Fire-retardant fire-resistant integrated medium voltage power cable

Abstract

The application discloses a kind of fire-retardant fire-resistant integrated medium voltage power cable, belong to cable technical field, the present application includes cable core, cable core is equipped with three, the outer surface of three cable cores is provided with inner filling part, the surface of inner filling part is provided with compression resistance part, compression resistance part includes outer support ring, the inner circle surface of outer support ring is evenly provided with multiple V-shaped plates, V-shaped plate is made of thermoplastic polyurethane elastomer material, V-shaped plate and the inner wall of outer support ring have triangle cavity, triangle cavity is filled with alkali-free glass fiber fragments, the present application is by setting compression resistance part and the multilayer fire-retardant fire-resistant structure that is formed by oxygen barrier layer, heat insulation layer, insulating barrier layer, fire-resistant layer, arc cavity pipe and its internal fire-retardant gas, can form complete thermal protection chain from outside to inside when cable encounters fire, effectively suppresses flame spread and isolates external high temperature, solves the problem that it is difficult to guarantee the power-on capacity of line during the duration of fire in actual fire high-temperature environment.

Description

Technical Field

[0001] This invention relates to the field of cable technology, specifically to a flame-retardant and fire-resistant integrated medium-voltage power cable. Background Technology

[0002] Medium-voltage power cables are widely used in urban power distribution networks, industrial plants, and high-rise buildings for power transmission. Their flame-retardant and fire-resistant properties are directly related to the integrity of power supply lines and personnel safety in the event of a fire. Conventional medium-voltage cables typically use a single flame-retardant sheath layer or fill the gaps between the cable cores with flame-retardant materials to slow the spread of flames. However, in the high-temperature environment of an actual fire, external heat can still be rapidly transferred to the internal insulated cores, leading to insulation failure or conductor melting. This makes it difficult to guarantee the power-carrying capacity of the line during the fire. At the same time, cables may be subjected to external impacts or compression during laying and use. Traditional cable structures do not provide sufficient buffer protection for the internal cable cores, making them prone to local deformation or even breakage, affecting the reliable operation of the power system. Summary of the Invention

[0003] The purpose of this invention is to provide a flame-retardant and fire-resistant integrated medium-voltage power cable. By setting up a pressure-resistant part and a multi-layer flame-retardant and fire-resistant structure composed of an oxygen barrier layer, a heat insulation layer, an insulation barrier layer, a fire-resistant layer, an arc-shaped cavity tube and its internal flame-retardant gas, a complete thermal protection chain from the outside to the inside can be formed when the cable encounters a fire. This effectively inhibits the spread of flames and isolates external high temperatures, solving the problem that it is difficult to guarantee the power supply capacity of the line during the duration of a fire in a high-temperature environment.

[0004] This invention is achieved through the following technical solution: This invention relates to a flame-retardant and fire-resistant integrated medium-voltage power cable, comprising a cable core, wherein there are three cable cores, and an inner filling part is provided on the outer surface of the three cable cores. The inner filling part is provided with a pressure-resistant part, and the pressure-resistant part includes an outer support ring. Multiple V-shaped plates are uniformly provided on the inner ring surface of the outer support ring. The V-shaped plates are made of thermoplastic polyurethane elastomer material. There is a triangular cavity between the V-shaped plates and the inner wall of the outer support ring. The triangular cavity is filled with alkali-free glass fiber fragments. An inner support ring is provided on the inner side of the multiple V-shaped plates.

[0005] Furthermore, the outer surface of the cable core is laminated with a conductor shielding layer, the outer surface of the conductor shielding layer is laminated with an insulation layer, the outer surface of the insulation layer is laminated with an insulating shielding layer, and the outer surface of the insulating shielding layer is laminated with a metal shielding layer.

[0006] Furthermore, the cable core is a round conductor made of oxygen-free copper tightly stranded together. The conductor shielding layer is made of extruded cross-linked semi-conductive shielding material, the insulation layer is made of chemically cross-linked polyethylene material, and the insulation shielding layer is made of extruded cross-linked peelable semi-conductive shielding material. The conductor shielding layer, insulation layer, and insulation shielding layer are formed in one step using a "three-layer co-extrusion" process. The metal shielding layer is made of oxygen-free soft copper strip material.

[0007] Furthermore, the inner filling part includes a fixing sleeve, the inner ring surface of which is provided with three flame-retardant filling blocks, the three cable cores are located between the three flame-retardant filling blocks, and the outer surface of the metal shielding layer is in contact with the surface of the flame-retardant filling blocks.

[0008] Furthermore, the flame-retardant filler block is made of low-smoke halogen-free flame-retardant material, and the fixing sleeve is made of nylon woven mesh material interwoven and wrapped.

[0009] Furthermore, the outer surface of the outer support ring is composited with an oxygen barrier layer, the outer surface of the oxygen barrier layer is composited with a heat insulation layer, the outer surface of the heat insulation layer is composited with an insulating barrier layer, the outer surface of the insulating barrier layer is composited with a fire-resistant layer, the outer surface of the fire-resistant layer is composited with an armor layer, and the outer surface of the armor layer is composited with an outer protective layer.

[0010] Furthermore, the oxygen barrier layer is made of halogen-free, low-smoke, flame-retardant polyolefin material, the heat insulation layer adopts a high-temperature resistant ceramicized silicone rubber extrusion or wrapping structure, the insulation barrier layer is made of fluorine-gold synthetic mica tape with overlapping wrapping, the fire-resistant layer is made of ceramicized silicone rubber composite tape with overlapping wrapping, the armor layer adopts a double-layer steel tape gap wrapping structure, and the outer protective layer is made of low-smoke, halogen-free, flame-retardant polyolefin material.

[0011] Furthermore, the outer surface of the outer protective layer is uniformly provided with multiple arc-shaped cavities, and multiple partition plates are uniformly provided inside the arc-shaped cavities. The cavity between the arc-shaped cavities and two adjacent partition plates is filled with flame-retardant gas. The arc-shaped cavities are made of silicone rubber material, and the flame-retardant gas is carbon dioxide.

[0012] The present invention has the following beneficial effects: 1. This invention features a multi-layered flame-retardant and fire-resistant structure consisting of a pressure-resistant section and an oxygen-barrier layer, a heat-insulating layer, an insulating barrier layer, a fire-resistant layer, an arc-shaped cavity tube, and internal flame-retardant gas. The arc-shaped cavity tube forms a ceramicized protective layer upon contact with fire and releases carbon dioxide to isolate oxygen. The outer protective layer and oxygen-barrier layer decompose upon heating, producing inert gas and a carbonized layer that absorbs a large amount of heat. The heat-insulating layer sinters into a low-thermal-conductivity ceramic shell to prevent high temperatures from being conducted inward. The insulating barrier layer and fire-resistant layer provide insulation and structural support respectively in the flame. Simultaneously, the flame-retardant filler blocks in the inner filling section act as an internal flame-retardant barrier to further delay heat transfer. This forms a complete thermal protection chain from the outside in when the cable encounters a fire, effectively suppressing flame spread and isolating external high temperatures. This ensures that the cable can maintain circuit integrity for a longer period in high-temperature flames, solving the problem that traditional cables cannot guarantee continuous power supply in high-temperature fire environments.

[0013] 2. This invention utilizes multiple V-shaped plates evenly arranged in the pressure-resistant section and alkali-free glass fiber fragments filled in the triangular cavity. When the cable is subjected to external radial impact or compression, the outer support ring transmits the pressure to the V-shaped tip of the V-shaped plate. The V-shaped plate is made of thermoplastic polyurethane elastomer, and its elastic bending deformation converts the concentrated load into stress dispersed along the plate surface. At the same time, the alkali-free glass fiber fragments in the triangular cavity further absorb and disperse the impact energy by squeezing and rubbing against each other when under pressure. After the external pressure is eliminated, the V-shaped plate quickly returns to its original shape due to the high elasticity of the material, thereby effectively buffering external impact and preventing the cable core from breaking or permanently deforming due to pressure, significantly improving the pressure resistance reliability of the cable during laying and use.

[0014] 3. This invention uses three irregularly shaped flame-retardant filling blocks made of low-smoke halogen-free flame-retardant material in the inner filling section to tightly fit the outer surface of the three cable cores and fill the gaps between adjacent cable cores, forming an independent wrapping support for the three cable cores. At the same time, the fixing sleeve is made of nylon braided mesh material to intertwine and wrap, binding and fixing the three flame-retardant filling blocks and the three cable cores into a whole. This ensures that each cable core is always in a predetermined geometric position during bending, vibration or thermal expansion and contraction of the cable, avoiding relative torsion or mutual friction, thereby maintaining a uniform electric field distribution and ensuring electrical stability during long-term operation. At the same time, this filling structure also serves as an internal flame-retardant barrier to further enhance the fire resistance of the cable.

[0015] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a power cable.

[0017] Figure 2 This is a schematic diagram of the cross-sectional structure of a power cable.

[0018] Figure 3 This is a schematic diagram of the compression-resistant part.

[0019] Figure 4 This is a schematic diagram of the V-shaped plate.

[0020] Figure 5 This is a schematic diagram of the installation structure of the cable core and the inner filling part.

[0021] Figure 6 for Figure 5 Enlarged view of point A in the middle.

[0022] In the diagram: 1. Cable core; 101. Conductor shielding layer; 102. Insulation layer; 103. Insulation shielding layer; 104. Metal shielding layer; 2. Inner filling part; 201. Fixing sleeve; 202. Flame-retardant filling block; 3. Compression-resistant part; 301. Outer support ring; 302. Inner support ring; 303. V-shaped plate; 304. Triangular cavity; 4. Oxygen barrier layer; 5. Heat insulation layer; 6. Insulation barrier layer; 7. Fire-resistant layer; 8. Armoring layer; 9. Outer protective layer; 10. Arc-shaped cavity tube; 1001. Separator plate. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Please see Figure 1-6This invention provides a technical solution: a flame-retardant and fire-resistant integrated medium-voltage power cable, comprising cable core 1, of which three are provided. The outer surface of cable core 1 is laminated with a conductor shielding layer 101, the outer surface of the conductor shielding layer 101 is laminated with an insulation layer 102, the outer surface of the insulation layer 102 is laminated with an insulating shielding layer 103, and the outer surface of the insulating shielding layer 103 is laminated with a metal shielding layer 104. Cable core 1 is a circular conductor made of oxygen-free copper tightly stranded using a layered tight stranding process, resulting in a smooth and round surface that facilitates uniform electric field distribution. The conductor's DC resistance at 20℃ meets the requirements of IEC60228 standard. The long-term operating temperature can reach 90℃, and the maximum temperature during a short circuit can reach 250℃ for a duration not exceeding 5 seconds. The conductor shielding layer 101 is made of extruded cross-linked semi-conductive shielding material and is uniformly coated on the surface of the cable core 1 to uniformly distribute the electric field on the surface of the cable core 1 and prevent air gap discharge between the cable core 1 and the insulation layer 102. The insulation layer 102 is made of chemically cross-linked polyethylene material, and the insulation eccentricity meets the standard requirements. It is free of impurities and bubbles, and has sufficient cross-linking degree. It undertakes the main insulation function for medium-voltage power transmission and meets the electrical performance requirements for long-term cable operation. The insulating shielding layer 103 is made of extruded cross-linked peelable semi-conductive shielding material. The conductor shielding layer 101, insulation layer 102, and insulation shielding layer 103 are tightly bonded to the insulation layer 102, with a smooth and uniform surface covering. The electric field on the outer surface of the uniform insulation layer 102, together with the metal shielding layer 104, forms a uniform electric field distribution. The conductor shielding layer 101, insulation layer 102, and insulation shielding layer 103 are formed in one step using a "three-layer co-extrusion" process, ensuring a clean interface and tight bonding, effectively improving the stability and reliability of cable operation. The metal shielding layer 104 is made of oxygen-free soft copper strip material, composited on the surface of the insulation shielding layer 103 by overlapping copper strip wrapping or loosely winding copper wire with reverse wrapping of copper strip. It is used to carry short-circuit current and shield external electromagnetic interference. As a fault current path, the outer surfaces of the three cable cores 1 are provided with inner filling parts 2. The inner filling parts 2 include fixing sleeves 201. The inner ring surface of the fixing sleeves 201 is provided with three flame-retardant filling blocks 202. The three cable cores 1 are located between the three flame-retardant filling blocks 202. The outer surface of the metal shielding layer 104 is attached to the surface of the flame-retardant filling blocks 202. The flame-retardant filling blocks 202 are made of low-smoke halogen-free flame-retardant materials to ensure the structural stability of the cable cores 1 and provide a good flame-retardant barrier. The fixing sleeves 201 are made of nylon braided mesh material to ensure the tensile strength of the cable. The surface of the inner filling parts 2 is provided with compression-resistant parts 3.

[0025] The pressure-resistant part 3 includes an outer support ring 301. Multiple V-shaped plates 303 are evenly distributed on the inner surface of the outer support ring 301. The V-shaped plates 303 are made of thermoplastic polyurethane elastomer material, which can quickly recover after being compressed and has flame-retardant properties. A triangular cavity 304 is formed between the V-shaped plates 303 and the inner wall of the outer support ring 301. The triangular cavity 304 is filled with alkali-free glass fiber fragments. Inner support rings 302 are arranged on the inner sides of the multiple V-shaped plates 303. The inner support rings 302 are composite on the surface of the fixing sleeve 201. An oxygen barrier layer 4 is composite on the outer surface of the outer support ring 301. A heat insulation layer 5 is composite on the outer surface of the oxygen barrier layer 4. An insulating barrier layer 6 is composite on the outer surface of the heat insulation layer 5. A fire-resistant layer 7 is composite on the outer surface of the insulating barrier layer 6. An armor layer 8 is composite on the outer surface of the fire-resistant layer 7. An outer protective layer 9 is composite on the outer surface of the armor layer 8. The oxygen barrier layer 4 is made of halogen-free, low-smoke, flame-retardant polyolefin material. The oxygen layer 4 has a thickness of 2.0mm~3.0mm. Under high-temperature conditions, it decomposes to produce water vapor and inert gases, diluting the oxygen concentration, inhibiting flame spread, and achieving oxygen barrier isolation. The flame retardants aluminum hydroxide or magnesium hydroxide in the material decompose upon heating, releasing water of crystallization, absorbing a large amount of heat, and lowering the temperature of the cable core 1. At high temperatures, a dense carbonized layer is formed, blocking the flame from spreading inwards. The heat insulation layer 5 uses a high-temperature resistant ceramicized silicone rubber extrusion or wrapping structure. The thickness of the heat insulation layer 5 is 1.5mm~2.0mm. The ceramicized silicone rubber maintains good flexibility and elasticity at room temperature and rapidly sinterstens under flame conditions ≥300℃ to form a hard ceramic-like shell. This shell has excellent thermal insulation and electrical insulation properties, effectively preventing high-temperature heat from being conducted into the cable core 1, protecting the internal insulated core from heat damage. In terms of electrical performance, the volume resistivity of the ceramicized silicone rubber is as high as ≥10¹. 5With a breakdown strength ≥30kV / mm and a strength of Ω·cm, it provides reliable protection for high-voltage insulation. Its applicable temperature range is -60℃ to +200℃, adaptable to various harsh working conditions. Insulation barrier layer 6 is made of overlapping fluorine-gold synthetic mica tape. Mica tape has excellent high-temperature insulation properties; the synthetic mica tape can maintain insulation performance for more than 3 hours in a 1000℃ flame. Under high fire temperatures, mica crystal water evaporates and absorbs heat, while the mica sheets form a dense insulation barrier, protecting the insulation integrity between conductors. Fire-resistant layer 7 is made of overlapping ceramicized silicone rubber composite tape with an overlap rate ≥50%. The ceramicized silicone rubber tape sinters in the flame to form a hard shell, complementing the mica tape. The mica tape provides insulation retention, while the ceramicized silicone rubber tape provides structural support and a fire barrier. Together, they can maintain circuit integrity for more than 90 minutes in a 950~1000℃ flame. Armor layer 8 uses a double-layer steel tape gap wrapping structure, with the metal tapes interleaved... The locking spiral winding forms a flexible armor structure, combining high-strength armor with excellent flexibility, facilitating cable laying and construction. It also creates a discontinuous contact interface between the inner and outer sheaths, allowing for slight deformation and slippage during thermal expansion, reducing the risk of delamination and improving flame retardancy. The armor material can be galvanized steel strip or stainless steel strip to enhance corrosion resistance. The outer protective layer 9 is made of low-smoke, halogen-free, flame-retardant polyolefin material, with a thickness of 2.5mm~3.5mm. It features high flame retardancy (oxygen index ≥30%, passing the bundled Class A burning test); low smoke density (light transmittance ≥60% during combustion, facilitating personnel evacuation in fires); halogen-free and non-toxic (halogen acid gas released during combustion has a pH value ≥4.3, conductivity ≤10μS / mm, and extremely low corrosiveness); and excellent processing and mechanical properties (good extrusion flowability and mechanical strength, meeting cable laying and usage requirements). It also boasts high flame retardancy (oxygen index ≥30%, passing the bundled Class A burning test).

[0026] The outer surface of the outer protective layer 9 is uniformly provided with multiple arc-shaped cavities 10. Multiple partition plates 1001 are uniformly arranged inside the arc-shaped cavities 10. The cavity between the arc-shaped cavities 10 and two adjacent partition plates 1001 is filled with flame-retardant gas. The arc-shaped cavities 10 are made of silicone rubber material. As the first fire barrier for the cable, they have excellent fire safety. When exposed to fire, they can form a hard ceramic protective layer to ensure that the circuit continues to work in a fire. The flame-retardant gas is carbon dioxide, which can quickly isolate oxygen and reduce the degree of cable combustion.

[0027] Under normal power transmission conditions, the three cable cores 1 respectively undertake the transmission of three-phase power. The conductor shielding layer 101 uniformly distributes the electric field on the surface of the cable core 1 to avoid partial discharge. The insulation layer 102 withstands the rated voltage and ensures the electrical safety of long-term operation. The insulating shielding layer 103 further uniformizes the electric field and together with the metal shielding layer 104 forms an electric field shield. The metal shielding layer 104 also serves as a short-circuit current path and an electromagnetic shielding layer. The three flame-retardant filler blocks 202 in the inner filling part 2 are tightly attached to the outer surface of the three cable cores 1. The fixing sleeve 201 binds and fixes the three flame-retardant filler blocks 202 and the three cable cores 1 into a whole, ensuring that the cable cores 1 will not undergo relative displacement when the cable is bent or vibrated, maintaining the geometric position stability between the three-phase cable cores 1, thereby maintaining a uniform electric field distribution. In the pressure-resistant part 3, the V-shaped plate 303 is made of thermoplastic polyurethane elastomer, which has good elasticity and flame retardancy. When the cable is subjected to external radial impact or compression, the pressure first acts on the outer support ring 301. The retainer 301 transmits pressure to the V-shaped tips of multiple V-shaped plates 303. The V-shaped plates 303 undergo elastic bending deformation, increasing the V-angle and converting the radial pressure into a dispersed force along the hypotenuse of the V-shaped plates 303. At the same time, the alkali-free glass fiber fragments filled in the triangular cavity 304 squeeze and rub against each other when under pressure, further absorbing and dispersing the impact energy. When the external pressure is removed, the V-shaped plates 303 quickly return to their original V-shaped state due to the high elasticity of the thermoplastic polyurethane elastomer, thereby effectively buffering the external impact and preventing the cable core 1 from breaking or permanently deforming due to pressure.

[0028] In the high-temperature environment of a fire, the arc-shaped cavity 10 on the surface of the outer protective layer 9 first comes into contact with the flame. The silicone rubber material rapidly sinterstalizes upon contact with the flame, forming a hard ceramic protective layer. When the carbon dioxide gas inside the arc-shaped cavity 10 expands due to heat, it causes the arc-shaped cavity 10 to rupture. The released carbon dioxide gas quickly covers the cable surface, diluting the oxygen concentration and inhibiting the initial spread of the flame. The outer protective layer 9 itself is made of low-smoke halogen-free flame-retardant polyolefin material with an oxygen index of not less than 30%. In the flame, it forms a carbonized layer and releases water vapor, further blocking oxygen. The aluminum hydroxide or magnesium hydroxide flame retardant in the oxygen barrier layer 4 decomposes when heated, releasing water of crystallization, absorbing a large amount of heat, reducing the internal temperature of the cable, and simultaneously forming a dense carbonized layer, preventing the flame from spreading inward. The heat insulation layer... The ceramicized silicone rubber in layer 5 rapidly sintersects at temperatures above 300°C to form a hard, ceramic-like shell. This shell has extremely low thermal conductivity, effectively preventing external high temperatures from being conducted into the cable core 1. The fluorine-gold synthetic mica tape in insulation barrier layer 6 maintains its insulation performance for more than 3 hours in a 1000°C flame. While the mica crystal water evaporates and absorbs heat, the mica sheets form a dense insulation barrier, preventing short circuits between conductors. The ceramicized silicone rubber composite tape in fire-resistant layer 7 sintersects in the flame to form a hard shell, working synergistically with the mica tape in insulation barrier layer 6. The mica tape maintains insulation integrity, while the ceramicized silicone rubber tape provides structural support and a fire barrier. Together, they ensure that circuit integrity is maintained for more than 90 minutes in a 950°C to 1000°C flame. The double-layer steel tape wrapping structure of armor layer 8 provides mechanical protection, and its discontinuous contact interface allows for small-amplitude deformation and slippage during thermal expansion, preventing delamination due to thermal stress. The flame-retardant filler block 202 in the inner filling section 2 is made of low-smoke halogen-free flame-retardant material, serving as an internal flame-retardant barrier to further delay heat conduction to the cable core 1, ensuring that the three cable cores 1 can still maintain normal power transmission under high fire temperatures. Through the synergistic effect of the above-mentioned multi-layer flame-retardant, fire-resistant, and heat-insulating structures, combined with the flame-retardant filling of the inner filling section 2 and the elastic buffering of the pressure-resistant section 3, the cable of the present invention can effectively protect the internal insulated cores in a fire environment, maintain the integrity of the circuit's power transmission, and effectively buffer pressure when subjected to external impacts to prevent cable breakage, thus achieving integrated flame-retardant, fire-resistant, and pressure-resistant performance.

[0029] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A flame-retardant and fire-resistant integrated medium-voltage power cable, comprising a cable core (1), characterized in that: The cable core (1) is provided in three parts, and the outer surface of the three cable cores (1) is provided with an inner filling part (2), and the surface of the inner filling part (2) is provided with a pressure-resistant part (3). The pressure-resistant part (3) includes an outer support ring (301). The inner surface of the outer support ring (301) is uniformly provided with a plurality of V-shaped plates (303). The V-shaped plates (303) are made of thermoplastic polyurethane elastomer material. There is a triangular cavity (304) between the V-shaped plate (303) and the inner wall of the outer support ring (301). The triangular cavity (304) is filled with alkali-free glass fiber fragments. The inner side of the plurality of V-shaped plates (303) is provided with an inner support ring (302).

2. The flame-retardant and fire-resistant integrated medium-voltage power cable according to claim 1, characterized in that, The outer surface of the cable core (1) is coated with a conductor shielding layer (101), the outer surface of the conductor shielding layer (101) is coated with an insulation layer (102), the outer surface of the insulation layer (102) is coated with an insulating shielding layer (103), and the outer surface of the insulating shielding layer (103) is coated with a metal shielding layer (104).

3. The flame-retardant and fire-resistant integrated medium-voltage power cable according to claim 2, characterized in that, The cable core (1) is a circular conductor made of oxygen-free copper tightly stranded. The conductor shielding layer (101) is made of extruded cross-linked semi-conductive shielding material. The insulation layer (102) is made of chemically cross-linked polyethylene material. The insulation shielding layer (103) is made of extruded cross-linked peelable semi-conductive shielding material. The conductor shielding layer (101), insulation layer (102) and insulation shielding layer (103) are formed in one step using a "three-layer co-extrusion" process. The metal shielding layer (104) is made of oxygen-free soft copper strip material.

4. The flame-retardant and fire-resistant integrated medium-voltage power cable according to claim 3, characterized in that, The inner filling part (2) includes a fixing sleeve (201), and the inner ring surface of the fixing sleeve (201) is provided with three flame-retardant filling blocks (202). The three cable cores (1) are located between the three flame-retardant filling blocks (202), and the outer surface of the metal shielding layer (104) is in contact with the surface of the flame-retardant filling block (202).

5. The flame-retardant and fire-resistant integrated medium-voltage power cable according to claim 4, characterized in that, The flame-retardant filler block (202) is made of low-smoke halogen-free flame-retardant material, and the fixing sleeve (201) is made of nylon woven mesh material interwoven and wrapped.

6. The flame-retardant and fire-resistant integrated medium-voltage power cable according to claim 1, characterized in that, The outer surface of the outer support ring (301) is coated with an oxygen barrier layer (4), the outer surface of the oxygen barrier layer (4) is coated with a heat insulation layer (5), the outer surface of the heat insulation layer (5) is coated with an insulating barrier layer (6), the outer surface of the insulating barrier layer (6) is coated with a fire-resistant layer (7), the outer surface of the fire-resistant layer (7) is coated with an armor layer (8), and the outer surface of the armor layer (8) is coated with an outer protective layer (9).

7. The flame-retardant and fire-resistant integrated medium-voltage power cable according to claim 6, characterized in that, The oxygen barrier layer (4) is made of halogen-free, low-smoke, flame-retardant polyolefin material. The heat insulation layer (5) adopts a high-temperature resistant ceramicized silicone rubber extrusion or wrapping structure. The insulation barrier layer (6) is made of fluorine-gold synthetic mica tape with overlapping wrapping. The fire-resistant layer (7) is made of ceramicized silicone rubber composite tape with overlapping wrapping. The armor layer (8) adopts a double-layer steel tape gap wrapping structure. The outer protective layer (9) is made of low-smoke, halogen-free, flame-retardant polyolefin material.

8. The flame-retardant and fire-resistant integrated medium-voltage power cable according to claim 7, characterized in that, The outer protective layer (9) has a plurality of arc-shaped cavities (10) uniformly arranged on its outer surface. A plurality of partition plates (1001) are uniformly arranged inside the arc-shaped cavities (10). The cavity between the arc-shaped cavities (10) and two adjacent partition plates (1001) is filled with a flame-retardant gas. The arc-shaped cavities (10) are made of silicone rubber material and the flame-retardant gas is carbon dioxide.

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