A cross-linked polyethylene insulated overhead cable with rapidly cross-linked silane and its preparation method

Abstract

This invention relates to the field of power cable technology and discloses a cross-linked polyethylene insulated overhead cable with rapidly cross-linked silane and its preparation method, comprising: a conductor located at the center of the cable; a conductor shielding layer extruded on the outside of the conductor; an insulation layer extruded on the outside of the conductor shielding layer; an insulation shielding layer extruded on the outside of the insulation layer; a metal shielding layer disposed on the outside of the insulation shielding layer; and an outer sheath of the cable disposed on the outside of the metal shielding layer. A heat storage component located at an area prone to overheating is disposed on the outside of the outer sheath of the cable. The heat storage component allows heat to be transferred to the cable joint or local circuit when overheating occurs due to overload, increased contact resistance, etc. Once the temperature reaches the set melting point of the phase change material, the phase change material will undergo a phase change and absorb a large amount of latent heat, thus stabilizing the temperature of the overheated area near the phase change point, forming a thermal buffer, and preventing uncontrolled temperature rise and heat spread within a certain range.

Description

Technical Field

[0001] This invention relates to the field of power cable technology, and in particular to a cross-linked polyethylene insulated overhead cable with rapidly cross-linked silane and its preparation method. Background Technology

[0002] Cross-linked polyethylene (XLPE) insulated overhead cables are a widely used type of cable in medium and low voltage power distribution networks. Their typical structure, from the inside out, includes a conductor, a conductor shield (inner semi-conductive layer), an XLPE insulation layer, an insulation shield (outer semi-conductive layer), a metal shield, and an outer sheath. The XLPE insulation layer, through chemical cross-linking, gives it excellent heat resistance, mechanical strength, and electrical properties. The inner and outer semi-conductive shields are used to smooth the electric field distribution, the metal shield is used to balance the electric field and conduct fault current, and the outermost sheath provides environmental protection.

[0003] However, during long-term operation, especially in high-load, high-temperature environments or at poorly crimped joints, such cables pose a certain risk of localized overheating. If the heat generated in hot spots cannot be dissipated in time, the temperature of the insulation material will continue to rise, accelerating its thermal aging process. This will not only degrade the insulation performance (such as dielectric strength) but may also cause faults such as thermal breakdown. Existing cable structures lack active thermal management mechanisms, relying solely on the material's own thermal conductivity and passive heat dissipation from the sheath surface. This makes it difficult to cope with sudden or continuous overload heating, and heat is prone to accumulate locally and may spread to adjacent areas, becoming a major bottleneck restricting the improvement of cable current carrying capacity and long-term operational reliability. In addition, traditional homogeneous semiconductor shielding layers have room for optimization in dealing with microscopic defects on the conductor surface and achieving ideal dielectric matching with the insulation layer, which may affect the extreme uniformity of the electric field distribution. Summary of the Invention

[0004] The technical problem to be solved by this invention is that traditional cables, due to the lack of an active thermal management mechanism, are prone to local overheating when overloaded or in poor contact, and the heat is difficult to dissipate, which seriously restricts their operational reliability and current carrying capacity. To address this, we propose a cross-linked polyethylene insulated overhead cable with rapidly cross-linked silane and its preparation method.

[0005] To achieve the above objectives, this application adopts the following technical solution: a cross-linked polyethylene insulated overhead cable with rapidly cross-linkable silane, comprising: a conductor located at the center of the cable; a conductor shielding layer, extruded on the outside of the conductor, wherein the concentration of its conductive filler is distributed in a gradient decreasing from the inside to the outside; an insulation layer, extruded on the outside of the conductor shielding layer, composed of rapidly cross-linkable silane-grafted polyethylene material; an insulation shielding layer, extruded on the outside of the insulation layer, wherein the concentration of its conductive filler is distributed in a gradient increasing from the inside to the outside; a metal shielding layer disposed on the outside of the insulation shielding layer; and a cable outer sheath disposed on the outside of the metal shielding layer; wherein a heat storage component is disposed on the outside of the cable outer sheath at a location prone to overheating, the heat storage component... The component includes a heat-conducting plate disposed outside the cable outer sheath, and a storage cavity disposed inside the heat-conducting plate. The storage cavity is filled with a phase change material. When the temperature reaches the melting point of the phase change material, the phase change material absorbs a large amount of heat through the latent heat of phase change, maintaining the temperature near its phase change point. A heat flow directional transmission component is disposed between the heat storage component and the cable outer sheath. The heat flow directional transmission component is used to regulate the heat transfer between the cable outer sheath and the heat storage component. Its configuration is as follows: during the process of heat transfer from the cable outer sheath to the heat storage component, the heat flow directional transmission component exhibits a high thermal conductivity state; during the process of the phase change material solidifying inside the heat storage component and dissipating heat to the environment, the heat flow directional transmission component exhibits a low thermal conductivity state.

[0006] Preferably, the outer wall of the cable outer sheath is uniformly provided with fixing grooves along the circumference, and the heat-conducting plate is installed in the fixing grooves.

[0007] Preferably, the heat-conducting plate is made of high thermal conductivity aluminum alloy, and the outer wall of the heat-conducting plate is uniformly provided with protruding heat dissipation fins.

[0008] Preferably, the heat flow directional transmission component includes a composite thermal pad disposed between the heat-conducting plate and the cable outer sheath, the composite thermal pad being composed of an elastic matrix, microcapsule phase change material and highly thermally conductive filler.

[0009] Preferably, the elastic matrix is ​​liquid silicone rubber, the microcapsule phase change material uses paraffin as the core material and urea-formaldehyde resin or melamine resin as the wall material, and the high thermal conductivity filler is boron nitride sheet.

[0010] Preferably, the heat flow directional transmission component includes a recess disposed on the side of the heat-conducting plate facing the outer sheath of the cable, a bimetallic strip is installed on the inner side of the recess, an upper contact finger is disposed on the inner wall of the recess, a lower contact finger is movably sleeved on the outer side of the upper contact finger near the outer sheath of the cable, and a pair of follower rods are disposed on the side wall of the lower contact finger, respectively located on the upper and lower sides of the middle of the bimetallic strip.

[0011] Preferably, there are multiple upper and lower contact fingers, each corresponding to a specific one. The multiple lower contact fingers are connected as one unit by a heat-conducting connecting rod, and the follower rod is disposed on the side wall of one or more of the lower contact fingers.

[0012] Preferably, the phase change material is paraffin wax.

[0013] Preferably, it further includes an overload recording mechanism disposed on the heat-conducting plate. The overload recording mechanism is located at one end of the heat-conducting plate on the top of the cable outer sheath. The overload recording mechanism includes a piston plate disposed at one end of the storage cavity. An elastic structure for piston plate reset is disposed on the side of the piston plate away from the phase change material. A linkage rod extending to the outside of the heat-conducting plate is disposed on the side of the piston plate away from the phase change material. An overload recording shell corresponding to the linkage rod is disposed at the end of the heat-conducting plate away from the phase change material. The end of the linkage rod away from the piston plate passes through the lower end of the overload recording shell and is provided with a notch. An indicator ball adapted to the notch is stacked on the inner side of the overload recording shell. The overload recording shell is a transparent structure.

[0014] This invention also includes an embodiment, specifically a method for preparing a rapidly cross-linked polyethylene insulated overhead cable with silane, comprising the following steps: S1: preparing a rapidly cross-linked silane-grafted polyethylene material, specifically comprising: preparing a catalyst-loaded nano-carrier masterbatch; adding polyethylene base material, silane monomer, initiator, and the nano-carrier masterbatch to a reactive extruder for a melt grafting reaction to obtain a silane-grafted polyethylene material; granulating the silane-grafted polyethylene material to obtain a rapidly cross-linked insulating material; S2: simultaneously extruding a conductor shielding layer, an insulation layer, and a conductor insulation layer onto the conductor using a co-extrusion process. An insulating shielding layer; wherein, by controlling the distribution of conductive filler in the semiconductor material, the conductor shielding layer formed by extrusion has a conductive filler concentration gradient that decreases from the inside to the outside; and the insulating shielding layer has a conductive filler concentration gradient that increases from the inside to the outside; the insulating layer uses the rapidly cross-linkable insulating material prepared in step S; S3: a metal shielding layer is set outside the insulating shielding layer; S4: a cable outer sheath is extruded over the metal shielding layer; S5: the cable core with the extruded cable outer sheath is subjected to warm water cross-linking treatment to obtain the finished cable; S6: a heat storage component and a heat flow directional transmission component are installed at a designated position on the cable outer sheath.

[0015] The technical effects and advantages of this invention are as follows: By placing the heat storage component at a specific location on the outer sheath of the cable, this invention introduces active thermal management capabilities into the cable. When the cable joint or local circuit overheats due to overload, increased contact resistance, or other reasons, the heat is transferred to the heat storage component. Once the temperature reaches the set melting point of the phase change material, the phase change material will undergo a phase change and absorb a large amount of latent heat, which can stably maintain the temperature of the overheated part near the phase change point, forming a thermal buffer. This can effectively prevent the uncontrolled rise in temperature and the longitudinal spread of heat within a certain range, breaking the limitation of traditional cables relying solely on passive heat dissipation. This fundamentally improves the thermal stability and long-term reliability of the cable in the face of instantaneous overload and continuous high-load operation.

[0016] In this invention, a heat flow directional transfer component installed between the heat storage component and the cable outer sheath further optimizes the efficiency of thermal management. Through its unique material or mechanical structure design, the heat flow directional transfer component exhibits directional dependence in its thermal conductivity: when the cable overheats, the heat flow directional transfer component exhibits a high thermal conductivity state, accelerating the transfer of heat to the heat storage component. When the heat source disappears and the phase change material begins to solidify and release heat, the heat storage component automatically switches to a high insulation state, ensuring that the latent heat released during solidification is directed to the external environment for dissipation, rather than being transferred back to the cooled cable body. This achieves heat flow guidance and control, avoids additional thermal stress on the cable insulation during periodic thermal cycles, and improves the intelligence and economy of the entire thermal management process. In this invention, the gradient composite structure design of the conductor shielding layer and the insulation shielding layer optimizes the electric field distribution. The conductor shielding layer adopts a conductive filler gradient that decreases from the inside to the outside, which can more thoroughly smooth the microscopic protrusions on the conductor surface and suppress electric field concentration. The insulation shielding layer adopts a reverse gradient, which achieves ideal dielectric matching with the insulation layer and low-resistance contact with the metal shielding layer. The two work together to significantly reduce the maximum field strength at the interface on both sides of the insulation layer, suppress the probability of early insulation degradation phenomena such as electrical treeing and water treeing, and provide key protection for the long-term electrical life of the cable. Attached Figure Description

[0017] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts:

[0018] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 This is a schematic diagram of the cross-sectional structure of the present invention; Figure 3 This is a structural diagram of the heat-conducting plate and fixing groove of the present invention in a disassembled state; Figure 4 This is a schematic diagram of the overall structure of the second embodiment of the heat flow directional transmission component of the present invention and the heat-conducting plate; Figure 5 This is a schematic diagram of the overall structure of the first embodiment of the heat flow directional transmission component of the present invention and the heat-conducting plate; Figure 6 This is a schematic diagram of the specific structure of the second embodiment of the heat flow directional transfer component of the present invention; Figure 7 This is a schematic cross-sectional view of the heat-conducting plate of the present invention.

[0019] Legend: 1. Cable outer sheath; 2. Heat-conducting plate; 3. Heat sink; 4. Conductor; 5. Conductor shielding layer; 6. Insulation layer; 7. Insulation shielding layer; 8. Metal shielding layer; 9. Notch; 10. Fixing groove; 11. Overload recording shell; 12. Recess; 13. Bimetallic strip; 14. Lower contact finger; 15. Composite thermal pad; 16. Thermally conductive connecting rod; 17. Follower rod; 18. Connecting shaft; 19. Storage cavity; 20. Phase change material; 21. Piston plate; 22. Linkage rod; 23. Elastic structure; 24. Indicator ball; 25. Upper contact finger. Detailed Implementation

[0020] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0021] Reference Figure 2 As shown, a cross-linked polyethylene insulated overhead cable with rapidly cross-linked silane comprises, from the inside out: a conductor 4, a conductor shielding layer 5, an insulation layer 6, an insulation shielding layer 7, a metal shielding layer 8, and an outer cable sheath 1. The conductor 4 is made of multi-stranded electrical-grade aluminum or aluminum alloy, which can be compressed to reduce the outer diameter. This design ensures the cable's necessary conductivity and mechanical strength, making it the carrier of electrical energy transmission.

[0022] The conductor shielding layer 5 is extruded onto the outside of the conductor 4. It is a functionally graded composite material layer formed by co-extrusion process. The inner surface of the conductor shielding layer 5 has the highest concentration of conductive filler to fully smooth the microscopic protrusions and electric field on the surface of the conductor 4. The concentration gradient decreases towards the outer layer. When it reaches the outer surface, its dielectric constant is optimally matched with the insulation layer 6. This gradient structure can extremely homogenize the electric field on the conductor surface, effectively suppressing electrical treeing or water treeing caused by conductor tip discharge from the source, and significantly improving the long-term electrical life of the cable.

[0023] The insulating layer 6 is extruded onto the outside of the conductor shielding layer 5 and is composed of a rapidly cross-linkable silane-grafted polyethylene material. Specifically, a catalyst supported on a nano-carrier is used, and the silane is efficiently grafted during the reactive extrusion process. This makes the insulating layer 6 react faster than traditional materials in the subsequent warm water cross-linking process, which not only greatly improves production efficiency and reduces energy consumption, but also results in a better microstructure and long-term aging performance due to the uniform and rapid cross-linking.

[0024] The insulating shielding layer 7 is extruded on the outside of the insulating layer 6. This layer forms a symmetrical gradient design with the conductor shielding layer 5, but the gradient direction is opposite. The concentration of conductive filler on its inner surface is low to form an excellent interface with the insulating layer 6 that is smooth and dielectrically matched. The concentration gradient increases towards the outer layer, and it has high conductivity at the outer surface. This ensures a gapless, low-resistance ohmic contact with the subsequent metal shielding layer 8, eliminates the contact gap and potential difference between the insulating shielding layer 7 and the metal shielding layer 8, further optimizes the electric field distribution, and improves the short-circuit current carrying capacity.

[0025] The gradient composite structure design of conductor shielding layer 5 and insulation shielding layer 7 optimizes the electric field distribution. Conductor shielding layer 5 adopts a conductive filler gradient that decreases from the inside to the outside, which can more thoroughly smooth the micro protrusions on the surface of conductor 4 and suppress electric field concentration. Insulation shielding layer 7 adopts a reverse gradient, which achieves ideal dielectric matching with insulation layer 6 and low-resistance contact with metal shielding layer 8. The two work together to significantly reduce the maximum electric field strength at the interface on both sides of insulation layer 6, suppress the probability of early insulation degradation phenomena such as electrical treeing and water treeing, and provide key protection for the long-term electrical life of the cable.

[0026] The metal shielding layer 8 is wrapped around the outside of the insulating shielding layer 7 and is made of loosely wound tinned copper wire or copper strip. Its main functions are: first, to serve as a short-circuit fault current path for the cable; and second, to shield the internal electric field of the cable so that it does not leak out. This layer structure is a standard and necessary structure for medium and high voltage cables, and will not be described in detail.

[0027] The cable outer sheath 1 is located outside the metal shielding layer 8. The cable outer sheath 1 is made of black weather-resistant polyethylene or high-density polyethylene, with sufficient carbon black added to resist ultraviolet rays. Its main function is to provide mechanical protection and resistance to environmental corrosion for all internal structures of the cable. It is the first physical barrier for the long-term stable operation of the cable.

[0028] like Figures 1-3 , Figure 7As shown, a heat storage component is installed at a designated position on the outside of the cable outer sheath 1. This heat storage component is located near the area prone to overheating. The heat storage component mainly consists of a heat-conducting plate 2 installed on the outside of the cable outer sheath 1. The heat-conducting plate 2 is made of high thermal conductivity aluminum alloy, and protruding heat sinks 3 are evenly distributed on the outer wall of the heat-conducting plate 2. The heat sinks 3 can increase the heat dissipation area and accelerate heat dissipation. In order to reduce the protrusion of the heat-conducting plate 2 and ensure stable installation, a fixing groove 10 is evenly distributed circumferentially on the outer wall of the cable outer sheath 1. The heat-conducting plate 2 is installed in the fixing groove 10. The fixing groove 10 is preferably precision machined by CNC turning or special milling equipment after the cable outer sheath 1 is extruded, cooled and shaped, to ensure the dimensional accuracy and surface finish of the groove. The fixing of the heat-conducting plate 2 to the inner wall of the fixing groove 10 preferably uses high thermal conductivity aluminum alloy. A silicone rubber adhesive with strong bonding strength is used for bonding and fixing, while ensuring heat transfer. A storage cavity 19 is provided on the inner side of the heat-conducting plate 2. The storage cavity 19 is filled with a phase change material 20. When the temperature reaches the melting point of the phase change material 20, the phase change material 20 absorbs a large amount of heat through the latent heat of phase change, maintaining the temperature near its phase change point. The phase change material 20 is preferably a paraffin-based shaped composite material. Specifically, it uses paraffin as the heat storage medium, high-density polyethylene or ethylene-vinyl acetate copolymer as the supporting skeleton, and expanded graphite or carbon nanotubes can be added to improve the overall thermal conductivity. The advantages of this material are high latent heat of phase change, stable chemical properties, no supercooling phenomenon, and the phase change temperature can be adjusted by the length of the paraffin carbon chain. Moreover, there is no risk of leakage after shaping, making it very suitable for the long-term operating environment of cables.

[0029] By placing the heat storage component at a specific location on the cable's outer sheath 1, active thermal management capabilities are introduced into the cable. When the cable joint or local circuit overheats due to overload, increased contact resistance, or other reasons, the heat is transferred to the heat storage component. Once the temperature reaches the set melting point of the phase change material 20, the phase change material 20 will undergo a phase change and absorb a large amount of latent heat, which can stably maintain the temperature of the overheated part near the phase change point, forming a thermal buffer. This can effectively prevent the uncontrolled rise in temperature and the longitudinal spread of heat within a certain range, breaking the limitation of traditional cables relying solely on passive heat dissipation. This fundamentally improves the thermal stability and long-term reliability of the cable in the face of instantaneous overload and continuous high-load operation.

[0030] Furthermore, a heat flow directional transmission component is provided between the heat storage component and the fixing groove 10 on the cable outer sheath 1. This component regulates the heat transfer between the cable outer sheath 1 and the heat storage component. Its configuration is as follows: during the heat transfer from the cable outer sheath 1 to the heat storage component, the component exhibits high thermal conductivity; during the solidification of the phase change material 20 within the heat storage component and its dissipation of heat to the environment, the component exhibits low thermal conductivity. The heat flow directional transmission component includes at least two embodiments:

[0031] First embodiment: as follows Figure 5As shown, the heat flow directional transmission component includes a composite thermal pad 15 disposed between the heat-conducting plate 2 and the cable outer sheath 1. The composite thermal pad 15 is composed of an elastic matrix, microcapsule phase change material, and high thermal conductivity filler. The elastic matrix is ​​preferably liquid silicone rubber, which has good flexibility and resistance to high and low temperatures after curing. The microcapsule phase change material is preferably prepared by in-situ polymerization with paraffin wax as the core material and urea-formaldehyde resin or melamine resin as the wall material, and the particle size can be controlled between 10-100 micrometers. The high thermal conductivity filler is preferably boron nitride sheet. When preparing the composite thermal pad 15, the microcapsule phase change material and sheet-like boron nitride and other high thermal conductivity fillers are uniformly dispersed in uncured silicone rubber, then cast into a film and heated to cure. This process is mature and easy to realize industrial production. The detailed process will not be described in detail.

[0032] Second embodiment: as follows Figure 4 and Figure 6 As shown, the heat flow directional transfer component includes a recess 12 disposed on the side of the heat-conducting plate 2 facing the cable outer sheath 1. A bimetallic strip 13 is installed on the inner side of the recess 12. An upper contact finger 25 is disposed on the inner wall of the recess 12. A lower contact finger 14 is movably sleeved on the outer side of the upper contact finger 25 near the cable outer sheath 1. A pair of follower rods 17 are disposed on the side wall of the lower contact finger 14, located on the upper and lower sides of the middle of the bimetallic strip 13 respectively. In order to increase the heat conduction performance, there are multiple upper contact fingers 25 and multiple lower contact fingers 14, which correspond one-to-one. The multiple lower contact fingers 14 are connected into one unit by heat-conducting connecting rods 16. The follower rods 17 are disposed on the side wall of one or more of the lower contact fingers 14. When the bimetallic strip 13 is heated, it bends downward, thereby passing through the follower rods 17. 7 drives multiple lower contact fingers 14 to move downwards and contact the inner wall of the fixing groove 10 to achieve high thermal conductivity. In order to fix the bimetallic strip 13, a connecting shaft 18 is elastically or flexibly connected to the end inside the recess 12. The end of the bimetallic strip 13 is movably mounted on the connecting shaft 18. For applications with an operating temperature range of 55-80℃, the bimetallic strip 13 can be made of manganese copper steel / Invar steel combination, which has a high thermal sensitivity coefficient. If higher requirements are required for response speed or corrosion resistance, a brass / Invar steel combination can also be selected. For scenarios with higher operating temperatures, a high-temperature alloy combination such as NiCr / NiSi can be selected. The specific model can be selected and customized according to the specific bending temperature, sensitivity and environmental adaptability required by calculation.

[0033] The heat flow directional transfer component installed between the heat storage component and the cable outer sheath 1 further optimizes the efficiency of thermal management. Through its unique material or mechanical structure design, the heat flow directional transfer component makes its heat conduction performance directional: when the cable is overheated, the heat flow directional transfer component exhibits a high thermal conductivity state, accelerating the transfer of heat to the heat storage component. When the heat source disappears and the phase change material 20 begins to solidify and release heat, the heat storage component automatically switches to a high insulation state, ensuring that the latent heat released during the solidification period is directed to the external environment for dissipation, rather than being transferred back to the cooled cable body. This achieves heat flow guidance and control, avoids additional thermal stress on the cable insulation during periodic thermal cycles, and improves the intelligence and economy of the entire thermal management process.

[0034] In addition, such as Figure 4 , Figure 5 , Figure 7 As shown, the present invention also includes an overload recording mechanism disposed on the heat-conducting plate 2. The overload recording mechanism is located at one end of the heat-conducting plate 2 at the top of the cable outer sheath 1. The overload recording mechanism includes a piston plate 21 movably and sealed at one end of the storage cavity 19. An elastic structure 23 for resetting the piston plate 21 is disposed on the side of the piston plate 21 away from the phase change material 20. The elastic structure 23 is preferably a spring. A linkage rod 22 extending to the outside of the heat-conducting plate 2 is disposed on the side of the piston plate 21 away from the phase change material 20. To increase the stability of the elastic structure 23, the elastic structure can be... 23 is mounted on the outside of the linkage rod 22. The end of the heat-conducting plate 2 away from the phase change material 20 is provided with an overload recording shell 11 corresponding to the linkage rod 22. The end of the linkage rod 22 away from the piston plate 21 passes through the lower end of the overload recording shell 11 and is provided with a notch 9. An indicator ball 24 adapted to the notch 9 is stacked on the inner side of the overload recording shell 11. The displacement of the linkage rod 22 can push out the bottommost indicator ball 24 through the notch 9. Then the indicator ball 24 can fall down by its own weight. The overload recording shell 11 is a transparent structure, which makes it easy to observe the position and number of the indicator balls 24.

[0035] The overload recording mechanism provides a physical diagnostic tool for cable condition-based maintenance. This mechanism utilizes the volume change that inevitably occurs when the phase change material 20 undergoes a phase change to drive the piston plate 21 and the linkage rod 22 to move, thereby reducing the size of the indicator ball 24. This generates displacement markers corresponding to overheating events, providing maintenance personnel with an intuitive, reliable, and tamper-proof physical record of overheating history. It enables visualized tracing of the local thermal experience of the cable, greatly facilitating the identification of weak points in the line, condition assessment, and the formulation of preventive maintenance plans, and improving the refinement and intelligence of power asset management.

[0036] This invention also relates to an embodiment, specifically a method for preparing a rapidly cross-linked polyethylene insulated overhead cable with silane, used for the preparation of the aforementioned rapidly cross-linked polyethylene insulated overhead cable with silane, specifically including the following steps:

[0037] Step 1: Preparation of rapidly cross-linkable silane-grafted polyethylene material. The specific steps include: preparation of nano-catalytic support: hydrophobically modified porous nano-silica, then impregnated in a solution of dibutyltin dilaurate, so that the loading of dibutyltin dilaurate reaches 10%-25% of the support weight, dried and melt-granulated with a small amount of LDPE to prepare catalyst masterbatch.

[0038] In-situ reactive grafting: In a twin-screw reactive extruder, the following formulation is continuously fed: 100 parts low-density polyethylene, 1.5-2.5 parts vinyltrimethoxysilane, 0.05-0.15 parts dicumyl peroxide, and 3-8 parts of the above catalyst masterbatch; the temperature and screw speed of each stage are precisely controlled to complete the efficient grafting reaction of silane onto the polyethylene molecular chain in the molten state; this formulation and process ensure that the catalyst is protected during processing and released in a controlled manner in the subsequent crosslinking stage, which is the key to achieving rapid crosslinking.

[0039] Granulation: The grafted product is extruded, cooled, and granulated to obtain a rapidly cross-linkable insulating material.

[0040] Step 2: Preparation of the cable body, the specific steps of which include: Three-layer co-extrusion: Using a precision three-layer co-extrusion production line and a special die head, by independently controlling the rheological properties and filler distribution of two special semiconductor materials in the flow channel, conductor shielding layer 5, insulation layer 6 and insulation shielding layer 7 with gradient concentration characteristics are simultaneously extruded on conductor 4 to achieve seamless integrated molding, wherein the insulation layer 6 adopts the above-mentioned rapidly cross-linkable insulation material.

[0041] Cooling and shaping: The extruded cable core is immediately placed into a cooling water tank for rapid cooling and shaping.

[0042] Shielding and sheathing: A metal shielding layer 8 is wrapped around the cooled cable core, followed by extrusion of a black weather-resistant polyethylene cable outer sheath 1.

[0043] Rapid warm water crosslinking: Immerse the cable core in a 75-85℃ warm water bath for 2.5-4 hours to complete the rapid and full crosslinking of insulation layer 6.

[0044] Post-processing: After cross-linking is completed, the cable is cooled, dried, and tested before being coiled into a reel.

[0045] Subsequently, according to the customer's customized needs, a fixing groove 10 can be set at a designated position on the outer sheath 1 of the cable, and then the heat conduction plate 2 and other structures can be installed.

[0046] The reactive grafting and nano-carrier catalytic rapid crosslinking process used in the insulation material has improved production efficiency and product quality. By loading the catalyst onto the nano-carrier and achieving controlled release, combined with precise grafting reaction control, the activation energy of the reaction in the subsequent warm water crosslinking of the insulation material is reduced and the speed is greatly increased. This not only directly reduces production energy consumption and increases production line capacity, but also improves the long-term thermomechanical properties and electrical stability of the resulting insulation layer due to the more uniform and complete crosslinking reaction.

[0047] Working principle: When the cable temperature rises due to overload or increased contact resistance, heat is transferred to the heat storage module via the cable outer sheath 1. The phase change material 20 within this module absorbs a large amount of latent heat and undergoes a solid-liquid phase change when it reaches its melting point, thus stabilizing the temperature of the overheated area near the phase change point and preventing uncontrolled temperature rise. The heat flow directional transfer component, located between the heat storage module and the cable outer sheath 1, exhibits thermal conductivity that varies with its own temperature: when the temperature of the heat flow directional transfer component is higher than its inherent state transition temperature, the interface exhibits high thermal conductivity, forming an efficient heat path between the cable outer sheath 1 and the heat storage module, accelerating heat dissipation. When the heat source weakens or disappears, and the phase change material 20 begins to solidify and release heat, the interface temperature drops below the state transition temperature, automatically transitioning to a low thermal conductivity state, which inhibits solidification. Latent heat is transferred towards the outer sheath 1 of the cable, causing the heat to dissipate to the environment mainly through the heat-conducting plate 2 and the heat sink 3. At the same time, the volume change of the phase change material 20 during melting and solidification, in conjunction with the elastic structure 23, can drive the piston plate 21 and the linkage rod 22 integrated on the heat-conducting plate 2 to produce corresponding reciprocating displacement. The linkage rod 22 pushes out the lowermost indicator ball 24 through the notch 9, and the upper indicator ball 24 falls, producing changes in displacement and quantity, which can be accumulated, thereby intuitively recording and displaying the number of overheating events or the relative severity that have occurred in this part, providing a direct basis for condition assessment and preventive maintenance. It should be noted that the indicator ball 24 can be made of biodegradable environmentally friendly materials or a collection structure can be set up in the area where the indicator ball 24 falls to collect and recycle it.

[0048] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. A cross-linked polyethylene insulated overhead cable with rapidly cross-linked silane, characterized in that, include: The conductor located at the center of the cable; The conductor shielding layer is extruded onto the outside of the conductor, and the concentration of its conductive filler is distributed in a gradient from the inside to the outside. An insulating layer, extruded onto the outside of the conductor shielding layer, is composed of rapidly cross-linkable silane-grafted polyethylene material; an insulating shielding layer, extruded onto the outside of the insulating layer, has a conductive filler concentration that increases from the inside to the outside in a gradient distribution; a metal shielding layer is disposed on the outside of the insulating shielding layer; a cable outer sheath is disposed on the outside of the metal shielding layer; a heat storage component located in an easily overheated area is disposed on the outside of the cable outer sheath, the heat storage component includes a heat-conducting plate disposed on the outside of the cable outer sheath, and a storage cavity is disposed on the inner side of the heat-conducting plate, the storage cavity being filled with a phase change material, when the temperature reaches the melting point of the phase change material, the phase change material absorbs a large amount of heat through the latent heat of phase change, maintaining the temperature near its phase change point; a heat flow directional transfer component is disposed between the heat storage component and the cable outer sheath, the heat flow directional transfer component is used to regulate the heat transfer between the cable outer sheath and the heat storage component, its configuration is: when heat passes through an electric... During the heat transfer process from the cable outer sheath to the thermal storage component, the heat flow directional transfer component exhibits a high thermal conductivity state. During the solidification of the phase change material within the thermal storage component and its dissipation of heat to the environment, the heat flow directional transfer component exhibits a low thermal conductivity state. The system also includes an overload recording mechanism mounted on a heat-conducting plate. This mechanism is located at one end of the heat-conducting plate at the top of the cable outer sheath. The overload recording mechanism includes a piston plate located at one end of the storage cavity. An elastic structure for piston plate resetting is provided on the side of the piston plate away from the phase change material. A linkage rod extending to the outside of the heat-conducting plate is provided on the side of the piston plate away from the phase change material. An overload recording shell corresponding to the linkage rod is provided at the end of the heat-conducting plate away from the phase change material. The end of the linkage rod away from the piston plate penetrates the lower end of the overload recording shell and has a notch. An indicator sphere adapted to the notch is stacked inside the overload recording shell. The overload recording shell is a transparent structure.

2. The cross-linked polyethylene insulated overhead cable with rapidly cross-linkable silane as described in claim 1, characterized in that: The outer wall of the cable sheath is uniformly provided with fixing grooves along the circumference, and the heat-conducting plate is installed in the fixing grooves.

3. The cross-linked polyethylene insulated overhead cable with rapidly cross-linkable silane as described in claim 1, characterized in that: The heat-conducting plate is made of high thermal conductivity aluminum alloy, and the outer wall of the heat-conducting plate is uniformly provided with protruding heat dissipation fins.

4. The cross-linked polyethylene insulated overhead cable with rapidly cross-linkable silane as described in claim 2, characterized in that: The heat flow directional transmission component includes a composite thermal pad disposed between the heat-conducting plate and the cable outer sheath. The composite thermal pad is composed of an elastic matrix, microcapsule phase change material and high thermal conductivity filler.

5. The cross-linked polyethylene insulated overhead cable with rapidly cross-linkable silane as described in claim 4, characterized in that: The elastic matrix is ​​liquid silicone rubber, the microcapsule phase change material uses paraffin as the core material and urea-formaldehyde resin or melamine resin as the wall material, and the high thermal conductivity filler is boron nitride sheet.

6. The cross-linked polyethylene insulated overhead cable with rapidly cross-linkable silane as described in claim 2, characterized in that: The heat flow directional transmission component includes a recess on the side of the heat-conducting plate facing the outer sheath of the cable. A bimetallic strip is installed on the inner side of the recess. An upper contact finger is provided on the inner wall of the recess. A lower contact finger is movably sleeved on the outer side of the upper contact finger near the outer sheath of the cable. A pair of follower rods are provided on the side wall of the lower contact finger, located on the upper and lower sides of the middle of the bimetallic strip, respectively.

7. The cross-linked polyethylene insulated overhead cable with rapidly cross-linkable silane as described in claim 6, characterized in that: The number of upper and lower contact fingers is multiple and corresponds one-to-one. The multiple lower contact fingers are connected as one unit by a heat-conducting connecting rod. The follower rod is disposed on the side wall of one or more of the lower contact fingers.

8. The cross-linked polyethylene insulated overhead cable with rapidly cross-linkable silane as described in claim 1, characterized in that: The phase change material is paraffin.

9. A method for preparing a rapidly cross-linked polyethylene insulated overhead cable with silane-based rapid cross-linking capability, used in the preparation of the rapidly cross-linked polyethylene insulated overhead cable with silane-based rapid cross-linking capability according to any one of claims 1-8, characterized in that, Includes the following steps: S1: Preparation of rapidly crosslinkable silane-grafted polyethylene material, the specific steps of which include: preparing a catalyst-loaded nanocarrier masterbatch; adding polyethylene base material, silane monomer, initiator and the nanocarrier masterbatch into a reactive extruder to carry out a melt grafting reaction to prepare silane-grafted polyethylene material; granulating the silane-grafted polyethylene material to obtain a rapidly crosslinkable insulating material; S2: Simultaneously extruding a conductor shielding layer, an insulating layer and an insulating shielding layer onto a conductor through a co-extrusion process; wherein, by controlling the distribution of conductive filler in the semiconductor material... The process involves: S1) forming a conductor shielding layer with a decreasing conductive filler concentration gradient from the inside out; and S2 forming an insulating shielding layer with an increasing conductive filler concentration gradient from the inside out; the insulating layer uses the rapidly cross-linkable insulating material prepared in step S1; S3) setting a metal shielding layer outside the insulating shielding layer; S4) extruding a cable outer sheath outside the metal shielding layer; S5) subjecting the cable core with the extruded cable outer sheath to warm water cross-linking treatment to obtain the finished cable; and S6) installing a heat storage component and a heat flow directional transmission component at a designated location on the cable outer sheath.

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