Flame-retardant polyethylene cable

Abstract

The present application relates to cable technical field, and disclose a kind of flame-retardant polyethylene cable, including multiple conductors, further comprising: multiple conductors are mutually fixed by filling block, and multiple circumferentially uniform distribution material reduction grooves are arranged in the outer wall of filling block;Fixedly connected with the inner sheath of filling block outer wall, the outer sheath is connected with the outer sheath of inner sheath outer wall, and annular structure storage groove is arranged between the inner sheath outer wall and the outer sheath inner wall, and the outer sheath is fixedly connected with the inner sheath by compression ring, and the storage groove is separated into multiple independent chambers along the conductor axis direction by compression ring;The present application can reduce the material between adjacent threading holes by material reduction groove, reduce the accumulation of heat in filling block, and the filling rope is placed in material reduction groove, can absorb the heat generated by local overload, delay temperature rise, improve short-time current carrying capacity, store flame-retardant gas in chamber, when flame burns chamber, carbon dioxide stored in the interior can be ejected from the flame of break, so as to inhibit combustion and reduce flame propagation ability.

Description

A flame-retardant polyethylene cable Technical Field

[0001] This invention relates to the field of cable technology, specifically to a flame-retardant polyethylene cable. Background Technology

[0002] Polyethylene (PE) cables are widely used due to their good electrical insulation and processing properties. However, ordinary polyethylene is a flammable material with a limiting oxygen index (LOI) of only about 17%. When exposed to fire, it is extremely easy to ignite and drips molten material, which helps to spread the fire. It cannot meet the requirements of current flame retardant standards (such as the B1 flame retardant requirement in GB 31247-2014 "Classification of Burning Performance of Cables and Optical Fibers").

[0003] Currently, common flame retardant modification methods mainly include adding halogenated or halogen-free flame retardants. Although halogenated flame retardants have high flame retardant efficiency, they release highly toxic and corrosive gases such as dioxins and hydrogen halides during combustion, and their use has been restricted in many countries. Commonly used halogen-free flame retardants, such as aluminum hydroxide and magnesium hydroxide, are environmentally friendly and produce low smoke, making them the most commonly used method in existing technologies.

[0004] However, existing flame-retardant polyethylene cables still have shortcomings: during use, due to the thick internal filler layer, heat easily accumulates at the filler layer, resulting in excessively high center temperature and causing the insulation layer to melt; in addition, existing cables lack fire extinguishing structures, making it difficult to effectively suppress the spread of fire. Summary of the Invention

[0005] This invention provides a flame-retardant polyethylene cable that reduces the wall thickness of the filler block 5 by opening a feeding groove on its outer wall, thereby reducing heat accumulation. An independent chamber for storing flame-retardant gas is fixedly set between the outer and inner sheaths. After the chamber is burned through in a fire, the gas can be sprayed towards the flames to achieve a fire extinguishing effect, thus solving the problems of heat accumulation and lack of fire extinguishing structure mentioned in the background art.

[0006] This invention provides the following technical solution:

[0007] A flame-retardant polyethylene cable includes multiple conductors and further comprises: multiple conductors fixed together by a filler block, wherein the filler block has a through hole, and the multiple conductors are respectively located in the through hole; the outer wall of the filler block has multiple circumferentially evenly distributed material reduction grooves; an inner sheath fixedly connected to the outer wall of the filler block, an outer sheath connected to the outer wall of the inner sheath, a storage groove with an annular structure between the inner wall of the outer sheath and the inner sheath, and the outer sheath is fixedly connected to the inner sheath by a pressure ring, the pressure ring dividing the storage groove into multiple independent chambers along the conductor axis, the chambers storing flame-retardant gas.

[0008] As a preferred embodiment of the present invention, a filling rope is provided in the material reduction groove, the filling rope extending along the axial direction of the conductor, and the filling rope is used for heat dissipation of the conductor.

[0009] As a preferred embodiment of the present invention, the filling rope comprises 60% sodium sulfate decahydrate; 10% sodium acetate trihydrate; 25% expanded perlite; 3% borax and 2% thickener.

[0010] As a preferred embodiment of the present invention, the outer wall of the filling block is fixedly connected to a wrapping layer, the outer wall of the filling rope abuts against the inner wall of the wrapping layer and the inner wall of the material reduction groove, and the outer wall of the wrapping layer is fixedly connected to a steel belt armor, and the inner wall of the inner sheath is fixedly connected to the outer wall of the steel belt armor.

[0011] As a preferred embodiment of the present invention, a first shielding layer is fixedly connected to the outer wall of the conductor, an insulating layer is fixedly connected to the outer wall of the first shielding layer, and a second shielding layer is fixedly connected to the outer wall of the insulating layer.

[0012] As a preferred embodiment of the present invention, both the first shielding layer and the second shielding layer are made of carbon black-filled semi-conductive polyolefin material.

[0013] As a preferred embodiment of the present invention, the insulating layer is made of nano-composite cross-linked flame-retardant polyethylene material.

[0014] As a preferred embodiment of the present invention, the insulating layer is composed of: high-density polyethylene: 100 parts, magnesium hydroxide: 40-50 parts, nano montmorillonite: 5-8 parts, ammonium polyphosphate: 8-10 parts, charring agent: 5 parts, triazine gas-source flame retardant: 3-5 parts, and radiation crosslinking sensitizer: 2-3 parts.

[0015] As a preferred embodiment of the present invention, a metal woven mesh is fixedly connected inside the outer sheath.

[0016] As a preferred embodiment of the present invention, the flame-retardant gas is carbon dioxide, and the gas pressure range is 0.05MPa-0.4MPa.

[0017] Compared with the prior art, the present invention provides a flame-retardant polyethylene cable, which has the following beneficial effects:

[0018] 1. In this flame-retardant polyethylene cable, by opening a uniformly distributed circumferentially distributed material-reducing groove on the outer wall of the filler block, the material between adjacent wire holes can be reduced, increasing the heat dissipation surface of the filler block, thereby reducing the accumulation of heat in the filler block. Moreover, the filler rope containing sodium sulfate decahydrate, sodium acetate trihydrate, expanded perlite, borax, and thickener placed in the material-reducing groove can absorb the heat generated by local overload, delay the temperature rise, and increase the short-term current carrying capacity.

[0019] 2. In this flame-retardant polyethylene cable, a storage tank for storing flame-retardant gas is provided between the inner sheath and the outer sheath. The storage tank forms an independent chamber along the conductor axis via a pressure ring. When the inner sheath or the outer sheath is ignited, the flame burns through the chamber, and the carbon dioxide stored inside can be ejected from the opening, thereby inhibiting combustion and reducing the flame propagation ability.

[0020] The parts of this device not described herein are the same as or can be implemented using existing technologies. This invention can reduce the material between adjacent wire holes by using a material reduction groove, thereby increasing the heat dissipation surface of the filler block and reducing the accumulation of heat in the filler block. Moreover, placing a filler rope in the material reduction groove can absorb the heat generated by local overload, delay the temperature rise, and increase the short-term current carrying capacity. The invention stores flame-retardant gas in the chamber. When the flame breaks through the chamber, the carbon dioxide stored inside can be ejected from the rupture, thereby inhibiting combustion and reducing the flame propagation ability. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, the elements or parts are not necessarily drawn to actual scale.

[0022] Figure 1 is a first-view perspective three-dimensional schematic diagram of the present invention;

[0023] Figure 2 is a second perspective perspective view of the present invention;

[0024] Figure 3 is a schematic diagram of the axial section of the present invention;

[0025] Figure 4 is a cross-sectional schematic diagram of the present invention;

[0026] Figure 5 is a three-dimensional schematic diagram of the filling block of the present invention;

[0027] Figure 6 is a three-dimensional schematic diagram of the filling rope of the present invention.

[0028] In the diagram: 1. Conductor; 2. First shielding layer; 3. Insulation layer; 4. Second shielding layer; 5. Filler block; 501. Threading hole; 502. Material reduction groove; 6. Wrapping tape layer; 7. Steel tape armor; 8. Inner sheath; 801. Outer sheath; 802. Storage tank; 803. Metal braided mesh; 9. Filler rope. Detailed Implementation

[0029] 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.

[0030] Referring to Figures 1-6, a flame-retardant polyethylene cable includes multiple conductors 1, preferably made of copper. Taking three conductors as an example, the three conductors are evenly distributed circumferentially. The diameter of the conductors 1 ranges from 5mm to 30mm, preferably 10mm. The cable also includes: multiple conductors 1 fixed together by a filler block 5. The filler block 5 has wire-passing holes 501, with each conductor 1 located within one of the holes 501. That is, three wire-passing holes 501 are provided, evenly distributed circumferentially, for fixing the conductors 1. Multiple evenly distributed material-reducing grooves 502 are provided on the outer wall of the filler block 5. There are two to six material-reducing grooves 502, preferably three, and the three are located between adjacent wire-passing holes 501. This allows for the reduction of material between adjacent wire-passing holes 501, reducing heat accumulation in the filler block 5. The axial section of the material-reducing groove 502 is V-shaped, with the larger opening facing the outer wall of the filler block 5. Of course, in other embodiments, the axial section of the material-reducing groove 502 can be rectangular or semi-circular. In use, by providing uniformly distributed circumferentially distributed material-reducing grooves 502 on the outer wall of the filler block 5, material between adjacent wire holes 501 can be reduced, increasing the heat dissipation surface of the filler block 5, thereby reducing heat accumulation within the filler block 5 and improving thermal stability and service life. An inner sheath 8 is fixedly connected to the outer wall of the filler block 5, and an outer sheath 801 is connected to the outer wall of the inner sheath 8. A ring-shaped storage groove 802 is formed between the inner wall of the outer sheath 801 and the outer wall of the inner sheath 8. The outer sheath 801 is fixedly connected to the inner sheath 8 by a pressure ring, which divides the storage groove 802 into multiple independent chambers along the axis of the conductor 1. These chambers store flame-retardant gas. In other words, by fitting the outer sheath 801 onto the outer wall of the inner sheath 8 and hot-pressing one end of the outer sheath 8 to the inner sheath 8 to form the storage groove 802, flame-retardant gas can be released from the opening of the storage groove 802. The interior is filled with a flame-retardant gas, preferably carbon dioxide, at a pressure range of 0.05 MPa to 0.4 MPa, preferably 0.1 MPa. After filling, the other end of the outer sheath 801 is also fixedly connected to the inner sheath 8 by hot pressing, that is, the pressure ring is hot-pressed. The pressure rings are evenly distributed along the axial direction of the conductor 1. At this time, the length of the chamber on the axial direction is 5 mm to 20 mm, preferably 10 mm, and the length of the pressure ring on the axial direction is greater than or equal to 5 mm, preferably 5 mm. In use, a storage tank 802 for storing the flame-retardant gas is provided between the inner sheath 8 and the outer sheath 801. The storage tank 802 forms an independent chamber along the axial direction of the conductor 1 via the pressure ring. When the inner sheath 8 or the outer sheath 801 is ignited, the flame burns through the chamber, and the carbon dioxide stored inside can be ejected from the rupture, thereby inhibiting combustion and reducing the flame propagation ability.

[0031] In use, by providing a material reduction groove 502 evenly distributed in a circular pattern on the outer wall of the filler block 5, the material between adjacent wire holes 501 can be reduced, increasing the heat dissipation surface of the filler block 5, thereby reducing the accumulation of heat in the filler block 5. Moreover, by placing a filler rope 9 composed of 60% sodium sulfate decahydrate, 10% sodium acetate trihydrate, 25% expanded perlite, 3% borax, and 2% thickener in the material reduction groove 502, the heat generated by local overload can be absorbed, the temperature rise can be delayed, and the short-term current carrying capacity can be increased.

[0032] By providing a storage tank 802 for storing flame-retardant gas between the inner sheath 8 and the outer sheath 801, the storage tank 802 forms an independent chamber along the axial direction of the conductor 1 via a pressure ring. When the inner sheath 8 or the outer sheath 801 is ignited, the flame burns through the chamber, and the carbon dioxide stored inside can be ejected from the opening, thereby suppressing combustion and reducing the flame propagation capability.

[0033] Referring to Figures 5 and 6, a filler rope 9 is provided inside the material reduction groove 502. The filler rope 9 extends along the axial direction of the conductor 1. In actual use, both ends of the material reduction groove 502 are sealed. When the cable is cut for use, the cut material reduction groove 502 is resealed with sealant. The filler rope 9 is used for heat dissipation of the conductor 1. The components of the filler rope 9 are 60% sodium sulfate decahydrate, 10% sodium acetate trihydrate, 25% expanded perlite, 3% borax, and 2% thickener. This composite material is a white granular solid that does not release any substances at room temperature. It absorbs heat and melts at high temperatures but does not flow, and recrystallizes after cooling. It is not suitable for high-frequency vibration environments.

[0034] In one embodiment, the filler rope 9 can also achieve heat absorption and temperature rise delay by incorporating an integrated phase change material (PCM). When the cable experiences localized overload and heating, the PCM undergoes a solid-liquid phase change at a specific temperature, absorbing a large amount of latent heat while maintaining a relatively constant temperature, effectively "locking in" excess heat and slowing down the temperature rise of the cable core. Simultaneously, the high specific heat capacity or thermally conductive material in the filler rope 9 can increase the overall heat capacity and promote lateral heat diffusion, preventing hot spot accumulation. Upon cooling, the PCM re-solidifies, releasing heat and achieving a reversible cycle.

[0035] In one embodiment, the filler rope 9 is further defined. The filler rope 9 absorbs heat generated by local overload and slows down the temperature rise rate. If the above components are simply made into a solid rope structure and placed in the heat-reducing groove 502, its ability to slow down the temperature rise is limited in actual use. This is mainly because during direct contact, a sudden increase in local temperature can damage the filler rope 9, thus limiting its heat absorption function. Therefore, the structure of the filler rope 9 is further optimized, specifically including an inner core heating layer, a middle core heat-conducting layer, and an outer heating layer. The outer heating layer has several heat-conducting plates on the side near the heat-reducing groove 502, and the heat-reducing groove 502 has several fins on the side facing the heating layer. The fins and heat-conducting plates are arranged alternately. The middle core heat-conducting layer is constructed by a heat-conducting wire spirally surrounding the outer layer of the inner core heating layer. Specifically, this heat-conducting wire is formed by a single heat-conducting wire... The outermost layer of the heating element begins to wind around the bottom. As it winds outward from the top, it continues downward, spiraling around the inner core heating layer without contacting it, thus forming a cavity structure. When the heating wire spirals back to near the bottom of the inner core heating layer, the process is repeated, extending outward and spiraling upward around the inner core heating layer, further forming a cavity structure. The outermost heating wire is close to the inner wall of the outer heating layer. Thermally conductive gel is also filled into the cavity structure of the inner core heating layer. The outer heating layer wraps around the inner core heating layer. The inner core heating layer is a solid body made by uniformly mixing 60% sodium sulfate decahydrate, 10% sodium acetate trihydrate, 25% expanded perlite, 3% borax, and 2% thickener; it can also be an integrated phase change material (PCM). The thermally conductive gel is formulated with silicone oil, thermally conductive filler, and crosslinking agent. The thermally conductive filler is boron nitride.

[0036] The outer heating layer is made of flexible aluminum foil, and the fins are mounted on the flexible aluminum foil.

[0037] By setting up a three-layer structure of filling rope 9, the outer heating layer, with its fins and heat-conducting plates arranged in an alternating pattern, can disperse and transfer high-temperature heat to the core heat-conducting layer in a shorter time, rapidly reducing the high temperature of the layout. By setting up a spiral structure of heat-conducting wires, the temperature has a stronger rotation and diversion structure in the construction space, so that the heat transferred to the core heat-conducting layer is circulated and dispersed within the core heat-conducting layer by the spiral heat-conducting wires. Under the action of the spiral heat-conducting wires, and in synergy with the heat-conducting gel, the cooling effect can be further dispersed and gradually transferred to the core heat-conducting layer, where the core heat-conducting layer performs the final heat absorption.

[0038] Referring to Figures 1-4, a wrapping layer 6 is fixedly connected to the outer wall of the filler block 5. The outer wall of the filler rope 9 abuts against the inner wall of the wrapping layer 6 and the inner wall of the material reduction groove 502. A steel strip armor 7 is fixedly connected to the outer wall of the wrapping layer 6. The inner wall of the inner sheath 8 is fixedly connected to the outer wall of the steel strip armor 7. One or two layers of cold-rolled steel strips are spirally wrapped around the wrapping layer 6. Here, one layer is taken as an example. The mechanical protection capability of the cable is greatly improved at a lower cost. It is especially suitable for fixed laying environments that need to withstand pressure, impact, extrusion and biological damage.

[0039] A first shielding layer 2 is fixedly connected to the outer wall of conductor 1. An insulating layer 3 is fixedly connected to the outer wall of the first shielding layer 2, and a second shielding layer 4 is fixedly connected to the outer wall of the insulating layer 3. The first shielding layer 2 is closely attached to the outer surface of conductor 1 and located between conductor 1 and insulating layer 3. It can fill unevenness on the surface of conductor 1 (such as stranding gaps), avoid electric field concentration, eliminate small air gaps between conductor 1 and insulation, prevent partial discharge, and form a uniform cylindrical electric field distribution. The second shielding layer 4 is located on the outer surface of insulating layer 3. It can smooth the outer surface of the main insulation, eliminate air gaps between insulation and metal shielding, and make the electric field uniformly distributed along the radial direction of the cable, providing a good grounding path in case of fault. Both the first shielding layer 2 and the second shielding layer 4 are made of carbon black-filled semi-conductive polyolefin material. That is, cross-linked polyethylene is used as the matrix, and conductive agents such as carbon black are added. The formulation of the second shielding layer 4 is more refined, focusing on surface smoothness and peel performance.

[0040] Insulation layer 3 is made of nano-composite cross-linked flame-retardant polyethylene material. Here, the composition of insulation layer 3 (nano-composite cross-linked flame-retardant polyethylene material) is as follows: high-density polyethylene (HDPE): 100 parts, magnesium hydroxide (surface silane modified): 40-50 parts, nano-montmorillonite (OMMT): 5-8 parts, ammonium polyphosphate (APP): 8-10 parts, charring agent (pentaerythritol PER): 5 parts, triazine gas-source flame retardant: 3-5 parts, and radiation cross-linking sensitizer (trimethylolpropane trimethacrylate TMPTMA): 2-3 parts. Through a synergistic flame-retardant mechanism of "condensed phase and gas phase," the nanofiller forms a dense char layer, APP / PER promotes charring, and magnesium hydroxide absorbs heat and releases water vapor to dilute combustible gases, significantly increasing the LOI to over 30%, while reducing the total amount of flame retardant added and maintaining the material's toughness.

[0041] The outer sheath 801 is internally fixed with a metal braided mesh 803, which improves the explosion-proof effect of the outer sheath 801 during use. The materials of the inner sheath 801 and the outer sheath 801 are: 60 parts ethylene-vinyl acetate copolymer (EVA, VA content 40%), 40 parts linear low-density polyethylene (LLDPE), 100 parts aluminum hydroxide (microencapsulated), 0.5-1.0 parts graphene oxide, 2 parts anti-dripping agent (polytetrafluoroethylene micropowder), and appropriate amounts of processing aids (lubricant, antioxidant). The introduction of graphene forms a three-dimensional network structure, enhancing the strength of the carbon layer and inhibiting heat transfer; microencapsulated aluminum hydroxide improves compatibility with the matrix and enhances mechanical properties.

[0042] In this invention, during use, by providing uniformly distributed circumferentially distributed material-reducing grooves 502 on the outer wall of the filler block 5, the material between adjacent wire holes 501 can be reduced, increasing the heat dissipation surface of the filler block 5, thereby reducing the accumulation of heat within the filler block 5. Furthermore, placing a filler rope 9 with a composition of 60% sodium sulfate decahydrate, 10% sodium acetate trihydrate, 25% expanded perlite, 3% borax, and 2% thickener within the material-reducing grooves 502 can absorb heat generated by localized overload, delay temperature rise, and increase short-term current carrying capacity. A storage tank 802 for storing flame-retardant gas is provided between the inner sheath 8 and the outer sheath 801. The storage tank 802 forms an independent chamber along the conductor 1 axis via a pressure ring. When the inner sheath 8 or the outer sheath 801 is ignited, the flame breaks through the chamber, and the carbon dioxide stored inside can be ejected from the rupture, thereby suppressing combustion and reducing flame propagation.

[0043] Specifically, the material composition of insulation layer 3 is as follows: High-density polyethylene (HDPE, 100 parts): As the continuous matrix material of insulation layer 3, HDPE has excellent electrical insulation, chemical corrosion resistance, and processing fluidity. Its molecular chain is regular and its crystallinity is high, which gives the cable good mechanical strength and resistance to environmental stress cracking. It is a traditional preferred material for medium and low voltage cable insulation; Surface silane-modified magnesium hydroxide (40 to 50 parts): Magnesium hydroxide [Mg(OH)2] is a typical halogen-free environmentally friendly flame retardant. At high temperature (340℃), it decomposes into magnesium oxide and water vapor, absorbing a large amount of heat and diluting combustible gases, effectively inhibiting the spread of flames. Surface silane modification can significantly improve its compatibility with HDPE matrix, reduce agglomeration, and improve dispersion uniformity, thus maintaining good mechanical and dielectric properties even at high filler content; Nano-montmorillonite (OMMT, 5-8 parts): Organically intercalated montmorillonite (OMMT) can form a "layered silicate nanocomposite structure" in the polymer, which acts as a physical barrier: it promotes the formation of a dense char layer during combustion, hindering heat and oxygen transfer; at the same time, it improves the tensile strength, heat distortion temperature and dimensional stability of the material, and improves anti-aging performance; Ammonium polyphosphate (APP, 8-10 parts) and charring agent (PER, 5 parts): APP is a highly efficient acid-gas source intumescent flame retardant. When heated, it decomposes to produce phosphoric acid substances, which catalyze the dehydration of PER (pentaerythritol) to form a porous and heat-insulating intumescent char layer. This char layer effectively isolates the ignition source and reduces the heat release rate, achieving an "expansion flame retardant" effect and significantly improving the limiting oxygen index (LOI) and UL-94 flame retardant rating of the material. Triazine-based gas-source flame retardants (3-5 parts): such as melamine derivatives, release non-flammable gases (e.g., NH3) upon heating, diluting the oxygen concentration and participating in the construction of the expansion char layer, enhancing the synergistic flame retardant effect. Their high nitrogen content and thermal stability make them an excellent complement to the APP / PER system. Irradiation crosslinking sensitizer (TMPTMA, 2-3 parts): Trimethylolpropane trimethacrylate (TMPTMA) contains three polymerizable double bonds, significantly improving the crosslinking efficiency of HDPE under electron beam or gamma ray irradiation. After crosslinking, a three-dimensional network structure is formed, greatly improving the material's heat resistance (operating temperature up to 105℃–125℃), creep resistance, environmental stress cracking resistance, and short-circuit overload capacity.

[0044] In addition, the specific processing method of insulation layer 3 is as follows: Raw material pretreatment: Dry the powder additives such as magnesium hydroxide, OMMT, APP, and PER at 80℃-100℃ for 4 hours to remove moisture; silane-modified magnesium hydroxide does not require additional treatment, but must be stored in a moisture-proof environment; Dry mixing and premixing: Weigh each component according to the formula ratio and mix in a high-speed mixer for 10-15 minutes to ensure that the powder is evenly dispersed in the HDPE granules to obtain a premix; Twin-screw extrusion granulation: Melt blending is performed using a co-rotating parallel twin-screw extruder: Temperature setting: 160℃–190℃ (gradually increasing temperature from feed to die). Screw speed: 200rpm-300rpm. Vacuum degassing: Remove moisture and volatiles. After cooling, the extruded strip is granulated to obtain flame-retardant cross-linked HDPE cable material; Extrusion insulation layer 3: A three-layer co-extrusion production line is used to uniformly coat the masterbatch onto the shielded copper core of conductor 1 through an extruder; Die design ensures concentricity, extrusion temperature: 170℃-190℃, and cooling water tank for staged cooling to prevent internal stress; Irradiation cross-linking: The extruded cable is irradiated and cross-linked through an electron accelerator, with an irradiation dose of 80kGy-120kGy. Under the action of TMPTMA, a CC bond cross-linking network is formed between HDPE molecular chains; Testing and finished products: After cross-linking, electrical tests (partial discharge, breakdown strength), flame retardancy tests (LOI≥30%, V-0 grade), thermal elongation tests, etc. are performed. After passing the tests, the cables are packaged into reels.

[0045] Components not described in detail in this article are existing technologies.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flame-retardant polyethylene cable, comprising multiple conductors (1), characterized in that, Also includes: Multiple conductors (1) are fixed together by a filler block (5), wherein the filler block (5) has a wire hole (501), and the multiple conductors (1) are respectively located in the wire hole (501). The outer wall of the filler block (5) is provided with multiple circumferentially evenly distributed material reduction grooves (502). An inner sheath (8) is fixedly connected to the outer wall of the filler block (5), and an outer sheath (801) is connected to the outer wall of the inner sheath (8). A storage groove (802) with an annular structure is provided between the inner wall of the outer sheath (801) and the inner sheath (8). The outer sheath (801) is fixedly connected to the inner sheath (8) by a pressure ring. The pressure ring divides the storage tank (802) into multiple independent chambers along the axial direction of the conductor (1). The chambers store flame-retardant gas. A filling rope (9) is provided in the material reduction tank (502). The filling rope (9) extends along the axial direction of the conductor (1). The filling rope (9) is used for heat dissipation of the conductor (1). The components in the filling rope (9) include 60% sodium sulfate decahydrate, 10% sodium acetate trihydrate, 25% expanded perlite, 3% borax, and 2% thickener.

2. The flame-retardant polyethylene cable according to claim 1, characterized in that, The outer wall of the filling block (5) is fixedly connected to the wrapping layer (6), the outer wall of the filling rope (9) abuts against the inner wall of the wrapping layer (6) and the inner wall of the material reduction groove (502) respectively, and the outer wall of the wrapping layer (6) is fixedly connected to the steel belt armor (7), and the inner wall of the inner sheath (8) is fixedly connected to the outer wall of the steel belt armor (7).

3. The flame-retardant polyethylene cable according to claim 1, characterized in that, The conductor (1) has a first shielding layer (2) fixedly connected to its outer wall, an insulating layer (3) fixedly connected to its outer wall, and a second shielding layer (4) fixedly connected to its outer wall.

4. The flame-retardant polyethylene cable according to claim 3, characterized in that, The first shielding layer (2) and the second shielding layer (4) are both made of carbon black-filled semi-conductive polyolefin material.

5. A flame-retardant polyethylene cable according to claim 3, characterized in that, The insulating layer (3) is made of nano-composite cross-linked flame-retardant polyethylene material.

6. A flame-retardant polyethylene cable according to claim 5, characterized in that, The insulating layer (3) is composed of: high-density polyethylene: 100 parts, magnesium hydroxide: 40-50 parts, nano montmorillonite: 5-8 parts, ammonium polyphosphate: 8-10 parts, charring agent: 5 parts, triazine gas-source flame retardant: 3-5 parts, and radiation crosslinking sensitizer: 2-3 parts.

7. A flame-retardant polyethylene cable according to claim 1, characterized in that, A metal woven mesh (803) is fixedly connected inside the outer sheath (801).

8. A flame-retardant polyethylene cable according to claim 1, characterized in that, The flame-retardant gas is carbon dioxide, with a pressure range of 0.05 MPa to 0.4 MPa.

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