JPH0378728B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an optical fiber composite insulator that is mainly used when forming a fault point detection system in a power transmission/distribution line network, a substation, etc., and a method for manufacturing the same. (Prior Art) There is a desire to develop a system for quickly detecting and restoring failure points that occur in power transmission and distribution lines or substations due to lightning accidents or the like. For this reason, abnormal current and abnormal voltage detection devices have conventionally been used that utilize optical sensors having the Faraday effect and the Pockels effect. In these devices, the sensor attached to the power distribution line and the fault point detector must be insulated from the transmission voltage and current, so it is necessary to perform insulation using an insulator. Therefore, in order to transmit only optical signals and maintain electrical insulation, it is necessary to use an optical fiber composite insulator with built-in optical fibers. The fiber optic composite insulator used for this purpose is
Since it is also used as an ordinary insulator, it is necessary to maintain mechanical strength, electrical insulation properties, etc. over a long period of time in addition to its optical signal transmission function. Traditionally, optical fiber composite insulators have been divided into types that use organic materials as sealing materials to maintain airtightness between the optical fiber and porcelain, and types that use inorganic materials, each with their own advantages and disadvantages. There is. (Problems to be Solved by the Invention) Among these, the type using organic materials does not require high-temperature heat treatment in the optical fiber sealing process after insulator manufacture, and is easy to manufacture. The surface is exposed to a harsh temperature and humidity environment of approximately 60℃ due to heat absorption during the day, and approximately -20℃ due to radiation cooling in midwinter, and is constantly charged with electricity. Eventually, there was a problem that the weather resistance of the material deteriorated, making it impossible to use it as an optical fiber composite insulator. An object of the present invention is to solve the above-mentioned problems and to provide an optical fiber composite insulator that has excellent long-term airtightness while using an organic sealing material, and a method for manufacturing the same. (Means for Solving the Problems) The optical fiber composite insulator of the present invention is an optical fiber composite insulator in which a through hole is provided in the insulator body, and at least one or more optical fibers are inserted into the through hole and hermetically sealed. A resin having a Young's modulus of 10 Kg/mm ² or more and a tensile strength of 300 Kg/cm ² or more at room temperature is used for the coating portion that airtightly adheres the optical fiber body, and a sealing material is used between the coating portion and the inner cavity of the insulator. It is characterized by the use of silicone rubber. Further, the method for manufacturing an optical fiber composite insulator of the present invention includes a method for manufacturing an optical fiber composite insulator in which a through hole is provided in the insulator body, and at least one or more optical fibers are inserted into the inside of the through hole and hermetically sealed. The coating part that hermetically seals the fiber body has a Young's modulus of 10 Kg/mm2 or ^more at room temperature and a tensile strength of 300 Kg/mm2.
By using a resin of cm ² or more, applying a primer treatment to the surface of the covering part, filling silicone rubber between the covering part and the insulator lumen, and curing the silicone rubber at a temperature of 60°C or more, It is characterized by an airtight seal between the optical fiber and the insulator body. (Function) The present invention provides an optical fiber coating material and a sealing material that can withstand environmental stress such as temperature changes in the usage environment and maintain airtight properties over a long period of time in an organic sealing type optical fiber composite insulator. This is due to the discovery of a combination of organic materials. In other words, a resin having a Young's modulus at room temperature of 10 Kg/mm ² or more and a tensile strength at room temperature of 300 Kg/cm ² or more is used as the coating material for the optical fiber, and a sealing material between the coating and the inner cavity of the insulator is used. As silicone rubber preferably elongation at break is 300
By using silicone rubber with a tensile strength of 30 Kg/cm ² or more, the light is resistant to temperature changes in the usage environment and can maintain its airtight properties over a long period of time, as is clear from the examples below. It was discovered that fiber composite insulators can be manufactured. (Example) FIG. 1 is a diagram showing the configuration of an example of the optical fiber composite insulator of the present invention. In FIG. 1, an optical fiber 3 is inserted into an inner hole 2 penetrating the center of an insulator 1, and tapered portions 4-4 are inserted at both ends of the inner hole 2.
1, 4-2 are provided. Further, flange fittings 5-1 and 5-2 are provided at both ends of the insulator 1, and the structure is configured to be used when the insulators 1 are stacked in multiple stages.
Further, in order to maintain airtightness within the insulator 1 and to fix the optical fiber 3, the tapered portions 4-1, 4-2 and the inside of the inner hole 2 are sealed with silicone rubber 6. At this time, a resin having predetermined material properties is used as the coating for the optical fiber 3, and preferably silicone rubber 6 having predetermined material properties is used. In order to manufacture the optical fiber composite insulator having the above-described structure, first, an optical fiber 3 whose covering portion is made of a resin having predetermined material properties is prepared. Next, after applying a silane coupling material or the like to the surface of the coated portion of the prepared optical fiber 3 and performing primer treatment, the optical fiber 3 having the coated portion after the primer treatment is inserted into the inner hole 2 of the insulator 1. Insert.
In this state, the inner hole 2 of the insulator 1 and the tapered part 4-
1 and 4-2, a liquid silicone rubber 6 preferably having predetermined material properties is injected, the silicone rubber is filled between the coating portion and the inner cavity of the insulator 1, and the silicone rubber 6 is cured at 60°C. By heating at the above temperature, it is possible to obtain an optical fiber composite insulator in which the optical fiber 3 and the porcelain of the insulator 1 are hermetically sealed with silicone rubber. An actual example will be explained below. Example 1 First, the material properties of the resin constituting the coating portion of the optical fiber and the material properties of silicone rubber as the sealing material were tested. Considering the airtightness of the optical fiber itself and ease of handling during sealing, an optical fiber with a coating consisting of a primary coating and a buffer layer was selected. Furthermore, the type of resin constituting the covering portion was selected based on parameters such as Young's modulus and elongation at break. Furthermore, the surface of the optical fiber coated portion was subjected to primer treatment. The silicone rubber used as the sealing material for sealing the coating and the porcelain was selected based on parameters such as curing mechanism, tensile strength after curing, elongation at break, and hardness. In the optical fiber composite insulator of the present invention, a plurality of optical fibers are installed in a through hole previously provided inside the porcelain so that they do not come into contact with each other, and then a gap between the inner cavity of the through hole and the optical fiber is formed. Liquid silicone rubber was used because it was necessary to inject silicone rubber into the gaps between the optical fibers. The curing mechanism of silicone rubber is generally classified into condensation type and addition type. The condensed type is characterized by crosslinking and curing through a condensation reaction, and also by generating reaction by-products. On the other hand, in the addition type, Si-H-containing siloxane undergoes an addition reaction with an unsaturated Japanese group in the presence of a catalyst, resulting in crosslinking and curing. Table 1 shows the material properties of the coating that is in close contact with the optical fiber. Table 2 shows the material properties of the silicone rubber used for sealing.

【table】

【table】

[Table] With these selected material combinations, the length is 200mm,
For each test level, we created 10 test specimens with optical fibers sealed inside porcelain tubes with an inner diameter of 10 mm and an outer diameter of 20 mm.
A deterioration test was conducted under accelerated temperature and humidity conditions that occur in a natural environment. Figure 2 shows the shape and material composition of the test specimen, and Figure 3 shows an enlarged view of the optical fiber. In FIGS. 2 and 3, 11 is a porcelain tube, 12 is an optical fiber main body, 13 is silicone rubber, and 14 is a covering portion. In the deterioration test, one cycle consisted of holding the specimen in a hot water tank at 80°C and an antifreeze tank at -20°C for 30 minutes each, and the test specimen was subjected to thermal shock by repeatedly putting it in and out for the number of cycles shown in Table 3. In addition, the sealing state after thermal shock was evaluated. Table 3 shows the thermal shock test results for each material combination. The evaluation items in the comprehensive evaluation shown in Table 3 are the light transmission test of the optical fiber to check whether the optical fiber has been cut, the adhesion of the sealing interface between the silicone rubber and the coating surface of the optical fiber, and the adhesion between the silicone rubber and the porcelain. This is an AC withstand voltage test to check the adhesion of the interface. The evaluation results are ○ if the test specimen passes both light transmittance and withstand voltage after each thermal shock test, and 1/10 to 3/10.
The case where the optical fiber is damaged and no light passes through or there is a through-break due to withstand voltage is expressed as △, and the case where 3/10 or more of the optical fiber is broken and no light passes through or there is a through-break is expressed as ×.

【table】

【table】

[Table] As shown in Table 3, the materials for the coating part of the optical fiber include A, B, which has a high Young's modulus and
The test specimens sealed with silicone rubber using C and D both satisfied the 500 cycle thermal shock test and gave good results. The material of the coating part of the optical fiber is A, B, C,
Among the test specimens using D, the test specimens sealed with porcelain using condensation type silicone rubber of f and p were both 500
Although the cycle was satisfactory, deterioration was observed after 1500 cycles. The form of breakdown is dielectric breakdown at the sealing interface between the porcelain surface and the silicone rubber. When curing the silicone rubber filled in the narrow and long part as in the present invention, the condensation type silicone rubber has a slow rate of curing inside, and also generates unstable by-products inside. This is thought to be due to insufficient strength of the sealing interface. On the other hand, the material of the coating part of the optical fiber is A,
Among the test specimens using B, C, and D, the test specimens sealed with porcelain using additive silicone rubbers a, b, c, p, and o similarly did not deteriorate during the 500-cycle thermal shock test; Deterioration occurred in some or all of the samples after 1500 cycles or more. When observing the form of destruction, it is often the case that the optical fiber is cut or protrudes from the sealed end. Comparing the thermal expansion coefficients of porcelain and silicone rubber, silicone rubber is about 30 times higher than porcelain. Considering the residual stress generated during sealing and the thermal stress generated during thermal shock testing, tensile stress occurs due to thermal expansion of silicone rubber at high temperatures, causing the silicone rubber to break, causing damage to the optical fiber coating and silicone rubber. This is thought to cause destruction of the sealing interface or cutting of the optical fiber. In addition, the material of the coating part of the optical fiber is A,
Among the test specimens using B, C, and D, addition type silicone rubber d, e, g, h, i, j, k, l, m, n
The specimen sealed with porcelain maintains its initial translucency and airtight insulation even after 4000 cycles of thermal shock testing. On the other hand, test specimens using E, F, G, and H, which have low Young's modulus and low tensile strength, as materials for the optical fiber coating were subjected to 500 cycles of thermal shock for some or all of the tests. My body deteriorated. As for the form of destruction, it was found that a crack that occurred in the coating of the optical fiber extended to the silicone rubber, leading to dielectric breakdown. These results show that it is basically preferable to use a material with a high Young's modulus and tensile strength as the covering part of the optical fiber for sealing the optical fiber and porcelain using silicone rubber. It has become clear that silicone rubber, which has a large tensile strength and a large amount of elongation until breaking, is resistant to expansion and contraction due to temperature changes because the rubber itself is highly elastic, and is preferable for sealing optical fibers and porcelain. Example 2 Next, curing conditions for silicone rubber were investigated. Using the same test specimen as in Example 1, the sealing curing temperature and curing time of silicone rubber and the state of deterioration by a thermal shock test were investigated. The test method and evaluation method are the same as in Example 1. The results of the thermal shock test are shown in Table 4.

[Table] For addition-type high temperature curing silicone rubber, the curing temperature and curing time are inversely related, and the higher the temperature, the shorter the curing time. In this example, the combination of silicone rubber i and material A of the coating part of the optical fiber, which maintained the initial performance even after the thermal shock test in Example 1 and obtained good results, was used in the curing conditions and after the thermal shock test. The deterioration characteristics were investigated. As a result, when the curing temperature was 60°C or higher, the optical fiber and translucency after the thermal shock test under the same conditions as in Example 1 were determined.
It was confirmed that there were no problems with the withstand voltage of the test specimen. Usually, in sealed bodies having different coefficients of thermal expansion, residual stress is generated due to the temperature difference between the temperature at the time of sealing and the temperature after cooling (room temperature). Considering long-term temperature stress, sealing conditions with low residual stress are preferable.
From this point of view, sealing at low temperatures is considered desirable. However, in the present invention, the coefficient of thermal expansion of the coating portion of the silicone rubber and the optical fiber is extremely large compared to that of the porcelain and the optical fiber, so the residual stress in the silicone rubber acts as tensile stress. If the curing temperature is high as a result of X-ray radiography,
It was confirmed that micro closed cells are generated within silicone rubber to relieve stress. The closed cells generated during high-temperature curing absorb the thermal expansion of silicone rubber by disappearing when the specimen is exposed to high temperatures in a thermal shock test. On the other hand, at a low curing temperature such as 40°C, no closed cells are generated. Therefore, it is thought that the thermal expansion of the silicone rubber at high temperatures cannot be absorbed, resulting in peeling of the interface between the optical fiber coating and the silicone rubber sealing part. Example 3 Next, the influence of primer treatment on the surface of the coated portion of the optical fiber was investigated. Using the same test specimen as in Example 1, the presence or absence of a primer treatment in which a silane coupling material or the like was applied to the surface of the coated portion of the optical fiber and the state of deterioration by a thermal shock test were investigated. The test method and evaluation method are the same as in Example 1. The thermal shock test results are shown in Table 5.

[Table] In this example, the optical fiber was coated with a combination of silicone rubber i and optical fiber coating materials A and D, which maintained the initial performance even after the thermal shock test in Example 1 and obtained good results. The presence or absence of primer treatment on the surface of the part and its deterioration characteristics after thermal shock were investigated. As a result, for both coating material A and D, dielectric breakdown occurred during the withstand voltage test due to peeling of the sealing interface between the optical fiber coating and silicone rubber after the thermal shock test on the surface of the coating without primer treatment. .
It was confirmed that primer treatment of the optical fiber coating is preferable in order to maintain a more stable sealing state between the optical fiber coating and the silicone rubber. The present invention is not limited only to the embodiments described above, and numerous modifications and changes are possible. For example, the structure of the optical fiber composite insulator shown in the above embodiment, the number of optical fibers to be inserted, etc. are not limited to the embodiment. Needless to say, any number is fine. (Effects of the Invention) As is clear from the above description, according to the optical fiber composite insulator and the manufacturing method thereof of the present invention, an optical fiber of a type in which the optical fiber is inserted into the inner hole of the insulator and sealed with an organic material is produced. In composite insulators,
By limiting the combination of the material for the coating portion of the optical fiber and the sealing material, it is possible to obtain an optical fiber composite insulator with excellent thermal shock properties and long-term airtightness while using an organic sealing material.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the configuration of an example of the optical fiber composite insulator of the present invention, Fig. 2 is a diagram showing the shape and material composition of a test specimen used in an example of the present invention, and Fig. 3 is a diagram showing the configuration of an example of the optical fiber composite insulator of the present invention. FIG. 3 is an enlarged cross-sectional view of the fiber. 1...Insulator, 2...Inner hole, 3...Optical fiber,
4-1, 4-2...Tapered portion, 5-1, 5-2...
...Flange fitting, 6,13...Silicone rubber,
11...Porcelain tube, 12...Optical fiber body, 14
...covering part.

Claims (1)

[Scope of Claims] 1. In an optical fiber composite insulator in which a through hole is provided in the insulator body and at least one optical fiber is inserted into the insulator body and hermetically sealed, a covering portion that hermetically seals the optical fiber body includes: A resin forming a buffer layer with a Young's modulus of 10 Kg/mm ² or more and a tensile strength of 300 Kg/cm ² or more at room temperature was used, and silicone rubber was used as a sealing material between the coating and the inner cavity of the insulator. An optical fiber composite insulator characterized by: 2. The optical fiber composite insulator according to claim 1, wherein a silicone rubber having material properties such as elongation at break of 300% or more and tensile strength of 30 Kg/cm ^{2 or} more is used as the sealing material. 3. In a method for manufacturing an optical fiber composite insulator, in which a through hole is provided in the insulator body, at least one optical fiber is inserted into the insulator body and hermetically sealed, the covering portion that hermetically seals the optical fiber body is heated at room temperature. Young's modulus is 10Kg/mm2 or ^more and tensile strength is 300Kg/
By using a resin of cm ² or more, applying a primer treatment to the surface of the covering part, filling silicone rubber between the covering part and the insulator lumen, and curing the silicone rubber at a temperature of 60°C or more, A method for producing an optical fiber composite insulator, characterized in that the optical fiber and the insulator body are hermetically sealed.