Fire resistant cable for fire resistant test of cable under building fire temperature condition

Abstract

This invention discloses a fire-resistant cable for fire resistance testing under building fire heating conditions. It includes a central reinforcing core surrounded by multiple copper conductors, each covered with an insulation layer. A protective layer, a metal sheath, an isolation layer, a heat insulation layer, and an outer sheath are sequentially arranged around the copper conductors. Isolation sections are provided on the isolation and heat insulation layers, with spaced-apart ceramizable clay layers on the inner and outer walls of these isolation sections. This invention, by setting isolation sections, creates a segmented fire-resistant outer layer structure for the cable. Furthermore, the ceramizable clay layers on the inner and outer walls of the isolation sections, with gaps between them, allow the ceramizable clay to ceramize upon heating, forming a ceramic protection layer with pores or cavities. This significantly improves the flame-retardant effect along the cable's length. The gaps within the isolation sections also improve the cable's bending performance, facilitating corner laying.

Description

Technical Field

[0001] This invention relates to the field of fire-resistant cable technology, specifically to a fire-resistant cable for fire resistance testing under building fire temperature rise conditions. Background Technology

[0002] A cable is a device for transmitting electrical energy or signals, usually consisting of several or several groups of conductors. In buildings, the safe use of cables necessarily requires fire protection. Existing fire-resistant cables can basically meet the needs of daily use, but there are still some shortcomings that need to be improved.

[0003] CN120600396A discloses a fire-resistant cable, relating to the field of wire and cable technology. The fire-resistant cable includes a cable core, a filling layer, and an outer sheath. The cable core includes multiple wire cores and a separator frame. The separator frame is formed by extruding ceramicized polyolefin material or ceramicized silicone rubber material between the multiple wire cores and covers at least part of the structure of each wire core to stabilize the multiple wire cores in the separator frame. The filling layer is located on the outer periphery of the cable core. The outer sheath is located on the outer periphery of the filling layer. According to the fire-resistant cable of the present invention, in a fire, the high temperature of the flame and the environment will ceramicize the separator frame, forming a ceramic block with good insulation effect and solidity, which continues to play a good role in insulation, support, and separation. The separated multiple wire cores are not prone to short circuits, ensuring that the cable can withstand long-term flame burning and will not fail rapidly.

[0004] In the prior art, as described in the aforementioned patent, the cable achieves protection against fire-induced temperature rise by setting a structure with high-temperature ceramicization function. However, along the length of the cable, its components still transmit heat, which can easily lead to multi-point combustion damage. Therefore, there is an urgent need for a fire-resistant cable that can withstand fire-induced temperature rise in building fires to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a fire-resistant cable for fire resistance testing under building fire heating conditions, in order to overcome the above-mentioned shortcomings in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A fire-resistant cable for fire resistance testing under building fire temperature rise conditions includes a central reinforcing core, with multiple copper conductors arranged closely around the reinforcing core. The copper conductors are covered with an insulation layer. A protective layer, a metal sheath, an isolation layer, a heat insulation layer, and an outer sheath are sequentially arranged on the outside of the multiple copper conductors. The gaps between the protective layer and each copper conductor, as well as the gaps between the reinforcing core and each copper conductor, are filled with a filling material. Isolation sections are provided on the isolation layer and the heat insulation layer. The inner and outer rings of the isolation sections are provided with spaced-apart ceramizable mud.

[0007] Preferably, the insulating layer and the protective layer are made of calcined mica tape.

[0008] Preferably, the metal sleeve is made of aluminum.

[0009] Preferably, the material of the isolation layer is polyethylene.

[0010] Preferably, the material of the heat insulation layer is fireproof putty composed of magnesium hydroxide and aluminum hydroxide, or a silica aerogel layer, or a composite layer of fireproof putty and silica aerogel.

[0011] Preferably, the silica aerogel layer is made of strip-shaped flexible aerogel felt, which is made by multi-layer overlapping wrapping through a wrapping machine on a cable forming machine.

[0012] Preferably, the outer sheath is made of low-smoke halogen-free polyolefin.

[0013] Preferably, the outer sheath is provided with a folding ring, one end of which is movably connected to the outer sheath, and the other end is bonded to the outer sheath by hot melt adhesive. The heat insulation layer is provided with a triggering component for causing the folding ring to fold outward after the hot melt adhesive melts.

[0014] Preferably, the triggering component includes an annular groove inside the heat insulation layer near the isolation section, an isolation ring is movably disposed in the annular groove, an explosive body is disposed on one side of the isolation ring near the isolation section, and a metal sheet is disposed on the other side, one end of the metal sheet is fixedly connected to one end of the outer sheath of the folding ring, and the other end is thermally connected to the explosive body.

[0015] Preferably, the heat insulation layer is provided with a guide groove that matches the metal sheet, and a throat groove is provided between the annular groove and the guide groove to communicate with each other. The metal sheet passes through the throat groove, and an extrusion member that matches the throat groove is provided on the isolation ring.

[0016] In the above technical solution, the beneficial effects of the present invention are: The fire-resistant cable tested under the building's fire-heating conditions features an isolation section, creating a segmented structure for the cable's fire-resistant outer layer. Ceramizable mud is applied to the inner and outer walls of the isolation section, with a gap between the two layers. Upon heating, the ceramizable mud undergoes ceramization, forming a ceramic protection layer with pores or cavities. This significantly improves the flame-retardant effect along the cable's length. Furthermore, the gaps within the isolation section enhance the cable's bending performance, facilitating corner laying.

[0017] It should be understood that the foregoing general description and the following detailed description are exemplary and illustrative only, and are not intended to limit this disclosure.

[0018] This application provides an overview of various implementations or examples of the technology described in this disclosure, and is not a full disclosure of the entire scope or all features of the disclosed technology. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0020] Figure 1 This is a schematic diagram of the radial cross-sectional structure of the present invention; Figure 2 This is a schematic diagram of the axial cross-sectional structure of the first embodiment of the present invention; Figure 3 This is a schematic diagram of the axial cross-sectional structure of the second embodiment of the present invention; Figure 4 For the present invention Figure 3 Enlarged structural diagram at point A; Figure 5 This is a three-dimensional structural schematic diagram of the second embodiment of the present invention.

[0021] Explanation of reference numerals in the attached figures: 1. Reinforcing core; 2. Copper conductor; 3. Insulation layer; 4. Protective layer; 5. Metal sleeve; 6. Isolation layer; 7. Heat insulation layer; 8. Outer sheath; 9. Filler material; 10. Ceramizable clay; 11. Folding ring; 12. Annular groove; 13. Isolation ring; 14. Explosive body; 15. Metal sheet; 16. Guide groove; 17. Throat groove; 18. Extrusion part; 19. Pore; 20. Displacement ring; 21. Interlocking hole. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0023] Please see Figure 1-5The present invention provides a fire-resistant cable for fire resistance testing under building fire temperature rise conditions, comprising a reinforcing core 1 located at the center, a plurality of copper conductors 2 arranged closely around the reinforcing core 1, an insulation layer 3 covering the outside of the copper conductors 2, a protective layer 4, a metal sheath 5, an isolation layer 6, a heat insulation layer 7 and an outer sheath 8 arranged sequentially on the outside of the plurality of copper conductors 2, a filling material 9 being provided in the gaps between the protective layer 4 and each copper conductor 2 and the gaps between the reinforcing core 1 and each copper conductor 2, and isolation sections being provided on the isolation layer 6 and the heat insulation layer 7, with spaced ceramic mortar 10 provided on the inner and outer ring inner walls of the isolation sections.

[0024] Specifically, the reinforcing core 1 is located at the center of the cable. Its main function is to improve the cable's mechanical strength and tensile and bending resistance, ensuring that the cable core structure does not deform or break during laying, installation, and high-temperature environments such as fires. The material used is aramid fiber or galvanized steel wire, combining lightweight, high strength, and heat resistance to provide stable support for the multiple copper conductors 2, preventing displacement and ensuring reliable electrical connections. The copper conductors 2 are preferably multi-strand oxygen-free copper strands, using a tightly compressed multi-strand fine copper wire structure, significantly improving the cable's flexibility and bending performance, adapting to complex wiring environments. The oxygen content of the oxygen-free copper is <0.001%, avoiding cuprous oxide embrittlement at high temperatures, ensuring high conductivity and structural integrity even in flames of 750-1000℃, providing a stable current path for emergency power supply. The filler material 9 is made of inorganic flame-retardant powder, its functions being: fixing the conductor position to prevent displacement during operation leading to insulation wear; blocking the lateral spread of flames within the conductor gaps; and forming a multi-level flame-retardant barrier in conjunction with the insulation layer 7, enhancing overall fire resistance integrity and improving the cable's structural stability in flames. The isolation section is formed when the isolation layer 6 and the heat insulation layer 7 are separated in the middle, creating a cavity structure between the metal sleeve 5 and the outer sheath 8. In this section, the outer wall of the metal sleeve 5 and the inner wall of the outer sheath 8 are coated with a layer of ceramizable clay 10, with a gap remaining between the two layers of ceramizable clay 10. When heated, the ceramizable clay 10 forms a composite heat insulation structure with the air within the isolation section. At high temperatures, the ceramizable clay 10 forms a hard ceramic layer with excellent heat insulation properties, while air is a poor conductor of heat; the combination of these two elements significantly improves the heat insulation effect. In practical use, this technical solution creates a segmented structure for the fireproof outer layer of the cable by setting up an isolation section. Ceramizable mud 10 is applied to the inner and outer walls of the isolation section, with a gap between the two layers of ceramizable mud 10. When heated, the ceramizable mud 10 becomes ceramizable and forms a ceramic protection with pores or cavities, which greatly improves the flame retardant effect along the length of the cable. Furthermore, the gaps within the isolation section improve the bending performance of the cable and facilitate the laying of the cable at corners.

[0025] Compared with the prior art, the fire-resistant cable proposed in this embodiment of the invention for fire resistance testing under building fire heating conditions has a segmented structure formed by setting an isolation section. The inner and outer rings of the isolation section are respectively provided with ceramizable mud 10, with a gap between the two layers of ceramizable mud 10. After being heated, the ceramizable mud 10 becomes ceramizable and forms a ceramic protection mixed with pores or cavities. This greatly improves the flame retardant effect along the length of the cable. In addition, the gap in the isolation section improves the bending performance of the cable and facilitates the laying of the cable at corners.

[0026] As a preferred technical solution in this embodiment, the insulating layer 3 and the protective layer 4 are made of calcined mica tape. Specifically, under flame burning, the mica is transformed into a dense ceramic layer that is non-melting, non-combustible, and non-carbonizing, effectively isolating the direct erosion of the conductor by the flame.

[0027] As a preferred technical solution in this embodiment, the metal sleeve 5 is made of aluminum. Specifically, the aluminum sleeve has multiple functions: mechanical protection, pressure and impact resistance, preventing damage from external forces; electromagnetic shielding, suppressing external interference and signal leakage; waterproof and rodent-proof, blocking environmental moisture and biological corrosion; and it can also serve as a grounding conductor PE wire, improving electrical safety. Aluminum is lightweight and has moderate thermal conductivity, which helps to distribute heat evenly and avoid local overheating.

[0028] As a preferred technical solution in this embodiment, the material of the isolation layer 6 is polyethylene. Specifically, the main function of polyethylene is to block water and moisture, prevent moisture from penetrating inward, avoid a decrease in insulation resistance and electrochemical corrosion; it also has good electrical insulation and heat resistance, ensuring stable dielectric properties even in high-temperature environments, and excellent compatibility with adjacent layer materials.

[0029] As a preferred technical solution in this embodiment, the material of the heat insulation layer 7 is fireproof putty composed of magnesium hydroxide and aluminum hydroxide, or a silica aerogel layer, or a composite layer of fireproof putty and silica aerogel. Specifically, the inorganic fireproof putty made by mixing magnesium hydroxide and aluminum hydroxide in a certain proportion has the following flame retardant mechanism: First, magnesium hydroxide decomposes at around 380°C and aluminum hydroxide at around 200°C, absorbing a large amount of reaction heat during decomposition, which greatly reduces the surface temperature of the material; Second, the fireproof putty decomposes and releases a large amount of water vapor, diluting the oxygen concentration and forming a gas phase barrier; Third, after the fireproof putty decomposes, it generates high-temperature resistant magnesium oxide and aluminum oxide solid residues, which cover the burning surface, forming a dense heat insulation layer and preventing combustible gases from escaping and oxygen from penetrating. Silica aerogel layers have extremely low thermal conductivity and lightweight properties. Replacing fireproof putty with aerogel composite layers allows the use of its nanoporous structure to form a thermal barrier. In the event of a fire, it can more effectively prevent external high temperatures from being transmitted into the cable, buying more time for fire rescue and significantly reducing cable weight and diameter. With a composite layer of fireproof putty and silica aerogel, the aerogel layer can effectively reduce the direct impact of external heat on the cable's interior, delaying its melting or combustion. At the same time, it can form a double protection with the fireproof putty, greatly improving the overall fire resistance of the cable.

[0030] As a further preferred technical solution in this embodiment, the silica aerogel layer is made of strip-shaped flexible aerogel felt, which is processed by multi-layer overlapping wrapping on a cable forming machine. Specifically, the aerogel is made into felt, blanket, or strip, and then wrapped or wrapped around the outside of the cable insulation layer to form a highly efficient heat insulation barrier. By adding fibers (such as nano-alumina fibers) for reinforcement, a composite aerogel layer with a certain strength is formed, and then shaped by extrusion and other processes. Introducing fiber reinforcement or using a pre-composite form of aerogel felt utilizes the fiber skeleton to bear mechanical stress while retaining the heat insulation performance of the aerogel. The aerogel felt is cut into strips and wound in the same direction or cross direction on the extruded insulation cable using a winding machine. After the aerogel layer is wound, a conventional sheath material is extruded on the outer layer to provide mechanical protection and environmental sealing. The aerogel felt itself has good flexibility and a certain mechanical strength, and can be well compatible with the cable structure. This silica aerogel layer processing technology is simple, has good compatibility with existing cable production equipment, and the thickness is easy to control.

[0031] As a preferred technical solution in this embodiment, the outer sheath 8 is made of low-smoke halogen-free polyolefin. Specifically, the outer sheath 8 uses a halogen-free polyolefin matrix, which releases no toxic gases such as hydrogen halides and dioxins during combustion, has extremely low smoke density, meets the safety evacuation requirements of densely populated places, and has strong self-extinguishing properties, extinguishing immediately upon removal of the flame, without dripping molten material, thus preventing the spread of fire. This material is environmentally friendly and non-toxic, suitable for scenarios with stringent environmental and personal safety requirements, such as subways, hospitals, and data centers.

[0032] In actual use, it was found that the outer sheath 8 is the outermost layer of the cable. Once ignited, it can easily spread along the cable path. Furthermore, due to the thermal conductivity of the metal inside the cable, the inside and outside of the cable can be heated simultaneously, which can damage the entire cable.

[0033] In another embodiment of the present invention, a folding ring 11 is provided on the outer sheath 8. One end of the folding ring 11 is movably connected to the outer sheath 8, and the other end is bonded to the outer sheath 8 by hot melt adhesive. A triggering component is provided in the heat insulation layer 7 for folding the folding ring 11 outward after the hot melt adhesive melts. Specifically, the folding ring 11 and the outer sheath 8 are integral. By cutting an annular slit along the cross-section of the outer sheath 8, the end portion of the outer sheath 8 at this slit is the folding ring 11. The folding ring 11 is not bonded or otherwise fixed to the heat insulation layer 7. At this slit, the folding ring 11 is bonded to one end of the other side of the outer sheath 8 by hot melt adhesive. The folding ring 11 is elastic and can accommodate deformation when folded outward. Two folding rings 11 are arranged symmetrically. The triggering component is triggered when the end of the folding ring 11 bonded to the outer sheath 8 by hot melt adhesive is heated, causing the hot melt adhesive to melt and the end of the folding ring 11 to resume its movement. The triggering component causes the folding ring 11 to fold outward, thereby disconnecting it from the outer sheath 8 on one side and forming a gap, which can avoid direct heat conduction and the spread of combustion.

[0034] As a preferred embodiment, the triggering component includes an annular groove 12 disposed inside the heat insulation layer 7 near the isolation section. An isolation ring 13 is movably disposed within the annular groove 12. An explosive body 14 is disposed on one side of the isolation ring 13 near the isolation section, and a metal sheet 15 is disposed on the other side. One end of the metal sheet 15 is fixedly connected to one end of the outer sheath 8 bonded to the folding ring 11, while the other end is thermally connected to the explosive body 14. Specifically, the annular groove 12 is disposed inside the heat insulation layer 7 and outside the isolation layer 6; the isolation ring 13 moves axially within the annular groove 12; the explosive body 14 is preferably an azide compound, triggered by high temperature. The trigger temperature is 270-300℃, and the melting temperature of the hot melt adhesive bonded between the folding ring 11 and the outer sheath 8 is around 270℃. The explosive body 14 triggers an explosion, generating a large amount of gas. The metal sheet 15 is preferably a copper alloy with good thermal conductivity, keeping the temperature of the hot melt adhesive approximately the same as the temperature of the explosive body 14. The metal sheet 15 is bent and has a certain degree of elasticity. Preferably, there are multiple metal sheets 15, evenly arranged circumferentially on the isolation ring 13. Each metal sheet 15 is connected to one end of the folding ring 11 to form a metal ring. One side of the metal ring is fixedly connected to the folding ring 11, and the other side is bonded to the outer sheath 8 by hot melt adhesive. When the hot melt adhesive melts, the molten hot melt adhesive continues to transfer heat to the metal sheet 15. As the temperature continues to rise, the explosive body 14 is quickly triggered to explode. The explosive body 14 explodes on the side of the isolation ring 13 near the isolation section, which pushes the isolation ring 13 away from the isolation section. Then, the isolation ring 13 pushes the folding ring 11 to fold over through the metal sheet 15.

[0035] As a preferred technical solution of this embodiment, the heat insulation layer 7 is provided with a guide groove 16 that matches the metal sheet 15. A throat groove 17 is provided between the annular groove 12 and the guide groove 16 to communicate. The metal sheet 15 is disposed through the throat groove 17. An extrusion member 18 that matches the throat groove 17 is provided on the isolation ring 13. Specifically, the inner wall of the guide groove 16 is provided with an arc-shaped slope. When the metal sheet 15 moves, it slides along the slope. Thus, when the isolation ring 13 pushes the metal sheet 15, the metal sheet 15 extends outward and bends further to complete the action of driving the folding ring 11 to fold. The width of the inner wall of the throat groove 17 near the annular groove 12 is greater than the width of the inner wall near the guide groove 16. The throat groove 17 and the extrusion member 18 are wedge-shaped. The end of the extrusion member 18 is provided with an elastic protrusion. The width of the end of the extrusion member 18 with the protrusion is greater than the minimum inner wall width of the throat groove 17 in the free state. In actual use, the isolation ring 13 is pushed by the explosive body 14 under the force of the explosion. The isolation ring 13 drives the extrusion member 18 to squeeze through the throat groove 17. During this process, the protrusion at the end of the extrusion member 18 is first compressed and then reset, and then locked into the end of the throat groove 17 near the guide groove 16. This fixes the isolation ring 13, maintaining the outward folding state of the folding ring 11 on the one hand, and sealing the throat groove 17 on the other hand to prevent the gas generated by the explosion of the explosive body 14 from leaking outward.

[0036] As a preferred technical solution in this embodiment, the annular groove 12 is provided with a vent 19 that connects to the interior of the isolation section on the side near the isolation section. A displacement ring 20 that blocks the vent 19 is provided inside the isolation section. Multiple circumferentially arranged interactive holes 21 are provided on both the inner and outer walls of the displacement ring 20. Specifically, the vent 19 is used to guide the gas generated after the explosion of the explosive body 14 to the interior of the isolation section. The displacement ring 20 is set close to the vent 19. When the ceramizable mud 10 is not heated, it remains solid and the displacement ring 20 is limited to the edge of the ceramizable mud 10. When the ceramizable mud 10 is heated, it first transforms into a glass phase and then sintersects and solidifies. In practical use, after the explosive body 14 is triggered by explosion, a large amount of high-temperature gas is generated. Because the vent 19 is blocked by the displacement ring 20, the gas cannot flow through in time. Therefore, a large amount of gas is generated inside the annular groove 12 of the isolation ring 13 near the isolation section. This causes the isolation ring 13 to move away from the isolation section, triggering the folding ring 11 to fold outwards. After the isolation ring 13 can no longer move, more gas expands in the annular groove 12 and is then introduced into the vent 19. At this time, due to the overall thermal conductivity of the cable, it can be ceramicized. When the mud 10 is heated to a certain extent, it is in the glass phase and softens. Then, the gas in the annular groove 12 is discharged through the pore 19 and expands rapidly on the side of the displacement ring 20 near the pore 19, causing the displacement ring 20 to move away from the pore 19. During the movement, the interlocking holes 21 on the inner and outer walls of the displacement ring 20 allow high-temperature gas to pass through. Thus, the high-temperature gas mixes with the glass phase ceramizable mud 10, causing the ceramizable mud 10 to heat up rapidly for sintering and solidification, forming an effective heat-insulating ceramic structure that prevents heat from extending along the length of the cable.

[0037] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A fire-resistant cable for fire resistance testing under building fire temperature rise conditions, characterized in that, The structure includes a central reinforcing core (1), around which multiple copper conductors (2) are arranged closely. The copper conductors (2) are covered with an insulating layer (3). A protective layer (4), a metal sleeve (5), an isolation layer (6), a heat insulation layer (7), and an outer sheath (8) are arranged sequentially on the outside of the multiple copper conductors (2). The gaps between the protective layer (4) and each copper conductor (2) and between the reinforcing core (1) and each copper conductor (2) are filled with filling material (9). An isolation section is provided on the isolation layer (6) and the heat insulation layer (7). The isolation section is the middle part where the isolation layer (6) and the heat insulation layer (7) are separated, thus forming a cavity structure between the metal sleeve (5) and the outer sheath (8). In this part, the outer wall of the metal sleeve (5) and the inner wall of the outer sheath (8) are coated with a layer of ceramicizable mud (10), and there is a gap between the two layers of ceramicizable mud (10). The outer sheath (8) is made of low-smoke halogen-free polyolefin. The outer sheath (8) is provided with a folding ring (11). One end of the folding ring (11) is movably connected to the outer sheath (8), and the other end is bonded to the outer sheath (8) by hot melt adhesive. The heat insulation layer (7) is provided with a trigger component for folding the folding ring (11) outward after the hot melt adhesive melts. The triggering component includes an annular groove (12) provided inside the heat insulation layer (7) near the isolation section. An isolation ring (13) is movably provided in the annular groove (12). An explosive body (14) is provided on one side of the isolation ring (13) near the isolation section, and a metal sheet (15) is provided on the other side. One end of the metal sheet (15) is fixedly connected to one end of the outer sheath (8) of the folding ring (11), and the other end is thermally connected to the explosive body (14). The heat insulation layer (7) is provided with a guide groove (16) that matches the metal sheet (15). A throat groove (17) is provided between the annular groove (12) and the guide groove (16) to communicate. The metal sheet (15) passes through the throat groove (17). An extrusion piece (18) that matches the throat groove (17) is provided on the isolation ring (13).

2. The fire-resistant cable for the fire resistance test under building fire temperature rise conditions according to claim 1, characterized in that, The insulating layer (3) and the protective layer (4) are made of calcined mica tape.

3. The fire-resistant cable for the fire resistance test under building fire temperature rise conditions as described in claim 1, characterized in that, The metal sleeve (5) is made of aluminum.

4. The fire-resistant cable for the fire resistance test under building fire temperature rise conditions according to claim 1, characterized in that, The material of the isolation layer (6) is polyethylene.

5. The fire-resistant cable for the fire resistance test under building fire temperature rise conditions according to claim 1, characterized in that, The material of the heat insulation layer (7) is fireproof mud composed of magnesium hydroxide and aluminum hydroxide, or a silica aerogel layer, or a composite layer of fireproof mud and silica aerogel.

6. The fire-resistant cable for the fire resistance test under building fire temperature rise conditions according to claim 5, characterized in that, The silica aerogel layer is made of strip-shaped flexible aerogel felt, which is processed by multi-layer overlapping wrapping using a wrapping machine on a cable forming machine.

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