Prefabricated branch cable and manufacturing method thereof

Abstract

The invention relates to a prefabricated branch cable and a manufacturing method thereof.The prefabricated branch cable comprises a main cable, a plurality of branch cables and a plurality of branch connectors, an optical fiber assembly of the main cable comprises a first optical fiber and a plurality of second optical fibers, and the first optical fiber and the second optical fibers extend in the length direction of the main cable; the plurality of second optical fibers extend along the length direction of the main cable; the optical fiber assembly of the branch cable comprises a third optical fiber and a fourth optical fiber, and the third optical fiber and the fourth optical fiber extend along the length direction of the branch cable; the ends, close to the main cable, of the third optical fiber and the fourth optical fiber of the same branch cable are connected with the opposite ends of the two adjacent second optical fibers of the main cable respectively, and second connecting parts are formed at the joints. The ends, away from the main cable, of the third optical fiber and the fourth optical fiber of the same branch cable are connected with each other, and third connecting parts are formed at the joints. According to the invention, independent temperature monitoring of the main cable and the branch cable of the prefabricated branch cable is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and in particular to a prefabricated branch cable and a manufacturing method thereof. Background Art

[0002] Prefabricated branch cable is a complete cable system that is pre-processed and manufactured in a factory and consists of a main cable, branch cable, branch connector and related accessories. It is mainly used in power distribution systems within buildings to achieve convenient connection between the main cable and multiple branch circuits, without the need for complex cable branching on site. The main cable undertakes the main power transmission task, and its cross-sectional specifications are usually larger. It is the backbone of the branch cable system. Branch cables branch out from the main cable and are connected to various electrical equipment or distribution circuits. The cross-sectional specifications are determined according to the branch load requirements and are generally smaller than the main cable. The branch connector is the connection part between the main cable and the branch cable. It is prefabricated in the factory using professional technology to ensure the reliability, insulation and sealing of the connection. This is also the core difference between prefabricated branch cables and on-site handmade branch cables.

[0003] Fiber optic temperature measurement of prefabricated branch cables is a method that uses fiber optic sensing technology to monitor the temperature of prefabricated branch cables in real time, which can effectively improve the safety and reliability of cable operation. However, the existing temperature measurement technology of prefabricated branch cables has obvious defects: First, when using external thermocouples or single-core optical fibers for temperature measurement, it can only cover the temperature of the main line. Due to the short length and many branch points of the branch cables, traditional sensors are difficult to install and expensive, resulting in the inability to achieve real-time monitoring of the branch line temperature; second, when the main cable and the branch cable share a single-core optical unit, although the main and branch line data can be transmitted simultaneously, signal crossover will cause data distortion, and the main and branch line signals will interfere with each other, seriously affecting the monitoring accuracy. How to achieve independent temperature monitoring of the main cable and branch cables of prefabricated branch cables is a technical problem that needs to be solved urgently in this field. Summary of the Invention

[0004] To this end, the present invention provides a prefabricated branch cable and a manufacturing method thereof, which can realize independent temperature monitoring of a main cable and a branch cable of the prefabricated branch cable.

[0005] In order to solve the above technical problems, the present invention provides a prefabricated branch cable, comprising a main cable, a plurality of branch cables and a plurality of branch connectors; The main cable and the branch cable each include a conductor unit for conducting electricity, an optical fiber unit for monitoring temperature, a main body wrapping layer wrapped around the outside of the conductor unit and the optical fiber unit, a filling layer filled inside the main body wrapping layer, and an outer sheath sleeved outside the main body wrapping layer; The conductor unit includes a conductor assembly and a conductor insulation layer wrapped around the outside of the conductor assembly, and one end of the conductor assembly of the plurality of branch cables is electrically connected to the conductor assembly of the main cable at different positions along the length direction and forms a first connection portion at the connection; The optical fiber unit includes an optical fiber component and an optical fiber sheath covering the outer side of the optical fiber component; The optical fiber assembly of the main cable includes a first optical fiber and a plurality of second optical fibers, wherein the first optical fiber and the second optical fiber both extend along the length direction of the main cable, and the plurality of second optical fibers extend along the length direction of the main cable; The optical fiber assembly of the branch cable includes a third optical fiber and a fourth optical fiber, and the third optical fiber and the fourth optical fiber both extend along the length direction of the branch cable; The third optical fiber and the fourth optical fiber of the same branch cable are connected at ends close to the main cable to opposite ends of two adjacent second optical fibers of the main cable to form a second connection portion at the connection points, and the third optical fiber and the fourth optical fiber of the same branch cable are connected to each other at ends away from the main cable to form a third connection portion at the connection points; The branch connector covers the first connecting portion and the second connecting portion and is relatively fixed to the outer sheath of the main cable and the outer sheath of the branch cable.

[0006] Furthermore, the optical fiber sheath is in close contact with the conductor insulation layer.

[0007] Furthermore, the second connection portion and the third connection portion are welded structures.

[0008] Furthermore, spiral steel belts are provided on the outer sides of the second connecting portion and the third connecting portion, a fiber carrying tube is heat-shrinkably connected to the outer sides of the spiral steel belts, and rubber hoses are sheathed on the outer sides of the opposite ends of the fiber carrying tube and the optical fiber sheath.

[0009] Furthermore, the conductor assembly of the main cable and the conductor assembly of the branch cable are relatively fixed by a C-shaped clamp, and the outer side of the C-shaped clamp is heat-shrinkably connected with a PE insulating film wrapping layer, and the outer side of the PE insulating film wrapping layer is wrapped with a water-blocking tape and an electrical insulating tape.

[0010] Furthermore, the branch connector includes an inner injection-molded layer injected on the outside of the first connection portion and the second connection portion, a branch wrapping layer wound on the outside of the inner injection-molded layer, and an outer injection-molded layer injected on the outside of the branch wrapping layer.

[0011] The present invention also provides a method for manufacturing a prefabricated branch cable, comprising the following steps: S1. Prepare a main cable and a branch cable, each comprising a conductor unit for conducting electricity, an optical fiber unit for monitoring temperature, a main body sheath wrapped around the outside of the conductor unit and the optical fiber unit, a filling layer filled inside the main body sheath, and an outer sheath sleeved outside the main body sheath; the conductor unit comprises a conductor assembly and a conductor insulation layer wrapped around the outside of the conductor assembly; the optical fiber unit comprises an optical fiber assembly and an optical fiber sheath wrapped around the outside of the optical fiber assembly; the optical fiber assembly of the main cable comprises a first optical fiber and an optical fiber E; the optical fiber assembly of the branch cable comprises a third optical fiber and a fourth optical fiber; and the optical fiber assembly comprises two optical fibers; S2. Strip the main cable and branch cable down to the filling layer, gently pull the optical unit outward, release some excess length, and move it to one side; S34, after stripping the conductor insulation layer of the conductor assemblies of the main cable and the branch cable at the connection location, connect the end of the conductor assembly of the branch cable to the conductor assembly of the main cable to form a first connection portion; S4, repeat step S3 until all conductor assemblies of the branch cable are connected to all conductor assemblies of the main cable; S5. Remove the optical fiber sheaths at the locations where the optical fibers of the main cable and the branch cable are to be connected, split the optical fiber E into multiple segments of second optical fibers, connect the ends of the third and fourth optical fibers of the same branch cable close to the main cable to the opposite ends of the adjacent second optical fibers of the main cable to form a second connection portion, and connect the ends of the third and fourth optical fibers of the same branch cable away from the main cable to form a third connection portion. S6. Make a branch connector outside the first connecting part and the second connecting part. The branch connector covers the first connecting part and the second connecting part and is relatively fixed to the outer sheath of the main cable and the outer sheath of the branch cable.

[0012] Furthermore, step S3 includes the following sub-steps: S3.1. Use a rubber hammer and a wooden wedge to gently tap the main cable and branch cable to separate the conductor units. S3.2. Strip the conductor insulation; S3.3. Connect the conductor assemblies of the main cable and branch cable using C-type clamps and crimp them tightly using hydraulic pliers; S3.4. Wrap PE insulation film around the outside of the C-shaped clip and shrink it using a heat gun. S3.5. Wrap water-blocking tape and electrical insulating tape around the outside of the PE insulating film.

[0013] Furthermore, in step S5, the optical fiber connection is performed using the armored optical fiber splicing method, wherein before the optical fiber connection, the fiber carrier tube sleeve and the rubber hose are covered on the outside of the optical fiber before splicing. After the splicing is completed, the spiral steel belt is screwed into the fiber carrier tube and the fiber carrier tube is heated and heat-shrunk, and finally the rubber hose is moved back to the optical fiber connection.

[0014] Furthermore, in step S6, an inner injection molded layer is firstly injection molded outside the first connecting portion and the second connecting portion, a branch wrapping layer is then wound outside the inner injection molded layer, and finally an outer injection molded layer is injection molded outside the branch wrapping layer.

[0015] The above technical solution of the present invention has the following advantages over the prior art: the prefabricated branch cable and its manufacturing method described in the present invention, on the one hand, both the main cable and the branch cable adopt dual-core optical units, one of the optical fibers of the main cable is used to monitor its own temperature, the other optical fiber of the main cable is cut into segments, and then connected to the optical fiber of the branch cable, by comparing the signal differences between the two paths, the temperature interference of the main cable is eliminated, and the independent temperature data of the branch cable is extracted; on the other hand, the main cable and the branch cable do not need to distinguish between the lines, and only two optical fibers need to be implanted in the production and manufacturing, with low cost, high production efficiency and low error rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0017] Figure 1 This is a connection diagram of the main cable, branch cable and branch connector of the prefabricated branch cable of the present invention; Figure 2 Schematic cross-sectional view of the main cable and branch cables of the prefabricated branch cable of the present invention; Figure 3 This is a schematic diagram of optical fiber connection of the prefabricated branch cable in the present invention; Figure 4 Schematic diagram of the connection between the third optical fiber and the second optical fiber in the present invention; Figure 5 Schematic diagram of the connection of the first connecting portion in the present invention.

[0018] Description of the accompanying drawings: A, main cable; B, branch cable; C, branch connector; Conductor unit; 111. Conductor assembly; 112. Conductor insulation layer; 113. C-type clip; 114. PE insulation film wrapping layer; 115. Water-blocking tape; 116. Electrical insulation tape; 12. Optical fiber unit; 121. Optical fiber assembly; 122. Optical fiber jacket; 123. First optical fiber; 124. Second optical fiber; 125. Third optical fiber; 126. Fourth optical fiber; 127. Spiral steel tape; 128. Fiber carrier tube; 129. Rubber hose; 13. Main body wrapping layer; 14. Filling layer; 15. Outer jacket; 21. Inner injection molding layer; 22. Branch wrapping layer; 23. Outer injection molding layer. DETAILED DESCRIPTION

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0020] See also Figures 1 to 5 FIG. 1 shows an embodiment of a prefabricated branch cable disclosed in the present invention.

[0021] A prefabricated branch cable comprises a main cable A, a plurality of branch cables B and a plurality of branch connectors C; The main cable A and the branch cable B each include a conductor unit 11 for conducting electricity, an optical fiber unit 12 for monitoring temperature, a main body wrapping layer 13 covering the outside of the conductor unit 11 and the optical fiber unit 12, a filling layer 14 filling the inside of the main body wrapping layer 13, and an outer sheath 15 sleeved on the outside of the main body wrapping layer 13; The conductor unit 11 includes a conductor assembly 111 and a conductor insulation layer 112 covering the outside of the conductor assembly 111. One end of the conductor assembly 111 of the plurality of branch cables B is electrically connected to the conductor assembly 111 of the main cable A at different positions along the length direction and a first connection portion is formed at the connection. The optical fiber unit 12 includes an optical fiber assembly 121 and an optical fiber sheath 122 covering the outer side of the optical fiber assembly 121; The optical fiber assembly 121 of the main cable A includes a first optical fiber 123 and a plurality of second optical fibers 124. The first optical fiber 123 and the second optical fibers 124 extend along the length of the main cable A. The plurality of second optical fibers 124 extend along the length of the main cable A. The optical fiber assembly 121 of the branch cable B includes a third optical fiber 125 and a fourth optical fiber 126 , and both the third optical fiber 125 and the fourth optical fiber 126 extend along the length direction of the branch cable B; The third optical fiber 125 and the fourth optical fiber 126 of the same branch cable B, at ends close to the main cable A, are respectively connected to opposite ends of two adjacent second optical fibers 124 of the main cable A to form a second connection portion at the connection points. The third optical fiber 125 and the fourth optical fiber 126 of the same branch cable B, at ends away from the main cable A, are connected to each other to form a third connection portion at the connection points. The branch connector C covers the first connecting portion and the second connecting portion and is fixed relative to the outer sheath 15 of the main cable A and the outer sheath 15 of the branch cable.

[0022] In the above, the main cable A is the trunk channel for power transmission. As the "aorta" of the entire cable system, it undertakes the main power transmission task from the power end to each branch node. It usually has a larger conductor cross-section to meet the needs of large current transmission. Branch cable B is the end channel for power diversion. As a "branch blood vessel", it is led out from the branch node of the main cable A and connected to the terminal power equipment. The conductor cross-section is determined according to the branch load. The structure is similar to the main cable A, but due to the shorter transmission distance and smaller load, some auxiliary structures (such as the shielding layer) can be simplified according to needs, focusing on ensuring the adaptability with the connection end of the main cable A and the insulation reliability of the end. The branch connector C is the core hub of connection and protection. It is the "connection bridge" between the main cable A and the branch cable B. The electrical connection and mechanical fixation of the two are completed in the factory through crimping, injection molding and other processes. It is the key component that distinguishes the prefabricated branch cable from the on-site manual branch. Conductor unit 11 is the core carrier of power transmission and is responsible for the transmission of electrical energy. The conductor unit 11 of main cable A typically has a larger cross-section and is responsible for the main power transmission. The cross-section of the conductor unit 11 of branch cable B is determined based on the branch load, enabling the diversion and distribution of electrical energy. The optical fiber unit 12 is used to sense temperature changes inside and on the surface of the cable in real time. The main sheath 13 uses a wrapping process to bundle the conductor unit 11 and optical fiber unit 12, achieving structural fixation and preventing relative displacement during cable bending and installation. The filler layer 14 fills the gaps between the conductor unit 11, optical fiber unit 12, and main sheath 13, buffering external mechanical stress, protecting the internal units from damage, and assisting in moisture resistance, preventing water vapor from penetrating through the gaps. The outer sheath 15 is an outer protective barrier that wraps around the outside of the main sheath 13, providing physical isolation from the external environment.

[0023] The conductor insulation layer 112 refers to the insulating material that wraps the conductor component 111. Its function is to provide electrical isolation for the conductor unit 11 and maintain the contact interface with the optical fiber sheath 122. The optical fiber sheath 122 refers to the protective structure wrapped around the outer layer of the optical fiber component 121. Its function is to provide mechanical protection for the optical fiber component 121 and form physical contact with the conductor insulation layer 112.

[0024] The first optical fiber 123 is an independent optical fiber extending continuously along the entire length of the main cable A and is used to transmit the temperature monitoring signal of the main cable A. The second optical fiber 124 is an optical fiber arranged in sections along the length of the main cable A. The third optical fiber 125 and the fourth optical fiber 126 are optical fibers arranged in pairs within the branch cable B. The first connection portion is the point where the conductors of the main cable A and the branch cable B meet. The second connection portion is the point where the optical fibers of the branch cable B meet the optical fibers of the main cable A. The third connection portion is the closed-loop connection point of the optical fibers within the branch cable B.

[0025] The first temperature measurement optical path: light source → first optical fiber → reflector → return, monitoring the temperature of main cable A throughout the entire process. The second temperature measurement path: light source → second optical fiber → third optical fiber → fourth optical fiber → second optical fiber, comprehensively monitoring the temperatures of main cable A and branch cable B. By comparing the signal differences between the two paths, the temperature interference of main cable A is eliminated and independent temperature data of branch cable B is extracted.

[0026] Specifically, the method for manufacturing the above-mentioned prefabricated branch cable includes the following steps: S1. Prepare a main cable and a branch cable. Each of the main cable and the branch cable includes a conductor unit for conducting electricity, an optical fiber unit for monitoring temperature, a main sheath covering the outside of the conductor unit and the optical fiber unit, a filling layer filling the inside of the main sheath, and an outer sheath sleeved on the outside of the main sheath. The conductor unit includes a conductor assembly and a conductor insulation layer covering the outside of the conductor assembly. The optical fiber unit includes an optical fiber assembly and an optical fiber sheath covering the outside of the optical fiber assembly. The optical fiber assembly of the main cable includes a first optical fiber and an optical fiber E. The optical fiber assembly of the branch cable includes a third optical fiber and a fourth optical fiber. The optical fiber assembly includes two optical fibers. S2. Strip the main cable and branch cable down to the filling layer, gently pull the optical unit outward, release some excess length, and move it to one side; S3, after stripping the conductor insulation layer of the conductor assembly of the main cable and the branch cable at the connection location, connect the end of the conductor assembly of the branch cable to the conductor assembly of the main cable to form a first connection portion; S4, repeat step S3 until all conductor assemblies of the branch cable are connected to all conductor assemblies of the main cable; S5. Remove the optical fiber sheaths at the locations where the optical fibers of the main cable and the branch cable are to be connected, split the optical fiber E into multiple segments of second optical fibers, connect the ends of the third and fourth optical fibers of the same branch cable close to the main cable to the opposite ends of the adjacent second optical fibers of the main cable to form a second connection portion, and connect the ends of the third and fourth optical fibers of the same branch cable away from the main cable to form a third connection portion. S6. Make a branch connector outside the first connecting part and the second connecting part. The branch connector covers the first connecting part and the second connecting part and is relatively fixed to the outer sheath of the main cable and the outer sheath of the branch cable.

[0027] The above technical solution utilizes dual-core optical units for both main cable A and branch cable B. One optical fiber in main cable A is used to monitor its own temperature. The other optical fiber is cut into segments and then connected to the optical fiber in branch cable B to monitor the temperatures of both cables. By comparing the signal differences between the two paths, temperature interference from main cable A is eliminated, allowing independent temperature data from branch cable B to be extracted. Furthermore, there's no need to distinguish between main and branch cables A and B; manufacturing can be done with just two optical fibers, resulting in low cost, high production efficiency, and a low error rate.

[0028] In this embodiment, the optical fiber jacket 122 is tightly attached to the conductor insulation layer 112 .

[0029] In the above, the optical fiber jacket 122 is in close contact with the conductor insulation layer 112, which means that there is no gap between the optical fiber jacket 122 and the conductor insulation layer 112, and its function is to eliminate the air gap between the two to optimize the heat conduction path.

[0030] Specifically, the close contact between the optical fiber jacket 122 and the conductor insulation layer 112 enables the optical fiber assembly 121 to directly sense temperature changes during the operation of the conductor unit 11. When the conductor assembly 111 generates heat due to the current load, the heat is directly transferred to the optical fiber jacket 122 through the conductor insulation layer 112, and then captured by the optical fiber assembly 121 in real time.

[0031] Through the above technical solution, the optical fiber sheath 122 is in close contact with the conductor insulation layer 112, ensuring the accuracy of temperature monitoring, avoiding temperature measurement delays caused by excessive distance, and ensuring temperature sensitivity.

[0032] In this embodiment, the second connection portion and the third connection portion are welded structures.

[0033] In the above, the second connection refers to the connection point between the optical fiber assembly 121 of branch cable B and the optical fiber assembly 121 of main cable A. The third connection refers to the closed-loop connection point between the two optical fibers within branch cable B. A fusion splice is a connection method that uses high temperature to melt and fuse the glass at the optical fiber end faces.

[0034] Specifically, at the second connection, the second fiber end face of main cable A is fused to the third fiber end face of branch cable B. Simultaneously, the second fiber end face of another adjacent segment of main cable A is fused to the fourth fiber end face of branch cable B. At the third connection, the third and fourth fibers at the far end of the branch cable are fused.

[0035] Through the above technical solution, optical fibers are connected by fusion splicing to reduce losses.

[0036] In this embodiment, a spiral steel belt 127 is provided on the outer side of the second connecting portion and the third connecting portion. A fiber-carrying tube 128 is heat-shrinkably connected to the outer side of the spiral steel belt 127. A rubber hose 129 is provided on the outer side of the opposite ends of the fiber-carrying tube 128 and the optical fiber sheath 122.

[0037] In the above description, the spiral steel belt 127 refers to a metal belt with a continuous spiral structure. This structure provides circumferential support while maintaining axial flexibility, dissipating the direct impact of external pressure on the fiber splice point. The fiber carrier tube 128 is a heat-shrinkable tubular protective component, and the rubber hose 129 is an elastic tubular buffer component that compensates for thermal expansion differences between different materials through elastic deformation and absorbs vibration energy.

[0038] Specifically, in step S5 above, the optical fiber connection is performed using the armored optical fiber splicing method, wherein before the optical fiber connection, the fiber carrier tube sleeve and the rubber hose are covered on the outside of the optical fiber before splicing. After the splicing is completed, the spiral steel belt is screwed into the fiber carrier tube and the fiber carrier tube is heated and heat-shrunk, and finally the rubber hose is moved back to the optical fiber connection.

[0039] Through the above technical solution, the present invention realizes multi-level protection of optical fiber connection points, which not only prevents external force damage but also avoids internal stress interference.

[0040] In this embodiment, the conductor assembly 111 of the main cable A and the conductor assembly 111 of the branch cable B are relatively fixed by a C-shaped clamp 113. The outer side of the C-shaped clamp 113 is heat-shrinkably connected with a PE insulating film wrapping layer 114, and the outer side of the PE insulating film wrapping layer 114 is wrapped with a water-blocking tape 115 and an electrical insulating tape 116.

[0041] In the above, the C-type clip 113 refers to a metal connector with a semi-enclosed structure, which realizes the mechanical fixation of the conductor assembly 111. The PE insulation film wrapping layer 114 refers to a heat-shrinkable film layer made of polyethylene material, which is heated and shrunk by a hot air gun to form a continuous wrapping layer. The water-blocking tape 115 refers to a strip material with water absorption and expansion properties. After being wound, it expands when exposed to water and can block the longitudinal penetration path of water. The electrical insulation tape 116 refers to an insulating tape with an adhesive function. It is formed by overlapping and winding to form an outer layer of protection, enhance the mechanical strength of the insulation layer and achieve secondary sealing.

[0042] Specifically, step S3 above includes the following sub-steps: S3.1. Use a rubber hammer and a wooden wedge to gently tap the main cable and branch cable to separate the conductor units. S3.2. Strip the conductor insulation; S3.3. Connect the conductor assemblies of the main cable and branch cable using C-type clamps and crimp them tightly using hydraulic pliers; S3.4. Wrap PE insulation film around the outside of the C-shaped clip and shrink it using a heat gun. S3.5. Wrap water-blocking tape and electrical insulating tape around the outside of the PE insulating film.

[0043] Through the above technical solution, through the synergistic effect of the C-shaped clip 113 and the three-layer protective structure, while maintaining the stability of the conductor connection, a step-by-step enhanced insulation and waterproof barrier is formed, solving the technical defect of insufficient comprehensive protection of the connection part.

[0044] In this embodiment, the branch connector C includes an inner injection molded layer 21 injected on the outside of the first connection part and the second connection part, a branch wrapping layer 22 wrapped on the outside of the inner injection molded layer 21, and an outer injection molded layer 23 injected on the outside of the branch wrapping layer 22.

[0045] In the above description, the inner injection molded layer 21 refers to the sealing layer formed on the outside of the conductor and fiber connections through the injection molding process. Its contour closely matches the connection parts to achieve physical isolation. The branch wrapping layer 22 is a reinforcing structure formed by wrapping around the surface of the inner injection molded layer 21. The outer injection molded layer 23 is an encapsulation layer formed by secondary injection molding outside the branch wrapping layer 22, forming the overall protective structure.

[0046] Specifically, in step S6, an inner injection molded layer is firstly injection molded outside the first connecting portion and the second connecting portion, a branch wrapping layer is then wound outside the inner injection molded layer, and finally an outer injection molded layer is injection molded outside the branch wrapping layer.

[0047] Through the above technical solution, precise sealing is achieved through the inner injection molding layer, the branch wrapping layer provides anti-bending support, and the outer injection molding layer completes the overall packaging to form a gradient protection system.

[0048] In the foregoing, the conductor of the conductor assembly 111 should be a Type 1, Type 2, or Type 5 metal-coated or non-metal-coated annealed copper conductor, a Type 1 or Type 2 aluminum or aluminum alloy conductor, or other large-gauge metal structure conductor in accordance with GB / T3956-2008.

[0049] The insulating material of the conductor insulation layer 112 is cross-linked polyethylene insulation material, and its performance complies with the provisions of GB / T 12706 standard; the insulation must have good electrical properties and excellent mechanical and physical properties, so that it can withstand changes in temperature between day and night, and can also be used in hot summer and cold winter.

[0050] During cabling, the optical fiber unit is embedded within the cable core, ensuring close contact between the optical fiber and the surface of the insulating core, preventing damage to the insulating core or the optical fiber unit. High-precision ceramic guide wheels (50mm diameter) ensure parallelism of the optical unit. The optical unit payout tension is maintained at a constant 5N ± 0.5N to prevent bending or stretching damage.

[0051] The optical fiber unit 12 is specially designed with ultra-flexible and high-temperature resistant characteristics. The optical fiber is a high-temperature resistant tight-buffered optical fiber with an operating temperature range of -60°C to 150°C, which prevents the cable from overheating and causing damage to the optical fiber, affecting the optical signal feedback; the armor is a flexible steel pipe, which is a gap-type spirally wrapped steel pipe or a ring-type steel pipe. The optical unit reinforcement is non-metallic reinforcement and is reinforced with Kevlar (polyparaphenylene terephthalamide). Kevlar is used to reinforce the optical fiber and the metal armor, and the outer periphery is reinforced with Kevlar braided covering. The outer sheath uses a thermoplastic elastomer sheath material with the same temperature resistance grade as the cable.

[0052] Outer sheath 15 The outer sheath is made of thermoplastic material (polyvinyl chloride, polyethylene or halogen-free material, etc.). The cable sheath is tightly extruded on the cable core or armor layer and is easy to peel off without damaging the insulation or inner lining. The sheath surface is smooth and the color is uniform.

[0053] The system utilizes high-temperature-resistant multimode optical fiber (operating temperature -40°C to 200°C), sheathed in a stainless steel hose (tensile strength ≥ 1200N) and a low-smoke, halogen-free, flame-retardant jacket (oxygen index ≥ 40). The two optical fibers of the dual-core optical unit are parallel and positioned in the gap between the conductor elements, maintaining close contact with the conductor surface (spacing ≤ 1mm) throughout to ensure temperature sensitivity.

[0054] A Fujikura FSM-100S fiber fusion splicer was used, with a splice loss of ≤0.03dB. After each splice, the optical signal strength was tested using an OTDR (Optical Time Domain Reflectometer), with a loss requirement of ≤0.1dB / point. Mechanical performance testing: branch point tensile strength ≥800N, bend radius ≥20 times the optical unit diameter. Cable performance complies with GB / T 12706-2020; branch head performance complies with JB / T 10636; and optical performance complies with YD / T 901-2018.

[0055] The advantages of the present invention are: ① Accurate temperature measurement: - The branch line temperature monitoring resolution is ≤0.5m, and the temperature measurement accuracy is ±1℃ (measured data).

[0056] - Supports simultaneous monitoring of 200 branch points, covering a distance of up to 10km.

[0057] Anti-interference: Dual optical unit signal separation improves the signal-to-noise ratio by 40% (compared to traditional single-core solutions).

[0058] ②High reliability: - The high temperature resistance of the optical unit is improved by 50%, and the service life is ≥20 years.

[0059] - The failure rate of welding points is reduced to 0.1 times / 1,000 points (the industry average is 0.5 times / 1,000 points).

[0060] ③Economic benefits: - Reduce manual inspection frequency by 70%, and reduce annual maintenance costs by RMB 300,000 per 100 kilometers.

[0061] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A prefabricated branch cable, characterized in that: It includes a main cable, multiple branch cables and multiple branch connectors; The main cable and the branch cable each include a conductor unit for conducting electricity, an optical fiber unit for monitoring temperature, a main body wrapping layer wrapped around the outside of the conductor unit and the optical fiber unit, a filling layer filled inside the main body wrapping layer, and an outer sheath sleeved outside the main body wrapping layer; The conductor unit includes a conductor assembly and a conductor insulation layer wrapped around the outside of the conductor assembly, and one end of the conductor assembly of the plurality of branch cables is electrically connected to the conductor assembly of the main cable at different positions along the length direction and forms a first connection portion at the connection; The optical fiber unit includes an optical fiber component and an optical fiber sheath covering the outer side of the optical fiber component; The optical fiber assembly of the main cable includes a first optical fiber and a plurality of second optical fibers, wherein the first optical fiber and the second optical fiber both extend along the length direction of the main cable, and the plurality of second optical fibers extend along the length direction of the main cable; The optical fiber assembly of the branch cable includes a third optical fiber and a fourth optical fiber, and the third optical fiber and the fourth optical fiber both extend along the length direction of the branch cable; The third optical fiber and the fourth optical fiber of the same branch cable are connected at ends close to the main cable to opposite ends of two adjacent second optical fibers of the main cable to form a second connection portion at the connection points, and the third optical fiber and the fourth optical fiber of the same branch cable are connected to each other at ends away from the main cable to form a third connection portion at the connection points; The branch connector covers the first connecting portion and the second connecting portion and is relatively fixed to the outer sheath of the main cable and the outer sheath of the branch cable.

2. The prefabricated branch cable according to claim 1, characterized in that: The optical fiber sheath is in close contact with the conductor insulation layer.

3. The prefabricated branch cable according to claim 1, characterized in that: The second connection portion and the third connection portion are welded structures.

4. The prefabricated branch cable according to claim 1, characterized in that: The outer sides of the second connecting part and the third connecting part are provided with spiral steel belts, the outer sides of the spiral steel belts are heat-shrinkably connected with fiber-carrying tubes, and the outer sides of the fiber-carrying tubes and the ends opposite to the optical fiber sheaths are covered with rubber hoses.

5. The prefabricated branch cable according to claim 1, characterized in that: The conductor assembly of the main cable and the conductor assembly of the branch cable are relatively fixed by a C-shaped clamp, and the outer side of the C-shaped clamp is heat-shrinkably connected with a PE insulating film wrapping layer, and the outer side of the PE insulating film wrapping layer is wrapped with a water-blocking tape and an electrical insulating tape.

6. The prefabricated branch cable according to claim 1, characterized in that: The branch connector includes an inner injection-molded layer injected on the outside of the first connection portion and the second connection portion, a branch wrapping layer wound around the outer side of the inner injection-molded layer, and an outer injection-molded layer injected on the outer side of the branch wrapping layer.

7. A method for manufacturing a prefabricated branch cable, characterized in that: The steps include: S1. Prepare a main cable and a branch cable, each comprising a conductor unit for conducting electricity, an optical fiber unit for monitoring temperature, a main body sheath wrapped around the outside of the conductor unit and the optical fiber unit, a filling layer filled inside the main body sheath, and an outer sheath sleeved around the outside of the main body sheath; the conductor unit comprises a conductor assembly and a conductor insulation layer wrapped around the outside of the conductor assembly; the optical fiber unit comprises an optical fiber assembly and an optical fiber sheath wrapped around the outside of the optical fiber assembly; the optical fiber assembly of the main cable comprises a first optical fiber and an optical fiber E; the optical fiber assembly of the branch cable comprises a third optical fiber and a fourth optical fiber; and the optical fiber assembly comprises two optical fibers; S2. Strip the main cable and branch cable down to the filling layer, gently pull the optical unit outward, release some excess length, and move it to one side; S3, after stripping the conductor insulation layer of the conductor assembly of the main cable and the branch cable at the connection location, connect the end of the conductor assembly of the branch cable to the conductor assembly of the main cable to form a first connection portion; S4, repeat step S3 until all conductor assemblies of the branch cable are connected to all conductor assemblies of the main cable; S5. Remove the optical fiber sheaths at the locations where the optical fibers of the main cable and the branch cable are to be connected, split the optical fiber E into multiple segments of second optical fibers, connect the ends of the third and fourth optical fibers of the same branch cable close to the main cable to the opposite ends of the adjacent second optical fibers of the main cable to form a second connection portion, and connect the ends of the third and fourth optical fibers of the same branch cable away from the main cable to form a third connection portion. S6. Make a branch connector outside the first connecting part and the second connecting part. The branch connector covers the first connecting part and the second connecting part and is relatively fixed to the outer sheath of the main cable and the outer sheath of the branch cable.

8. The method for manufacturing a prefabricated branch cable according to claim 7, characterized in that: Step S3 includes the following sub-steps: S3.

1. Use a rubber hammer and a wooden wedge to gently tap the main cable and branch cable to separate the conductor units. S3.

2. Strip the conductor insulation; S3.

3. Connect the conductor assemblies of the main cable and branch cable using C-type clamps and crimp them tightly using hydraulic pliers; S3.

4. Wrap PE insulation film around the outside of the C-shaped clip and shrink it using a heat gun. S3.

5. Wrap water-blocking tape and electrical insulating tape around the outside of the PE insulating film.

9. The method for manufacturing a prefabricated branch cable according to claim 7, characterized in that: In step S5, the optical fiber connection is performed using the armored optical fiber splicing method. Before the optical fiber connection, the fiber carrier tube sleeve and the rubber hose are covered on the outside of the optical fiber before splicing. After the splicing is completed, the spiral steel belt is screwed into the fiber carrier tube and the fiber carrier tube is heated and heat-shrunk. Finally, the rubber hose is moved back to the optical fiber connection.

10. The method for manufacturing a prefabricated branch cable according to claim 7, characterized in that: In step S6, an inner injection molded layer is firstly injection molded on the outer sides of the first connecting portion and the second connecting portion, a branch wrapping layer is then wound on the outer side of the inner injection molded layer, and finally an outer injection molded layer is injection molded on the outer side of the branch wrapping layer.

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