a three-layer co-extruded insulation layer, a phase-separated aluminum wire shielding layer 6, a second semi-conductive resistive water tape 7, an aluminum-plastic composite tape longitudinal wrapping layer 8, and a single-core semi-conductive outer sheath 9. The three-layer co-extruded insulation layer, from the inside out, includes a conductor shielding layer 2, an XLPE insulation layer 3, and an insulation shielding layer 4. The single-core semi-conductive outer sheath 9 is wrapped around the outside of the aluminum-plastic composite tape longitudinal wrapping layer 8 and is electrically connected to the aluminum-plastic composite tape longitudinal wrapping layer 8. After the three single-core cables are bundled together, the outer wall of the single-core semi-conductive outer sheath 9 is electrically connected to the armor layer. The aluminum-plastic composite tape longitudinal wrapping layer 8, the single-core semi-conductive outer sheath 9, and the armor layer together constitute an equipotential grounding system.

[0022] For the aluminum conductor 1, it serves as the conductive core of the cable, responsible for transmitting electrical energy. In this embodiment, the aluminum conductor 1 is made of high-purity aluminum rods through drawing and stranding. The conductor's center line is a circular single wire, and the outer layer is a trapezoidal single wire stranded structure. The conductor's outer diameter is controlled at 22.2±0.2mm, and its DC resistance at 20℃ is less than or equal to 0.0778Ω / km. The conductor structure is dense, without broken strands, loose strands, or burr defects. Using aluminum conductor 1 instead of copper conductor reduces raw material costs and lightens the cable's weight, facilitating transportation and laying in land-based engineering projects.

[0023] The three-layer co-extruded insulation layer comprises, from the inside out, a conductor shielding layer 2, an XLPE insulation layer 3, and an insulation shielding layer 4. The conductor shielding layer 2 is used to equalize the electric field distribution on the conductor surface, preventing localized electric field concentration caused by burrs or protrusions on the conductor surface and thus preventing partial discharge. The XLPE insulation layer 3, or cross-linked polyethylene insulation layer, is the main insulation layer of the high-voltage cable, bearing the core functions of withstanding system voltage and preventing breakdown. The insulation shielding layer 4 is used to equalize the electric field distribution on the outer surface of the insulation layer, making the electric field distribution within the insulation layer more uniform. In this embodiment, the nominal thickness of the conductor shielding layer 2 is 0.6 mm, the nominal thickness of the XLPE insulation layer 3 is 11.0 mm with a minimum thickness greater than or equal to 10.45 mm, the nominal thickness of the insulation shielding layer 4 is 1.0 mm with a minimum thickness greater than or equal to 0.8 mm, and the insulation eccentricity is less than or equal to 5%. The above parameters ensure insulation reliability at a voltage level of 66kV. The 11.0mm insulation layer thickness, combined with a field strength of 4.84kV / mm at the conductor shield and 2.55kV / mm at the insulation shield layer 4, effectively prevents insulation breakdown and aging. Both conductor shield layer 2 and insulation shield layer 4 are made of domestically produced 110kV-grade semi-conductive shielding material, and XLPE insulation layer 3 is made of domestically produced 110kV-grade ultra-clean XLPE insulation material. This achieves domestic substitution of core materials for high-voltage cables, eliminating dependence on imported insulation materials.

[0024] The phase-separated aluminum wire shielding layer 6 is disposed on the outside of the three-layer co-extruded insulation layer and is used to transmit short-circuit current and provide electromagnetic shielding. In this embodiment, the phase-separated aluminum wire shielding layer 6 is made of 42 aluminum wires with a single diameter of 1.35mm twisted together, with an average spacing of less than or equal to 3mm, and is intermittently wrapped with 1×15mm×0.3mm aluminum strip, with a gap width of 40-60mm. The aluminum wire twisting and the aluminum strip intermittent wrapping together constitute the metal shielding layer, wherein the aluminum wires are loosely wrapped on the outside of the first semiconducting resistive water strip 5, and the aluminum strip is tightly wrapped with the aluminum wires in a reverse intermittent wrapping manner. This structure can not only ensure the electrical continuity of the shielding, but also help to fix the wrapped first semiconducting resistive water strip 5 and prevent it from loosening and falling off.

[0025] The second semiconducting resistive water tape 7 is wrapped around the outside of the phase-separated aluminum wire shielding layer 6. The second semiconducting resistive water tape 7 is made of double-sided semiconducting resistive water tape with a thickness of 0.60 mm, wrapped in one layer with an overlap rate of 45%-50%. This second semiconducting resistive water tape 7 provides a flat load-bearing surface for the subsequent longitudinal wrapping of the aluminum-plastic composite tape.

[0026] The aluminum-plastic composite tape longitudinal wrapping layer 8 is located outside the second semi-conductive water-blocking tape 7. The aluminum-plastic composite tape longitudinal wrapping layer 8 uses a 190mm × 0.25mm double-sided aluminum-plastic composite tape for single-strand independent longitudinal wrapping, with an overlap width of 15-17mm. This longitudinal wrapping layer forms an independent metal shield and radial water-blocking channel. Because the aluminum-plastic composite tape longitudinal wrapping layer is independently completed on a single-core wire, its shielding continuity and radial water-blocking performance are determined only by the outer diameter of the single core and are not affected by the roundness during subsequent three-core cabling.

[0027] The single-core semi-conductive outer sheath 9 is made of semi-conductive polyethylene, with a thickness of 3.0 mm, an outer diameter of 61.5 mm, and a volume resistivity less than or equal to 100 Ω·m. This single-core semi-conductive outer sheath 9 tightly wraps around the outer side of the aluminum-plastic composite tape longitudinal sheath 8, achieving electrical connection with it. After the three single-core cables are cabled, the outer wall of the single-core semi-conductive outer sheath 9 is tightly bonded to the armor layer, achieving full electrical conduction. This allows the aluminum-plastic composite tape longitudinal sheath 8, the single-core semi-conductive outer sheath 9, and the armor layer to collectively form a global equipotential grounding system. This equipotential grounding system can forcibly equalize the potential of the three-phase shielding layer, eliminating potential differences between the three phases and thus suppressing the generation of induced circulating currents in the sheath. Compared to the thick-walled, all-encompassing metal sheath in submarine cable structures, the equipotential grounding system in this embodiment can be achieved solely through the coupling of the low-cost semi-conductive sheath and the armor layer, eliminating the need for a bulky and expensive all-encompassing metal sheath. Meanwhile, because each single-core cable uses an independent aluminum-plastic composite longitudinal sheath 8 and a single-core semi-conductive outer sheath 9, the forming accuracy of the single-core shielding layer and water-blocking layer depends only on the outer diameter of the single core and is not constrained by the roundness of the three-core cable. This avoids the problems of wrinkles, incomplete bonding, and waterproof failure that easily occur when the overall sheath structure is used for large-diameter cable. The first-pass yield of cable can be effectively improved, and there is no need to configure expensive overall sheathing equipment and materials, achieving a technical effect that balances high reliability and low cost.

[0028] Aluminum conductor 1 is a stranded aluminum conductor 1, with a circular single wire as its center line and trapezoidal single wires as its outer layer. Stranded aluminum conductor 1 refers to an aluminum conductor 1 manufactured through wire drawing and stranding processes. Specifically, the center line of the conductor is a circular single wire, and the outer layer is made of trapezoidal single wires stranded together. The trapezoidal single wires can fit tightly together after stranding, resulting in small conductor gaps and a high compression coefficient. This higher compression coefficient allows for a smaller conductor outer diameter and a denser structure, thereby reducing the conductor's DC resistance and improving its conductivity. Simultaneously, the denser conductor surface is smoother, which facilitates the uniform coverage of the subsequent conductor shielding layer 2 and avoids electric field concentration caused by uneven conductor surfaces.

[0029] Both the conductor shielding layer 2 and the insulating shielding layer 4 are made of semi-conductive shielding material, and the XLPE insulating layer 3 is made of cross-linked polyethylene insulating material.

[0030] In high-voltage cables, the performance of the insulation material directly determines the cable's voltage rating and service life. In this embodiment, both the conductor shielding layer 2 and the insulation shielding layer 4 are made of semi-conductive shielding material, specifically domestically produced 110kV-grade semi-conductive shielding material. The XLPE insulation layer 3 is made of cross-linked polyethylene insulation material, specifically domestically produced 110kV-grade ultra-clean XLPE insulation material. All of the above materials are domestically produced high-voltage cable-specific materials, capable of meeting the insulation requirements of 66kV high-voltage transmission. Using domestic materials to replace imported materials reduces raw material costs and delivery time, achieving independent control over the core materials of high-voltage cables. The insulation layer thickness is 11.0mm, ensuring sufficient insulation margin at the 66kV voltage level, while also possessing good aging resistance and breakdown resistance.

[0031] Each single-core cable also includes a semi-conductive wrapping tape, a first semi-conductive resistive water tape 5, and a second semi-conductive resistive water tape 7. The semi-conductive wrapping tape is wrapped between the aluminum conductor 1 and the three-layer co-extruded insulation layer. The first semi-conductive resistive water tape 5 is wrapped between the three-layer co-extruded insulation layer and the phase-separated aluminum wire shielding layer 6. The second semi-conductive resistive water tape 7 is wrapped between the aluminum wire shielding layer and the aluminum-plastic composite tape longitudinal wrapping layer 8.

[0032] A semi-conductive wrapping tape, made of semi-conductive nylon tape with a thickness of 0.14 mm, is placed between the aluminum conductor 1 and the three-layer co-extruded insulation layer. It is wrapped twice with an overlap of 10%-20%. The function of this semi-conductive wrapping tape is to equalize the potential on the conductor surface, avoid electric field concentration on the conductor surface, and provide a uniform electric field environment for the subsequent three-layer co-extruded insulation layer, thereby improving insulation reliability. A first semi-conductive water-resistant tape 5 is placed between the three-layer co-extruded insulation layer and the phase-separated aluminum wire shielding layer 6, and a second semi-conductive water-resistant tape 7 is placed between the aluminum wire shielding layer and the longitudinal wrapping layer 8 of the aluminum-plastic composite tape. In this embodiment, both the first and second semi-conductive water-resistant tapes 5 and 7 are double-sided semi-conductive water-resistant tapes with a specification of 60 mm × 0.6 mm and a wrapping overlap of 45%-50%. The first semi-conductive water-resistant tape 5 wraps around the outside of the three-layer co-extruded insulation layer, achieving the first radial water blocking and preventing moisture from penetrating the insulation layer from the outside. The second semi-conductive water-resistant tape 7 is wrapped around the outside of the phase-separated aluminum wire shielding layer 6, achieving a second radial water blocking effect and further enhancing the waterproof performance. The double semi-conductive water-resistant tape structure design ensures that even if the outer second semi-conductive water-resistant tape 7 is damaged during cabling or laying, the inner first semi-conductive water-resistant tape 5 can still play a water-blocking role, thereby effectively protecting the insulation layer from moisture intrusion and extending the cable's service life.

[0033] The phase-separated aluminum wire shielding layer 6 includes aluminum wires and aluminum strips. The aluminum wires are twisted together and disposed on the outside of the first semiconducting resistive water strip 5, and the aluminum strips are disposed on the outside of the aluminum wires in a gap-wrapping manner.

[0034] The function of the phase-separated aluminum wire shielding layer 6 is to provide metallic shielding and radial mechanical support. In this embodiment, there are 42 aluminum wires, each with a diameter of 1.35 mm, loosely wound around the outside of the first semiconducting resistive water strip 5, with a twist pitch of 8-10 times the outer diameter and an average spacing of less than or equal to 3 mm. The aluminum strip has a specification of 1×15 mm×0.3 mm and is arranged in a gap-wrapping manner on the outside of the aluminum wires, with a gap width of 40-60 mm, approximately 2-3 times the width of the aluminum strip. The loose winding of the aluminum wires provides the main shielding and current-carrying path, while the reverse gap-wrapping of the aluminum strip serves to tighten the aluminum wires and fix the first semiconducting resistive water strip 5, while also assisting in providing electrical continuity of the shielding. The combined use of aluminum wires and aluminum strips reduces material costs and lightens the cable's weight compared to single copper wire shielding.

[0035] The aluminum-plastic composite strip longitudinal wrapping layer 8 is bonded to the single-core semi-conductive outer sheath 9 as a whole. The single-core semi-conductive outer sheath 9 is made of semi-conductive polyethylene.

[0036] The bonding between the longitudinal wrapping layer 8 of the aluminum-plastic composite tape and the single-core semi-conductive outer sheath 9 is achieved by simultaneously extruding the semi-conductive polyethylene sheath and then vacuum-cooling it in stages after the longitudinal wrapping of the aluminum-plastic composite tape is completed. Specifically, the overlap width of the longitudinal wrapping of the aluminum-plastic composite tape is 15-17mm. Immediately after longitudinal wrapping, the tape enters the extruder head, where the semi-conductive polyethylene sheath is extruded onto the outside of the longitudinal wrapping layer 8 of the aluminum-plastic composite tape. The two are bonded together under the action of heat and pressure. This bonding structure ensures good and lasting electrical continuity between the longitudinal wrapping layer 8 of the aluminum-plastic composite tape and the single-core semi-conductive outer sheath 9, avoiding potential differences caused by poor contact. Simultaneously, the bonding also secures the overlap of the longitudinal wrapping layer 8 with the sheath material, preventing loosening or slippage of the longitudinal wrapping overlap during subsequent cabling and laying processes. The single-core semi-conductive outer sheath 9 is made of semi-conductive polyethylene. This material has both the mechanical protection and environmental resistance of polyethylene and the semi-conductive properties. Its volume resistivity is less than or equal to 100 Ω·m, which can achieve equipotential connection with the longitudinal cladding layer 8 of the aluminum-plastic composite strip.

[0037] The high-voltage land cable also includes a cable wrapping tape 10 and an outer sheath. The cable wrapping tape 10 is wrapped around the outside of three single-core cables. The armor layer is wrapped around the outside of the cable wrapping tape 10. The outer sheath is wrapped around the outside of the armor layer. The armor layer is a double-layer galvanized steel tape armor layer 11, and the outer sheath is 12.

[0038] After the three single-core cables are bundled, a bundling tape 10 is installed on the outside of the cable cores to tighten them and prevent them from loosening and deforming. The bundling tape 10 consists of two layers, each with a specification of 0.2mm × 60mm, and is wrapped in an overlapping left-handed manner. After the bundling tape 10 is wrapped around the outside of the three single-core cables, the armor layer is wrapped around the outside of the bundling tape 10. In this embodiment, the armor layer is a double-layer galvanized steel tape armor layer 11, with a steel tape specification of 60mm × 0.8mm and a minimum thickness greater than or equal to 0.72mm. The steel tape is wrapped in a gap manner with a gap width of 24.0–28.8mm. This double-layer steel tape armor layer 11 can withstand the mechanical pressure, impact, and tensile force during onshore construction and operation, meeting the mechanical protection requirements for onshore laying. At the same time, the steel tape armor layer 11, as part of the equipotential grounding system, is electrically connected to the outer wall of the single-core semi-conductive outer sheath 9 throughout its entire length, participating in the forced equalization of the three-phase shielding potential. The outer sheath wraps around the outer side of the armor layer. Its material can be polyethylene (HDPE), with a nominal thickness of 4.0 mm and a minimum thickness of 3.60 mm or more. The outer sheath 12 is used to isolate external moisture, dust, and acid and alkali corrosion, protecting the cable conductor and internal structural components from the influence of the external environment and extending the overall service life of the cable.

[0039] In this embodiment, the graphite coating layer is formed by applying conductive graphite paint to the surface of the outer sheath 12, with a coating thickness of 0.1-0.15 mm. After coating, the surface resistivity is less than or equal to 100 Ω, and the coating is uniform, without any missed areas or lumps. The function of this graphite coating layer is to reduce the surface resistivity of the cable outer sheath, facilitating grounding continuity during cable laying and subsequent operation and maintenance. During the operation of high-voltage cables, the accumulation of static electricity on the surface of the outer sheath may affect operational safety; the graphite coating layer provides a path for static discharge. Simultaneously, after cable laying is completed, the integrity of the outer sheath can be detected through the graphite coating layer to determine whether the outer sheath was damaged during laying.

[0040] In summary, this embodiment provides a 66kV insulated three-core aluminum-plastic composite tape longitudinally wrapped high-voltage land cable, which consists of, from the inside out, an aluminum conductor, a conductor shield, an XLPE insulation layer, an insulation shield layer, a semi-conductive resistive water tape, a phase-separated aluminum wire shield layer, a semi-conductive resistive water tape, an aluminum-plastic composite tape longitudinally wrapped layer, a semi-conductive PE sheath, cable filling, cable wrapping tape, a steel tape armor layer, a non-woven fabric isolation layer, an outer sheath, and an outer electrode. The cable consists of three single-core cables arranged symmetrically in an equilateral triangle, forming the main body of the cable core. Cable filling ropes fill the gaps between the three single-core cables and between the single-core cables and the cable wrapping tape, ensuring the stability and uniform roundness of the cable core structure. The cable wrapping tape is wrapped around the outside of the cable filling ropes to tighten the cable core and prevent it from loosening and deforming. A steel tape armor layer is wrapped around the outside of the cable wrapping tape, suitable for onshore laying requirements, and is used to withstand mechanical pressure and impact during onshore construction and operation, providing reliable mechanical protection. The outer sheath is wrapped around the outside of the steel tape armor layer to isolate it from external moisture, dust, and acid / alkali corrosion, protecting the cable conductor and internal structural components from external environmental influences and extending the overall service life of the cable. A graphite coating layer is applied to the outside of the outer sheath to reduce the cable surface resistivity, facilitating cable laying, grounding, and subsequent maintenance and inspection.

[0041] Through three core structural innovations—a full-area equipotential grounding system, integrated molding of single-core independent shielding, and a lightweight all-aluminum land-adaptation system—the project has solved three major technical challenges when transplanting three-core high-voltage structures to the land: grounding stability, molding reliability, and engineering economy. This fills the technological gap in 66kV three-core high-voltage land cables, reduces long-distance power transmission losses and engineering costs for new energy sources, and features stable grounding, excellent waterproof performance, and high cost-effectiveness. It is suitable for power transmission scenarios from wind power and photovoltaic new energy power generation to substations, and can help improve industry standards and enhance the level of domestic application of high-voltage cables.

[0042] This structure eliminates the need for a thick-walled, all-encompassing metal sheath. It achieves forced equalization of the three-phase shielding potential solely through coupling between a low-cost semi-conductive sheath and the armor layer, completely eliminating the sheath-induced circulating current caused by the three-phase potential difference. Compared to the medium-voltage three-core structure upgrade solution, it reduces the sheath circulating current and the steady-state temperature rise under rated current, making it perfectly suited for long-distance laying operations on land with poor heat dissipation conditions.

[0043] The aluminum-plastic composite tape longitudinal wrapping layer adopts a single independent longitudinal wrapping method, and is extruded, heated and bonded in an integrated manner with the single-core semi-conductive outer sheath. The forming accuracy of the single-core shielding layer and water-blocking layer is determined only by the outer diameter of the single core, and is completely unaffected by the roundness constraint of the three-core cable.

[0044] Addressing the industry challenge of controlling the roundness of 66kV large-section insulated conductors with an outer diameter exceeding 130mm after cabling, this solution lowers the shielding and waterproofing forming precision requirements from the cabling level to the single-core level, completely avoiding the risks of wrinkles, missed bonding, and waterproofing failure associated with the all-in-one aluminum-plastic sheathing process. The first-pass yield of cabling is significantly improved, and the expensive all-in-one metal sheathing equipment and materials for submarine cables are eliminated, reducing the cost of shielding and waterproofing per kilometer. This achieves a balance between high reliability and low cost, a technical effect that cannot be obtained by those skilled in the art through conventional process adjustments.

[0045] Comparison and verification Three control samples were set up under the same environmental conditions: 25℃, rated current carrying capacity 630A, laying length 10km, and soil thermal resistivity 2.0K. Benchmarking tests were conducted under standard land-based operating conditions at m / W to simulate the real-world environment of land-based installations for new energy power plants. Circulation and temperature rise were calculated according to the GB 50217-2018 standard formula and verified through prototype testing. The pass rate data was derived from industry production statistics and actual measurements from a 1200m trial production run in this project. Cost data was obtained from the trial production cost review report.

[0046] Comparative Example 1: A three-core cable upgraded to a 66kV voltage level based on a medium-voltage phase-separated aluminum-plastic structure; Comparative Example 2: 66kV three-core submarine armored cable, directly laid on land; Example: The 66kV three-core high-voltage land cable prepared in this example.

[0047] The comparison results are shown in Table 1. Table 1. Comparison of the prototype scheme in this embodiment with the 66kV three-core submarine cable.

[0048] The comparative results prove that the present invention is not a simple superposition of existing technologies, but rather achieves superior electrical performance for land operation through structural innovation, while significantly reducing cost and weight compared to submarine cable solutions. It solves the core technical pain points of long-distance three-core high-voltage cables on land, and the technical effects are unpredictable by those skilled in the art based on existing technologies. It possesses outstanding substantive features and significant progress.

[0049] This embodiment also provides a method for manufacturing the above-mentioned insulated three-core aluminum-plastic composite high-voltage land cable, such as... Figure 3 As shown, it includes the following steps: An aluminum conductor is prepared. A conductor shielding layer, an XLPE insulation layer, and an insulation shielding layer are sequentially formed on the outside of the aluminum conductor using a three-layer co-extrusion process. After extrusion, the conductor is degassed. A first semiconducting resistance water tape is wrapped around the outside of the insulation shielding layer. A phase-separated aluminum wire shielding layer is prepared on the outside of the first semiconducting resistance water tape. A second semiconducting resistance water tape is wrapped around the outside of the phase-separated aluminum wire shielding layer. An aluminum-plastic composite tape is longitudinally wrapped around the outside of the second semiconducting resistance water tape of each single-core wire. A single-core semiconducting outer sheath is simultaneously extruded on the outside of the longitudinally wrapped aluminum-plastic composite tape. The three single-core wires with single-core semiconducting outer sheaths are cabled together. A cable wrapping tape is wrapped around the outside of the cable cores. Armoring is performed on the outside of the cable wrapping tape. An outer sheath is extruded on the outside of the armor layer.

[0050] In the preparation of the aluminum conductor, high-purity aluminum rods are selected and processed through wire drawing and stranding to form 400mm² profiled aluminum conductors. The center line is a circular single wire, and the outer layer is a trapezoidal single wire. The outer diameter of the conductor is strictly controlled to be 22.2±0.2mm to ensure a dense conductor structure without broken strands, loose strands, or burr defects. The conductor stranding pitch ratio is 12, and the compaction factor is greater than or equal to 0.95.

[0051] In the three-layer co-extrusion molding process, a catenary cross-linking production line is used, with the extrusion temperature controlled at 180-200℃. The semi-conductive conductor shielding layer, XLPE insulation layer, and semi-conductive insulating shielding layer are extruded sequentially. Specifically, the nominal thickness of the conductor shield is 0.6mm, the nominal thickness of the XLPE insulation layer is 11.0mm, and the nominal thickness of the insulating shielding layer is 1.0mm, with an insulation eccentricity of less than or equal to 5%. The three layers are co-extruded in a single step, resulting in a continuous, dense insulation structure without delamination defects. After extrusion, the material undergoes degassing treatment in an oven according to specifications to remove byproducts generated during the cross-linking reaction, preventing these byproducts from forming air gaps within the insulation layer and thus reducing insulation performance. The insulation and shielding materials are produced and used within one year to avoid material aging affecting insulation performance.

[0052] In the phase-separated shielding wrapping step, a first semi-conductive resistive water tape is overlapped and wrapped around the outside of the insulating shielding layer. The first semi-conductive resistive water tape is a double-sided semi-conductive resistive water tape with specifications of 60mm × 0.6mm and a wrapping overlap rate of 45%-50%. A phase-separated aluminum wire shielding layer is prepared outside the first semi-conductive resistive water tape, specifically by using 42 aluminum wires with a single diameter of 1.35mm twisted to the left, with a twist pitch of 8-10 times the outer diameter and an average spacing of less than or equal to 3mm. A matching 1×15mm × 0.3mm aluminum strip is wrapped around it to the right with a gap width of 40-60mm. A second semi-conductive resistive water tape is then wrapped around the outside of the phase-separated aluminum wire shielding layer. The material and specifications of the second semi-conductive resistive water tape are the same as those of the first semi-conductive resistive water tape.

[0053] In the step of simultaneously processing the longitudinal wrapping and sheathing of the aluminum-plastic composite tape, aluminum-plastic composite tape is longitudinally wrapped around the outside of the second semi-conductive resistive water tape of each single-core wire. The aluminum-plastic composite tape has a specification of 190mm × 0.25mm, and the longitudinal wrapping overlap width is 15-17mm. After the longitudinal wrapping is completed, a single-core semi-conductive outer sheath is simultaneously extruded on the outside of the longitudinally wrapped aluminum-plastic composite tape. The single-core semi-conductive outer sheath is made of semi-conductive polyethylene with a nominal thickness of 3.0mm, an outer diameter of 61.5mm, and a volume resistivity of less than or equal to 100Ω·m. During the extrusion process, a vacuum segmented cooling method is used to ensure that the aluminum-plastic composite tape and the sheath are firmly bonded, without wrinkles or gaps, and that the surface of the sheath is bright and uniform.

[0054] In the cabling and shaping process, three single-core wires with single-core semi-conductive outer sheaths are cabled from right to left, with a cabling pitch of 3984-5312mm (approximately 30-40 times the outer diameter of the cable core). Four sets of 12×90mm PP ropes are used to fill the gaps between the single-core wires, controlling the non-circularity of the cable after cabling to be less than or equal to 10%, ensuring the stability of the three-core equilateral triangle arrangement, achieving three-phase magnetic field self-balance, and reducing induced loss and electromagnetic interference. After cabling, a left-overlapping cabling tape is wrapped around the outside of the cable core, consisting of two layers of tape, each layer measuring 0.2mm×60mm, arranged in an overlapping left-overlapping wrapping manner. A 100m commissioning production line is added to specifically control the longitudinal wrapping process of the aluminum-plastic composite tape after three-core cabling, eliminating defects such as wrinkles, weak adhesion, and incomplete adhesion.

[0055] In the armoring and outer sheathing processing steps, a 0.2mm×140mm non-woven fabric isolation layer is longitudinally wrapped around the outside of the cable wrapping tape. Then, a double-layer galvanized steel strip gap armoring is performed. The steel strip specifications are 60mm×0.8mm, with a minimum thickness greater than or equal to 0.72mm, a gap width of 24.0-28.8mm, and a right-hand winding direction. The upper steel strip overlaps the middle of the gap between the lower steel strip, ensuring a tight fit between the inner wall of the steel strip and the outer wall of the single-core semi-conductive outer sheath, and maintaining full electrical conductivity. After armoring, the outer diameter is 137.2mm, and the armoring is tight, flat, and free from looseness or damage. An outer sheath is extruded outside the armor layer, with a nominal thickness of 4.0mm, a minimum thickness greater than or equal to 3.60mm, and an outer diameter of 146.4mm. Product markings are laser-engraved on the surface of the sheath, and a conductive graphite coating is uniformly applied to form a graphite coating layer with a coating thickness of 0.1-0.15mm. The surface resistivity after coating is less than or equal to 100Ω.

[0056] Final inspection and acceptance: In accordance with IEC 60840, GB / T 11017 and customized enterprise standards, a full set of performance tests, including partial discharge, power frequency withstand voltage, sheath withstand voltage, and peel force, are completed. After passing the tests, the products are packaged and put into storage.

[0057] A customized 66kV three-core high-voltage land cable testing and verification system and enterprise standards are provided, filling a gap in industry standards. The testing standards meet the following requirements: no detectable discharge of more than 10pC under 1.73U0, no breakdown at 95kV / 30min power frequency withstand voltage, no breakdown at 25kV / 1min DC sheath withstand voltage, and peel force of adhesive sheath ≥1.0N / mm.

[0058] To make the technical solutions provided by the embodiments of the present invention clearer, an example is used to illustrate the present invention: A 66kV insulated three-core aluminum-plastic composite strip longitudinally clad high-voltage terrestrial cable, specifically YJLSAY63 38 / 66kV 3×400mm², is suitable for power transmission from 3.3MW wind turbines and photovoltaic power generation sides to 220kV step-up substations. Specific structural parameters and manufacturing processes are as follows: 1. Conductor preparation: High-purity aluminum rods are selected and drawn and twisted to form 400mm² aluminum conductors. The center line is a circular single wire, and the outer layer is a trapezoidal single wire. The outer diameter of the conductor is controlled at 22.2±0.2mm. The measured DC resistance of the conductor at 20℃ is ≤0.0778Ω / km. The conductor is free of broken strands, loose strands, and burr defects.

[0059] 2. Three-layer co-extrusion and degassing: A suspension cross-linking production line is used with an extrusion temperature of 180-200℃. A 0.6mm thick semi-conductive conductor shield, an 11.0mm thick XLPE insulation layer, and a 1.0mm thick semi-conductive insulation shield are extruded sequentially. The thinnest point of the insulation is ≥10.45mm thick, and the eccentricity is ≤5%. After extrusion, the insulation and shielding materials are degassed in an oven. The production and use period of the insulation and shielding materials shall not exceed one year.

[0060] 3. Phase-by-phase shielding wrapping: A 60mm × 0.6mm double-sided semi-conductive resistive water tape is overlapped and wrapped around the outside of the insulating shielding layer, with an overlap rate of 45%~50%. An aluminum wire shielding layer is prepared by left-hand twisting of 42 1.35mm aluminum wires, paired with a right-hand wrapping of 1×15mm × 0.3mm aluminum strip with a gap width of 40~60mm. The average spacing between the aluminum wires is ≤3mm, ensuring a uniform and defect-free shielding layer. A second 60mm × 0.6mm double-sided semi-conductive resistive water tape is then overlapped and wrapped around the outside of the aluminum wire shielding layer, with an overlap rate of 45%~50%.

[0061] 4. Processing of longitudinal wrapping and sheath of aluminum-plastic composite tape: Longitudinal wrapping of single wire core with 190mm×0.25mm aluminum-plastic composite tape, with an overlap width of 15~17mm, and simultaneous extrusion of 3.0mm thick semi-conductive PE sheath, vacuuming and segmented cooling to ensure that the composite tape is firmly bonded, without wrinkles or missing adhesive, and the sheath surface is bright and uniform.

[0062] 5. Cable processing: Three single-core wires are cabled in a right direction with a cable pitch of 3984~5312mm. Four sets of 12×90mm PP ropes are used for filling and leveling. After cable formation, the overall outer diameter is 132.8mm and the cable non-roundness is ≤10%. Then, two layers of 0.2mm×60mm cable wrapping tape are wrapped in a left direction to fix the wire core structure.

[0063] 6. Armoring and Outer Sheath Processing: A 0.2mm×140mm non-woven fabric isolation layer is longitudinally wrapped around the outside of the semi-conductive sheath. Two layers of 60mm×0.8mm galvanized steel strips are used for right-hand gap armoring to form a steel strip armor layer with a gap width of 24.0~28.8mm. The steel strip joints are flat and welded without burrs. Finally, a 4.0mm thick polyethylene (HDPE) outer sheath is extruded, with the thinnest point ≥3.60mm. The product logo is laser-engraved on the surface of the sheath, and graphite is uniformly coated to form the outer electrode.

[0064] 7. Finished Product Testing: All tests are conducted in accordance with the customized enterprise standards and IEC 60840 and GB / T 11017 standards. There is no partial discharge above 10pC at 1.73U0, no breakdown at 95kV power frequency withstand voltage for 30 minutes, no breakdown at 25kV DC sheath withstand voltage for 1 minute, and the peel force of the bonded sheath is ≥1.0N / mm. All indicators meet the standards.

[0065] Employing an all-aluminum lightweight structure, all metal functional layers are made of aluminum, replacing the traditional copper structure, significantly reducing product weight and production costs, and facilitating on-site transportation and installation. The conductor uses 400mm² stranded aluminum conductors with a compaction factor ≥0.95, an outer diameter of 22.2mm, and a stranding ratio of 12, resulting in a dense structure and excellent conductivity, with a DC resistance ≤0.0778Ω / km at 20℃.

[0066] While meeting the requirements of high-capacity power transmission, protection of land machinery, and electrical performance, the cable weight per unit kilometer is reduced by 40.2% compared to a three-core submarine cable of the same voltage. It can be directly adapted to conventional land cable laying equipment, eliminating the need for specialized submarine cable construction equipment and reducing the construction cost per kilometer by 55%. At the same time, the all-aluminum material system significantly reduces raw material costs, with the cost per kilometer being only 57.3% of that of a three-core submarine cable of the same voltage, perfectly matching the core demand for cost reduction in new energy projects.

[0067] Compared with existing technologies, it also has the following advantages: 1. Filling a technological gap in the industry, pioneering a 66kV three-core high-voltage land cable structure. Breaking the industry's status quo of single-core structures for 66kV and above high-voltage land cables, this is the first time a three-core high-voltage structure has been applied to land-based new energy power transmission scenarios. Unlike traditional three-core submarine cable structures, it is suitable for land-based laying and operating conditions, and can effectively promote the establishment and improvement of the industry's three-core high-voltage land cable standard system.

[0068] 2. Achieve full domestic production and mass application of high-voltage cables. Abandon the traditional reliance on imported insulation materials for high-voltage cables, and adopt domestically produced insulation and shielding materials for mass production. This will significantly reduce raw material costs and supply cycles, achieve self-sufficiency and control over core materials for high-voltage cables, and improve the level of domestic production and application of high-voltage cables in China.

[0069] 3. Optimized structure, improving both performance and cost-effectiveness. It adopts a special structure in which single-core independent aluminum-plastic composite tape is longitudinally wrapped before being cabled as a whole. Each core structure is independent and not constrained by the roundness of the cable, thus solving the defects of poor roundness and weak waterproof performance of traditional monolithic structures.

[0070] 4. The all-aluminum lightweight structure significantly reduces the product's weight, facilitating transportation and installation. Compared to three single-core high-voltage cables, the project cost is significantly reduced, perfectly meeting the cost reduction needs of new energy projects.

[0071] 5. Stable grounding system with high operational reliability. Through the equipotential design of the semi-conductive sheath, aluminum-plastic composite longitudinal wrapping layer, and armored steel tape, a dedicated three-core high-voltage cable grounding system is constructed. This effectively solves problems such as uneven potential, excessive circulating current loss, deteriorated contact resistance, and excessive temperature rise under high-voltage conditions, eliminating long-term operational safety hazards and improving the cable's operational stability and service life.

[0072] 6. Customized standard system with strong engineering adaptability. Addressing the current lack of industry standards, we have established exclusive testing and verification programs and enterprise standards, along with supporting R&D of high-voltage dedicated accessory installation and laying processes. This solves the problems of lack of acceptance criteria and construction standards for new products, and can be tailored to the pain points of long-distance power transmission for new energy customers, significantly reducing transmission losses and improving the transmission efficiency of new energy projects.

[0073] While the specific embodiments of the present invention have been described above, they are not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. An insulated tri-core aluminum-poly composite tape high voltage land cable, characterized by, Three single-core cables and an armor layer are included. Each single-core cable includes, from inside to outside, an aluminum conductor, a three-layer co-extrusion insulation layer, a phase separation aluminum wire shielding layer, a semi-conductive water-blocking tape, an aluminum-plastic composite tape longitudinal wrapping layer, and a single-core semi-conductive outer sheath.

2. The insulated tri- core ACP high voltage land cable of claim 1, wherein, The three-layer co-extrusion insulation layer includes, from inside to outside, a conductor shielding layer, an XLPE insulation layer, and an insulation shielding layer.

3. The insulated tri- core ACP high voltage land cable of claim 1, wherein, The aluminum conductor is a type line stranded aluminum conductor.

4. The insulated tri- core ACP high voltage land cable of claim 1 wherein, The conductor shielding layer and the insulation shielding layer are both made of semi-conductive shielding material, and the XLPE insulation layer is made of cross-linked polyethylene insulation material.

5. The insulated tri- core ACP high voltage land cable of claim 1 wherein, Each single-core cable further includes a semi-conductive wrapping tape, a first semi-conductive water-blocking tape, and a second semi-conductive water-blocking tape.

6. The insulated tri- core ACP high voltage land cable of claim 1 wherein, The phase separation aluminum wire shielding layer includes aluminum wires and an aluminum tape.

7. The insulated tri- core ACP high voltage land cable of claim 1 wherein, The aluminum-plastic composite tape longitudinal wrapping layer and the single-core semi-conductive outer sheath are integrated by bonding.

8. The insulated tri- core ACP high voltage land cable of claim 7, wherein, The high-voltage land cable further includes a cabling wrapping tape and an outer sheath.

9. The insulated tri- core ACP high voltage land cable of claim 1 wherein, The surface of the outer sheath is coated with graphite to form a graphite coating layer.

10. A method of manufacturing an insulated high-voltage land cable of a three-core aluminum-polymer composite tape, characterized by The outer diameter of the aluminum conductor is 22.2±0.2 mm, and the direct current resistance of the aluminum conductor at 20°C is less than or equal to 0.0778Ω / km. The method includes the following steps: Preparation of a type line tight aluminum conductor; A three-layer co-extrusion process is used to form a conductor shielding layer, an XLPE insulation layer, and an insulation shielding layer on the outside of the aluminum conductor. A first semi-conductive water-blocking tape is wrapped on the outside of the insulation shielding layer, a phase separation aluminum wire shielding layer is prepared on the outside of the first semi-conductive water-blocking tape, and a second semi-conductive water-blocking tape is wrapped on the outside of the phase separation aluminum wire shielding layer. An aluminum-plastic composite tape is independently longitudinally wrapped on a single core, and a single-core semi-conductive outer sheath is simultaneously extruded. Three single-core cores with single-core semi-conductive outer sheaths are cabled, and a cabling wrapping tape is wrapped on the outside of the cabled core. The outer sheath is extruded on the outside of the armor layer.

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