Temperature-sensing photoelectric composite cable and preparation method thereof

Abstract

The invention discloses a temperature-sensing photoelectric composite cable and a preparation method thereof, relates to the technical field of cables, and successfully develops a composite cable with real-time accurate temperature sensing and high-reliability power supply capabilities through the design of semicircular groove embedded optical fibers and the compounding of multiple layers of functional materials. The insulating layer is made of a ceramic polyolefin material, so that ceramic formation in case of fire can be realized. Once encountering high-temperature flames, the composite material can be sintered into a hard and compact ceramic layer to form a protective shell, so that the flames and oxygen are effectively isolated, and the integrity of an internal conductor structure in a certain time is protected, thereby winning precious time for emergency power supply and escape and rescue. And the ceramic polyolefin material is subjected to a two-step process to ensure that polysilazane is uniformly dispersed in a matrix, so that the ceramic polyolefin material provides electrical insulation and mechanical properties which are the same as those of common polyolefin during normal work.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cables, in particular to a temperature sensing optical-electric composite cable and a preparation method thereof. BACKGROUND

[0002] With the rapid development of smart cities, smart grids, large data centers and comprehensive pipe corridors, the requirements for the integration, intelligence and safety of cables are increasing. The traditional laying method is to install power cables, communication optical cables and temperature sensing systems separately, which not only occupies a large amount of space, increases construction cost and complexity, but also makes it difficult to accurately and globally monitor the temperature of the cable body in real time during the later operation and maintenance.

[0003] There are some optical-electric composite cables in the prior art, which usually place the optical fiber unit and the conductive unit simply side by side in the same sheath. However, these composite cables have the following obvious defects: 1. Weak temperature sensing ability: Most of them use discrete temperature sensing elements (such as thermocouples), which can only provide point temperature measurement and cannot realize continuous and long-distance distributed temperature monitoring, resulting in monitoring blind area. 2. Insufficient reliability: As a sensing medium, the optical fiber unit is easily affected by mechanical stress (such as extrusion and stretching) and thermal stress in the complex cable structure, resulting in attenuation or inaccuracy of the temperature measurement signal. 3. Lack of safety performance: Especially in power transmission applications, the flame retardant performance of the cable is crucial. Ordinary materials will burn and produce a large amount of smoke and toxic gas under fire conditions, and cannot provide early warning in the early stage of fire. 4. Unreasonable structure design: There is a lack of effective coordination and protection design between the optical fiber and the conductor, which may cause signal interference or mutual damage. Therefore, there is an urgent need for a new type of optical-electric composite cable that integrates distributed temperature sensing, high flame retardant characteristics and stable and reliable structure. SUMMARY

[0004] In view of the above deficiencies of the prior art, the present application provides a temperature sensing optical-electric composite cable and a preparation method thereof, which improves the overall flame retardant, fire-resistant, low-smoke and halogen-free characteristics of the cable.

[0005] To achieve the above-mentioned application purposes, the technical solutions adopted by the present application are as follows: A temperature sensing optical-electric composite cable and a preparation method thereof are provided, which comprises a cable core, a filling layer, a flame-retardant tape layer and a flame-retardant sheath layer from inside to outside; the cable core comprises a plurality of cable core wires, the cable core wire comprises a power conductor unit and an insulating layer from inside to outside, and the power conductor unit is obtained by twisting a plurality of conductive filaments; the insulating layer is made of ceramicized polyolefin material; One of the cable core wires is a temperature sensing cable core wire, and a semicircular groove is arranged on the outer surface of the insulating layer of the temperature sensing cable core wire, and an optical fiber sensing unit is embedded in the semicircular groove; The filling layer is a plurality of filling ropes made of low-smoke and halogen-free flame-retardant polyolefin material; The flame-retardant wrapping layer adopts a double-layer overlapping wrapping structure, the inner layer is an alkali-free glass fiber tape, and the outer layer is a mica tape. The flame-retardant sheath layer is obtained by extrusion coating of low-smoke halogen-free flame-retardant polyolefin material.

[0006] Further, the optical fiber sensing unit comprises, from inside to outside, an optical fiber filament, a nylon tight sleeve layer and a flame-retardant polyester tape; the flame-retardant polyester tape is longitudinally wrapped outside the nylon tight sleeve layer.

[0007] Further, the ceramization polyolefin material is prepared from 100 parts of ethylene-vinyl acetate copolymer, 5-15 parts of polysilazane, 20-40 parts of ultra-low density polyethylene, 30-60 parts of magnesium hydroxide / aluminum hydroxide, 5-15 parts of zinc borate, 1-5 parts of silane coupling agent and 0.5-2 parts of antioxidant; the ceramization polyolefin material is sintered into a hard and dense ceramic layer under high-temperature flame, forming a protective shell to isolate the flame and oxygen and protect the internal structure.

[0008] Further, the content of vinyl acetate in the ethylene-vinyl acetate copolymer is 28%.

[0009] Further, the preparation method of the insulation layer is as follows: A1: after mixing 20-30 parts of ethylene-vinyl acetate copolymer, 5-15 parts of polysilazane and 1-5 parts of silane coupling agent, the mixture is extruded by a double-screw extruder, cooled by a water tank and then cut into particles to obtain polysilazane master batch; A2: after uniformly mixing the polysilazane master batch, 70-80 parts of ethylene-vinyl acetate copolymer, 20-40 parts of ultra-low density polyethylene, 30-60 parts of magnesium hydroxide or aluminum hydroxide, 5-15 parts of zinc borate and 0.5-2 parts of antioxidant, the mixture is extruded on the power conductor unit to obtain the insulation layer of the ceramization polyolefin material.

[0010] Further, the low-smoke halogen-free flame-retardant polyolefin material is prepared from 40 parts of linear low-density polyethylene, 60 parts of ethylene-vinyl acetate copolymer, 20-35 parts of nitrogen-phosphorus intumescent flame retardant, 40-70 parts of aluminum hydroxide, 10-30 parts of ceramization flame retardant, 1-3 parts of lubricant and 0.5-2 parts of antioxidant.

[0011] Further, the content of vinyl acetate in the ethylene-vinyl acetate copolymer is 40%.

[0012] Further, the preparation method of the flame-retardant sheath layer is as follows: after uniformly mixing all the materials, the materials are subjected to high-shear melt blending, vacuum devolatilization and granulation by a double-screw extruder to obtain a master batch, and the master batch is extruded on the outside of the flame-retardant wrapping layer by an extruding machine to obtain the flame-retardant sheath layer.

[0013] The application further provides a preparation method of the temperature-sensing photoelectric composite cable. S1: a copper rod or an aluminum rod is drawn into a conductive wire of a required diameter through a wire drawing machine, and the conductive wire is annealed to eliminate internal stress; S2: a plurality of the annealed conductive wires are stranded to obtain a power conductor unit, and an insulating layer is extruded on the power conductor unit through an extruding machine; two kinds of molds are used during extrusion, one mold is circular and used for extruding to obtain a common cable core wire, and the other mold is provided with a semicircular protrusion and used for extruding to obtain a temperature sensing cable core wire; S3: a nylon tight sleeve layer is extruded on the optical fiber wire, and then a flame-retardant polyester tape is longitudinally wrapped outside the nylon tight sleeve layer to obtain an optical fiber sensing unit, the optical fiber sensing unit is embedded in the semicircular groove of the temperature sensing cable core wire and is bonded and fixed; S4: a plurality of cable core wires, temperature sensing cable core wires and low-smoke halogen-free flame-retardant polyolefin filling ropes are concentrically stranded, a flame-retardant wrapping tape inner layer is formed by wrapping a flame-retardant wrapping tape around the concentrically stranded cable core wires, temperature sensing cable core wires and low-smoke halogen-free flame-retardant polyolefin filling ropes, and then a mica tape is overlapped and wrapped to form a complete flame-retardant wrapping tape layer; S5: a low-smoke halogen-free flame-retardant polyolefin material is extruded on the flame-retardant wrapping tape layer to form a flame-retardant sheath layer, and a temperature sensing optical-electric composite cable is obtained after cooling.

[0014] Further, in step S4, the wrapping overlap rate of the alkali-free glass fiber tape and the mica tape is greater than or equal to 25%.

[0015] The beneficial effects of the present application are: The present application successfully develops a composite cable with real-time accurate temperature sensing and high reliability power supply capacity by embedding a semicircular groove type optical fiber design and a multi-layer functional material composite. The insulating layer adopts ceramicized polyolefin material which can realize "ceramic formation when encountering fire". Once encountering high temperature flame, it can sinter into a hard and dense ceramic layer to form a protective shell, effectively isolating the flame and oxygen, and protecting the integrity of the internal conductor structure for a certain period of time, thereby gaining valuable time for emergency power supply and escape rescue. The ceramicized polyolefin material ensures uniform dispersion of polysilazane in the matrix through a two-step process, providing good electrical insulation and mechanical properties as ordinary polyolefin during normal operation.

[0016] The double-layer flame-retardant wrapping tape layer cooperates with the inner and outer insulating layers and the flame-retardant sheath layer to construct a "multi-level, gradient" passive fireproof system. A breakthrough balance is achieved between distributed temperature measurement accuracy, safety performance and long-term reliability. Experimental data show that the comprehensive performance is significantly better than traditional optical-electric separation schemes and ordinary composite cable technology, and the overall cost is controllable through material modification and process innovation, which has large-scale industrialization potential. The product is particularly suitable for intelligent power grids, data centers and comprehensive pipe corridors with high reliability requirements, and can effectively realize real-time accurate sensing and early warning of cable state, significantly improving the safety and service life of energy transmission systems. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 This is a schematic cross-sectional view of the cable according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the cross-section of the fiber optic sensing unit; Among them, 1. Cable core wire, 11. Power conductor unit, 12. Insulation layer, 2. Fiber optic sensing unit, 21. Single-mode fiber optic, 22. Nylon tight-buffered layer, 23. Flame-retardant polyester tape, 3. Filling layer, 4. Semi-circular groove, 5. Flame-retardant wrapping tape layer, 6. Flame-retardant sheath layer, 7. Temperature-sensing cable core wire. Detailed Implementation

[0018] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0019] Example 1 As attached Figure 1 and attached Figure 2 As shown, this embodiment prepares a cable core with two cable core wires 1 and one temperature sensing cable core wire 7. The power conductor unit 11 adopts a type 2 stranded soft conductor, and the conductive wire is made of copper. In specific implementation, the number of cable core wires 1 and temperature sensing cable core wires 7 in the cable core can be selected according to the actual situation. The power conductor unit 11 can also be a single-strand hard conductor, and the conductive wire material can also be aluminum. The temperature-sensing optoelectronic composite cable is prepared using the following steps: S1: The copper rod is drawn into a conductive wire with a diameter of 0.25mm using a wire drawing machine. The conductive wire is then annealed to eliminate internal stress. At the same time, the surface of the conductive wire is conventionally tin-plated. S2: Take 36 conductive wires and twist them together to obtain power conductor unit 11, with a nominal cross-sectional area of ​​1.5mm². 2 An insulation layer 12 with a thickness of 0.6 mm is formed by extruding on the outside of the power conductor unit 11 using an extruder. Two molds are used during extrusion: one mold is circular and is used to extrude ordinary cable core wire 1; the other mold has a semi-circular protrusion and is used to extrude temperature-sensing cable core wire 7. A semi-circular groove 4 with a depth of 0.4 mm and a width of 0.8 mm is formed on the surface of the temperature-sensing cable core wire 7. The ceramic polyolefin material of the insulation layer 12 adopts 100 parts of ethylene-vinyl acetate copolymer with 28% content of ethylene acetate, 12 parts of polysilazane, 35 parts of ultra-low density polyethylene ULDPE, 50 parts of magnesium hydroxide with particle size of 2 μm, 10 parts of zinc borate, 1 part of silane coupling agent, 0.3 parts of antioxidant 1010 and 0.5 parts of antioxidant 168; In specific implementation, the magnesium hydroxide reduces the material temperature by decomposition endothermic and releases water vapor to dilute the combustible gas, and the magnesium hydroxide can be replaced by aluminum hydroxide with the same effect. The antioxidant in the ceramic polyolefin material is one or more of antioxidant 1010, antioxidant 168 and antioxidant 626 in any proportion; the silane coupling agent is one or more of amino silane and epoxy silane in any proportion.

[0020] The mass parts of the polysilazane can also be 5, 8, 10 or 15 parts; the mass parts of the ultra-low density polyethylene ULDPE can also be 20, 25, 30 or 40 parts; the mass parts of the magnesium hydroxide can also be 30, 40 or 60 parts; the mass parts of the zinc borate can also be 5, 8, 12 or 15 parts; the total mass parts of the oxidant can also be 0.5, 1.0, 1.5 or 2 parts; and the mass parts of the silane coupling agent can also be 2, 3, 4 or 5 parts.

[0021] The preparation method of the insulation layer 12 is as follows: A1: 20%~30% of the total mass parts of the ethylene-vinyl acetate copolymer, the polysilazane and the silane coupling agent are mixed in a high-speed mixer for 5~10 minutes, extruded by a double-screw extruder, cooled by a water tank and then pelletized to obtain polysilazane master batch; A2: the polysilazane master batch, the remaining ethylene-vinyl acetate copolymer, the ultra-low density polyethylene, the magnesium hydroxide, the zinc borate and the antioxidant are mixed uniformly and then extruded on the power conductor unit 11 to obtain the insulation layer 12 of the ceramic polyolefin material. The temperature of each temperature zone of the extruder is set as follows: 120℃ for the first zone, 135℃ for the second zone, 145℃ for the third zone, 150℃ for the head and 155℃ for the mold.

[0022] S3: the optical fiber filament adopts G.657.A2 bending-resistant single-mode optical fiber 21, and in specific implementation, a multi-mode optical fiber can also be used. A nylon tight sleeve layer 22 with an outer diameter of 0.9±0.05 mm is extruded on the outside of the optical fiber filament. A flame-retardant polyester tape 23 with a thickness of 0.05 is longitudinally wrapped on the outside of the nylon tight sleeve layer 22 to obtain an optical fiber sensing unit 2. The optical fiber sensing unit is embedded in the semicircular groove 4 of the temperature-sensing cable core wire 7. UV dispensing equipment is used for point gluing every 200 mm, and then the UVLED curing oven is used for instantaneous curing with a wavelength of 365 nm and a power of 800 mJ / cm 2 .

[0023] S4: two cable core wires 1, temperature sensing cable core wire 7 and filling rope with a diameter of 2.5 mm are concentrically twisted by a 1+6 cage twister with a twisting pitch of 20 times the cable core diameter; the filling rope is made of PP material, and other low-smoke halogen-free flame-retardant polyolefin materials can also be used in specific implementation; the filling rope forms a filling layer 3; After twisting, a 0.1 mm thick and 25 mm wide alkali-free glass fiber tape is used to wrap and cover at a wrapping coverage rate of not less than 25%, and the wrapping forms a flame-retardant tape inner layer. Then, a 0.2 mm thick and 25 mm wide mica tape is used to wrap and cover at a wrapping coverage rate of not less than 25%, and the wrapping forms a complete flame-retardant tape layer outside the flame-retardant tape inner layer. The wrapping tension is controlled at 5-10 N to ensure that the tape is tight but not deformed.

[0024] S5: low-smoke halogen-free flame-retardant polyolefin material for forming the flame-retardant sheath layer 6 is prepared: 40 parts of linear low-density polyethylene LLDPE, 60 parts of ethylene-vinyl acetate copolymer with an ethylene-vinyl acetate content of 40%, 30 parts of nitrogen-phosphorus intumescent flame retardant, 60 parts of aluminum hydroxide with a particle size of 1-2 μm, 15 parts of ceramic flame retardant (DFR-03), 0.3 parts of antioxidant 1076, 0.4 parts of antioxidant P-EPQ and 2.0 parts of lubricant are uniformly mixed; In specific implementation, magnesium hydroxide reduces the temperature of the material by decomposition and heat absorption, and releases water vapor to dilute combustible gas. Magnesium hydroxide can be replaced by aluminum hydroxide with the same effect. The antioxidant in the low-smoke halogen-free flame-retardant polyolefin material is one or more of antioxidant 1076, antioxidant 1098, antioxidant 168, antioxidant P-EPQ in any proportion; The mass fraction of the nitrogen-phosphorus intumescent flame retardant can also be 20, 25 or 35 parts; the mass fraction of magnesium hydroxide can also be 40, 50 or 70 parts; the mass fraction of the ceramic flame retardant can also be 10, 20, 25 or 30 parts; the mass fraction of the lubricant can also be 1, 1.5, 2.5 or 3 parts; and the total mass fraction of the oxidant can also be 0.5, 1.0, 1.5 or 2 parts; Outside the flame-retardant tape layer, a Φ90 mm single-screw extruder is used to extrude a low-smoke halogen-free flame-retardant polyolefin material to form a flame-retardant sheath layer 6 with a nominal thickness of 1.2 mm. The temperature of each zone of the extruder is set as follows: zone 1 110℃, zone 2 125℃, zone 3 135℃, head 140℃, and die 145℃. A pressurized eye die is used to ensure that the sheath layer is dense and well adhered to the tape layer.

[0025] Slow cooling is performed through a staged cooling water tank (first stage 60℃ warm water cooling, second stage room temperature water cooling) to prevent internal stress caused by rapid cooling. After being pulled by a track and monitored by an online diameter gauge, the cable is wound onto a Φ1600 mm spool, and the final outer diameter of the cable is about 9.5 mm.

[0026] Example 2 The difference between this embodiment and embodiment 1 is that, when preparing the insulation layer 12, all raw materials are directly mixed in a high-speed mixer for 5-10 minutes and then extruded by a double-screw extruder to prepare a master batch, and then the master batch is extruded and coated. The remaining step parameters are consistent.

[0027] The insulation layer 12 prepared in embodiment 1 and the insulation layer 12 prepared in this embodiment are scanned by SEM, and it is found that, in the insulation layer 12 prepared in embodiment 1, polysilazane particles are uniformly dispersed in a size of less than 5 microns, while in the insulation layer 12 of this embodiment, polysilazane appears to be severely agglomerated in a size of more than 50 microns; The tensile strength test is performed on the cable prepared in embodiment 1 and the cable of this embodiment, and the results are: the tensile strength of embodiment 1 is 16.5 MPa, and the elongation at break is 280%; while the tensile strength of this embodiment is 9.8 MPa, and the elongation at break is 85%. It can be known that the "two-step method" process of the present application effectively eliminates the destructive effect of agglomerates as stress defect points on the toughness of the material.

[0028] The 950℃ fire resistance test is performed on the two cables, and it is found that a hard ceramic protective layer is formed on the surface of the cable prepared in embodiment 1, while the ceramic body of this embodiment is cracked and crushed due to uneven shrinkage.

[0029] Embodiment 3 The difference between this embodiment and embodiment 1 is that ordinary cross-linked polyethylene XLPE is used as the insulation layer 12.

[0030] The 950℃ fire resistance test is performed on the cables prepared in embodiment 1 and this embodiment, and under the condition of 950℃ flame, embodiment 1 using the method of the present application still maintains the line integrity for more than 180 minutes; while this embodiment using ordinary XLPE insulation layer 12 is broken down within 25 minutes; This more than 7 times performance gap is due to the difference in the fundamental mechanism of the material: XLPE rapidly decomposes and carbonizes at high temperature, losing insulation and structural support; while the ceramic polyolefin material of the present application forms a hard ceramic-like skeleton through phase change, which not only effectively insulates the flame, but also provides stable mechanical support for the conductor, thereby extending the survival time of the circuit from minutes to hours under extreme conditions, providing a fundamental guarantee for safety evacuation and power supply for critical equipment.

[0031] Embodiment 4 The difference between this embodiment and embodiment 1 is that the flame-retardant sheath layer 6 is prepared by using halogen-containing flame-retardant sheath material PVC.

[0032] The flame retardant grade of the present embodiment and that of Example 1 both reach the highest flame retardant grade V-0 of UL94, but when burning, the smoke density grade SDR of Example 1 is <15, far lower than the SDR of the present embodiment which is >90; it is proved that the light transmittance of the flame-retardant sheath layer 6 of the present application is extremely high (>85%), while the halogen-containing sheath produces dense black smoke, the smoke density difference is more than 6 times, and the visibility of the fire site is very different. More importantly, the gas toxicity, the pH value of the combustion product of Example 1 is ≥6.5 and the electrical conductivity is ≤3 μS / mm, which proves that it is non-toxic and non-corrosive, while the pH value of the present embodiment is <4.0 and the electrical conductivity is >10 μS / mm, the surface burning will produce strong acidic, highly corrosive and toxic gas. In addition, Example 1 has a higher oxygen index (≥38%), while the oxygen index of the present embodiment is ≥30%; it shows that it is more difficult to be ignited. Data analysis shows that the sheath layer of the present application completely solves the secondary disaster problem of traditional materials "flame-retardant but producing dense smoke and toxic gas" while maintaining the highest flame-retardant grade, realizing the high safety in the true sense.

[0033] Example 5 Take Example 1, rated voltage 0.6 / 1 kV, conductor cross section 1.5 mm 2 , integrated G.657.A2 optical fiber.

[0034] Market-purchased traditional halogen-free flame-retardant cable of the same specification (Comparison 1): commercially available high-quality halogen-free flame-retardant polyolefin sheath power cable (model: WDZA-YJY 0.6 / 1 kV 2×1.5). Only contains power lines, without any temperature measurement function, represents the current mainstream pure power transmission scheme.

[0035] Market-purchased ordinary composite cable simply integrated with distributed optical fiber DTS (Comparison 2): commercially available ordinary optical-electric composite cable (model: WDZA-GYFTZY 2×1.5+2×1.0 G.652D). Its structure is to simply twist the ordinary tight sheath optical fiber unit and the insulated core in the same sheath, representing the existing integration scheme in the market which has not solved the problems of optical fiber protection and temperature measurement accuracy.

[0036] The accuracy, reliability and response speed of the distributed temperature measurement function are verified by temperature monitoring performance comparison test. Three 15-meter-long Example 1 and Comparison 2 are connected to the distributed optical fiber temperature measurement system (DTS). An accurate local constant temperature heat source (80℃) is set at a distance of 10.5 meters from the first end. Comparison 1 cannot be tested. The hot spot position located by the DTS system, the measured temperature value and the signal loss value after the system is stabilized are recorded. The results are shown in Table 1 as follows; Table 1

[0037] The bundled combustion test (Class A) was performed according to the standard GB / T18380.33-2008, and the line integrity (fire resistance) test was performed according to the standard GB / T19216.21-2003, under the condition of 950℃ flame and mechanical vibration for 90 minutes, the rated voltage was applied to the conductors of Example 1 and Comparative Examples 1 and 2 during the test, and whether the line was smooth was monitored. The results are shown in Table 2 below; Table 2

[0038] The bending fatigue test was performed on Example 1 and Comparative Examples 1 and 2: Example 1 and Comparative Example 2 were bent 90 degrees forward and backward on a Φ20mm mandrel, 5000 times in a cycle, and the change in optical fiber additional loss was tested. The heat aging test was also performed: Example 1 and Comparative Example 1 were placed in a circulating air oven at 135℃ for 168 hours (7 days), and after being taken out, the change rate of tensile strength and elongation at break of the insulation and sheath material was tested. The results are shown in Table 3 below; Table 3

[0039] From the above tests, it can be seen that the cable obtained by the method of the present application realizes real-time self-sensing function of temperature, and has high safety performance in flame retardation and fire resistance. Compared with the traditional cable, the example integrates distributed temperature measurement capability without significantly increasing the structural complexity. Compared with the existing ordinary optical and electrical composite cable, the "micro-groove embedded" structure used in the present application helps to improve the temperature measurement stability and reduce the risk of optical fiber damage; the matched synergistic flame-retardant material system further improves the fireproof performance of the cable. Through the synergistic design of materials and structure, the cable has achieved comprehensive improvement in distributed temperature measurement accuracy (positioning accuracy ±0.25m), fire resistance performance (fire resistance time >180min / 950℃) and long-term reliability (fatigue test loss <0.05dB). Experimental data show that its comprehensive performance is significantly better than that of traditional optical and electrical separation scheme and ordinary composite cable technology, and through material modification and process innovation, the overall cost is controllable, and it has large-scale industrialization potential. The product is especially suitable for smart grid, data center and comprehensive pipe gallery and other scenes with high reliability requirements, and can effectively realize real-time and accurate sensing and early warning of cable state, significantly improve the safety and service life of energy transmission system.

Claims

1. A temperature sensing photoelectric composite cable, characterized by, The cable comprises, from inside to outside, a cable core, a filling layer, a flame-retardant wrapping layer and a flame-retardant sheath layer; the cable core comprises a plurality of cable core wires, each cable core wire comprises a power conductor unit and an insulation layer, the power conductor unit is formed by twisting a plurality of conductive filaments, and the insulation layer is made of ceramicized polyolefin material; One of the cable core wires is a temperature sensing cable core wire, a semicircular groove is arranged on the outer surface of the insulation layer of the temperature sensing cable core wire, and an optical fiber sensing unit is embedded in the semicircular groove; The filling layer is a plurality of filling ropes made of low-smoke halogen-free flame-retardant polyolefin material; The flame-retardant wrapping layer adopts a double-layer overlapping wrapping structure, the inner layer is an alkali-free glass fiber tape, and the outer layer is a mica tape; The flame-retardant sheath layer is obtained by extrusion coating of low-smoke halogen-free flame-retardant polyolefin material.

2. The temperature-sensitive photoelectric composite cable according to claim 1, characterized in that, The optical fiber sensing unit comprises, from inside to outside, an optical fiber filament, a nylon tight sleeve layer and a flame-retardant polyester tape; the flame-retardant polyester tape is wrapped longitudinally outside the nylon tight sleeve layer.

3. The temperature-sensitive photoconductive composite cable of claim 1, wherein, The ceramicized polyolefin material is prepared from 100 parts of ethylene-vinyl acetate copolymer, 5-15 parts of polysilazane, 20-40 parts of ultra-low-density polyethylene, 30-60 parts of magnesium hydroxide or aluminum hydroxide, 5-15 parts of zinc borate, 1-5 parts of silane coupling agent and 0.5-2 parts of antioxidant; the ceramicized polyolefin material is sintered into a hard and dense ceramic layer under high-temperature flame, forming a protective shell to isolate the flame and oxygen and protect the internal structure.

4. The temperature-sensitive photoelectric composite cable according to claim 3, characterized in that The content of vinyl acetate in the ethylene-vinyl acetate copolymer is 28%, and the antioxidant is a combination of one or more of antioxidant 1010, antioxidant 168 and antioxidant 626 in any proportion.

5. The temperature-sensitive photoelectric composite cable according to claim 4, characterized in that The preparation method of the insulation layer is as follows: A1: 20-30 parts of ethylene-vinyl acetate copolymer, 5-15 parts of polysilazane and 1-5 parts of silane coupling agent are mixed, then extruded by a double-screw extruder, cooled in a water tank and cut into particles to obtain polysilazane masterbatch; A2: the polysilazane masterbatch, 70-80 parts of ethylene-vinyl acetate copolymer, 20-40 parts of ultra-low-density polyethylene, 30-60 parts of magnesium hydroxide or aluminum hydroxide, 5-15 parts of zinc borate and 0.5-2 parts of antioxidant are uniformly mixed and extruded on the power conductor unit to obtain the insulation layer of the ceramicized polyolefin material.

6. The temperature-sensitive photoelectric composite cable of claim 1, wherein, The low-smoke halogen-free flame-retardant polyolefin material is prepared from 40 parts of linear low-density polyethylene, 60 parts of ethylene-vinyl acetate copolymer, 20-35 parts of nitrogen-phosphorus intumescent flame retardant, 40-70 parts of aluminum hydroxide, 10-30 parts of ceramicized flame retardant, 1-3 parts of lubricant and 0.5-2 parts of antioxidant.

7. The temperature-sensitive photoelectric composite cable according to claim 6, characterized in that The content of vinyl acetate in the ethylene-vinyl acetate copolymer is 40%, and the antioxidant is a combination of one or more of antioxidant 1076, antioxidant 1098, antioxidant 168 and antioxidant P-EPQ in any proportion.

8. The temperature-sensitive photoelectric composite cable of claim 6, wherein, The preparation method of the flame-retardant sheath layer is as follows: all the materials are uniformly mixed, then subjected to high-shear melt blending, vacuum devolatilization and granulation by a double-screw extruder to obtain a masterbatch, and the masterbatch is extruded outside the flame-retardant wrapping layer by an extruding machine to obtain the flame-retardant sheath layer.

9. A process for the production of a temperature sensing photoconductive composite cable as claimed in any one of claims 1 to 8, characterized in that, The following specific steps are adopted: S1: The copper or aluminum rod is drawn into a conductive wire of the required diameter using a wire drawing machine, and the conductive wire is annealed to eliminate internal stress; S2: Several annealed conductive wires are twisted together to obtain a power conductor unit, and an insulation layer is formed by extruding the power conductor unit through an extruder; two types of molds are used during extrusion: one mold is circular and is used to extrude ordinary cable core wires; the other mold has semi-circular protrusions and is used to extrude temperature-sensing cable core wires. S3: Extrude a layer of nylon tight-buffered layer over the optical fiber, and then use flame-retardant polyester tape to longitudinally wrap the nylon tight-buffered layer to obtain the optical fiber sensing unit. Embed the optical fiber sensing unit into the semi-circular groove of the temperature sensing cable core wire and fix it with adhesive. S4: After concentrically twisting several cable cores, temperature sensing cable cores and low smoke halogen-free flame-retardant polyolefin filler ropes, wrap them around alkali-free glass fiber tape to form a flame-retardant inner layer, and then overlap and wrap them around mica tape to form a complete flame-retardant inner layer. S5: A flame-retardant sheath layer is formed by extruding low-smoke halogen-free flame-retardant polyolefin material over the flame-retardant wrapping layer, and after cooling, a temperature-sensing optoelectronic composite cable is obtained.

10. The method of claim 9, wherein, In step S4, the wrapping overlap rate of both alkali-free glass fiber tape and mica tape is greater than or equal to 25%.

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