Environment-friendly flame-retardant medium-voltage cable

Abstract

The invention discloses an environment-friendly flame-retardant medium-voltage cable, and relates to the technical field of cables, the outer side of an inner conductor is provided with a flame-retardant protection assembly, the flame-retardant protection assembly comprises flame-retardant filling bodies, the middle parts of the opposite side surfaces of the adjacent flame-retardant filling bodies are provided with supporting grooves, and arc-shaped spring plates are adhered to the interiors of the supporting grooves. The outer side of the cable is extruded and collided, the impact force is attenuated layer by layer, the situation that the cable is damaged due to collision and impact is reduced, when the outer side of the cable is frozen, the heating wire emits heat, and the cable is prevented from being damaged. When the cable is deiced, the inflatable strip outside the insulating middle layer is uniformly heated, the outer insulating layer is pushed to bulge, and the ice layer outside is jacked open, so that the ice layer is broken and falls off, and compared with the conventional deicing method which only depends on heating, the energy consumption is lower, the cable is environment-friendly and energy-saving, the deicing effect is better, and the cable is more favorably protected.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cables, in particular to an environmentally friendly flame-retardant medium-voltage cable. BACKGROUND

[0002] Medium-voltage cables are key equipment for power transmission systems, with typical voltage levels of 6-35kV, and are mainly used in urban power distribution and industrial power supply scenarios. The number of cores of a medium-voltage cable needs to be determined according to the type of power supply system, load characteristics, and use scenarios. Commonly used cores include three, four, and five. Environmentally friendly cables refer to cable products made of environmentally friendly materials, meeting safety standards, and having less impact on the environment, and are mainly used for power transmission and signal processing.

[0003] However, the environmentally friendly medium-voltage cables on the market have complex use environments, compact internal structures, and poor impact resistance. During laying and use, the outer insulation layer is often broken due to external collisions or extrusion, and the insulation layer is easily damaged due to icing in cold environments, which can easily cause fires and other safety problems during subsequent use. SUMMARY

[0004] The present application provides an environmentally friendly flame-retardant medium-voltage cable that can effectively solve the problems of environmentally friendly medium-voltage cables with complex use environments, compact internal structures, and poor impact resistance, which often cause the outer insulation layer to break due to external collisions or extrusion during laying and use, and the insulation layer is easily damaged due to icing in cold environments, which can easily cause fires and other safety problems during subsequent use.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solution: an environmentally friendly flame-retardant medium-voltage cable, comprising an inner conductor, a flame-retardant protection assembly is installed on the outer side of the inner conductor, the flame-retardant protection assembly comprises a flame-retardant filler; The inner conductor is wrapped with a flame-retardant filler, support grooves are formed in the middle of the opposite sides of adjacent flame-retardant fillers, and a pad is uniformly bonded inside each support groove. Two opposite pads are respectively connected to the two sides of an arc-shaped spring plate, and the arc-shaped spring plate is bonded inside the support groove. A reinforced braided tube is arranged between three flame-retardant fillers, the reinforced braided tube is filled with an aluminum hydroxide bag, and a center support block is uniformly sleeved on the outer side of the reinforced braided tube. The opposite sides of adjacent center support blocks are respectively bonded to the two ends of a connecting rubber block.

[0006] According to the above technical solution, the outer side of the flame-retardant filler is wrapped with a heat-conducting layer, the heat-conducting layer is provided with a heating groove near the gap between the flame-retardant fillers, a heating wire is inlaid in the heating groove, and the outer side of the heating wire is wrapped with heat-conducting silica gel.

[0007] According to the technical scheme, the heat-conducting layer is wrapped with an insulating middle layer, the insulating middle layer is uniformly distributed with isolation strips, the isolation strips are uniformly embedded with inflation strips, the isolation strips are wrapped with an outer insulating layer, and the outer insulating layer is wrapped with an outer protective film.

[0008] According to the technical scheme, the end face of the flame-retardant filling body is in the shape of one-third of a semicircle, and three flame-retardant filling bodies are combined into a cylinder.

[0009] According to the technical scheme, the center support block and the connecting rubber block have the same end face shape, the flame-retardant filling body is provided with a heat-conducting groove near the center support block, and the end of the center support block contacts the outer side of the inner conductor.

[0010] According to the technical scheme, the flame-retardant filling body is provided with a groove corresponding to the heat-generating groove on the outer side, and the heat-conducting silica gel is curved on the side close to the insulating middle layer.

[0011] According to the technical scheme, the outer protective film is provided with a replacement and impurity removal assembly on the outer side, and the replacement and impurity removal assembly comprises a replacement semicircular shovel. The outer protective film is symmetrically sleeved with a replacement semicircular shovel on the outer side, one end of the replacement semicircular shovel is welded with a guide edge, a rolling groove is formed in the end of the guide edge away from the replacement semicircular shovel, and rolling rods are uniformly rotatably embedded in the rolling groove. Symmetrical connection buffer grooves are formed in the end of the guide edge, blind pipes are movably embedded in the connection buffer grooves, one end of each blind pipe is fixedly connected with one end of the connection buffer groove, and a connection end block is arranged between the two blind pipes opposite to the two ends of the connection spring. Arc-shaped reinforcing rods are symmetrically welded in the middle of the transmission connecting rod, and splicing hook plates are welded at the two ends of the arc-shaped reinforcing rods.

[0012] According to the technical scheme, the replacement semicircular shovel is in the structure of a semicircular cylinder with a rounded corner at one end, the inner diameter of the replacement semicircular shovel is equal to the outer diameter of the outer protective film, and the inner side of the replacement semicircular shovel is a smooth curved surface.

[0013] According to the technical scheme, the end face of the connection end block is T-shaped, a clamping hole is symmetrically formed in one end of the blind pipe, a clamping rod is welded at the connection end block corresponding to the clamping hole, a connecting screw is penetratingly arranged at the connection end block close to the clamping rod, and the connecting screw is threadedly connected with the blind pipe.

[0014] According to the technical scheme, the thickness of the arc-shaped reinforcing rod is twice the thickness of the splicing hook plate, and the two splicing hook plates located at the same arc-shaped reinforcing rod are staggered.

[0015] Compared with the prior art, the present application has the following advantages: 1. It is equipped with flame-retardant protection components. The central support block and connecting rubber block are alternately sleeved on the outside of the reinforced braided tube as internal support for the cable, providing support. The connecting rubber block connects to the adjacent central support block to prevent the middle from collapsing while facilitating bending of the cable during use. During cable laying, if the outer side of the cable is squeezed and collided, the impact force is buffered by the air strip between the middle and outer insulation layers, reducing the impact transmitted to the inside of the cable. Then, it is buffered and absorbed by the pads and arc-shaped spring plates between the combined flame-retardant fillers. Finally, it is transmitted to the center of the cable, which is composed of the central support block and the connecting rubber block. The impact force is attenuated layer by layer, protecting the cable, reducing the damage caused by collisions and impacts, and reducing the breakage of its outer insulation layer, making the cable safer to use. When ice forms on the outside of the cable, the power to the heating wire is turned on. The heating wire heats up, and the heat is transferred to the heat-conducting layer through the thermally conductive silicone. This heat evenly heats the air-filled strip on the outside of the insulation layer. As the carbon dioxide inside the air-filled strip contracts when it freezes in the outside and expands when heated, it pushes the outer insulation layer up, breaking open the outer ice layer and causing it to break and fall off. This method utilizes the combined physical effects of the heating wire and the expansion of the gas. Compared to existing methods that rely solely on heating for de-icing, this method consumes less energy, is more environmentally friendly and energy-saving, has a better de-icing effect, and is more beneficial for cable protection. If the cable temperature continues to rise, the aluminum hydroxide in the aluminum hydroxide bag inside the reinforced braided tube decomposes. Under the combined action of air pressure and high temperature, the connection between the central support block and the connecting rubber block separates. Due to the restoring effect of the arc-shaped spring plate, gaps appear between the flame-retardant fillers. While absorbing heat, it separates each inner conductor, preventing the problematic inner conductors from coming into contact with each other and short-circuiting. It absorbs heat, cools down, and retards the flame while protecting the cable, preventing more serious problems from occurring in the cable, thus enhancing safety.

[0016] 2. Equipped with a replacement cleaning component, when ice or debris adheres to the outside of the cable, affecting maintenance, a replacement semi-circular shovel is engaged on the outside of the cable. Pulling the replacement cleaning component along the cable causes the rolling rod inside the guide edge to roll along the outside of the cable. The reciprocating movement of the replacement semi-circular shovel removes the attached debris and ice from the outside of the cable. During the pulling process, the connecting spring between the buffer groove and the blind tube deforms, changing the spacing of the replacement semi-circular shovel in accordance with the cable bending, preventing the replacement semi-circular shovel from scratching the outside of the cable, keeping the outside of the cable clean, facilitating maintenance, and also preventing ice from damaging the cable. In summary, during the process of replacing the cleaning components to scrape away ice on the outside of the cable, it can be used in conjunction with the flame-retardant protection components. The expansion and contraction of the air bar and the deformation of the outer insulation layer of the cable during the movement of the replacement semi-circular shovel accelerate the removal of the ice layer. The two components working together can achieve a better de-icing effect. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0018] In the attached diagram: Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the structure of the flame-retardant protection component of the present invention; Figure 3 This is a schematic diagram of the installation structure of the inflatable strip of the present invention; Figure 4 This is a schematic diagram of the mounting structure of the pad of the present invention; Figure 5 This is the present invention. Figure 4 A schematic diagram of the structure of region A; Figure 6 This is a schematic diagram of the structure of the replacement impurity removal component of the present invention; Figure 7 This is a schematic diagram of the installation structure of the rolling rod of the present invention; Figure 8 This is the present invention. Figure 7 A schematic diagram of the structure of region B; Figure 9 This is a schematic diagram of the installation structure of the arc-shaped reinforcing rod of the present invention; Labels in the diagram: 1. Inner conductor; 2. Flame-retardant protective components; 201. Flame-retardant filler; 202. Support groove; 203. Pad; 204. Arc-shaped spring plate; 205. Reinforced braided tube; 206. Aluminum hydroxide bag; 207. Central support block; 208. Connecting rubber block; 209. Thermal conductive layer; 210. Heating groove; 211. Heating wire; 212. Thermally conductive silicone; 213. Insulating middle layer; 214. Isolation strip; 215. Inflatable strip; 216. Outer insulation layer; 217. Outer protective film; 218. Thermal conductive groove; 3. Replace the impurity removal components; 301. Replace the semi-circular shovel; 302. Guide edge; 303. Rolling groove; 304. Rolling rod; 305. Connecting buffer groove; 307. Blind tube; 308. Connecting spring; 309. Connecting end block; 310. Transmission connecting rod; 311. Arc-shaped reinforcing rod; 312. Splicing hook plate; 313. Snap-fit ​​hole; 314. Snap-fit ​​rod; 315. Connecting screw. Detailed Implementation

[0019] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0020] Example: Figures 1-9As shown, the present invention provides an environmentally friendly flame-retardant medium-voltage cable technical solution, including an inner conductor 1, and a flame-retardant protection component 2 installed on the outside of the inner conductor 1. The flame-retardant protection component 2 includes a flame-retardant filler 201, a support groove 202, a pad 203, an arc-shaped spring plate 204, a reinforced braided tube 205, an aluminum hydroxide bag 206, a central support block 207, a connecting rubber block 208, a heat-conducting layer 209, a heating groove 210, a heating wire 211, a heat-conducting silicone 212, an insulating middle layer 213, a separator strip 214, an air-filled strip 215, an outer insulation layer 216, an outer protective film 217, and a heat-conducting groove 218. The inner conductor 1 is wrapped with a flame-retardant filler 201. The end face of the flame-retardant filler 201 is one-third semi-circular. The three flame-retardant fillers 201 are combined to form a cylinder to maintain the circular cross-section of the cable. Support grooves 202 are opened in the middle of the opposite sides of adjacent flame-retardant fillers 201. A pad 203 is evenly bonded inside the support groove 202. Two opposite pads 203 are respectively connected to the two sides of the arc-shaped spring plate 204. The arc-shaped spring plate 204 is bonded inside the support groove 202. A spacer is provided between the three flame-retardant fillers 201. The reinforced braided tube 205 is filled with an aluminum hydroxide bag 206. A central support block 207 is uniformly sleeved on the outside of the reinforced braided tube 205. The opposite faces of adjacent central support blocks 207 are respectively bonded to the two ends of the connecting rubber block 208. The end faces of the central support block 207 and the connecting rubber block 208 have the same shape. A heat-conducting groove 218 is opened on the flame-retardant filler 201 near the central support block 207. The end of the central support block 207 contacts the outside of the inner conductor 1 to accelerate heat transfer and facilitate the decomposition of aluminum hydroxide. The flame-retardant filler 201 is covered with a heat-conducting layer 209 on its outer side. A heating groove 210 is provided in the gap between the heat-conducting layer 209 and the flame-retardant filler 201. A heating wire 211 is embedded in the heating groove 210. The heating wire 211 is covered with a heat-conducting silicone 212 on its outer side. An insulating middle layer 213 is covered on the outer side of the heat-conducting layer 209. A groove is opened on the outer side of the flame-retardant filler 201 corresponding to the heating groove 210. The side of the heat-conducting silicone 212 near the insulating middle layer 213 is curved to improve the heat conduction effect. Isolation strips 214 are evenly distributed on the outer side of the insulating middle layer 213. An inflation strip 215 is evenly embedded between the isolation strips 214. An outer insulating layer 216 is covered on the outer side of the isolation strips 214. An outer protective film 217 is covered on the outer side of the outer insulating layer 216.

[0021] A replacement impurity removal component 3 is installed on the outside of the outer protective film 217. The replacement impurity removal component 3 includes a replacement semi-circular shovel 301, a guide edge 302, a rolling groove 303, a rolling rod 304, a connecting buffer groove 305, a blind tube 307, a connecting spring 308, a connecting end block 309, a transmission connecting rod 310, an arc-shaped reinforcing rod 311, a splicing hook plate 312, a snap-fit ​​hole 313, a snap-fit ​​rod 314, and a connecting screw 315. A replacement semi-circular shovel 301 is symmetrically fitted onto the outer side of the outer protective film 217. The replacement semi-circular shovel 301 is a semi-cylindrical structure with one end rounded. The inner diameter of the replacement semi-circular shovel 301 is equal to the outer diameter of the outer protective film 217. The inner side of the replacement semi-circular shovel 301 is a smooth curved surface, which facilitates the sliding of the replacement semi-circular shovel 301 along the outer side of the cable. A guide edge 302 is welded to one end of the replacement semi-circular shovel 301. A rolling groove 303 is opened at the end of the guide edge 302 away from the replacement semi-circular shovel 301. A rolling rod 304 is uniformly embedded inside the rolling groove 303. A connecting buffer groove 305 is symmetrically opened at the end of the guide edge 302. A blind tube 307 is movably embedded inside the connecting buffer groove 305. One end of the blind tube 307 and one end of the connecting buffer groove 305 are respectively fixedly connected to the two ends of the connecting spring 308. A connecting tube is installed between the two opposite blind tubes 307. The end block 309 has a T-shaped end face. One end of the blind tube 307 has symmetrically opened snap-fit ​​holes 313. The connecting end block 309 is welded with snap-fit ​​rods 314 corresponding to the snap-fit ​​holes 313. A connecting screw 315 is installed through the connecting end block 309 near the snap-fit ​​rod 314. The connecting screw 315 is threaded to the blind tube 307, which facilitates the installation and fixing of the transmission connecting rod 310. Two connecting end blocks 309 at the same height are respectively welded to both ends of the transmission connecting rod 310. A curved reinforcing rod 311 is symmetrically welded in the middle of the transmission connecting rod 310. A splicing hook plate 312 is welded to both ends of the curved reinforcing rod 311. The thickness of the curved reinforcing rod 311 is twice the thickness of the splicing hook plate 312. The two splicing hook plates 312 located on the same curved reinforcing rod 311 are staggered to facilitate the overlapping combination of the splicing hook plates 312. The working principle and usage process of this invention: The reinforcing braided tube 205 is a carbon fiber braided tube. The aluminum hydroxide bag 206 is filled with aluminum hydroxide powder and placed inside the reinforcing braided tube 205. The central support block 207 and the connecting rubber block 208 are alternately sleeved on the outside of the reinforcing braided tube 205 as internal support for the cable. The central support block 207 is made of aluminum alloy and provides support. The connecting rubber block 208 connects the adjacent central support block 207 to prevent the middle from collapsing and to facilitate bending of the cable during use. An environmentally friendly flame-retardant filler 201 is wrapped around the outer side of the inner conductor 1. Then, an arc-shaped spring plate 204 with mounting pads 203 on both sides is placed in the support groove 202. The pads 203 are glued and fixed in the support groove 202. The three flame-retardant fillers 201 are then combined together with the central support block 207 and the connecting rubber block 208 as the center. The heat-conducting layer 209 is wrapped around the outside of the flame-retardant filler 201. The heat-conducting layer 209 is mica tape wrapped around the outside of the flame-retardant filler 201. A heating wire 211 is embedded in the heating groove 210. The insulating middle layer 213 and the isolation strip 214 are then wrapped around the outside of the heat-conducting layer 209 by an extruder. An air-filling strip 215 is filled in the gap between the isolation strips 214. The air-filling strip 215 contains carbon dioxide. The outer insulation layer 216 is wrapped again by an extruder. Finally, an outer protective film 217 is wrapped around the outside of the outer insulation layer 216 by a wrapping machine. The outer protective film 217 is a carbon fiber film. During cable laying, if the outer side of the cable is squeezed and collided, the impact force is buffered by the air strip 215 between the insulation middle layer 213 and the outer insulation layer 216, reducing the impact transmitted to the inside of the cable. Then, it is buffered and absorbed by the pad 203 and the arc spring plate 204 between the combined flame-retardant fillers 201. Finally, it is transmitted to the center of the cable, which is composed of the central support block 207 and the connecting rubber block 208. The impact force is attenuated layer by layer, protecting the cable, reducing the damage caused by collisions and impacts, and reducing the breakage of its outer insulation layer, making the cable safer to use. If the cable is laid in a cold environment, and ice forms on the outside of the cable due to the damp and cold environment, the power supply to the heating wire 211 is turned on. The heating wire 211 heats up, and the heat is transferred to the heat-conducting layer 209 through the thermally conductive silicone 212. This heat evenly heats the air-filled strip 215 on the outside of the insulation middle layer 213. As the carbon dioxide inside the air-filled strip 215 contracts when it freezes in the outside and expands when heated, it pushes the outer insulation layer 216 to bulge, pushing open the outer ice layer and causing the ice layer to break and fall off. This method utilizes the heating of the heating wire 211 and the physical effect of gas expansion to work simultaneously. Compared with the existing method that only relies on heating to de-ice, it consumes less energy, is environmentally friendly and energy-saving, has a better de-icing effect, and is more conducive to the protection of the cable. If the cable experiences a fault or overload during use and overheats, and the temperature continues to rise, when the temperature reaches the decomposition temperature of aluminum hydroxide, the aluminum hydroxide in the aluminum hydroxide bag 206 inside the reinforced braided tube 205 decomposes. Under the dual action of air pressure and high temperature, the connection between the central support block 207 and the connecting rubber block 208 separates, and the gas produced by decomposition is discharged into the gap between the flame-retardant fillers 201. Due to the restoring effect of the arc-shaped spring plate 204, gaps appear between the flame-retardant fillers 201, and these gaps are filled with water vapor produced by the decomposition of aluminum hydroxide. While absorbing heat, this separates each inner conductor 1, preventing the problematic inner conductor 1 from contacting each other and short-circuiting. This process absorbs heat, cools down, and retards the flame while protecting the cable, preventing more serious problems from occurring and enhancing safety. When ice or debris adheres to the outside of the cable, affecting maintenance, remove the debris from a small section of the cable and then replace the semi-circular shovel 301 by clamping it onto the outside of the cable. Figure 6 Four replacement semi-circular shovels 301 are installed as shown. Then, the connecting end blocks 309 at both ends of the transmission connecting rod 310 are snapped into the blind tube 307, and the splicing hook plates 312 overlap each other. The connecting screws 315 connect the connecting end blocks 309 and the blind tube 307, and the four replacement semi-circular shovels 301 are combined into a whole. An insulating rod with a hook is installed in the hole after the splicing hook plates 312 overlap. Pull the replacement impurity removal component 3 along the cable. The rolling rod 304 in the guide edge 302 rolls along the outside of the cable. By reciprocatingly pulling the replacement semi-circular shovels 301, the attached debris and ice layer on the outside of the cable are removed. During the pulling process, the connecting spring 308 between the connecting buffer groove 305 and the blind tube 307 deforms and changes the spacing of the replacement semi-circular shovels 301 in accordance with the bending of the cable to prevent the replacement semi-circular shovels 301 from scratching the outside of the cable, keeping the outside of the cable clean, facilitating maintenance, and also preventing icing and damage to the cable. During the process of replacing the cleaning component 3 to scrape off the ice on the outside of the cable, it can be used in conjunction with the flame-retardant protection component 2. Through the thermal expansion and contraction of the air bar 215 and the deformation of the outer insulation layer 216 of the cable during the movement of the replacement semi-circular shovel 301, the removal of the ice layer is accelerated. The two components work together to achieve a better de-icing effect.

[0022] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An environmentally friendly flame-retardant medium voltage cable comprising an inner conductor (1), characterized in that: The inner conductor (1) is externally provided with a fire-retardant protection assembly (2), which comprises a fire-retardant filling body (201); The inner conductor (1) is externally wrapped with a fire-retardant filling body (201), the middle part of the opposite side of the fire-retardant filling body (201) is provided with a support groove (202), and the support groove (202) is uniformly attached with a pad (203) inside; the opposite two pads (203) are respectively connected to the two sides of an arc-shaped spring plate (204), and the arc-shaped spring plate (204) is attached inside the support groove (202). Three fire-retardant filling bodies (201) are provided with a reinforced braided tube (205) therebetween, the reinforced braided tube (205) is filled with an aluminum hydroxide bag (206) inside, and the reinforced braided tube (205) is uniformly sleeved with a center support block (207) outside; the opposite surfaces of the adjacent center support blocks (207) are respectively attached to the two ends of a connecting rubber block (208).

2. An environmentally friendly flame-retardant medium voltage cable according to claim 1, characterized in that, The fire-retardant filling body (201) is externally wrapped with a heat-conducting layer (209), the heat-conducting layer (209) is provided with a heating groove (210) near the gap between the fire-retardant filling bodies (201), the heating groove (210) is inlaid with a heating wire (211) inside, and the heating wire (211) is externally wrapped with a heat-conducting silica gel (212).

3. An environmentally friendly flame-retardant medium voltage cable according to claim 2, characterized in that, The heat-conducting layer (209) is externally wrapped with an insulating middle layer (213), the insulating middle layer (213) is uniformly distributed with an isolation strip (214) outside, the isolation strips (214) are uniformly embedded with an inflation strip (215) therebetween, the isolation strip (214) is externally wrapped with an outer insulating layer (216), and the outer insulating layer (216) is externally wrapped with an outer protective film (217).

4. The environmentally friendly flame-retardant medium voltage cable according to claim 1, characterized in that, The end face of the fire-retardant filling body (201) is a one-third semicircle, and three fire-retardant filling bodies (201) are combined into a cylinder.

5. The environmentally friendly flame-retardant medium voltage cable according to claim 1, characterized in that, The end faces of the center support block (207) and the connecting rubber block (208) are the same shape, the fire-retardant filling body (201) is provided with a heat-conducting groove (218) near the center support block (207), and the end of the center support block (207) contacts the outer side of the inner conductor (1).

6. The environmentally friendly flame-retardant medium voltage cable according to claim 3, characterized in that, The fire-retardant filling body (201) is externally provided with a groove corresponding to the heating groove (210), and the heat-conducting silica gel (212) is curved on the side close to the insulating middle layer (213).

7. The environmentally friendly flame-retardant medium voltage cable according to claim 3, characterized in that, The outer protective film (217) is externally provided with a replacement impurity removal assembly (3), and the replacement impurity removal assembly (3) comprises a replacement semicircular shovel (301); The outer protective film (217) is symmetrically sleeved with a replacement semicircular shovel (301) outside, one end of the replacement semicircular shovel (301) is welded with a guide edge (302), the guide edge (302) is provided with a rolling groove (303) away from one end of the replacement semicircular shovel (301), and the rolling groove (303) is uniformly rotatably inlaid with a rolling rod (304). The guiding edge (302) is symmetrically provided with a connecting buffer groove (305) at the end, the connecting buffer groove (305) is movably inlaid with a blind pipe (307), one end of the blind pipe (307) and one end of the connecting buffer groove (305) are fixedly connected with two ends of a connecting spring (308) respectively, two blind pipes (307) opposite to each other are provided with a connecting end block (309) between them, two connecting end blocks (309) at the same height are welded to two ends of a transmission connecting rod (310) respectively; The transmission connecting rod (310) is symmetrically welded with an arc-shaped reinforcing rod (311) at the middle, two ends of the arc-shaped reinforcing rod (311) are welded with a splicing hook plate (312) respectively.

8. An environmentally friendly flame-retardant medium voltage cable according to claim 7, characterized in that, The replacement semicircular shovel (301) is a semicircular cylindrical structure with one end being rounded, the inner diameter of the replacement semicircular shovel (301) is equal to the outer diameter of the outer protective film (217), and the inner side of the replacement semicircular shovel (301) is a smooth curved surface.

9. The environmentally friendly flame-retardant medium voltage cable according to claim 7, characterized in that, The end surface of the connecting end block (309) is T-shaped, one end of the blind pipe (307) is symmetrically provided with a clamping hole (313), the connecting end block (309) is welded with a clamping rod (314) at the position corresponding to the clamping hole (313), the connecting end block (309) is provided with a connecting screw (315) penetratingly installed near the clamping rod (314), and the connecting screw (315) is connected with the blind pipe (307) through threads.

10. The environmentally friendly flame-retardant medium voltage cable according to claim 7, characterized in that, The thickness of the arc-shaped reinforcing rod (311) is twice the thickness of the splicing hook plate (312), and two splicing hook plates (312) located at the same arc-shaped reinforcing rod (311) are staggered.

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