Polyethylene insulated aerial cable

Abstract

The application provides a polyethylene insulated overhead cable and relates to the technical field of overhead cables.The polyethylene insulated overhead cable comprises a cable, the cable comprising a core, a conductor shielding layer wrapped outside the core, and a cross-linked polyethylene layer wrapped outside the conductor shielding layer; and a protective sleeve provided on a maximum sag section of the cable, the protective sleeve comprising a sleeve body, both ends of the sleeve body being provided in an open structure, and the sleeve body being sleeved on the cable.By arranging the protective sleeve on the maximum sag section of the cable, the thinnest dynamic response area in the whole line can be protected, and after the sleeve body is sleeved on the cable, a space is naturally formed between the inner circumferential surface of the sleeve body and the outer circumferential surface of the cable.When the cable swings or is subjected to tensile deformation, the sleeve body can maintain a hanging posture by virtue of its own gravity, the relative displacement can be buffered when the cable swings, and the sleeve body can avoid rigidly constraining and rubbing and wearing the insulating layer of the cable.

Description

Technical Field

[0001] This invention relates to the field of overhead cable technology, and more specifically, to a polyethylene insulated overhead cable. Background Technology

[0002] Overhead cables, as a crucial component of urban power distribution networks and long-distance transmission lines, are typically erected between towers and exposed to the atmosphere for extended periods, enduring alternating effects from wind loads, snow loads, and solar radiation. In this type of installation, the cables between adjacent towers naturally form a catenary due to their own weight, with the lowest point of this catenary being the point of maximum sag for that span. This area represents the point of least tension within the entire span structure, yet it is a sensitive convergence zone for mechanical behavior: wind-induced line swaying and light wind vibrations reach their maximum amplitude here, making the maximum sag section the weakest link in the entire line most susceptible to fatigue damage.

[0003] To address these issues, conventional protective measures adopted by the industry include extruding thickened insulating sheaths along the entire conductor surface, installing vibration dampers, and arranging phase-to-phase spacers. However, the full-line sheathing solution significantly increases the self-weight per unit length of the line, increasing the load on towers and substantially raising project costs. While vibration dampers and spacers can suppress vibration, their points of application are usually close to the suspension end, lacking specificity for the lowest point of sag. Furthermore, all of these measures generally need to be installed simultaneously during cable laying, which is costly and difficult for existing overhead lines, sometimes even requiring power outages and affecting power supply reliability. Summary of the Invention

[0004] To address the above problems, the present invention provides a polyethylene insulated overhead cable.

[0005] This invention provides a polyethylene insulated overhead cable, comprising: The cable includes a conductor core, a conductor shielding layer covering the conductor core, and a cross-linked polyethylene layer covering the conductor shielding layer. A protective sleeve is installed on the maximum sag section of the cable. The protective sleeve includes a tube body with open ends, and the tube body is sleeved on the cable.

[0006] Optionally, the cross-linked polyethylene layer includes a cross-linked polyethylene inner insulation layer and a cross-linked polyethylene outer insulation layer, wherein the cross-linked polyethylene inner insulation layer covers the outside of the conductor shielding layer, and the cross-linked polyethylene outer insulation layer covers the outside of the cross-linked polyethylene inner insulation layer.

[0007] Optionally, the protective sleeve further includes an annular sealing sheet made of a breathable and waterproof material. The annular sealing sheet has an outer ring surface and an inner ring surface. The outer ring surface is connected to the inner circumferential surface of the end of the tube body, and the inner ring surface is connected to the outer circumferential surface of the cross-linked polyethylene outer insulation layer.

[0008] Optionally, an irregular annular cavity is formed between the protective sleeve and the cross-linked polyethylene outer insulation layer, and a plurality of damping spheres are provided at the bottom of the irregular annular cavity.

[0009] Optionally, the upper half of both sides of the inner circumferential surface of the tube is symmetrically provided with baffles, and multiple rubber columns are provided in the irregular annular cavity above two baffles, with the multiple rubber columns arranged end to end along the extension direction of the irregular annular cavity.

[0010] Optionally, the rubber column is a hollow structure, the rubber column is filled with an initiator, and the damping spheres are made of a material that reacts with the initiator to generate heat.

[0011] Optionally, the blocking piece is a shape memory metal spring, the fixed end of the shape memory metal spring is connected to the inner circumferential surface of the tube body, and the deformable end of the shape memory metal spring extends toward the outer circumferential surface of the cross-linked polyethylene outer insulation layer. When the shape memory metal spring is heated, the deformable end of the shape memory metal spring gradually bends upward.

[0012] Optionally, the deformable end of the shape memory metal spring is configured as a sharp edge.

[0013] Optionally, the initiator is a calcium chloride solution.

[0014] Optionally, the damping spheres are configured as composite particles of iron powder, aluminum powder and activated carbon.

[0015] The beneficial effects of the polyethylene insulated overhead cable of the present invention are as follows: By setting the protective sleeve on the maximum sag section of the cable, the present application can specifically protect the weakest dynamic response area of ​​the entire line. After the sleeve is placed on the cable, a space will naturally be formed between the inner circumference of the sleeve and the outer circumference of the cable. When the cable is swayed by the wind or undergoes tensile deformation, the sleeve can maintain its hanging posture by its own weight. When the cable is swayed by the wind, it can buffer the relative displacement and avoid the sleeve from causing hard constraints and frictional wear on the cable insulation layer. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure after application in an embodiment of the present invention; Figure 2 This is a front view after application in an embodiment of the present invention; Figure 3 This is a schematic diagram of the installation of the protective sleeve in an embodiment of the present invention; Figure 4 This is a schematic diagram of the protective sleeve in the absence of wind, according to an embodiment of the present invention. Figure 5 This is a schematic diagram illustrating the state of the protective sleeve in windy conditions according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the state when the lower part of the protective sleeve freezes according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the blocking sheet in its initial position in an embodiment of the present invention; Figure 8 This is a schematic diagram of the blocking sheet in a bent position in an embodiment of the present invention.

[0017] Explanation of reference numerals in the attached figures: 1. Cable; 11. Core; 12. Conductor shielding layer; 13. Cross-linked polyethylene inner insulation layer; 14. Cross-linked polyethylene outer insulation layer; 2. Protective sleeve; 21. Tube body; 211. Barrier plate; 2111. Edge; 212. Irregular annular chamber; 22. Annular sealing plate; 3. Rubber column; 4. Damping pellet. Detailed Implementation

[0018] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0019] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0020] In the description of this specification, the references to terms such as "embodiment," "one embodiment," "some implementations," "exemplary," and "one implementation," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or implementation is included in at least one embodiment or implementation of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or implementation. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or implementations.

[0021] The terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature.

[0022] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 As shown, an embodiment of the present invention provides a polyethylene insulated overhead cable, comprising: Cable 1, cable 1 includes a conductor core 11, a conductor shielding layer 12 covering the outside of the conductor core 11, and a cross-linked polyethylene layer covering the outside of the conductor shielding layer 12; The protective sleeve 2 is installed on the maximum sag section of the cable 1. The protective sleeve 2 includes a tube body 21 with open ends. The tube body 21 is sleeved on the cable 1.

[0023] Specifically, the conductor core 11 is typically made of multiple strands of copper or aluminum conductors twisted together. The conductor shielding layer 12 covering the conductor core 11 smooths the electric field distribution on the outer surface of the conductor core 11. Outside the conductor shielding layer 12, a cross-linked polyethylene layer acts as the main insulator, isolating the high-voltage conductor from the external environment. The cross-linked polyethylene material is transformed from linear polyethylene molecular chains into a three-dimensional network structure through chemical or physical cross-linking methods. This results in superior heat resistance, creep resistance, environmental stress cracking resistance, and aging lifespan compared to ordinary polyethylene. The improved design enables the cable 1 to perform insulation tasks under outdoor conditions for decades. The protective sleeve 2 is installed on the maximum sag section of the entire cable 1. The cable 1 hangs naturally between two towers, forming a catenary shape. The maximum sag section is located near the lowest point of the entire catenary. This area is the position with the least tension in the entire span, but it is also the mechanical window most sensitive to changes in external loads. The vibration of the cable 1 caused by wind is the position with the largest amplitude in the maximum sag section. Moreover, the icing load under snowfall or freezing rain weather also first and foremost changes the sag and stress state of this section.

[0024] In this optional embodiment, by setting the protective sleeve 2 on the maximum sag section of the cable 1, the weakest dynamic response area of ​​the entire line can be protected in a targeted manner. The protective sleeve 2 includes a tube body 21, and both ends of the tube body 21 are set as open structures. The open structures allow the tube body 21 to slide and fit along the axial direction of the cable 1 without disassembling the already installed cable 1 or cutting any of its components. After the tube body 21 is fitted onto the cable 1, a space will naturally be formed between the inner circumferential surface of the tube body 21 and the outer circumferential surface of the cable 1. When the cable 1 is swayed by the wind or undergoes tensile deformation, the tube body 21 can maintain its hanging posture by its own weight. When the cable 1 is swayed by the wind, it can buffer the relative displacement and avoid the tube body 21 causing hard constraints and frictional wear on the insulation layer of the cable 1.

[0025] Optionally, the cross-linked polyethylene layer includes a cross-linked polyethylene inner insulation layer 13 and a cross-linked polyethylene outer insulation layer 14, with the cross-linked polyethylene inner insulation layer 13 covering the outside of the conductor shielding layer 12 and the cross-linked polyethylene outer insulation layer 14 covering the outside of the cross-linked polyethylene inner insulation layer 13.

[0026] Specifically, the cross-linked polyethylene layer includes a cross-linked polyethylene inner insulation layer 13 and a cross-linked polyethylene outer insulation layer 14. The cross-linked polyethylene inner insulation layer 13 directly covers the outside of the conductor shielding layer 12 and is the main body for electrical insulation under rated voltage and overvoltage. Its thickness is designed according to the electric field strength requirements. The cross-linked polyethylene outer insulation layer 14 covers the outside of the cross-linked polyethylene inner insulation layer 13. The two can be formed in one step using a double-layer co-extrusion process on the same production line, or they can be extruded in stages to form a physically separable interface. The material formulation of the cross-linked polyethylene inner insulation layer 13 aims to achieve the highest electrical breakdown strength and the lowest dielectric loss. The cross-linked polyethylene outer insulation layer 14 can have additional light stabilizers, ultraviolet absorbers, thermo-oxidative anti-aging agents, and appropriate amounts of carbon black added to the base polyethylene material to specifically cope with outdoor solar radiation and large temperature difference environments.

[0027] In this optional embodiment, the direct benefit of the layered cross-linked polyethylene insulation structure is that it achieves physical separation of electrical function and weather protection function. Even if the cross-linked polyethylene outer insulation layer 14 develops surface powdering or micro-cracks under decades of sun, rain, wind and sand erosion, the cross-linked polyethylene inner insulation layer 13 can still maintain an intact insulation barrier, eliminating the risk of grounding short circuit fault caused by single-layer insulation damage. In addition, the cross-linked polyethylene outer insulation layer 14 provides a highly weather-resistant attachment surface for the protective sleeve 2. Any shaking and friction of the tube body 21 acts on the cross-linked polyethylene outer insulation layer 14 and will not damage the cross-linked polyethylene inner insulation layer 13, thus ensuring the insulation life of the cable body 1.

[0028] Furthermore, the protective sleeve 2 also includes an annular sealing sheet 22, which is made of breathable and waterproof material. The annular sealing sheet 22 has an outer ring surface and an inner ring surface. The outer ring surface is connected to the inner circumferential surface of the end of the tube body 21, and the inner ring surface is connected to the outer circumferential surface of the cross-linked polyethylene outer insulation layer 14.

[0029] Specifically, the protective sleeve 2 also includes an annular sealing sheet 22, which is made of a breathable and waterproof material. Such material is usually a non-porous polymer film with hydrophilic segments. Liquid water cannot pass through due to surface tension and hydrophobic segments, while gaseous water molecules can complete mass transfer through adsorption, diffusion and desorption of hydrophilic groups. The annular sealing sheet 22 has an outer ring surface and an inner ring surface. The outer ring surface is fixedly connected to the inner circumferential surface of the end of the tube body 21 by bonding. The inner ring surface is in circumferential contact with the outer circumferential surface of the cross-linked polyethylene outer insulation layer 14 through an elastic interference fit. Thus, the inner wall of the tube body 21, the outer surface of the cable 1 and the annular sealing sheets 22 at both ends together enclose a relatively closed internal gas-containing space, preventing rainwater, dust, insects and other external elements from directly intruding.

[0030] In this optional embodiment, the annular sealing sheet 22 can produce multi-climate adaptability based on its single characteristic of being breathable and waterproof. Under sunny conditions, the air inside the tube 21 expands due to heat and can be slowly depressurized in the form of water vapor through the annular sealing sheet 22, preventing the internal positive pressure from pushing the sealing structure. During rainfall, liquid water is completely blocked outside the tube, keeping the internal space dry. In high humidity but no rain, a small amount of water vapor diffuses in both directions to balance the internal and external humidity, preventing long-term condensation and water accumulation inside the tube 21. During snowfall, the outer surface of the sheet freezes and blocks the moisture permeability path, making the inside of the tube 21 nearly sealed, reducing heat loss due to ventilation, helping to retain the residual heat generated by power transmission, and slowing down the icing process outside the tube.

[0031] Optionally, an irregular annular chamber 212 is formed between the protective sleeve 2 and the cross-linked polyethylene outer insulation layer 14, and a plurality of damping spheres 4 are provided at the bottom of the irregular annular chamber 212.

[0032] Specifically, since the tube 21 is suspended on the cable 1 by its own weight, its top inner wall directly abuts against the top outer surface of the cross-linked polyethylene outer insulation layer 14, presenting an approximate line contact. Meanwhile, the bottom inner wall of the tube 21 is separated from the bottom outer surface of the cable 1 by the maximum distance. Therefore, an irregular annular chamber 212 with a crescent-shaped cross section is formed between the protective sleeve 2 and the cross-linked polyethylene outer insulation layer 14. The bottom of the irregular annular chamber 212 naturally forms a collection groove extending along the axial direction of the cable 1. Multiple damping spheres 4 are provided inside. The damping spheres 4 are made of metal or ceramic, have a smooth surface, and are spherical or near-spherical particles. Under the action of gravity, they naturally accumulate in the bottom groove and can slide and collide with each other.

[0033] In this optional embodiment, when the cable 1 swings laterally or vertically due to wind vibration, the tube 21 moves accordingly. The damping spheres 4 accumulated at the bottom lag behind the inner wall of the tube 21 and the surface of the cable 1 due to inertia. During this process, continuous collisions and friction occur between the damping spheres 4, between the damping spheres 4 and the tube 21, and between the damping spheres 4 and the cable 1. The vibration mechanical energy is converted into frictional heat energy and sound energy and dissipated. This directly reduces the amplitude of cable 1's galloping and wind vibration at the lowest point of the sag, delays the fatigue breakage of the conductor, and requires no external energy or maintenance.

[0034] Furthermore, the upper half of both sides of the inner circumferential surface of the tube body 21 is symmetrically provided with baffles 211, and multiple rubber columns 3 are provided in the irregular annular chamber 212 above the two baffles 211. The multiple rubber columns 3 are arranged end to end along the extension direction of the irregular annular chamber 212.

[0035] Specifically, baffles 211 are symmetrically arranged on the upper half of both sides of the inner circumferential surface of the tube 21. The baffles 211 extend along the inner wall of the tube 21 towards the center. Their lower surfaces and the upper part of the inner wall of the tube 21 define two relatively independent upper side regions. In the top region of the irregular annular cavity 212 above the two baffles 211 and below the inner top surface of the tube 21, multiple rubber columns 3 are placed. The rubber columns 3 are columnar, and their axes are placed along the extension direction of the irregular annular cavity 212. The multiple rubber columns 3 are arranged end to end to fill the upper side region. The rubber columns 3 are molded from natural rubber or synthetic rubber. They can be elastically compressed when subjected to radial extrusion force and return to their original shape after the external force is removed.

[0036] In this optional embodiment, when the cable 1 is not subjected to lateral disturbance, the arrangement of the rubber pillars 3 prevents excessive radial swaying gaps between the tube 21 and the cable 1. When a crosswind causes the cable 1 to sway laterally, the tube 21 will generate a lateral displacement relative to the cable 1 under inertia, resulting in a smaller gap in the upper region on one side. The rubber pillars 3 on the corresponding side are compressed by the inner wall of the tube 21 and the outer surface of the cable 1. The rubber pillars 3 absorb the impact kinetic energy when compressed and release elastic potential energy during the swing back, providing auxiliary restoring force. This forms a two-stage synergistic vibration reduction system with the collision energy dissipation of the bottom damping spheres 4, further suppressing the eccentric sway amplitude of the tube 21 relative to the cable 1. Figure 5 As shown, when the side wind blows the cable 1 to the right, the tube 21 will swing to the left, and the damping ball 4 will roll counterclockwise as a whole.

[0037] Optionally, the rubber column 3 is a hollow structure, and the rubber column 3 is filled with an initiator. The damping spheres 4 are made of a material that reacts with the initiator to generate heat.

[0038] Specifically, the rubber column 3 is designed as a hollow structure, forming a sealed hollow cavity inside. This cavity is filled with an initiator, which is a liquid reaction triggering substance. It is completely encapsulated within the elastic wall of the rubber column 3 and does not come into contact with the outside under normal conditions. The shape of the rubber column 3 remains the same as the original columnar size, and it can continue to play an elastic support role. The damping sphere 4 is made of a material that reacts with the initiator to generate heat, which means that the material of the damping sphere 4 itself is a solid chemically active substance. When it comes into contact with the initiator, the two will undergo an exothermic chemical reaction.

[0039] In this optional embodiment, when the device is not triggered, the initiator and the damping pellets 4 are physically isolated by the wall of the rubber column 3, and the two independently perform their respective functions. The rubber column 3 provides elastic constraint for vibration, and the damping pellets 4 provide damping for particle collision. When an external force causes the rubber wall to break, the initiator leaks from the hollow cavity and flows along the tube wall to the accumulation of damping pellets 4 at the bottom of the cavity. The initiator overflows the surface of the damping pellets 4, instantly activating an exothermic reaction. The heat generated by the reaction can heat the tube 21, thereby melting the ice on the outer wall of the tube 21, or raising the internal temperature of the tube 21 to prevent the formation of new ice.

[0040] Optionally, the blocking piece 211 is a shape memory metal spring. The fixed end of the shape memory metal spring is connected to the inner circumferential surface of the tube body 21, and the deformable end of the shape memory metal spring extends toward the outer circumferential surface of the cross-linked polyethylene outer insulation layer 14. When the shape memory metal spring is heated, the deformable end of the shape memory metal spring gradually bends upward.

[0041] Specifically, the blocking piece 211 is a shape memory metal spring, which can be made of nickel-titanium alloy or copper-based shape memory alloy. Its fixed end is rigidly connected to the inner circumferential surface of the tube body 21 by welding or riveting, and its deformable end extends toward the outer circumferential surface of the cross-linked polyethylene outer insulation layer 14. Under normal conditions below the alloy phase transformation temperature, the shape memory metal spring maintains the straight or slightly downward-sloping geometric shape given by pre-training, and acts as the blocking piece 211 to isolate the rubber pillar 3 in the upper side area. When the shape memory metal spring is heated and reaches the austenitic phase transformation end temperature, its internal crystal structure changes, and the deformable end will perform the preset shape memory action and gradually bend upward.

[0042] In this optional embodiment, the shape memory metal spring forms a thermo-mechanical converter. When the bottom of the irregular annular chamber 212 heats up due to vibration and friction or when the temperature of the tube 21 rises due to exposure to sunlight, the heat is transferred to the shape memory metal spring, causing the spring to bend upward. The bending action directly applies additional mechanical extrusion force to the rubber column 3 located above it, causing the compressive stress on the rubber column 3 to increase suddenly, thereby increasing the risk of the rubber column 3 wall rupture and loss of seal. That is, the shape memory metal spring's response to external temperature can actively trigger the outflow of the initiator.

[0043] Furthermore, the deformable end of the shape memory metal shrapnel is designed as a sharp blade 2111.

[0044] Specifically, the deformable end of the shape memory metal spring is set as a sharp edge 2111. The sharp edge 2111 is located at the end of the spring, and its cross section gradually narrows to form a sharp edge. It can be wedge-shaped or conical. When the shape memory metal spring bends upward as a whole due to heat, the sharp edge 2111 serves as the local point where the spring first contacts the rubber column 3. The contact area is much smaller than the width of the spring itself, thereby concentrating the bending force of the spring on a very small area.

[0045] In this optional embodiment, the tip 2111 significantly enhances the destruction efficiency of the shape memory metal spring on the rubber column 3. Under the same bending moment, the tip 2111 can generate extremely high local pressure on the surface of the rubber column 3. Especially when the ambient temperature is low and the rubber column 3 hardens and becomes brittle, the tip 2111 can easily pierce the rubber wall to form a crack, causing the internal initiator to leak prematurely. This means that the triggering of the rubber column 3 no longer depends on the overall crushing, but can be activated by piercing.

[0046] Furthermore, the initiator was set as a calcium chloride solution.

[0047] In this optional embodiment, the initiator is a calcium chloride solution. Calcium chloride is an inorganic salt, and its aqueous solution has a lower eutectic freezing point than ordinary water. When the mass fraction is appropriate, it can remain completely liquid at tens of degrees below zero Celsius. Calcium chloride solution has high conductivity and is a fully ionized strong electrolyte, which can provide sufficient ion migration pathways for the electrochemical process. This solution is encapsulated in the hollow cavity of the rubber column 3. When the device is not started, it exists only as a liquid filler. Choosing calcium chloride solution as the initiator ensures that the reaction triggering liquid filled in the rubber column 3 does not freeze in the extremely low temperature environment that the cable 1 may encounter during actual operation. This ensures that no matter how cold the environment is, once the rubber column 3 is broken, the liquid initiator can flow out immediately, and there is no risk of trigger failure due to ice blockage.

[0048] Optionally, the damping spheres 4 are made of composite particles of iron powder, aluminum powder and activated carbon.

[0049] In this optional embodiment, the damping sphere 4 is a composite particle of iron powder, aluminum powder, and activated carbon. This composite particle is formed by mixing fine iron powder, aluminum powder, and high specific surface area activated carbon powder, and then granulating or pressing it into solid spheres with a certain strength. Iron and aluminum are both reducing and active metals, and activated carbon is a porous material with electrical conductivity and adsorption capacity. All three are uniformly distributed within the same particle. This particle possesses both the high density of metals and the porous characteristics of activated carbon, resulting in high overall hardness and resistance to breakage during normal impact. Under normal conditions, its high density endows the damping sphere 4 with excellent inertial mass, enhancing its strength. To achieve the particle damping and vibration reduction effect, when the initiator composed of calcium chloride solution flows out from the broken rubber column 3 and wets the composite particles, the calcium chloride solution acts as an electrolyte, causing countless tiny galvanic cells to form between the iron powder, aluminum powder and activated carbon. Aluminum and iron undergo anodic loss-electron corrosion, releasing stable and lasting heat. This reaction can be carried out spontaneously using the particles' own components without the need for a continuous supply of external oxygen. The same particle is both a vibration damping body and a chemical heat source, achieving functional integration under extreme structural simplification, while also avoiding reliability and maintainability issues caused by additional heating elements or batteries.

[0050] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A polyethylene insulated overhead cable, characterized in that, include: The cable (1) includes a conductor (11), a conductor shielding layer (12) covering the outside of the conductor (11), and a cross-linked polyethylene layer covering the outside of the conductor shielding layer (12); A protective sleeve (2) is installed on the maximum sag section of the cable (1). The protective sleeve (2) includes a tube body (21) with open ends. The tube body (21) is fitted onto the cable (1).

2. The polyethylene insulated overhead cable as described in claim 1, characterized in that, The cross-linked polyethylene layer includes a cross-linked polyethylene inner insulation layer (13) and a cross-linked polyethylene outer insulation layer (14). The cross-linked polyethylene inner insulation layer (13) covers the outside of the conductor shielding layer (12), and the cross-linked polyethylene outer insulation layer (14) covers the outside of the cross-linked polyethylene inner insulation layer (13).

3. The polyethylene insulated overhead cable as described in claim 2, characterized in that, The protective sleeve (2) also includes an annular sealing sheet (22), which is made of breathable and waterproof material. The annular sealing sheet (22) has an outer ring surface and an inner ring surface. The outer ring surface is connected to the inner circumferential surface of the end of the tube body (21), and the inner ring surface is connected to the outer circumferential surface of the cross-linked polyethylene outer insulation layer (14).

4. The polyethylene insulated overhead cable as described in claim 3, characterized in that, An irregular annular chamber (212) is formed between the protective sleeve (2) and the cross-linked polyethylene outer insulation layer (14), and a plurality of damping spheres (4) are provided at the bottom of the irregular annular chamber (212).

5. The polyethylene insulated overhead cable as described in claim 4, characterized in that, The upper half of the inner circumferential surface of the tube (21) is symmetrically provided with baffles (211), and multiple rubber columns (3) are provided in the irregular annular chamber (212) above the two baffles (211). The multiple rubber columns (3) are arranged end to end along the extension direction of the irregular annular chamber (212).

6. The polyethylene insulated overhead cable as described in claim 5, characterized in that, The rubber column (3) is a hollow structure, and the rubber column (3) is filled with an initiator. The damping sphere (4) is made of a material that reacts with the initiator to generate heat.

7. The polyethylene insulated overhead cable as described in claim 6, characterized in that, The blocking piece (211) is a shape memory metal spring. The fixed end of the shape memory metal spring is connected to the inner circumferential surface of the tube body (21). The deformable end of the shape memory metal spring extends toward the outer circumferential surface of the cross-linked polyethylene outer insulation layer (14). When the shape memory metal spring is heated, the deformable end of the shape memory metal spring gradually bends upward.

8. The polyethylene insulated overhead cable as described in claim 7, characterized in that, The deformable end of the shape memory metal spring is designed as a sharp edge (2111).

9. The polyethylene insulated overhead cable as described in claim 7, characterized in that, The initiator is a calcium chloride solution.

10. The polyethylene insulated overhead cable as described in claim 9, characterized in that, The damping spheres (4) are made of iron powder, aluminum powder and activated carbon composite particles.

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