Economical flame-retardant fireproof high-voltage cable

Abstract

The utility model provides an economical flame-retardant fireproof high-voltage cable, which comprises a conductor, an insulating layer, a buffer layer, a metal shielding protective layer, a moisture-proof layer, a fireproof layer and an outer protective layer, a semi-conductive buffer water-blocking tape is wound on the surface of the insulating layer to form a buffer layer; the metal shielding protection layer is arranged on the outer surface of the buffer layer; the metal shielding protection layer adopts a smooth aluminum sheath structure; the moisture-proof layer coats the surface of the smooth aluminum sheath; the fireproof layer wraps the surface of the damp-proof layer, and refractory mortar and a ceramic silica gel belt in the fireproof layer are sintered and hardened at high temperature to form a heat insulation layer, so that erosion of high-temperature flames to the interior is effectively delayed, and continuous operation of an electric power system in a fire disaster is guaranteed; meanwhile, by adopting the smooth aluminum sheath as the metal shielding protection layer, the problems of non-uniform contact between the buffer layer and the metal protection layer, existence of air gaps and the like are solved, the outer diameter of the cable is reduced, the processing energy consumption is reduced, and the cost is effectively reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of cables, in particular to an economical flame-retardant and fire-resistant high-voltage cable. Background Art

[0002] At present, the high-voltage cables produced by the vast majority of enterprises are of the structure of corrugated aluminum sheath + conventional plastic outer sheath, mostly only having the flame-retardant function, with relatively simple structural technology, mainly composed of a conductor, insulation, buffer layer, metal aluminum sheath, and outer sheath. Such cables do not have the fire-resistant function of continuing to operate in a fire. The cables are prone to burning in a fire, and once burning occurs, it will lead to power interruption, increasing the danger of the fire. In addition, due to the fact that most of the existing cables adopt the corrugated aluminum sheath structure, there are air gaps and uneven contacts between the buffer layer and the metal sheath, with a large increase in thermal resistance and a larger outer diameter of the cable, which affects problems such as loading and logistics. Content of the Utility Model

[0003] The purpose of the utility model is to provide a cable structure that can not only solve the problem of uneven contact between the aluminum sheath and the buffer layer but also ensure the continuous operation of the power system in case of a fire.

[0004] To achieve the above purpose, the utility model proposes an economical flame-retardant and fire-resistant high-voltage cable, including a conductor, an insulating layer, a buffer layer, a metal shielding layer, a moisture-proof layer, a fire-resistant layer, and an outer protective layer:

[0005] The conductor adopts a segmented conductor structure, and conductor strands are made by drawing and stranding copper rods, and the conductor strands are separated by crepe paper;

[0006] The insulating layer is extruded and tightly coated on the surface of the conductor by co-extrusion of three layers to form a conductor shield, insulation, and insulation shield layer together; a semi-conductive buffer water-blocking tape is wound on the surface of the insulating layer to form a buffer layer for ensuring good electrical contact between the insulation shield layer and the metal shielding layer;

[0007] The metal shielding layer is arranged on the outer surface of the buffer layer; the metal shielding layer adopts a smooth aluminum sheath structure;

[0008] The moisture-proof layer is coated on the surface of the smooth aluminum sheath; the moisture-proof layer adopts a medium-density polyethylene coating structure and is arranged between the metal shielding layer and the fire-resistant layer;

[0009] The refractory layer adopts a refractory mud extrusion coating structure, which is extruded and coated on the surface of the moisture-proof layer, and the refractory mud is wound and fixed by a ceramized silica gel tape; the refractory mud and the ceramized silica gel tape are sintered and hardened under high fire temperature conditions to form a heat-insulating layer, which hinders most of the heat from transferring inward, and at the same time greatly improves the mechanical properties to protect the internal wire core; in addition, it can also maintain good performance under the action of various strong corrosive media such as acids, alkalis, and salts.

[0010] The outer sheath is coated on the outer surface of the refractory layer. The outer sheath uses a low-smoke and halogen-free flame-retardant sheath material, which has the characteristics of chemical corrosion resistance, halogen-free and low-smoke flame retardancy, preventing the fire from spreading over a long distance when on fire, and producing little or no smoke when burning.

[0011] Further, the smooth aluminum sheath is formed by cutting the edges of the aluminum strip with a corresponding forming die and bending it into a tubular structure, and then welding the seams by argon arc welding. There is no dripping inside the weld.

[0012] Further, the surface of the smooth aluminum sheath is smooth, round and free of bumps, pores, welding leaks, false welding and other defects; through the smooth aluminum sheath, the contact between the metal shielding layer and the buffer layer is uniform.

[0013] Further, the conductor adopts a segmented conductor structure, and a semiconductive resistive water tape is wound around the conductor and tied tightly after winding to reduce the influence of skin effect in the conductor.

[0014] Further, the moisture-proof layer adopts a polyethylene coating structure and is coated on the surface of the smooth aluminum sheath.

[0015] Further, in the buffer layer, the semiconductive buffer water-blocking tape is evenly wound around the surface of the insulating layer by winding; the winding direction is to the right, and the overlap is 45%-50%.

[0016] Further, the insulating layer adopts a cross-linked polyethylene and semiconductive material extrusion coating structure, which has the characteristics of high temperature resistance, strong insulation performance, non-melting, chemical corrosion resistance, high mechanical strength, environmental protection, etc.; the insulation shielding layer includes a semiconductive inner shielding layer, an XLPE insulating layer, and a semiconductive outer shielding layer. The XLPE insulating layer is arranged between the semiconductive inner shielding layer and the semiconductive outer shielding layer; the semiconductive inner shielding layer is arranged between the XLPE insulating layer and the conductor, and the semiconductive outer shielding layer is arranged between the insulating layer and the buffer layer. The semiconductive inner shielding layer, the insulating layer and the semiconductive outer shielding layer are simultaneously extruded under high pressure by cross-linked polyethylene and tightly coated on the surface of the conductor to form an integral insulation structure.

[0017] Further, the moisture-proof layer adopts a serrated polyethylene coating structure. The medium-density polyethylene material is extruded through a special serrated die and coated on the surface of the smooth aluminum sheath, so as to ensure that external water vapor and moisture will not enter the cable interior, causing oxidation of the copper wire and affecting the electrical performance. At the same time, the serrations can increase the contact area with the fireproof mud and prevent the fireproof mud from falling off; the average value of the coating thickness is not less than the nominal value, and the thickness of the thinnest point is not less than 90% of the nominal thickness; the length of the serrations is not less than 2.5 mm.

[0018] Further, the serrated side of the moisture-proof layer is connected to the refractory layer. The refractory mud is extruded and coated on the surface of the moisture-proof layer through a grouting machine; through a double-head wrapping machine, the ceramicized silica gel tape is wound around the surface of the refractory mud in an intermittent wrapping manner. The wrapping direction of the ceramicized silica gel tape is to the right, and the overlapping degree is 45%-50%. Among them, the fireproof mud material is prepared by mixing magnesium hydroxide and glass water in a ratio of 7:3.

[0019] Further, the outer sheath adopts a halogen-free low-smoke flame-retardant polyolefin coating structure and is shrink-wrapped on the outer surface of the refractory layer.

[0020] The preparation process of the economic type flame-retardant and fire-resistant high-voltage cable of the present utility model is as follows:

[0021] 1) Conductor production process: The conductor is made by drawing and stranding copper rods. A water-blocking tape is longitudinally wrapped in the middle of each layer of single wires, and a semiconductive water-blocking tape is wrapped around the conductor. After wrapping, it is tied tightly; during the process, it is ensured that the surface of the conductor is smooth, free of oil stains, burrs and sharp edges that damage the insulation.

[0022] 2) Insulation layer production process: The cross-linked polyethylene together with the inner and outer shields is extruded under high pressure and tightly coated on the surface of the conductor to form an integral insulation structure; among them, the average value of the coating thickness is not less than the nominal value, the thickness of the thinnest point is not less than 90% of the nominal thickness, the eccentricity is not more than 6%, and the extruded surface should be smooth without sharp corners, particles, burning, abrasion and other phenomena.

[0023] 3) Buffer layer production process: The semiconductive buffer water-blocking tape is evenly wound around the surface of the insulation shield layer by means of wrapping. During wrapping, moisture on the surface should be avoided. The wrapping direction is to the right, and the overlap is 45%-50% to ensure the tightness of the wrapping tape and the stability of the structure.

[0024] 4) Metal shield layer production process: After cutting the edges of the aluminum strip, it is bent into a tubular structure through a corresponding forming die, and then welded at the gap by means of argon arc welding to form a smooth aluminum sheath structure; it is required that there should be no dripping inside the weld seam, the surface of the aluminum sheath should be smooth, round and free of bruises, and there should be no defects such as air holes, missed welding and false welding.

[0025] 5) Moisture-proof layer production process: After extruding medium-density polyethylene through a serrated die on the die sleeve, it is coated on the surface of the smooth aluminum sheath. The average coating thickness should not be less than the nominal value, and the thickness at the thinnest point should not be less than 90% of the nominal thickness. The extruded surface should be smooth without particles, charring, abrasions, etc., and the serration length should not be less than 2.5 mm.

[0026] 6) Fire-resistant layer production process: Mix magnesium hydroxide and glass water in a ratio of 7:3 to form fire-resistant mud. Use a grouting machine to extrude and coat the fire-resistant mud on the surface of the moisture-proof layer; the average coating thickness should not be less than the nominal value, and the thickness at the thinnest point should not be less than 90% of the nominal thickness; the extruded surface should have no peeling, holes, etc.; after the grouting machine extrudes, immediately carry out ceramicized silica gel wrapping through a double-head wrapping machine, and use the intermittent wrapping method to wind the ceramicized silica gel tape on the surface of the fire-resistant mud. The wrapping direction of the ceramicized silica gel is to the right, with an overlap of 45%-50%, ensuring the smoothness and flatness of the wrapped tape and the stability of the structure.

[0027] 7) Outer sheath production process: Extrude and stretch the halogen-free low-smoke flame-retardant polyolefin material to form a sheath structure, which shrinks and wraps on the surface of the fire-resistant layer; among them, the average extruded thickness should not be less than the nominal value, and the thickness at the thinnest point should not be less than 90% of the nominal thickness. The extruded surface should be smooth without sharp corners, particles, charring, abrasions, etc.

[0028] Compared with the prior art, the advantages of the present utility model are as follows:

[0029] 1. The present utility model adopts a smooth aluminum sheath structure as the metal shielding layer. This smooth aluminum sheath structure can be formed in one step by argon arc welding or continuous extrusion, thereby reducing processing energy consumption. Its inner diameter is easier to control, and the contact between the smooth aluminum sheath and the buffer layer is more uniform, solving the problem that there is always an air gap between the corrugated aluminum sheath and the buffer layer in existing cables.

[0030] 2. The present utility model replaces the corrugated aluminum sheath in traditional cables with a smooth aluminum sheath. The tensile strength of aluminum in the circumferential direction of the smooth aluminum sheath is uniform and not easy to crack. Under the same conditions, compared with the corrugated aluminum sheath, the smooth aluminum sheath has a higher current-carrying capacity, a smaller cable outer diameter, lower cost, and better longitudinal water-blocking performance. While ensuring good contact between the metal shielding layer and the buffer layer, it avoids damage to the insulating layer, so that the leakage current, unbalanced current, and fault current of the insulating layer can flow evenly through the buffer layer.

[0031] 3. The present utility model uses polyethylene material to set the moisture-proof layer to prevent external water vapor and moisture from entering the cable interior and causing copper wire oxidation, and prevent the electrical performance from being affected; in addition, the connection end between the moisture-proof layer and the fire-resistant layer is serrated, increasing the contact area between the moisture-proof layer and the fire-resistant mud and preventing the fire-resistant mud from falling off.

[0032] 4. The utility model is provided with a refractory layer. By using refractory mud and ceramized silica gel tape, an insulating layer can be rapidly sintered and hardened at high temperatures, effectively hindering the transfer of heat to its interior, enhancing mechanical properties, protecting the inner core of the cable, and reducing the impact of strongly corrosive media on the cable. This enables the cable to maintain good performance under the action of various strongly corrosive media such as acids, alkalis, and salts, and has excellent fire resistance and corrosion resistance functions.

[0033] 5. The utility model adopts a segmented conductor structure to reduce the influence of the skin effect. Through the process structures and connection relationships of the insulating layer, buffer layer, metal shielding layer, moisture-proof layer, refractory layer, and halogen-free low-smoke flame-retardant polyolefin sheath, the erosion of high-temperature flames on the interior is effectively delayed, ensuring the continuous operation of the power system in case of a fire, reducing the damage of the fire to power equipment, and gaining valuable time for personnel evacuation and fire fighting and rescue. At the same time, problems such as uneven contact and air gaps between the buffer layer and the metal shielding layer are solved, the outer diameter of the cable is reduced, the processing energy consumption is lowered, and the cost is effectively reduced.

[0034] 6. The cable of the utility model has a simple process, relatively light cable weight, lower product cost, a relatively thin and flexible smooth aluminum sheath compared to a corrugated aluminum sheath, and can be more easily bent and installed in different positions; it is non-toxic, odorless, pollution-free, produces less smoke when burning, is environmentally friendly, safe, water-blocking, has a larger loading capacity on the reel compared to high-voltage cables on the market, is convenient and fast for construction and use, can be stored in a natural indoor state, and will not have quality problems after being stored for more than 35 years and can be used normally. It can pass the Class C flame-retardant standard specified in GB12666.5 and the fire resistance test of GB / T19666. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic diagram of the overall structure of the economic type flame-retardant and fire-resistant high-voltage cable of the utility model;

[0036] Figure 2 is a process flow chart for the production of the economic type flame-retardant and fire-resistant high-voltage cable of the utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] To make the objectives, technical solutions, and advantages of the utility model clearer, the technical solutions of the utility model will be further described below.

[0038] This embodiment provides an economic type flame-retardant and fire-resistant high-voltage cable, as Figure 1 shown, which includes a conductor 2, an insulating layer 6, a metal shielding layer, a moisture-proof layer 10, a refractory layer, and an outer sheath 13. Among them, the conductor 2 adopts a segmented conductor structure, and conductor strand blocks are obtained by drawing and stranding copper rods. The conductor strand blocks are separated by crepe paper 3, as Figure 1As shown, a crepe paper rope 1 is also provided at the hole in the middle of the stranded conductor 2. The crepe paper rope 1 is mainly used to fill the conductor gaps and support the conductor strands; a semiconductive resistive water tape 4 is wrapped around the outer surface of the conductor 2 and tightened after wrapping.

[0039] An insulating layer is provided on the outer surface of the semiconductive resistive water tape 4. The insulating layer adopts a crosslinked polyethylene extrusion coating structure, which has characteristics such as high temperature resistance, strong insulation performance, non-melting, chemical corrosion resistance, high mechanical strength, and environmental protection.

[0040] The above-mentioned insulating layer includes a semiconductive inner shield layer 5, an XLPE insulating layer 6, and a semiconductive outer shield layer 7. The insulating layer 6 is arranged between the semiconductive inner shield layer 5 and the semiconductive outer shield layer 7. Among them, the outer surface of the semiconductive resistive water tape 4 is connected to the XLPE insulating layer 6 through the semiconductive inner shield layer 5, so that the insulating layer is tightly coated on the surface of the conductor 2. The outer surface of the XLPE insulating layer 6 is wound with a semiconductive buffer water blocking tape 8 through the semiconductive outer shield layer 7 to form a buffer layer. In the buffer layer, the semiconductive buffer water blocking tape 8 is evenly wound on the surface of the insulating shield layer by a wrapping method; the wrapping direction is rightward, with an overlap of 45%-50%, which is used to ensure good electrical contact between the insulating shield layer and the metal shield sheath.

[0041] In this embodiment, the metal shield sheath adopts the structure of a smooth aluminum sheath 9. After cutting the edges of the aluminum strip, it is bent into a tubular structure through a corresponding forming die, and then welded at the gap by argon arc welding. It is required that there should be no dripping inside the weld seam, the surface of the aluminum sheath should be smooth, round, and free of scratches, and there should be no defects such as air holes, missed welds, and false welds. The experimental results of 110 kV power cables show that under the same conditions, the current-carrying capacity of the smooth aluminum sheath is about 15% higher than that of the corrugated aluminum sheath; the outer diameter of the cable is reduced by about 5-8 mm compared with the corrugated aluminum sheath structure (depending on different cable voltage levels and conductor specifications).

[0042] A moisture-proof layer 10 is provided on the outer surface of the metal shield sheath, as Figure 1 shown, the moisture-proof layer 10 is arranged between the metal shield sheath and the fire-resistant layer.

[0043] In this embodiment, the moisture-proof layer 10 adopts a serrated polyethylene coating structure. After the medium-density polyethylene material is extruded through a special serrated die, it is coated on the outer surface of the smooth aluminum sheath 9, so as to prevent external water vapor and moisture from entering the cable interior, causing copper wire oxidation and affecting electrical performance. Among them, the average coating thickness is not less than the nominal value, and the thickness of the thinnest point is not less than 90% of the nominal thickness; the serration length is not less than 2.5 mm.

[0044] As Figure 1As shown in the figure, a refractory layer is provided outside the moisture-proof layer 10. The serrated side of the moisture-proof layer 10 is connected to the refractory layer through refractory mud 11. The contact area between the polyethylene moisture-proof layer 10 and the refractory mud 11 is increased through the serrated connection end to prevent the fireproof mud from falling off.

[0045] In this embodiment, the refractory mud 11 is made of magnesium hydroxide and glass water modulated in a ratio of 7:3. The refractory layer extrudes the refractory mud 11 through a large grouting machine and coats it on the surface of the moisture-proof layer 10. Also, through a double-headed wrapping machine, the ceramicized silica gel tape 12 is wound around the surface of the refractory mud 11 in an intermittent wrapping manner. Among them, the wrapping direction of the ceramicized silica gel tape 12 is to the right, and the overlapping degree is 45%-50%.

[0046] The refractory layer adopts a refractory mud extrusion coating structure, which is extruded and coated on the surface of the moisture-proof layer 10, and the refractory mud 11 is wrapped and fixed through the ceramicized silica gel tape 12. Under the action of high temperature, the refractory mud 11 and the ceramicized silica gel tape 12 can quickly sinter and harden to form a heat insulation layer, thereby hindering most of the heat from transferring to its interior, protecting the internal wire core, and effectively improving the mechanical properties. In addition, it can also maintain good performance under the action of various strong corrosive media such as acids, alkalis, and salts, making it have good corrosion resistance.

[0047] As Figure 1 shown, an outer protective layer 13 is also provided outside the refractory layer. The outer protective layer 13 uses a low-smoke and halogen-free flame-retardant sheath material and adopts a halogen-free and low-smoke flame-retardant polyolefin coating structure. After the halogen-free and low-smoke flame-retardant polyolefin material is extruded and stretched, a sheath structure is formed and shrink-wrapped on the surface of the refractory layer, making it have the characteristics of chemical corrosion resistance, halogen-free and low-smoke flame-retardant performance, preventing the fire from spreading over a long distance during a fire, and producing little or no smoke during combustion.

[0048] The process preparation flow of the high-voltage cable in this embodiment is as Figure 2 shown, including the following steps:

[0049] 1) Conductor 2 production: Copper rods are drawn and stranded into conductor strand blocks, combined with copper tubes to form a cable. A water-blocking tape is longitudinally wrapped in the middle of each layer of single wires. A semiconductive water-blocking tape 4 is wrapped around the conductor 2, and it is tightened after wrapping. During the process, it is ensured that the surface of the conductor 2 is smooth, free of oil stains, burrs and sharp edges that damage the insulation.

[0050] 2) Insulation layer production: Crosslinked polyethylene is used to simultaneously extrude the XLPE insulation layer 6, the inner shielding layer 5 and the outer shielding layer 7 under high pressure, and tightly coat them on the surface of the conductor 2 to form an integral insulation structure. Among them, the average value of the coating thickness is not less than the nominal value, the thickness of the thinnest point is not less than 90% of the nominal thickness, the eccentricity is not more than 10%, and the extruded surface should be smooth, without sharp corners, particles, burning, abrasion and other phenomena.

[0051] 3) Production of buffer layer: The semiconductive buffer water-blocking tape 8 is evenly wound around the outer surface of the insulation shield layer through the wrapping method via the outer shield layer 7. During wrapping, moisture on the surface should be avoided. The wrapping direction is rightward, with an overlap of 45%-50%, ensuring the tightness of the tape and the stability of the structure.

[0052] 4) Production of metal shielding layer: After trimming the edges of the aluminum tape, it is bent into a tubular structure through a corresponding forming die, and then welded at the gap by argon arc welding to form a smooth aluminum sheath 9 structure and extruded. It is required that there should be no dripping inside the weld seam, the surface of the aluminum sheath should be smooth, round and free of scratches, and there should be no defects such as air holes, missed welding, and false welding.

[0053] 5) Production process of moisture-proof layer 10: Medium-density polyethylene is extruded through a die with sawteeth on the die sleeve and then coated on the surface of the smooth aluminum sheath 9. The average coating thickness should not be less than the nominal value, and the thickness at the thinnest point should not be less than 90% of the nominal thickness. The extruded surface should be smooth, without particles, burning, scratches, etc., and the sawtooth length should not be less than 2.5 mm.

[0054] 6) Production of fire-resistant layer: Magnesium hydroxide and water glass are mixed into fire-resistant mud 11 in a ratio of 7:3. Using a grouting machine, the fire-resistant mud 11 is extruded and coated on the surface of the moisture-proof layer 10; the average coating thickness should not be less than the nominal value, and the thickness at the thinnest point should not be less than 90% of the nominal thickness; there should be no phenomena such as peeling and holes on the extruded surface; after the grouting machine extrudes, immediately wrap the ceramicized silica gel tape 12 through a double-head wrapping machine. The ceramicized silica gel tape 12 is wound around the surface of the fire-resistant mud 11 in an intermittent wrapping manner. The wrapping direction of the ceramicized silica gel tape 12 is rightward, with an overlap of 45%-50%, ensuring the smoothness and flatness of the tape and the stability of the structure.

[0055] 7) Production of outer sheath 13: The halogen-free low-smoke flame-retardant polyolefin material is extruded and stretched to form an outer sheath 13 structure, which is shrink-wrapped on the surface of the fire-resistant layer; among them, the average extrusion thickness should not be less than the nominal value, and the thickness at the thinnest point should not be less than 90% of the nominal thickness. The extruded surface should be smooth, without sharp corners, particles, burning, scratches, etc.

[0056] The above are only the preferred embodiments of the present utility model and do not impose any limiting effect on the present utility model. Any person skilled in the art within the technical field, without departing from the scope of the technical solution of the present utility model, makes any form of equivalent replacement or modification and other changes to the technical solution and technical content disclosed by the present utility model, which are all within the content of the technical solution of the present utility model and still fall within the protection scope of the present utility model.

Claims

1. An economical flame-retardant and fire-resistant high-voltage cable, characterized in that, It includes a conductor, an insulating layer, a buffer layer, a metal shielding layer, a moisture-proof layer, a fire-resistant layer and an outer protective layer: The insulating layer is extruded in a three-layer co-extrusion manner to tightly wrap the conductor shielding, insulation, and insulation shielding layers together on the surface of the conductor; a semi-conductive buffer water-blocking tape is wound around the surface of the insulating layer to form a buffer layer; the metal shielding layer is provided on the outer surface of the buffer layer; The metal shielding layer adopts a smooth aluminum sheath structure; the moisture-proof layer is coated on the surface of the smooth aluminum sheath; the fire-resistant layer is extruded and coated with fire-resistant mud on the surface of the moisture-proof layer, and the fire-resistant mud is wound and fixed through a ceramized silica gel tape; the fire-resistant mud and the ceramized silica gel tape are sintered and hardened at high temperature to form a heat-insulating layer; the outer protective layer is coated on the outer surface of the fire-resistant layer.

2. The economical flame-retardant and fire-resistant high-voltage cable according to claim 1, wherein The smooth aluminum sheath is formed by cutting the edges of the aluminum strip with a corresponding forming die and bending it into a tubular structure, and then welding the seams by argon arc welding. There is no dripping inside the weld seam.

3. The economic flame-retardant and fire-resistant high-voltage cable according to claim 2, wherein The surface of the smooth aluminum sheath is smooth and round. Through the smooth aluminum sheath, the contact between the metal shielding layer and the buffer layer is uniform.

4. The economical flame-retardant and fire-resistant high-voltage cable according to claim 1, wherein A semi-conductive water-blocking tape is wound around the conductor.

5. The economical flame-retardant and fire-resistant high-voltage cable according to claim 1, characterized in that, In the buffer layer, the semi-conductive buffer water-blocking tape is evenly wound around the surface of the insulation shielding layer by a winding method; the winding direction is rightward, and the overlap is 45%-50%.

6. The economical flame-retardant and fire-resistant high-voltage cable according to claim 1, characterized in that, The insulating layer adopts a cross-linked polyethylene extrusion coating structure. The insulating layer includes a semi-conductive inner shielding layer, an XLPE insulating layer, and a semi-conductive outer shielding layer. The XLPE insulating layer is provided between the semi-conductive inner shielding layer and the semi-conductive outer shielding layer; the semi-conductive inner shielding layer is provided between the XLPE insulating layer and the conductor, and the semi-conductive outer shielding layer is provided between the XLPE insulating layer and the buffer layer. The semi-conductive inner shielding layer, the insulating layer, and the semi-conductive outer shielding layer are simultaneously extruded under high pressure and tightly wrapped on the surface of the conductor to form an integral insulation structure.

7. The economical flame-retardant and fire-resistant high-voltage cable according to claim 1, characterized in that, The moisture-proof layer adopts a serrated polyethylene coating structure and is coated on the surface of the smooth aluminum sheath; the average coating thickness is not less than the nominal value, and the thickness of the thinnest point is not less than 90% of the nominal thickness; the serration length is not less than 2.5 mm.

8. The economical flame-retardant and fire-resistant high-voltage cable according to claim 7, wherein, The serrated side of the moisture-proof layer is connected to the fire-resistant layer. The fire-resistant layer extrudes the fire-resistant mud onto the surface of the moisture-proof layer through a grouting machine; through a double-head winding machine, the ceramized silica gel tape is wound around the surface of the fire-resistant mud in an intermittent winding manner. The winding direction of the ceramized silica gel tape is rightward, and the overlap is 45%-50%.

9. The economic flame-retardant and fire-resistant high-voltage cable according to claim 1, wherein, The outer protective layer adopts a halogen-free low-smoke flame-retardant polyolefin coating structure and is shrink-wrapped on the outer surface of the fire-resistant layer.

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