Optical fiber replaceable monitoring cable and method for replacing same

Abstract

The application relates to a replaceable optical fiber monitoring cable and a replacement method thereof, and belongs to the technical field of optical fiber monitoring. Step one: when the optical fiber in the monitoring cable needs to be replaced, a part of the outer tube, the stainless steel wire layer and the inner tube at one end of the monitoring unit in the monitoring cable are peeled off in sequence, so that one end of the optical fiber unit to be replaced is exposed; step two: aramid yarn at one end of the exposed optical fiber unit to be replaced is peeled off, and the peeled aramid yarn and aramid yarn in the optical fiber unit to be installed are uniformly wound together, and the two are integrated; step three: the other end of the optical fiber unit to be replaced is uniformly pulled out, and the optical fiber unit to be replaced is uniformly wound on the take-up frame at a constant speed; the optical fiber unit to be installed is uniformly released through the pay-off frame at a constant speed, the optical fiber unit to be installed is pulled and introduced into the monitoring cable, and the replacement of the optical fiber is realized. The application can quickly replace the optical fiber, saves time and effort, and ensures that online monitoring can be continuously carried out during the use of the overhead cable.

Description

A replaceable fiber optic monitoring cable and its replacement method Technical Field

[0001] This invention relates to a replaceable fiber optic monitoring cable and its replacement method, belonging to the field of fiber optic monitoring technology. Background Technology

[0002] Overhead cables with metal structures, such as bridge cables, OPGW fiber-optic composite overhead ground wires, and OPPC fiber-optic composite overhead phase wires, generally require a service life of over 30 years. During service, the steel wires in these cables are prone to corrosion and vibration fatigue degradation, severely impacting the safety and durability of the lines. Furthermore, environmental temperature affects the thermal expansion and contraction of the cables, and factors such as strong winds and icing significantly influence cable vibration, all of which affect the overall safe service life. Therefore, achieving real-time monitoring of the long-term operating status of overhead cables to ensure safety throughout their service life is crucial for the development of overhead cable technology.

[0003] Currently, one of the more advanced methods for monitoring the condition of bridge cables is the use of fiber Bragg grating (FBG) sensors. FBG sensors offer advantages such as high sensing accuracy, resistance to electromagnetic interference, quasi-distributed sensing, absolute measurement, and good stability and durability. Smart cable solutions using FBG sensors primarily involve placing the sensors on the surface of the steel wires and outputting the signal via optical fiber. However, this approach has drawbacks. Both the FBG and the optical fiber are relatively brittle, making them prone to brittle fracture when placed on the steel wire surface. Furthermore, they are susceptible to environmental factors such as moisture and temperature within the cable, which can reduce the lifespan of the optical fiber.

[0004] For fiber optic composite cables such as OPGW and OPPC, since they already contain optical fibers for communication purposes, they can be directly used for fiber optic monitoring. However, because the current fiber optic unit structures are all in the form of oil-filled stainless steel tubes, when fiber optic failures occur or upgrades are needed without damaging the cable structure, it is not possible to easily and quickly replace the individual fibers. The entire OPGW or OPPC overhead cable must be replaced, resulting in a long construction period, high costs, and ultimately, not worthwhile. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a replaceable optical fiber monitoring cable and a replacement method thereof, which can quickly replace optical fibers when they fail or need to be replaced for upgrades, saving time and effort; and ensures continuous online monitoring during the use of overhead lines.

[0006] The technical solution adopted by the present invention to solve the above problems is as follows: a replaceable optical fiber monitoring cable, including an optical fiber unit, wherein an inner tube and an outer tube are sequentially sleeved on the outer periphery of the optical fiber unit from the inside to the outside, and a stainless steel wire layer is provided between the inner tube and the outer tube to form a monitoring unit. The monitoring unit and several cable wires constitute a monitoring cable. The optical fiber unit in the monitoring unit is led out and connected to an optical fiber demodulator through a wire.

[0007] The optical fiber unit includes an optical fiber bundle, an aramid yarn layer on the outer periphery of the optical fiber bundle, and a tight-fitting layer on the aramid yarn layer.

[0008] The aramid yarn layer comprises several aramid yarns, which are evenly placed on the outer periphery of the optical fiber bundle.

[0009] The tight-fitting layer is made of fluoroplastic.

[0010] The fiber bundle includes several optical fibers and an FRP central reinforcement member. The optical fibers are evenly arranged around the outer periphery of the FRP central reinforcement member, and the optical fibers and the FRP central reinforcement member are fixedly connected by an adhesive layer.

[0011] The number of optical fibers is 2 to 12.

[0012] The adhesive layer is a resin-cured component.

[0013] The inner tube has a wall thickness of 0.2–0.3 mm, and the outer tube has a wall thickness of 0.5–0.9 mm.

[0014] Both the inner and outer tubes are made of stainless steel.

[0015] A method for replacing a fiber optic replaceable monitoring cable, the method comprising the following steps:

[0016] Step 1: When it is necessary to replace the optical fiber in the monitoring cable, peel off a portion of the outer tube, stainless steel wire layer and inner tube at one end of the monitoring unit in the monitoring cable in sequence, so as to expose one end of the optical fiber unit to be replaced.

[0017] Step 2: Remove the aramid yarn from one end of the exposed fiber unit to be replaced, and evenly wrap the removed aramid yarn with the aramid yarn in the fiber unit to be installed, so that the fiber unit to be replaced and the fiber unit to be installed are a whole.

[0018] Step 3: Pull out the other end of the fiber optic unit to be replaced evenly, and then wind it up onto the take-up frame at a constant speed. The fiber optic unit to be installed is released at a constant speed through the pay-off frame. After being positioned by the positioning guide wheel, the fiber optic unit to be installed is dragged into the monitoring cable to realize the replacement of the fiber optic cable.

[0019] In step one, 15-25cm of the outer tube, stainless steel wire layer, and inner tube are each peeled off.

[0020] The take-up frame in step three is a take-up frame with tension speed control, and the pay-off frame is a pay-off frame with tension speed control.

[0021] Compared with the prior art, the advantages of the present invention are: a fiber optic replaceable monitoring cable,

[0022] 1. The inner tube, stainless steel wire layer and outer tube adopt an all-metal structure, which allows for rapid heat penetration and fast temperature response. At the same time, the optical fiber and the central FRP reinforcement are bonded together with resin to form an optical fiber bundle. The optical fiber bundle has certain mechanical strength and bending resistance, which ensures the safety of the optical fiber and facilitates the lead-out construction and subsequent replacement operations.

[0023] 2. The aramid yarn and fluoroplastic tight-fitting layer around the optical fiber bundle play a buffering and protective role. The aramid yarn has the characteristics of high strength and smooth surface, making it suitable as a traction component when replacing optical fibers. The fluoroplastic tight-fitting layer has good electrical properties and mechanical strength, and has the characteristics of smooth surface and self-lubrication. It can reduce the friction between the optical fiber unit and the inner wall of the inner tube when the fiber unit is dragged and replaced.

[0024] 3. For specific applications involving continuous cable burial, the monitoring unit requires high tensile and compressive strength (the cable wire tensile strength is approximately 2000MPa, and the lateral pressure is estimated at approximately 26KN / 100mm). The monitoring unit utilizes a protective structure of "inner tube + stainless steel wire layer + outer tube," exhibiting strong tensile and lateral compressive strength, as well as sealing protection. This structure effectively ensures the optical fiber is not damaged, isolating it from external force damage and moisture, thus guaranteeing its lifespan. Even under the immense mechanical forces of cable forming, stranding, and installation, the monitoring unit maintains its round shape without deformation, facilitating subsequent optical fiber replacement.

[0025] This application enables rapid replacement of optical fibers, saving time and effort; it also ensures continuous online monitoring during the use of overhead cables. Attached Figure Description

[0026] Figure 1 is a schematic diagram of a monitoring unit in a fiber optic replaceable monitoring cable according to an embodiment of the present invention;

[0027] Figure 2 is a structural diagram of a monitoring cable containing one monitoring unit;

[0028] Figure 3 is a structural diagram of a monitoring cable containing multiple monitoring units;

[0029] Figure 4 is a structural diagram of the fiber-replaceable OPGW;

[0030] Figure 5 is a structural diagram of the fiber optic replaceable OPPC;

[0031] Figure 6 is a schematic diagram of the fiber replacement operation of a fiber-replaceable monitoring cable.

[0032] In the diagram, 1 is the optical fiber, 2 is the FRP central reinforcement, 3 is the optical fiber bundle, 4 is the aramid yarn layer, 5 is the optical fiber unit, 6 is the inner tube, 7 is the stainless steel wire layer, 8 is the outer tube, 9 is the monitoring unit, 10 is the cable wire, 11 is the monitoring cable, 12 is the optical fiber unit to be installed, 13 is the cable laying frame, 14 is the positioning guide wheel, and 15 is the cable take-up frame. Detailed Implementation

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0034] As shown in Figure 1, a replaceable fiber optic monitoring cable in this embodiment includes several optical fibers 1 and an FRP (fiberglass reinforced plastic) central reinforcement 2. The optical fibers 1 are evenly arranged around the outer periphery of the FRP central reinforcement 2, and the optical fibers 1 and the FRP central reinforcement 2 are bonded together with photocurable resin to form an optical fiber bundle 3. An aramid yarn layer 4 is provided on the outer periphery of the optical fiber bundle 3, and a fluoroplastic tight-fitting layer is sleeved on the aramid yarn layer 4 to form a replaceable optical fiber unit 5. A thin-walled inner tube 6 is sleeved on the optical fiber unit 5 to provide sealing protection for the optical fiber. Multiple stainless steel wires are twisted around the outer periphery of the inner tube 6 to form a stainless steel wire layer 7. A thick-walled outer tube 8 is sleeved on the stainless steel wire layer 7 to form a monitoring unit 9. The diameter of the monitoring unit 9 is the same as the diameter of the cable wire 10. As shown in Figures 2 and 3, one or more monitoring units 9 and several cable wires 10 constitute a monitoring cable 11. The optical fibers in the monitoring unit 9 are led out from both ends of the monitoring cable 11, and the optical fibers 1 are connected to an optical fiber demodulator that can detect the temperature and vibration change signals of the optical fiber through wires. During the construction and service of the monitoring cable, the temperature and vibration status of different key parts of the cable wire can be tested by the fiber optic demodulator. Based on the principle that the temperature and vibration of the adjacent cable wire are consistent with those of the monitoring unit, the temperature and vibration data of different key parts of the cable wire can be obtained, thus realizing real-time monitoring of the temperature and vibration data of the cable wire.

[0035] Each optical fiber contains 2 to 12 fibers, and single-mode and multimode fibers can be selected according to actual needs, including fibers for communication applications. The fiber coating can be a conventional acrylic resin coating, or a carbon coating, polyimide, or other special coatings can be selected to meet the requirements of harsh environments such as fatigue resistance, hydrogen loss resistance, and high temperature resistance.

[0036] The FRP center reinforcement 2 can be made of GFRP (glass fiber reinforced) or KFRP (aramid fiber reinforced) to meet higher requirements for tensile strength and bending resistance.

[0037] The aramid yarn layer 4 serves as a buffer for protection and provides traction during replacement. The aramid yarn layer comprises several aramid yarns, evenly distributed around the outer periphery of the optical fiber bundle. PTFE or ETFE is extruded onto the aramid yarns to form a fluoroplastic sheathing layer.

[0038] The inner tube 6 has a wall thickness of 0.2–0.3 mm, and the outer tube has a wall thickness of 0.5–0.9 mm.

[0039] Both the inner tube 6 and the outer tube 8 are made of stainless steel.

[0040] As shown in Figure 6, a method for replacing a fiber optic replaceable monitoring cable includes the following steps:

[0041] Step 1: When it is necessary to replace the optical fiber in the monitoring cable, peel off 20cm of the outer tube, stainless steel wire layer and inner tube at one end of the monitoring unit in the monitoring cable in sequence, so as to expose the end of the optical fiber unit to be replaced.

[0042] Step 2: Remove the aramid yarn from one end of the fiber unit to be replaced, and evenly wrap the removed aramid yarn with the aramid yarn in the fiber unit to be installed. Bond them firmly with quick-drying adhesive so that the fiber unit to be replaced and the fiber unit to be installed become a whole.

[0043] Step 3: The fiber optic unit to be replaced is evenly pulled out from the other end of the monitoring cable and wound onto the I-beam reel at a uniform speed via the tension-speed controlled take-up frame 15. The fiber optic unit to be installed is then steadily released at a uniform speed via the tension-speed controlled release frame 13. After being positioned by the positioning guide wheel 14, the fiber optic unit to be installed is dragged into the monitoring cable, thus completing the fiber replacement.

[0044] As shown in Figures 4 and 5, the structure of the monitoring unit is adapted to the diameter of the cable wires in bridge cables or the aluminum-clad steel wires in OPGW and OPPC. The inner tube, stainless steel wire layer, and outer tube of this application adopt an all-metal structure, allowing for rapid heat penetration and temperature response. Simultaneously, the optical fiber and the central FRP reinforcement are resin-cured into an optical fiber bundle, which possesses certain mechanical strength and bending resistance, ensuring the safety of the optical fiber and facilitating its deployment and subsequent replacement. Furthermore, the aramid yarn and fluoroplastic sheathing layer surrounding the optical fiber bundle provide cushioning and protection. The aramid yarn, with its high strength and smooth surface, is suitable as a traction component during optical fiber replacement; the fluoroplastic sheathing layer has good electrical properties and mechanical strength, and also features a smooth surface and self-lubricating properties, reducing friction between the optical fiber unit and the inner wall of the inner tube during dragging and replacement. For specific applications involving continuous cable burial, the monitoring unit requires high tensile and compressive strength (the cable wire tensile strength is approximately 2000 MPa, and the lateral pressure is estimated at approximately 26 KN / 100 mm). The monitoring unit utilizes a protective structure of "inner tube + stainless steel wire layer + outer tube," exhibiting strong tensile and lateral compressive strength, along with sealing protection. This structure effectively protects the optical fiber from damage, isolating it from external force and moisture, thus ensuring its lifespan. Even under the immense mechanical forces of cable forming, stranding, and installation, the monitoring unit maintains its round shape without deformation, facilitating subsequent fiber replacement. This application enables rapid fiber replacement, saving time and effort, and ensures continuous online monitoring during the use of overhead cables.

[0045] In addition to the above embodiments, the present invention also includes other embodiments. All technical solutions formed by equivalent transformation or equivalent substitution should fall within the protection scope of the claims of the present invention.

Claims

1. A fiber optic replaceable monitoring cable, characterized in that: The system includes an optical fiber unit, with an inner tube and an outer tube sequentially fitted around its outer periphery from the inside out. A stainless steel wire layer is provided between the inner and outer tubes to form a monitoring unit. The monitoring unit and several cable wires constitute a monitoring cable. The optical fiber unit in the monitoring unit is led out and connected to an optical fiber demodulator via a wire. The optical fiber unit includes an optical fiber bundle, with an aramid yarn layer on its outer periphery and a tight-fitting layer on the aramid yarn layer. The aramid yarn layer includes several aramid yarns, which are evenly placed around the outer periphery of the optical fiber bundle. The tight-fitting layer is made of fluoroplastic. The optical fiber bundle includes several optical fibers and an FRP central reinforcement member. The several optical fibers are evenly arranged around the outer periphery of the FRP central reinforcement member and are fixedly connected by an adhesive layer. Both the inner and outer tubes are made of stainless steel.

2. The fiber optic replaceable monitoring cable according to claim 1, characterized in that: The number of optical fibers is 2 to 12.

3. The fiber optic replaceable monitoring cable according to claim 1, characterized in that: The adhesive layer is a resin-cured component.

4. The fiber optic replaceable monitoring cable according to claim 1, characterized in that: The inner tube has a wall thickness of 0.2~0.3mm, and the outer tube has a wall thickness of 0.5~0.9mm.

5. A method for replacing a fiber optic replaceable monitoring cable according to any one of claims 1 to 4, characterized in that: The replacement method includes the following steps: Step 1: When it is necessary to replace the optical fiber in the monitoring cable, a portion of the outer tube, stainless steel wire layer, and inner tube at one end of the monitoring unit in the monitoring cable are stripped off in sequence to expose one end of the optical fiber unit to be replaced; Step 2: The aramid yarn at one end of the exposed optical fiber unit to be replaced is stripped off, and the stripped aramid yarn is evenly wound together with the aramid yarn in the optical fiber unit to be installed, so that the optical fiber unit to be replaced and the optical fiber unit to be installed are a whole; Step 3: The other end of the optical fiber unit to be replaced is evenly dragged out and the optical fiber unit to be replaced is wound up onto the take-up frame at a uniform speed; the optical fiber unit to be installed is released at a uniform speed through the pay-off frame, and after being positioned by the positioning guide wheel, the optical fiber unit to be installed is dragged into the monitoring cable to realize the replacement of the optical fiber.

6. The method for replacing a fiber optic replaceable monitoring cable according to claim 5, characterized in that: In step one, 15-25cm of the outer tube, stainless steel wire layer, and inner tube are each peeled off.

7. The method for replacing a replaceable fiber optic monitoring cable according to claim 5, characterized in that: The take-up frame in step three is a take-up frame with tension speed control, and the pay-off frame is a pay-off frame with tension speed control.

Images