An anti-tensile and compressive optical fiber sensor and its intelligent cable

Abstract

The present invention discloses an anti-tensile and anti-compressive optical fiber sensor and its intelligent cable. The optical fiber sensor is composed of an optical fiber and a sheath. The optical fiber includes a core, a cladding, and a double-layer coating layer. The double-layer coating layer is obtained by photocuring of silicone resin. The silicone resin includes a branched polysiloxane containing double bonds, POSS, a mercapto compound, and a photoinitiator. A solvent-free silicone resin with high temperature resistance is used as the coating layer, and a stainless steel spiral tube and a stainless steel braided mesh reinforcement structure are used to endow the optical fiber with anti-tensile and anti-compressive properties. According to the principle of the stone arch bridge, the optical fiber is implanted into the cable, solving the problem that the optical fiber sensor is damaged by extrusion force during the cable production process.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical fiber sensors, and particularly relates to a tensile and compressive resistant optical fiber sensor and its intelligent cable. Background Art

[0002] During the operation of a power cable, the conductor, insulation layer, and metal shielding layer will all generate losses, causing the cable to heat up, increasing the working temperature of each part. The conductor temperature is an important characteristic value for determining the cable current-carrying capacity. When the cable is overloaded, the excessive temperature will affect the insulation performance of the insulating material, cause insulation aging, shorten the service life of the cable, and in severe cases, lead to fire and power outage accidents. Therefore, it is very necessary to monitor the temperature distribution of each layer of the cable in real time during the cable operation. Currently, the prior art monitors the cable current-carrying capacity online by monitoring the cable temperature. The temperature measurement methods mainly include the thermocouple method, the fiber Bragg grating monitoring method, the distributed optical fiber monitoring technology, etc. Among them, the thermocouple method is more widely used. However, this method generally only monitors the local temperature of the cable and cannot completely calculate the cable current-carrying capacity through data. This method also has certain deficiencies in accuracy and stability. The fiber Bragg grating monitoring method monitors the cable temperature through fiber Bragg grating sensors embedded in the cable body. The stability of this method has been improved to a certain extent, but it can only achieve quasi-distributed measurement of the cable temperature, and the number of fiber Bragg grating sensors will increase the input cost. The distributed optical fiber sensing technology has the advantages of anti-electromagnetic interference and continuous measurement of the temperature of each point along the cable. It has been applied to a certain extent in the project of cable temperature measurement. However, limited by technology, the optical fiber laying method is generally on the surface of the cable or the insulation layer surface, and its monitoring results are easily affected by internal and external environments, and it is difficult to accurately deduce the conductor temperature. The prior art mainly aims at measuring the cable skin temperature or the insulation surface temperature to deduce the conductor core temperature, and combines the surrounding environment temperature to obtain the real-time cable operation current-carrying capacity. The data is too single and cannot accurately reflect the internal temperature of the cable. The main problems of the optical fiber sensor itself are that the optical fiber coating layer has a small temperature measurement range and poor mechanical strength, and it is difficult to meet the requirement of the highest long-term working temperature of 90 °C for the cable conductor; during the processes of cable processing and construction, the optical fiber sensor bears a certain tensile stress and compressive stress, and the optical fiber is easily damaged, etc. Summary of the Invention

[0003] In order to overcome the deficiencies of the above prior art, the present invention uses a high-temperature resistant solvent-free silicone resin as the coating layer, adopts a stainless steel spiral tube and a stainless steel braided mesh reinforcement structure to give the optical fiber tensile and compressive resistant properties, and implants the optical fiber into the cable according to the principle of the stone arch bridge, solving the problem that the optical fiber sensor is damaged by the extrusion force during the cable production process.

[0004] The technical solution for achieving the object of the present invention is as follows: An anti-tensile and anti-compressive optical fiber sensor is composed of a core, a cladding, a double-layer coating layer, and a sheath. The double-layer coating layer is obtained by photocuring of silicone resin; the sheath includes Kevlar fiber, ethylene-tetrafluoroethylene copolymer, stainless steel spiral tube, and stainless steel braided mesh; the silicone resin includes branched polysiloxane containing double bonds, cage-shaped polyhedral oligomeric silsesquioxane (POSS) containing double bonds or mercapto groups, mercapto compounds, and photoinitiators; in the silicone resin, the molar ratio of the mercapto group to the double bond is (1.5 - 2):1; the photoinitiator is 1.5 - 2.5 w.t% of the silicone resin; the POSS is at least one of mercapto-POSS and double bond-containing POSS.

[0005] It should be noted that when preparing the silicone resin, operations need to be carried out in the dark during the period from adding the photoinitiator to curing.

[0006] Preferably, the POSS is at least one of octamercaptopropyl-POSS and octavinyl-POSS; the mercapto compound is one or several of 1,2-ethanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, and mercapto silicone oil; the photoinitiator is 2-hydroxy-2-methylphenylacetone.

[0007] More preferably, the POSS is octamercaptopropyl-POSS; the mercapto compound is mercapto silicone oil.

[0008] More preferably, the molar ratio of the mercapto group in the octamercaptopropyl-POSS to the double bond of the branched polysiloxane is 1:4.

[0009] Preferably, the branched polysiloxane containing double bonds is obtained by the following steps:

[0010] Vinyltriethoxysilane, diphenyldimethoxysilane, and hexamethyldisiloxane are added to a reaction kettle, and 8 - 12 mol / L concentrated hydrochloric acid and deionized water are added dropwise through a constant pressure funnel. At a temperature of 70 - 90 °C, after reacting for 2 - 4 h, activated molecular sieve is added, and the reaction is carried out at a temperature of 110 - 120 °C for 2 - 4 h. After the temperature drops to room temperature, the molecular sieve is filtered off, and washed with a mixed solution of saturated sodium bicarbonate aqueous solution and ethanol at least 2 times. The oil layer is separated and dried in vacuum to obtain the branched polysiloxane containing double bonds.

[0011] More preferably, the molar ratio of vinyltriethoxysilane, diphenyldimethoxysilane, hexamethyldisiloxane and deionized water is 1: (0.4 - 0.5): (0.03 - 0.05): (2 - 2.2); the concentrated hydrochloric acid is 2 - 2.5 w.t% of the total mass of the system; the activated molecular sieve is 24 - 28 w.t% of the total mass of the system.

[0012] Preferably, the preparation method of the anti-tensile and compressive fiber optic sensor is as follows:

[0013] S1. The fiber preform is released from the furnace under traction from the wire reel, passes through the inner coating cup filled with silicone resin, and after sizing by the die, a layer of silicone resin adheres to the outside of the fiber core. Through the ultraviolet curing furnace, the silicone resin cures under the action of ultraviolet light to form the first layer of the double-layer coating on the surface of the fiber core, and then passes through the outer coating cup filled with silicone resin to form the second layer of the double-layer coating through the ultraviolet curing furnace;

[0014] S2. The fiber optic cable with the double-layer coating obtained in step S1 is wound with Kevlar fiber, placed in an ethylene-tetrafluoroethylene copolymer sleeve, a stainless steel spiral tube is installed and then wound with another layer of Kevlar fiber, and finally a stainless steel braided mesh is sleeved on the outermost Kevlar material.

[0015] Preferably, in step S1, the traction speed is 50 - 80 m / min, the coating temperature is 50 - 60 °C, the coating pressure is 0.05 - 0.06 MPa, and the ultraviolet light intensity is 60 - 70 mW / cm2.

[0016] The present invention also protects an intelligent cable, including a fiber optic sensor, a conductor, a conductor shielding layer, an insulating layer, an insulating shielding layer, a communication optical cable, a filling rope, an isolating sleeve, a steel tape armor and an outer sheath. The fiber optic sensor is the fiber optic sensor prepared as above; the implantation process of the fiber optic sensor is to directly implant it into the cable conductor. According to the principle of the stone arch bridge, a 6-segment structure is adopted, which is composed of 6 tile-shaped strand blocks and 1 circular-shaped core sub-wire, and the fiber optic sensor is implanted at the center of the circular-shaped core sub-wire.

[0017] The fiber optic sensor is at the very center of the conductor. The single strands of the inner layer copper wire mainly bear the supporting forces such as FN1, FN2, FN3, etc. From the analysis of the attached drawing Figure 4 it can be seen that:

[0018]

[0019] The resultant force of all the forces on the single strands of the inner layer copper wire is zero, solving the problem that the fiber optic sensor is damaged by the extrusion force during the production process.

[0020] Beneficial effects

[0021] The present invention has the following beneficial effects:

[0022] 1. The solvent-free silicone resin is used as the optical fiber coating layer through photocuring, which has the advantages of low energy consumption, good film-forming property, and low volatile organic compound emissions; the hyperbranched structure is used for crosslinking, with a high crosslinking density, and the highly stable cage-like rigid skeleton structure of POSS is introduced to further improve the thermal stability of the coating layer.

[0023] 2. The stainless steel spiral tube and stainless steel braided mesh reinforcement structure are adopted to endow the optical fiber with tensile and compressive resistance properties.

[0024] 3. According to the principle of the stone arch bridge, the optical fiber is implanted into the cable, and the resultant force of all the forces on the single copper wire in the inner layer is zero, solving the problem that the optical fiber sensor is damaged by the extrusion force during the cable production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of the tensile and compressive resistant optical fiber sensor and its intelligent cable of the present invention;

[0026] In the figure: 100. Optical fiber sensor, 200. Conductor, 201. Conductor shielding layer, 202. Insulating layer, 203. Insulating shielding layer, 204. Filling rope, 205. Isolation sleeve, 206. Steel tape armor, 207. Outer sheath, 300. Communication optical cable; 110. Optical fiber, 120. Kevlar fiber, 130. Ethylene-tetrafluoroethylene copolymer, 140. Stainless steel spiral tube, 150. Stainless steel braided mesh;

[0027] Figure 2 It is a schematic diagram of the synthesis route and structure of the branched polysiloxane of the present invention;

[0028] Figure 3 It is the infrared spectrum diagram of vinyltriethoxysilane and the branched polysiloxane of the present invention;

[0029] Figure 4 It is the force analysis diagram of the optical fiber sensor in the conductor of the present invention;

[0030] Figure 5 It is the curve graph of the galvanic couple collecting the conductor temperature and the optical fiber sensor collecting the temperature under 500A and 600A currents in Application Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0032] In the examples, unless otherwise specified, the experimental methods used are all conventional methods. The materials, reagents, etc. used can be obtained from commercial sources unless otherwise specified.

[0033] The raw materials and equipment used in the examples and comparative examples are described as follows:

[0034] Vinyltriethoxysilane: Product number B604872, purchased from Shanghai Bohr Chemical Reagent;

[0035] Diphenyldimethoxysilane: Product number W810220, purchased from Aladdin Chemistry;

[0036] Hexamethyldisiloxane: Product number W320004, purchased from Aladdin Chemistry;

[0037] Mercapto silicone oil: Viscosity (25 °C) 500 mPas, mercapto molar fraction 3%, purchased from Shanghai Kelaman Reagent;

[0038] Phenylvinyl silicone oil: Viscosity (25 °C) 1500 mPas, phenyl molar fraction 30%, vinyl molar fraction 3.2%, Shanghai Jiadel Chemical Technology Co., Ltd.;

[0039] 2-Hydroxy-2-methylphenylpropanone: Photoinitiator 1173, purchased from Hubei Zhenbo Chemical Co., Ltd.;

[0040] Octamercaptopropyl-POSS: Purchased from Jinan Shicheng Organosilicon Technology Co., Ltd.;

[0041] OPTIGARDTM 03-6696: Purchased from Dow Chemical.

[0042] Branched polysiloxane (self-made):

[0043] 1 mol of vinyltriethoxysilane, 0.5 mol of diphenyldimethoxysilane and 0.05 mol of hexamethyldisiloxane were added to a reaction kettle. 2.4 w.t% of 12 mol / L concentrated hydrochloric acid and 2.2 mol of deionized water were added dropwise through a constant pressure funnel. After reacting at 90 °C for 3 h, 26 w.t% of activated molecular sieve was added to the system, and the reaction was carried out at 120 °C for 3 h. After the temperature was lowered to room temperature, the molecular sieve was filtered off, and washed with a mixed solution of saturated sodium bicarbonate aqueous solution and ethanol at least 2 times. The oil layer was separated and dried under vacuum to obtain branched polysiloxane.

[0044] Table 1 Organosilicon resin formulation

[0045]

[0046] After being formulated according to the recipe in Table 1 above, add 2-hydroxy-2-methylphenylpropanone as a photoinitiator in the dark, with the dosage being 2.0 w.t% of the total mass of the silicone resin. Then stir evenly in the dark, pour it into a coating cup, and degas it under vacuum in the dark. It can then be used for optical fiber coating.

[0047] An anti-tensile and anti-compressive optical fiber sensor is prepared as follows:

[0048] S1. The optical fiber preform is released from the wire reel at a speed of 80 m / min under the traction of the furnace, passes through the inner coating cup filled with silicone resin, with the coating temperature being 50 - 60 °C and the coating pressure being 0.05 - 0.06 Mpa. After sizing through the die, a layer of silicone resin adheres to the core. It passes through an ultraviolet curing furnace with an ultraviolet light intensity of 60 - 70 mW / cm2, and the silicone resin cures under the action of ultraviolet light to form the first layer of the double-layer coating on the core surface. Then it passes through the outer coating cup filled with silicone resin and forms the second layer of the double-layer coating through the ultraviolet curing furnace;

[0049] S2. The optical fiber with the double-layer coating obtained in step S1 is wound with Kevlar fiber, placed in an ethylene-tetrafluoroethylene copolymer sleeve, a stainless steel spiral tube is installed, and then wound with another layer of Kevlar fiber. Finally, a stainless steel braided mesh is sleeved on the outermost Kevlar material.

[0050] Examples 1 - 3

[0051] The silicone resins 1 - 3 are successively replaced in the inner coating cup and the outer coating cup, and Examples 1 - 3 are obtained by the above preparation method.

[0052] Comparative Examples 1 - 3

[0053] The silicone resins 4, 5 and the commercially available silicone resin OPTIGARDTM 03 - 6696 are successively replaced in the inner coating cup and the outer coating cup, and Comparative Examples 1 - 3 are obtained by the above preparation method.

[0054] Comparative Example 4

[0055] The difference from Example 3 is that the installation in step S2 is not carried out.

[0056] Application Example 1

[0057] An intelligent cable includes an optical fiber sensor, a conductor, a conductor shielding layer, an insulating layer, an insulating shielding layer, a communication optical cable, a filling rope, an isolating sleeve, a steel tape armor, and an outer sheath. The optical fiber sensor is the optical fiber sensor prepared in Example 3; the implantation process of the optical fiber sensor is to directly implant it into the cable conductor. According to the principle of the stone arch bridge, a 6-segment structure is adopted, which consists of 5 tile-shaped strand blocks and 1 circular-shaped core sub-wire, and the optical fiber sensor is implanted in the center of the circular-shaped core sub-wire.

[0058] Application Example 2

[0059] The difference from Application Example 1 is that the fiber optic sensor is implanted in the outer layer of the cable outer sheath.

[0060] The following are the test methods for the performance parameters involved in the present invention:

[0061] 1) Tensile force test: Take 3 specimens, each 50 meters long, and perform tensile force tests step by step with a microcomputer tensiometer at a tensile speed of 100 mm / min, and measure the additional loss with an optical power meter;

[0062] 2) High temperature resistance performance: Place the entire reel of fiber optic sensor in an oven for heating, and heat it at 250 °C for 2 h respectively, then cool it to room temperature, and measure the fiber attenuation value;

[0063] 3) Flattening force test: Take 3 specimens, each 50 meters long, and perform tests with a pressure device, and measure the additional loss with an optical power meter (requirements for the allowable flattening force of the fiber optic sensor: 3000 N / 10 cm for long term, keep for 5 min, additional loss ≤ 0.03 dB; 4000 N / 10 cm for short term, keep for 1 min, additional loss ≤ 0.1 dB. After the test, there should be no visually visible cracks in the fiber optic sensor);

[0064] 4) Temperature measurement reliability test of fiber optic sensor: Utilize the conductor of the built-in fiber optic sensor, and at the same time insert 1 set of thermocouples into the conductor. The conductor passes through a current booster and a current transformer, and the signal of the current transformer is connected to the console through a junction box. Apply a step current to the cable with zero initial current, and set the current carrying amounts to 500 A and 600 A respectively for testing.

[0065] Among them, 1-3) are the test methods for Examples 1-3 and Comparative Examples 1-4, and 4) are the test methods for Application Examples 1-2.

[0066] Table 2 Performance of the fiber optic sensor in tensile force test

[0067]

[0068] Table 3 High temperature resistance performance of the fiber optic sensor

[0069]

[0070] Table 4 Flattening force test of the fiber optic sensor

[0071]

[0072] As can be seen from the data in Tables 2 to 4, the high-temperature resistance of the optical fiber mainly depends on the properties of the coating. The high-temperature resistance of Examples 1 to 3 is good. Among Comparative Examples 1 to 3, the effects of Comparative Examples 1 and 2 are poor. Comparative Example 3 is a commercially available silicone resin, and the effect is good, but it is not as good as Examples 1 to 3. By comparing the data of Example 3 and Comparative Example 4, it can be seen that the voltage resistance and tensile resistance of the optical fiber are mainly provided by the outer sheath.

[0073] Obtained from the temperature measurement reliability test of the fiber optic sensor, the error between the conductor temperature collected by the thermocouple and the temperature collected by the fiber optic sensor in Application Example 1 is 0.05 to 0.1% when the time is 1 to 15 h; the error between the conductor temperature collected by the thermocouple and the temperature collected by the fiber optic sensor in Application Example 2 is 15.2 to 18.6% when the time is 1 to 15 h.

[0074] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and changes can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A tensile and compressive optical fiber sensor, consisting of an optical fiber and a sheath, characterized in that: The optical fiber comprises a core, a cladding, and a double-layer coating layer; the double-layer coating layer is obtained by photocuring an organic silicone resin; the organic silicone resin comprises a branched polysiloxane containing a double bond, POSS, a thiol compound, and a photoinitiator; in the organic silicone resin, the ratio of the amount of the thiol substance to the amount of the double bond substance is (1.8-2.2):1; the photoinitiator is 1.5-2.5 wt% of the organic silicone resin; the POSS is at least one of a thiol-containing POSS and a double-bond-containing POSS; The branched polysiloxane containing double bonds is obtained by the following steps: Add vinyl triethoxysilane, diphenyl dimethoxysilane and hexamethyldisiloxane into a reaction kettle, add concentrated hydrochloric acid and deionized water through a constant pressure funnel, react at a temperature of 70-90 ° C for 2-4 hours, add activated molecular sieves, react at a temperature of 110-120 ° C for 2-4 hours, and after the temperature drops to room temperature, filter out the molecular sieves, wash with a mixed solution of saturated sodium bicarbonate aqueous solution and ethanol at least twice, separate the oil layer, and vacuum dry to obtain a branched polysiloxane containing double bonds; The molar ratio of the vinyl triethoxysilane, diphenyl dimethoxysilane, hexamethyl disiloxane and deionized water is 1: (0.4-0.5): (0.03-0.05): (2-2.2).

2. The tensile and compressive optical fiber sensor according to claim 1, characterized in that: The sheath comprises Kevlar fiber, ethylene-tetrafluoroethylene copolymer, stainless steel spiral tube and stainless steel braided mesh.

3. The tensile and compressive optical fiber sensor according to claim 1, characterized in that: The POSS is at least one of octamercaptopropyl-POSS and octavinyl-POSS; the thiol compound is one or more of 1,2-ethanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol and mercapto silicone oil; and the photoinitiator is 2-hydroxy-2-methylphenylacetone.

4. The tensile and compressive resistant optical fiber sensor according to claim 1, characterized in that: The concentration of the concentrated hydrochloric acid is 8-12 mol / L, and the mass is 2-2.5 wt% of the total mass of the system; the activated molecular sieve is 24-28 wt% of the total mass of the system.

5. The tensile and compressive optical fiber sensor according to any one of claims 1 to 4, characterized in that: The preparation method of the tensile and compressive resistant optical fiber sensor is as follows: S1. The optical fiber preform rod is released from the furnace from the pay-off reel under the traction drive, passes through the inner coating cup filled with silicone resin, and after being sized by the mold, a layer of silicone resin adheres to the outside of the fiber core, passes through the ultraviolet curing furnace, and the silicone resin is cured under the action of ultraviolet light to form the first layer of the double-layer coating layer on the surface of the fiber core, and then passes through the outer coating cup filled with silicone resin and passes through the ultraviolet curing furnace to form the second layer of the double-layer coating layer; S2. The optical fiber with double coating obtained in step S1 is wound with Kevlar fiber, placed in an ethylene-tetrafluoroethylene copolymer sleeve, and then wound with a layer of Kevlar fiber after installing a stainless steel spiral tube. Finally, a stainless steel braided mesh is put on the outermost layer of Kevlar material.

6. The tensile and compressive resistant optical fiber sensor according to claim 5, characterized in that: The pulling speed in step S1 is 50-80 m / min, the coating temperature is 50-60 °C, the coating pressure is 0.05-0.06 MPa, and the UV intensity is 60-70 mW / cm 2 .

7. An intelligent cable, comprising an optical fiber sensor, a conductor, a conductor shielding layer, an insulating layer, an insulating shielding layer, a communication optical cable, a filling rope, an isolation sleeve, a steel belt armor and an outer sheath, characterized in that: The optical fiber sensor is the optical fiber sensor described in any one of claims 1 to 4; the optical fiber sensor implantation process is to directly implant it into the cable conductor, based on the stone arch bridge principle, using a 6-split structure, consisting of 6 tile-shaped blocks and 1 circular wire core wire, and the optical fiber sensor is implanted in the center of the circular wire core wire.

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