Lightning protection overhead insulated wire
By introducing a PTC intelligent control layer, a PCM thermal management buffer layer, and a thermochromic self-indicating layer into overhead insulated conductors, the problems of insufficient lightning protection reliability, thermal damage risks, and lack of self-diagnosis in existing technologies are solved, achieving efficient energy distribution and condition monitoring, and improving the safety and operation and maintenance efficiency of the power grid.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JIANGSU DADI CABLE CO LTD
- Filing Date
- 2025-12-25
- Publication Date
- 2026-04-10
AI Technical Summary
Existing overhead insulated conductor technology for lightning protection suffers from several problems, including reliability being constrained by the environment, inability to avoid insulation thermal damage, lack of self-diagnostic capabilities, bulky structure, passive and inefficient energy handling, and poor synergy among functional layers.
The design employs a conductor core, an inner insulation layer, an energy regulation and thermal management self-indicating composite layer, and an outer protective layer, including a PTC intelligent regulation layer, a PCM thermal management buffer layer, and a thermochromic self-indicating layer. Through a three-level linkage mechanism, it achieves current dispersion, heat buffering, and self-diagnosis functions.
It improves the reliability of lightning protection, avoids thermal damage to the insulation layer, has self-diagnostic capabilities, simplifies the structure, and enhances operation and maintenance efficiency and power grid reliability.
Smart Images
Figure CN121839281A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of insulated conductor technology, and in particular to a lightning-proof overhead insulated conductor. Background Technology
[0002] With the continuous development of power systems, especially distribution networks, overhead insulated conductors have been widely used due to their excellent insulation performance and high power supply reliability. However, in areas with frequent lightning activity, faults such as conductor breakage and insulation breakdown caused by lightning strikes occur frequently, seriously threatening the safe and stable operation of the power grid. Therefore, those skilled in the art have proposed various lightning protection technical solutions.
[0003] Existing technology 1: Metal or semi-conductive shielded conductor with a gap. This technology involves adding a layer of metal braided tape or extruded semi-conductive shielding layer outside the conductor insulation layer, and pre-setting an air gap (i.e., an arc-starting gap) between it and the grounding crossarm (or metal support). The design principle is that when a lightning overvoltage occurs, the air is preferentially broken down at the gap between the shielding layer and the crossarm to form an electric arc, allowing the lightning current to be discharged to the ground through the shielding layer and the arc channel, thereby protecting the conductor itself.
[0004] Existing technology 2: Composite conductors with parallel or integrated lightning protection wires. The idea behind this technology is to install one or more overhead ground wires (lightning protection wires) within the same span, or to twist a metal wire (such as aluminum-clad steel wire) together with a current-carrying conductor to form a composite structure, so that the metal wire serves as a priority lightning interception and current discharge channel.
[0005] Existing technology 3: Multi-layer composite sheath structure conductor, which focuses on improving the mechanical and electrical protection performance of the conductor by combining multiple functional materials.
[0006] Although the aforementioned existing technologies have improved the lightning protection capability of conductors to some extent, the following significant defects and technical problems still exist and urgently need to be solved: 1. Limited protection capabilities, insufficient reliability, and risk of wire breakage: For the "gap-shielded layer" technology (existing technology 1), its protective effect is highly dependent on the accuracy and stability of the preset gap distance. In actual operation, the gap distance can change due to wind swaying, thermal expansion and contraction, sag changes, and installation errors, potentially causing "gap failure"—if the gap is too large, it cannot reliably ignite an arc, and lightning voltage can directly break down the conductor insulation; if the gap is too small, a follow current arc can easily be generated under power frequency voltage, continuously burning the conductor. In addition, the arc burning location is random and the energy is concentrated. Under multiple lightning strikes or high current impacts, a single discharge point may not be able to effectively conduct energy, which may still lead to the shield layer melting or the insulation layer severely carbonized, ultimately causing the line to break.
[0007] 2. Unable to prevent "hidden damage" to insulation and lacks self-diagnostic capabilities: Current technologies primarily focus on the instantaneous current conduction during a lightning strike, neglecting the enormous Joule heat generated inside the conductor during the discharge of lightning current. This heat is rapidly conducted to the inner insulation layer, and even if it doesn't cause instantaneous breakdown, it can lead to irreversible thermal aging, damage to the cross-linked structure, or localized carbonization of the insulation material, forming "hidden damage." This damage reduces the long-term electrical strength of the insulation, creating potential fault points that cannot be detected through routine inspections, posing a long-term safety hazard to the power grid. All existing solutions lack the function of recording and indicating lightning strike events, making it impossible for maintenance personnel to determine which section of the conductor has been struck by lightning and the severity of the strike. They can only passively wait for faults to occur, which is detrimental to preventative maintenance.
[0008] 3. The structure is bulky and costly, and may affect electrical performance: Whether it's adding a metal shielding layer, an independent lightning protection wire, or complex multi-layer armor (such as existing technologies one, two, and three), all of these significantly increase the weight, diameter, and material cost of the conductors, and raise the mechanical load on the towers and the difficulty of construction and erection. Furthermore, the additional metal layer may alter the electric field distribution, increase the line capacitance and transmission loss, and potentially have adverse effects on power quality and current carrying capacity.
[0009] 4. Complex structure or poor coordination: Some composite structural solutions (such as prior art 3) integrate multiple functional layers, but the functions of each layer are relatively independent, lacking a coordinated linkage mechanism under transient and extreme events such as lightning strikes. For example, the armor layer provides mechanical protection and the flame-retardant layer improves fire resistance, but their integration with current conduction and thermal energy management is not close, failing to form a systematic and integrated solution for the entire process of lightning strikes (electric shock and thermal shock).
[0010] In summary, existing lightning protection overhead insulated conductor technologies generally suffer from technical problems such as reliability being constrained by the environment, inability to avoid insulation thermal damage, lack of self-diagnostic functions, bulky structure, passive and inefficient energy handling, and poor coordination among functional layers. Summary of the Invention
[0011] In view of the shortcomings of the prior art, the purpose of this invention is to provide a lightning protection overhead insulated conductor that can solve the technical problems that existing lightning protection overhead insulated conductor technologies generally suffer from: reliability being constrained by the environment, inability to avoid insulation thermal damage, lack of self-diagnosis function, bulky structure, passive and inefficient energy handling, and poor coordination among functional layers.
[0012] This invention provides a lightning-proof overhead insulated conductor, comprising: a conductor core, an inner insulation layer, an energy regulation and thermal management self-indicating composite layer, and an outer protective layer; The inner insulation layer covers the outside of the conductor core; The outer protective layer is disposed on the outermost layer of the inner insulation layer; The energy regulation and thermal management self-indicating composite layer is disposed between the inner insulation layer and the outer protective layer; the outer protective layer is a transparent or semi-transparent polyolefin elastomer material; The outer protective layer includes an outer protective surface modification layer, a PTC intelligent current limiting and energy diversion layer, and a PCM transient thermal buffer layer. The outer protective surface modification layer is a hydrophobic nano-coating with a micron-level conductive bump array on its surface to form a controllable initial discharge channel. The PTC intelligent current limiting and energy diversion layer is made of PTC material, and the PCM transient thermal buffer layer is made of PCM material.
[0013] Extremely high protection reliability: Through the three-level linkage mechanism of "arc initiation, current diversion, and dissipation", the huge lightning energy is gradually attenuated, dispersed at multiple points, and actively dissipated, fundamentally avoiding wire melting caused by energy concentration.
[0014] Preferably, the energy regulation and thermal management self-indicating composite layer is a three-layer co-extruded structure, comprising, from the outside to the inside: The PTC smart control layer contains positive temperature coefficient material particles dispersed in its matrix, which are used to trigger a sudden increase in resistance when lightning current enters in order to regulate the current distribution. The PCM thermal management buffer layer contains microencapsulated phase change material particles dispersed in its matrix to absorb and buffer transient heat generated by lightning strikes. Thermochromic self-indicating layer has thermochromic irreversible color-changing material particles dispersed in its matrix, which are used to cause a permanent color change when the temperature exceeds its color-changing threshold to indicate the location of lightning strike hotspots.
[0015] The switching temperature of the positive temperature coefficient material particles in the PTC smart control layer is between 80°C and 150°C. Furthermore, the volume concentration of the positive temperature coefficient material particles increases gradually from the inside to the outside in the radial direction of the PTC smart control layer. The matrix material of the PTC smart control layer is silicone rubber or ethylene-vinyl acetate copolymer, and the positive temperature coefficient material particles are surface-modified polymer-based composite material particles with multi-walled carbon nanotubes and carbon black as conductive fillers.
[0016] The microencapsulated phase change material particles in the PCM thermal management buffer layer have a core material that is a fatty acid eutectic mixture doped with expanded graphite nanosheets, with a phase change temperature between 65°C and 110°C; the wall material is polyurea or melamine resin. The PCM thermal management buffer layer matrix also contains sheet-like thermally conductive fillers that overlap to form a three-dimensional thermal bridge network, which promotes lateral thermal diffusion between the microencapsulated phase change material particles.
[0017] The thermochromic irreversible color-changing material particles in the thermochromic indicator layer comprise an inorganic color-changing component and an organic indicator. The inorganic color-changing component is cobalt aluminum spinel supported on a mesoporous silica carrier, and the organic indicator is a spiropyran compound encapsulated in the carrier. The color-changing material has at least two different color-changing temperature thresholds, including: a first threshold between 80°C and 100°C, producing a reversible or semi-reversible color change; and a second threshold between 130°C and 160°C, producing a permanent color change.
[0018] The thickness ratios of the PTC intelligent control layer, the PCM thermal management buffer layer, and the thermochromic self-indicator layer are 1, 2:2, and 5:1, respectively, and the total thickness of the energy control and thermal management self-indicator composite layer is 1 mm to 2.5 mm.
[0019] PTC Effect Intelligent Regulation: The lightning current initially flows through the low-resistance path of the PTC material. The instantaneous surge in current causes a rapid increase in the local temperature of this path, triggering the PTC effect. This sharp increase in local resistance forces the lightning current to automatically redirect, diffusing along new paths or over a larger area formed by other unheated PTC particles within the protective layer. This achieves adaptive nonlinear current diversion and limiting.
[0020] Phase change materials act as a heat absorber: During the process of current diffusion and Joule heating, the local temperature continues to rise. When the microcapsule phase change temperature is reached, the phase change material absorbs a large amount of heat, acting like a "radiator" to suppress the rate and peak of temperature rise, thus providing a valuable protection window for the core insulation layer.
[0021] Thermochromic permanent marking: If a lightning strike is exceptionally powerful, causing the local temperature to exceed the threshold of the thermochromic material, the material at that location will undergo a permanent color change. During maintenance and inspection, no specialized instruments are needed; the lightning strike hotspot can be clearly located visually, enabling intuitive self-diagnosis of "where it was struck, that's where it changed color."
[0022] A second aspect of the present invention provides a method for protecting overhead insulated conductors from lightning strikes, comprising the following steps: S1: Prepare the positive temperature coefficient material microparticles, the microencapsulated phase change material microparticles, and the thermo-induced irreversible color-changing material microparticles; S2: Mix the three functional microparticles with the corresponding elastomer matrix materials to prepare composite materials for forming PTC smart control layer, PCM thermal management buffer layer and thermochromic self-indicator layer. S3: On the conductor core covered with an inner insulation layer, a three-layer co-extrusion process is used to simultaneously extrude and fuse the three composite materials to form an integrated energy regulation and thermal management self-indicating composite layer. S4: The outer protective layer is extruded and formed outside the energy regulation and thermal management self-indicating composite layer.
[0023] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following: This invention integrates three major functions: Power Current Control (PTC), Transient Thermal Management (PCM), and Condition Self-Diagnosis (thermochromic). This forms a multi-layered, synergistic protection system that links electricity, heat, and light. Within microseconds to milliseconds of a lightning strike, the PTC layer responds first, intelligently limiting and adaptively diverting current through a sharp increase in resistance, suppressing energy injection at its source. The PCM layer absorbs a large amount of heat through phase change, buffering the temperature rise and providing a critical protection window for the inner insulation layer. This spatiotemporal synergy fundamentally avoids the problems of dark damage, thermal aging, and carbonization of the insulation layer caused by concentrated lightning current discharge in traditional solutions, elevating protection from "preventing wire breakage" to a higher level of "ensuring insulation lifespan."
[0024] This invention utilizes a built-in thermochromic irreversible color-changing layer, causing a permanent, visually perceptible color change at the hottest point on a conductor after it has been struck by lightning exceeding a certain threshold. This function solves the long-standing maintenance pain points of power distribution networks, namely, the difficulty in tracing lightning strike points and the inability to predict potential hazards. Maintenance personnel can quickly and accurately locate lightning-struck sections without the need for complex instruments, through routine inspections or drone patrols. This achieves an intelligent transformation from "passive repair after a fault" to "proactive early warning and preventative maintenance after an incident," significantly improving power grid maintenance efficiency and power supply reliability.
[0025] The gradient PTC layer of this invention achieves electric field homogenization and trigger response optimization through the gradient distribution design of PTC particles, ensuring reliable triggering and efficient current limiting for protection.
[0026] Networked PCM layer: The three-dimensional thermal bridge network constructed by sheet-like thermally conductive filler promotes the lateral diffusion of heat in the PCM layer, avoids local heat accumulation, improves the overall thermal management efficiency, and ensures the full utilization of the latent heat of the PCM.
[0027] Composite color-changing materials: By using inorganic and organic composite systems and mesoporous carrier encapsulation technology, the color-changing materials have a clear and customizable multi-level temperature threshold response, providing richer and more accurate indication information, as well as good weather resistance and stability.
[0028] This invention utilizes a co-extrusion process to form a three-layer functional structure in a single step. The interlayer interfaces are molecular-level fused, with no air gaps or adhesive layers, thus avoiding early failure caused by interlayer separation and interfacial discharge. This integrated structure exhibits high mechanical strength and excellent resistance to environmental stress, while simplifying the manufacturing process and ensuring consistent and repeatable product performance, making it suitable for large-scale industrial production.
[0029] The current-limiting effect of the PTC in this invention reduces the thermal load required for the PCM to handle; the effective thermal buffer of the PCM provides cooling protection for the PTC material after activation, preventing it from being damaged by overheating; the final temperature field controlled by the combined effect of the two precisely drives the indicating behavior of the color-changing layer. This deep coupling synergistic effect enables the overall protective performance, thermal management effect, and diagnostic accuracy to reach a level that cannot be achieved by any single technology or simple combination.
[0030] This invention not only greatly improves the lightning protection safety and long-term reliability of overhead insulated conductors, but also provides key underlying technical support for the state perception and lean operation and maintenance of smart grids through innovative self-diagnostic functions. Attached Figure Description
[0031] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.
[0032] Figure 1 This is a schematic diagram of the structure of an overhead insulated conductor for lightning protection provided in an embodiment of the present invention.
[0033] Figure 2 This is a side view structural diagram of an overhead insulated conductor for lightning protection provided in an embodiment of the present invention.
[0034] Figure 3 This is a schematic diagram of the structure of the energy regulation and thermal management self-indicating composite layer provided in an embodiment of the present invention.
[0035] Figure 4 This is a side view schematic diagram of the energy regulation and thermal management self-indicating composite layer provided in an embodiment of the present invention.
[0036] Figure 5 This is a bottom view of the structure of the energy regulation and thermal management self-indicating composite layer provided in an embodiment of the present invention.
[0037] Figure 6 This is a schematic diagram of the structure of the outer protective layer provided in an embodiment of the present invention.
[0038] Figure 7 This is a side view structural diagram of the outer protective layer provided in an embodiment of the present invention.
[0039] Explanation of reference numerals in the attached figures: 1-Conductor core; 2-Inner insulation layer; 3-Energy regulation and thermal management self-indicating composite layer; 31-PTC intelligent regulation layer; 32-PCM thermal management buffer layer; 33-Thermochromic self-indicating layer; 4-Outer protective layer; 41-Outer protective surface modification layer; 42-PTC intelligent current limiting and energy diversion layer; 43-PCM transient thermal buffer layer; 411-Micron-level conductive bump array. Detailed Implementation
[0040] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.
[0041] Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts disclosed in this invention.
[0042] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention.
[0043] Reference manual attached Figures 1 to 7 The present invention provides a structure for a lightning-proof overhead insulated conductor, comprising: a conductor core 1, an inner insulation layer 2, an energy regulation and thermal management self-indicating composite layer 3, and an outer protective layer 4; The inner insulating layer 2 covers the outside of the conductor core 1; The outer protective layer 4 is disposed on the outermost layer of the inner insulating layer 2; The energy regulation and thermal management self-indicating composite layer 3 is disposed between the inner insulation layer 2 and the outer protective layer 4; the outer protective layer 4 is a transparent or semi-transparent polyolefin elastomer material.
[0044] In one possible implementation, the outer protective layer 4 comprises, from the outside in, an outer protective surface modification layer 41, a PTC intelligent current limiting and energy diversion layer 42, and a PCM transient thermal buffer layer 43. The outer protective surface modification layer 41 is a hydrophobic nano-coating with a micron-level conductive bump array 411 on its surface to form a controllable initial discharge channel. The PTC intelligent current limiting and energy diversion layer 42 is made of PTC material, and the PCM transient thermal buffer layer 43 is made of PCM material.
[0045] In this embodiment of the invention, the beneficial effects are as follows: First stage: outer protective surface modification layer 41, a hydrophobic nano-coating is added to the surface of the outer protective layer to reduce water droplet adhesion and lower the surface flashover probability, and a micron-level conductive bump array is set on the surface to form a controllable initial discharge channel. Second stage: PTC intelligent current limiting and energy diversion layer 42. When lightning current enters, the PTC material experiences a rapid temperature rise under Joule heating, triggering the PTC effect. The resistance increases sharply, resulting in a cascading effect: the increased PTC resistance forces the lightning current to... a) Diffusion along the conductor axis to locate untriggered PTC regions. b) Diffusion radially into the conductor, dissipated through other parallel paths. c) Forming spatial-temporal adaptive desiccation Level 3: PCM transient thermal buffer layer 43 While limiting the current of PTC, PCM absorbs a large amount of instantaneous heat, suppresses the temperature rise rate, and provides a critical protection window of 50-100ms for the inner insulation layer.
[0046] In one possible implementation, the energy regulation and thermal management self-indicating composite layer 3 is a three-layer co-extruded structure, comprising, from the outside to the inside: PTC intelligent control layer 31, whose matrix contains positive temperature coefficient material particles, is used to trigger a sudden increase in resistance when lightning current enters to regulate the current distribution. PCM thermal management buffer layer 32, whose matrix contains microencapsulated phase change material particles, is used to absorb and buffer transient heat generated by lightning strikes; Thermochromic self-indicator layer 33 has thermochromic irreversible color-changing material particles dispersed in its matrix, which are used to undergo a permanent color change when the temperature exceeds its color-changing threshold to indicate the location of the lightning strike hotspot.
[0047] The thickness ratios of the PTC intelligent control layer 31, the PCM thermal management buffer layer 32, and the thermochromic self-indicator layer 33 are 1, 2:2, and 5:1, respectively, and the total thickness of the energy control and thermal management self-indicator composite layer 3 is 1 mm to 2.5 mm.
[0048] In this embodiment of the invention, the beneficial effect is that the energy regulation and thermal management self-indicating composite layer adopts a "sandwich" structure design: Outer layer: PTC intelligent control layer 31 directly interacts with lightning; middle layer: PCM thermal management buffer layer 32; inner layer: thermochromic self-indicating layer 33, close to the inner insulation layer. The three-layer functional gradient structure: PTC, PCM, and thermochromic material each perform their own functions and work together to achieve spatial and temporal coordinated protection: microsecond-level current limiting, millisecond-level thermal buffering, and permanent recording.
[0049] In one possible implementation, the switching temperature of the positive temperature coefficient material particles in the PTC smart control layer 31 is between 80°C and 150°C, and the volume concentration of the positive temperature coefficient material particles increases gradually from the inside to the outside in the radial direction of the PTC smart control layer 31. The matrix material of the PTC smart control layer 31 is silicone rubber or ethylene-vinyl acetate copolymer, and the positive temperature coefficient material particles are surface-modified polymer-based composite material particles with multi-walled carbon nanotubes and carbon black as conductive fillers.
[0050] In this embodiment of the invention, the beneficial effects include the special design of the PTC intelligent control layer 31, the gradient distribution structure: the PTC particle concentration increases from the inside to the outside, the parallel and series hybrid network: there are both parallel paths (initially low resistance) and series paths (high resistance after triggering) between PTC particles; the thermo-electric coupling design: the surface of the PTC particles is coated with a high thermal conductivity ceramic layer (such as AlN), which promotes rapid heat transfer and accelerates the triggering of the PTC effect.
[0051] In one possible implementation, the microencapsulated phase change material particles in the PCM thermal management buffer layer 32 have a core material that is a fatty acid eutectic mixture doped with expanded graphite nanosheets, with a phase change temperature between 65°C and 110°C; the wall material is polyurea or melamine resin; and the matrix of the PCM thermal management buffer layer 32 is further dispersed with sheet-like thermally conductive fillers, which overlap each other in the matrix to form a three-dimensional thermal bridge network to promote lateral thermal diffusion between the microencapsulated phase change material particles.
[0052] In this embodiment of the invention, the beneficial effect is: the phase change endothermic effect of PCM: First heat absorption: At the moment of lightning strike, PCM absorbs a large amount of latent heat (200-300J / g), suppressing temperature rise; Secondary heat absorption: The liquid PCM after phase change continues to absorb the remaining heat in the following minutes; Thermal diffusion: Thermal bridge fillers (such as graphene sheets) between microcapsules promote lateral heat diffusion and avoid local overheating; Thermal circulation management: Daytime heat dissipation: The PCM slowly releases the stored heat when the ambient temperature rises; Phase transition is reversible: PCM can revert to a solid state when cooled overnight, enabling it to be recycled. Failure warning: When the PCM reaches the limit of the number of phase change cycles, its thermal conductivity will decrease significantly.
[0053] In one possible implementation, the thermochromic irreversible color-changing material particles in the thermochromic indicator layer 33 comprise an inorganic color-changing component and an organic indicator. The inorganic color-changing component is cobalt aluminum spinel supported on a mesoporous silica carrier, and the organic indicator is a spiropyran compound encapsulated in the carrier. The color-changing material has at least two different color-changing temperature thresholds, including: a first threshold between 80°C and 100°C, producing a reversible or semi-reversible color change; and a second threshold between 130°C and 160°C, producing a permanent color change.
[0054] In this embodiment of the invention, the beneficial effect is that the thermochromic self-indicating layer 33 is designed to realize a three-level color-changing early warning system: Level 1 indication (60-80℃): Reversible thermochromic discoloration, indicating overload of the indicator wire. Level 2 indicator (100-120℃): Semi-reversible color change, indicating a minor lightning strike. Level 3 indicator (above 150℃): Permanent discoloration, indicating severe lightning strike. Spatial positioning function: The size of the color-changing area is positively correlated with the energy of the lightning strike; the color-changing pattern can indicate the direction of the lightning strike through an asymmetrical diffusion pattern; Enhanced remote identification: Fluorescent markers are added to the color-changing material, making it identifiable under ultraviolet light at night.
[0055] In one possible implementation, a method for protecting overhead insulated conductors from lightning strikes is proposed, comprising the following steps: S1: Prepare positive temperature coefficient material microparticles, the microencapsulated phase change material microparticles, and the thermo-induced irreversible color-changing material microparticles; S2: Mix the three functional microparticles with the corresponding elastomer matrix materials to prepare a composite material for forming the PTC smart control layer 31, the PCM thermal management buffer layer 32 and the thermochromic self-indicating layer 33. S3: On the conductor core 1 covered with the inner insulation layer 2, a three-layer co-extrusion process is used to simultaneously extrude and fuse the three composite materials to form the integrated energy regulation and thermal management self-indicating composite layer 3. S4: The outer protective layer 4 is extruded and formed outside the energy regulation and thermal management self-indicating composite layer 3.
[0056] In this embodiment of the invention, the preparation of microencapsulated phase change material microparticles includes the following main core material: a fatty acid eutectic mixture (such as lauric acid-palmitic acid, phase change temperature 65-85℃). The preparation steps include the following: Step 1: Core material nano-doping: 1. Heat the fatty acid mixture to 80℃ to melt it; 2. Add 2-5 wt% expanded graphite nanosheets; 3. Disperse ultrasonically for 30 minutes to form a uniform suspension; 4. Cool and solidify to obtain a thermally reinforced core material; Step 2: Raw material ratio for microencapsulation: core material (modified fatty acid): 100g, wall material monomer A (toluene diisocyanate): 15g, wall material monomer B (ethylenediamine): 8g, emulsifier (Span-80): 3g, deionized water: 300mL; Preparation process: 1. Aqueous phase preparation: Dissolve the emulsifier in water and stir to form a homogeneous aqueous phase; 2. Oil phase preparation: Mix the core material with monomer A and heat to 70℃ to melt; 3. Emulsification: The oil phase is dripped into the aqueous phase under high-speed shear (8000 rpm) and emulsified for 15 minutes; 4. Polymerization: Cool to 50℃, slowly add aqueous solution of monomer B, and react for 4 hours; 5. Post-treatment: filtration, washing, vacuum drying (40℃, 12 hours).
[0057] Step 3: Surface functionalization; 1. Disperse the microcapsules in an ethanol solution of silane coupling agent (KH-550); 2. Stir the reaction for 2 hours to graft amino groups onto the surface; 3. Wash and dry to obtain surface-functionalized PCM microcapsules.
[0058] In this embodiment of the invention, the preparation of positive temperature coefficient (PTC) material particles includes the following material system selection: Matrix: Ethylene-vinyl acetate copolymer (EVA) (significant PTC effect, good processability); Conductive filler: Multi-walled carbon nanotubes (MWCNT), carbon black (CB) composite filler; Synergistic filler: Barium titanate (BaTiO3) nanoparticles (enhancing PTC effect); The preparation steps include the following: Step 1: Packing material pretreatment: 1. MWCNT acidification treatment: Mix concentrated HNO3 and concentrated H2SO4 in a 1:3 ratio, add MWCNT, sonicate for 2 hours, wash until neutral, and dry to obtain carboxylated MWCNT. 2. BaTiO3 surface modification: Barium titanate nanoparticles were dispersed in an ethanol solution of silane coupling agent KH-570, reacted for 1 hour, and dried to obtain hydrophobic BaTiO3. Step 2: PTC composite material preparation (melt blending method), raw material ratio: EVA (VA content 28%): 100g, acidified MWCNT: 8g, conductive carbon black (particle size 30nm): 12g, modified BaTiO3: 15g, antioxidant 1010: 0.5g; Preparation process: 1. Premixing: Premix all raw materials in a high-speed mixer for 5 minutes; 2. Melt blending: Twin-screw extruder, temperature range 120-140℃; 3. Granulation: After extrusion, the mixture is water-cooled and pelletized to obtain PTC masterbatch; 4. Pulverization: Low-temperature pulverization with liquid nitrogen, followed by sieving to obtain PTC particles of 40-80μm; Step 3: Performance optimization; Crystallinity control: Crystallinity is controlled by adjusting the VA content and cooling rate in EVA (affecting PTC strength); Interface optimization: Adding 0% or 5% maleic anhydride-grafted EVA improves the filler-matrix interface; NTC effect suppression: Adding 1% crosslinking agent DCP slightly suppresses the NTC effect at high temperatures through crosslinking.
[0059] In this embodiment of the invention, the preparation of thermo-irreversible color-changing material particles includes the following material system: The inorganic-organic composite system is selected: inorganic color-changing component: CoAl2O4 (blue, color changes due to structural transformation at high temperature), organic indicator: spiropyran compounds (irreversible thermal ring-opening reaction), and support: mesoporous SiO2 nanospheres (to improve dispersibility and thermal stability). The preparation steps include the following: Step 1: Mesoporous SiO2 loaded with color-changing material Preparation of mesoporous SiO2 (sol-gel method): TEOS was hydrolyzed under the catalysis of ammonia water, CTAB was used as a template agent, and the reaction was carried out at 60°C for 24 hours. The template was removed by washing to obtain mesoporous SiO2 (pore size 5-8 nm). Color-changing component loading: Co(NO3)2 and Al(NO3)3 solutions were impregnated into mesoporous SiO2, dried, and then calcined at 600℃ for 2 hours to obtain a CoAl2O4 / SiO2 composite. Organic indicator encapsulation: Spiropyran is dissolved in ethanol, the above complex is added, the solvent is removed by rotary evaporation, and then vacuum dried; Step 2: Surface passivation and functionalization: 1. A 2nm Al2O3 layer was deposited on the particle surface using atomic layer deposition (ALD) technology. 2. Surface grafting of silane coupling agents improves compatibility with the elastomer matrix. Color-changing performance: Initial color: light blue Level 1 color change (80℃): Light purple (reversible) Secondary color change (120℃): Brownish-red (semi-reversible) Level 3 color change (150℃): Deep black (irreversible).
[0060] This invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this invention. To provide the public with a thorough understanding of this invention, specific details are described in detail in the preferred embodiments, while those skilled in the art will fully understand the invention even without these details. Furthermore, to avoid unnecessary misunderstanding of the essence of this invention, well-known methods, processes, procedures, components, and circuits are not described in detail.
[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the protection scope of the present invention.
Claims
1. A lightning-proof overhead insulated conductor, characterized in that, It includes a conductor core, an inner insulation layer, a self-indicating composite layer for energy regulation and thermal management, and an outer protective layer; The inner insulation layer covers the outside of the conductor core; The outer protective layer is disposed on the outermost layer of the inner insulation layer; The energy regulation and thermal management self-indicating composite layer is disposed between the inner insulation layer and the outer protective layer; The energy regulation and thermal management self-indicating composite layer is a three-layer co-extruded structure, comprising, from the outside to the inside: The PTC smart control layer contains positive temperature coefficient material particles dispersed in its matrix, which are used to trigger a sudden increase in resistance when lightning current enters in order to regulate the current distribution. The PCM thermal management buffer layer contains microencapsulated phase change material particles dispersed in its matrix to absorb and buffer transient heat generated by lightning strikes. Thermochromic self-indicating layer has thermochromic irreversible color-changing material particles dispersed in its matrix, which are used to cause a permanent color change when the temperature exceeds its color-changing threshold to indicate the location of lightning strike hotspots.
2. The lightning-proof overhead insulated conductor according to claim 1, characterized in that, The switching temperature of the positive temperature coefficient material particles in the PTC intelligent control layer is between 80°C and 150°C, and the volume concentration of the positive temperature coefficient material particles increases in a gradient from the inside to the outside in the radial direction of the PTC intelligent control layer.
3. The lightning-proof overhead insulated conductor according to claim 1, characterized in that, The matrix material of the PTC smart control layer is silicone rubber or ethylene-vinyl acetate copolymer, and the positive temperature coefficient material particles are surface-modified polymer-based composite material particles with multi-walled carbon nanotubes and carbon black as conductive fillers.
4. The lightning-proof overhead insulated conductor according to claim 1, characterized in that, The microencapsulated phase change material particles in the PCM thermal management buffer layer have a core material that is a fatty acid eutectic mixture doped with expanded graphite nanosheets, with a phase change temperature between 65°C and 110°C; and a wall material that is polyurea or melamine resin.
5. The lightning-proof overhead insulated conductor according to claim 1, characterized in that, The PCM thermal management buffer layer also contains sheet-like thermally conductive fillers dispersed in its matrix. These sheet-like thermally conductive fillers overlap each other in the matrix to form a three-dimensional thermal bridge network, which promotes lateral thermal diffusion between the microencapsulated phase change material particles.
6. The lightning-proof overhead insulated conductor according to claim 1, characterized in that, The thermochromic irreversible color-changing material particles in the thermochromic indicator layer contain an inorganic color-changing component and an organic indicator. The inorganic color-changing component is cobalt aluminum spinel supported in a mesoporous silica carrier, and the organic indicator is a spiropyran compound encapsulated in the carrier. The color-changing material has at least two different color-changing temperature thresholds.
7. A lightning-proof overhead insulated conductor according to claim 1, characterized in that, The thickness ratios of the PTC intelligent control layer, the PCM thermal management buffer layer, and the thermochromic self-indicator layer are 1, 2:2, and 5:1, respectively, and the total thickness of the energy control and thermal management self-indicator composite layer is 1 mm to 2.5 mm.
8. A lightning-proof overhead insulated conductor according to claim 1, characterized in that, The outer protective layer is a transparent or semi-transparent polyolefin elastomer material.
9. A lightning-proof overhead insulated conductor according to claim 1, characterized in that, The outer protective layer includes an outer protective surface modification layer, a PTC intelligent current limiting and energy diversion layer, and a PCM transient thermal buffer layer. The outer protective surface modification layer is a hydrophobic nano-coating with a micron-level conductive bump array on its surface to form a controllable initial discharge channel. The PTC intelligent current limiting and energy diversion layer is made of PTC material, and the PCM transient thermal buffer layer is made of PCM material.
10. A lightning-proof overhead insulated conductor according to claim 1, and a method for providing a lightning-proof overhead insulated conductor according to any one of claims 1-9, characterized in that, Includes the following steps: S1: Prepare the positive temperature coefficient material microparticles, the microencapsulated phase change material microparticles, and the thermo-induced irreversible color-changing material microparticles; S2: Mix the three functional microparticles with the corresponding elastomer matrix materials to prepare composite materials for forming PTC smart control layer, PCM thermal management buffer layer and thermochromic self-indicator layer. S3: On the conductor core covered with an inner insulation layer, a three-layer co-extrusion process is used to simultaneously extrude and fuse the three composite materials to form an integrated energy regulation and thermal management self-indicating composite layer. S4: The outer protective layer is extruded and formed outside the energy regulation and thermal management self-indicating composite layer.