JPH0456410B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to an optical fiber composite insulator that has improved air-tight sealing on the surface of an inner hole passing through the central portion of the insulator, thereby increasing sealing reliability. (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 power substations due to lightning strikes or the like. For this reason, conventionally, abnormal voltage and abnormal current detection systems using optical fibers using Pockels elements and Faraday elements have been used. Various structures of these optical fiber composite insulators have been disclosed. For example, in Japanese Patent Application Laid-open No. 158402/1987, the insulator has a through hole in the center of its shaft, and an optical fiber is inserted into this through hole. The optical fiber is sealed by filling all or part of the through-hole with an organic insulating material such as silicone rubber, and the technology prevents surface leakage of the insulator from reducing the insulation distance and heats the entire porcelain of the insulator. However, a technique is known in which molten glass is poured into the whole or part of the through hole to seal it. The optical fiber composite insulators used in these systems not only incorporate optical fibers to reliably transmit optical signals, but also have important conventional insulator functions. For example, in power substations, disconnectors such as switches may be replaced with optical fiber composite insulators to provide a failure point detection system. Since the optical fiber composite insulator in this case needs to replace the solid support insulator used in ordinary disconnectors, it is required to have electrical insulation performance equivalent to that of the solid support insulator. (Problem to be Solved by the Invention) In other words, it is necessary to continue to maintain electrical insulation performance like conventional insulators even if exposed to environmental temperature changes, humidity, etc. over a long period of time. In other words, it is not limited to the silicone rubber sealing type or the glass sealing type, but also the airtight sealing performance of the bond between the optical fiber, silicone rubber, and glass, or the airtight sealing of the bond between the inner hole surface passing through the insulator, silicone rubber, and glass. Maintaining performance over a long period of time is an important issue. However, no consideration has been given to the relationship between the surface of the inner hole passing through the insulator and the silicone rubber or organic material used as the sealing material for the optical fiber. The purpose of the present invention is to solve the above-mentioned problems by investigating the relationship between the inner hole surface and the sealing material.
The present invention aims to provide an optical fiber composite insulator that has the same electrical insulation performance as a conventional solid insulator even if it has the same shape. (Means for Solving the Problems) The optical fiber composite insulator of the present invention has an optical fiber inserted into an inner hole penetrating the central portion of the insulator, and an optical fiber that is sealed with silicone rubber to the surface of the inner hole. The fiber composite insulator is characterized in that the inner hole surface is a surface coated with a glaze and fired. Further, the optical fiber composite insulator of the present invention is an optical fiber composite insulator in which an optical fiber is inserted into an inner hole passing through a central portion of the insulator, and the optical fiber and the inner hole surface are sealed with an inorganic material. It is characterized by having a polished surface on the hole surface. (Function) The present invention provides an optical fiber composite insulator using an organic material or an inorganic material as a sealing material, which can maintain electrical insulation performance equivalent to that of a conventional solid support insulator in the same shape, and provide long-term hermetic sealing. This is due to the discovery of the relationship between the condition of the inner hole surface, which has excellent properties, and the sealing material. In other words, when using silicone rubber as a sealing material, by making the surface of the inner hole through which it is penetrated a glazed surface (hereinafter referred to as glazed surface), adhesive strength is improved and long-term stability is improved. It was found that the airtight performance was improved. Furthermore, it has been found that when an inorganic material such as glass is used as a sealing material, airtightness is improved by polishing the surface of the inner hole passing through the sealing material. As a result, by adjusting the surface of the inner hole of the optical fiber composite insulator to suit the sealing material, a sealing condition suitable for each sealing material can be obtained, the airtight performance of the bonded area is improved, and finally, It is possible to obtain a failure point detection system for power transmission lines and power substations using optical fiber composite insulators that have high airtight reliability and good electrical insulation properties. (Example) An actual example will be described below. Example 1 First, a case where an organic material is used as a sealing material will be described. Various types of perforated insulators 2 having shapes shown in FIG. 1 were prepared, each having an inner hole 1 passing through the center of the porcelain insulator. The porcelain material was the same as the solid support insulator used for the support stand of the switch in the substation. The diameter of the body of the insulator was 105mm, and the total length was 100mm. Further, insulators were prepared with inner hole diameters of 6, 8, and 10 mm passing through the center portion of the insulator shaft. Note that the open end of the perforated insulator 2 has a diameter 10 mm larger than the through hole diameter, and
A tapered portion 3 forming an angle of 30° with the axis is provided. The reason for providing this tapered portion 3 is to relieve internal pressure generated due to changes in environmental temperature after the silicone rubber is cured. In addition, the surface of the inner hole passing through the center of the insulator shaft can be glazed with the same glaze as the insulator surface (glazed surface; two-color glaze) or unglazed surface (surface fired without applying glaze). A test was conducted. . Note that the surface of the inner hole passing through the central part of the shaft of the insulator is usually made in an unglazed state because it is difficult to apply glaze. Optical fiber composite insulators were fabricated by sealing optical fibers to these insulators with silicone rubber, and performance tests were conducted. The optical fiber used in the test specimen was an optical fiber with only a primary coating and a buffer layer, taking into consideration the airtightness of the optical fiber itself and ease of handling during sealing. Furthermore, the surface of the buffer layer, which is the outermost layer of the optical fiber, was treated with a primer using a silane coupling material or the like to ensure airtight sealing with silicone rubber. Furthermore, as the silicone rubber used for sealing, we selected a material that is high temperature curing addition reaction type and has high tensile strength and elongation at break. Table 1 shows the material properties of the buffer layer and silicone rubber covering the optical fiber.

[Table] The test specimen was made by inserting two optical fibers into the inner hole of the porcelain insulator, and inserting one optical fiber into each.
It was fabricated by filling the periphery with silicone rubber under tension of Kg. Silicone rubber is 5Kg/cm ² after degassing and stirring for 30 minutes under a vacuum pressure of 1 Torr or less.
I pressed it in. When press-fitting silicone rubber, if you evacuate the air from the end opposite to the end where the silicone rubber is press-fitted, air bubbles will not get caught up in the bonding surfaces of the silicone rubber and porcelain, and the bonding surfaces of the silicone rubber and optical fiber. preferred. After filling with silicone rubber, it was stored in a constant temperature bath at 80°C for 6 hours to cure the silicone rubber and form an optical fiber composite insulator. For the optical fiber composite insulator produced in the above process, the heat resistance limit, cold temperature test, and after heat cycle
AC withstanding voltage test was conducted. The test method is shown below. 10 for cold testing
A test specimen was prepared and immersed in a 90°C hot water tank and a 0°C cold water tank five times at 30 minute intervals. After the test, the presence or absence of cracks was observed, and cases where cracks did not occur in all test specimens were marked ◎, and cases where cracks did occur were marked with ×. For the heat resistance limit test, 10 specimens were prepared, heated to a predetermined temperature at 30° C./hr, held at the predetermined temperature for 3 hours, then allowed to cool, and the external appearance was inspected. The test results are ◎ if there are no problems with all test specimens, △ if 1/10 of the test specimens have abnormalities such as cracks in appearance, popping out of silicone rubber, or changes in light transmittance. Cases in which an abnormality occurred in the test specimen of /10 or higher were indicated by ×. The test was first carried out at 80°C, and for healthy specimens after the test, it was subsequently carried out at 90°C, 100°C, 110°C, and 120°C. The heat cycle test was conducted by preparing 10 specimens and maintaining them at 90°C and -20°C for 3 hours in a constant temperature bath. The number of heat cycles was 500, 1,000, 1,500, 2,000, 2,500, and 3,000 cycles, and cracks were observed by appearance and AC withstand voltage tests were conducted. The AC voltage is 80% of the surface flash voltage.
It was applied for a minute. As a result of the test, if there was no problem in all the test specimens, it was marked ◎, if 1/10 of the test specimens had internal electrical penetration, it was △, and if 2/10 or more of the test specimens had penetration, it was marked with ×. The test results are shown in Table 2.

【table】

[Table] Yes.
From the results in Table 2, the following was confirmed.
Regarding the thermal testing, good results were obtained for both the glazed and unglazed inner hole surfaces. However, in the heat resistance limit test and heat cycle test, there was a difference in the results between the glazed and unglazed surfaces. In other words, in the heat resistance limit test, optical fiber composite insulators with glazed surfaces of glazes A and B have no problems up to 120°C, regardless of the diameter of the inner hole that penetrates, whereas when the inner hole is unglazed. The results showed that as the diameter of the through hole increases, the limit temperature of heat resistance decreases. This is because the difference in thermal expansion coefficient between silicone rubber and insulator porcelain is large, and when the silicone rubber expands during the heat resistance limit test, internal pressure is generated in the inner hole that the insulator passes through, causing the porcelain to break. It depends. Additionally, as a result of a heat cycle test, the optical fiber composite insulator with glazes A and B applied to the surface of the inner hole that penetrates showed good results with no cracks or decrease in AC withstand voltage up to 2500 cycles. . On the other hand, if the inner hole surface is unglazed, from 1500 cycles
After 2000 cycles, a decrease in AC withstand voltage was observed due to peeling of the adhesive. As a result of a disassembly investigation of an optical fiber composite insulator that had undergone the same number of heat cycles as a product with a low AC withstand voltage, peeling was observed at the adhesive interface between the surface of the inner hole and the silicone rubber, and the greater the number of heat cycles, the more peeling occurred. confirmed that it was in progress. Furthermore, an adhesive strength test was conducted using test pieces. A test piece measuring 40 mmφ x 10 mmH was prepared from the same porcelain material as the insulator used for the optical fiber composite insulator. The surface of the test piece to be bonded to the silicone rubber was a glazed surface (two levels of glaze color) and an unglazed surface. The test piece was prepared by bonding two pieces of porcelain that had been fired and polished into a predetermined shape using silicone rubber. The silicone rubber was prepared and used under the same conditions as the optical fiber composite insulator. The silicone rubber was cured at 80°C for 1 hour. Adhesive strength was tested using a tensile tester at a tensile speed of 25 mm/min using 20 test pieces of the same formulation and cured lot. The adhesive strength was calculated by dividing the load at which the silicone rubber of the adhesive part was cut by the adhesive cross-sectional area.
The forms of failure were peeling of the silicone rubber from the surface of the test piece and tensile failure of the silicone rubber itself. The cohesive failure rate was expressed as a percentage of the number of tensile failures of the silicone rubber itself in all test pieces.
The test results are shown in Table 3.

[Front] is the same brown glaze.
As a result of the adhesive strength test shown in Table 3, the test piece with the glazed surface had high adhesive strength, and the failure mode was cohesive failure depending on the tensile strength of the silicone rubber itself.
It can be seen that the adhesive interface is strong. It is also seen that the adhesive strength between the unglazed surface and the silicone rubber is high, and the airtightness after sealing is excellent. Example 2 Next, a case where an inorganic material is used as a sealing material will be described. Various types of perforated insulators 2 shown in FIG. 1 were prepared, each having an inner hole 1 passing through the center of the porcelain insulator. The porcelain material was the same as the solid support insulator used for the support stand of the switch in the substation. The diameter of the body of the insulator is
105mm, and the total length was 1000mm. The diameter of the inner hole passing through the center of the insulator shaft is 6 mm. In addition, both ends of the inner hole have a taper angle of 5°, and are 50mm in the axial direction of the insulator.
It has an opening. The inner surface of the inner hole was glazed with the white glaze used on the surface of the solid support insulator, an unglazed porcelain fired surface, and the fired porcelain was polished. The optical fiber has a core diameter of 80 μm and a cladding diameter.
It is a 125 μm silica glass fiber. Considering the optical fiber's own airtightness and ease of handling, an optical fiber with only a primary coating and a buffer layer was used. Furthermore, the optical fiber is used to ensure a perfect airtight seal between the glass in the sealing part and the optical fiber, and to prevent the coating of the organic optical fiber from burning due to the high temperature during melting and causing the sealing glass to foam. A 35 mm portion of the coated portion corresponding to the sealed portion of the glass was immersed in ethanol for 30 minutes, and then mechanically removed using a jacket stripper. A cylindrical body made of Kovar was prepared, having an outer periphery with a taper angle of 5°, which is the same as the opening at the end of the insulator, and an optical fiber insertion hole at the bottom, and which was coated with glass in advance. The cylindrical body made of Kovar, which had been processed and molded into the above shape, was previously subjected to surface cleaning and degreasing by acid treatment using FeCl ₃ solution. In addition, oxidation treatment was carried out to improve the wetting characteristics with glass and perfect the adhesion reaction during glass melting. The oxidation treatment conditions were 20 minutes in the air at 800°C.
Glass was sprayed onto the outer periphery of this cylindrical body made of Kovar to a thickness of about 1 mm. Thereafter, this cylindrical body was dried at 80°C for 30 minutes, and the glass was calcined at 320°C for 1 hour using an electric furnace. The cylindrical body with the glass calcined on the outer periphery is set in the opening of the inner hole passing through the insulator. Incidentally, the glass used was lead borate glass having a low melting point and a low coefficient of thermal expansion. Furthermore, a glass calcined body having the same taper angle as the outer periphery of the cylinder, a length of 35 mm, and an inner hole through which the optical fiber passes with the same outer diameter as the inner diameter of the cylinder is set on the bottom of the cylinder. . The glass calcined body is made by adding a small amount of methylcellulose (MC) and an organic binder to lead-borate glass, press-forming it with mixed water, processing the outer periphery, processing the optical fiber insertion hole, and heating at 50℃/hour. It was prepared by heating and holding at 320°C for 1 hour. Next, a seven-turn copper coil is placed around the outer circumference of the insulator, and a high frequency voltage is applied to the coil by a high frequency induced voltage generator. This high-frequency voltage generates a high-frequency induced current in the Kovar cylinder, causing it to self-heat. High frequency voltage and current conditions were set so that the temperature of the cylinder was 500°C. As a result, the predetermined temperature of 500°C was reached approximately 20 minutes after the application of the high-frequency voltage. The temperature was maintained at 500° C. for about 10 minutes, and during this time the upper end surface of the cylinder was pressed with a load of 20 kg to airtightly seal the outer periphery of the cylinder and the end opening. After this, natural cooling was performed. Furthermore, in order to protect the coating of the optical fiber protruding from the glass sealing part of the opening of the insulator, vacuum-defoamed silicone rubber was filled using a syringe.
It was cured at 80°C for 1 hour. In the series of manufacturing steps described above, first, the sealing process and the reinforcing process of the covering part were completed at one end of the insulator, and then the insulator was reversed and the process was carried out at the remaining end to produce an optical fiber composite insulator. After this, the flange fittings were attached with cement using the same method as for ordinary insulators, and the optical fiber composite insulator was completed. Table 4 shows the porcelain material for the insulator and the glass material for sealing used in this example.

[Table] Similar to Example 1, the optical fiber composite insulator produced in the above process was subjected to a heat resistance limit test, a cold heat test, and an AC withstand voltage test after heat cycling. The heat resistance limit test was first conducted at 120℃,
Regarding test specimens that are healthy after testing, 130,
It was carried out at 140 and 150°C. Also, the number of heat cycles is
The cycles were 2000, 3000, 4000, and 5000. The test results are shown in Table 5.

[Table] (Note) However, white glaze is the one used for ordinary solid support insulators.
From the results in Table 5, the following was confirmed.
Regarding the thermal testing, good results were obtained with no breakage occurring on the unglazed and polished inner surfaces of the inner holes. On the other hand, cracks occurred between the glass and the inner surface of the inner hole on the glazed surface. In heat resistance limit tests, optical fiber composite insulators with an unglazed inner hole and a polished surface showed
While there were no problems up to 150°C, cracks were observed in some parts at 140°C when the inner surface of the inner hole was glazed. As a result of the heat cycle test, optical fiber composite insulators with an unglazed or polished inner hole inner surface showed
Although good results were obtained with no cracks or decrease in AC withstand voltage up to 5,000 cycles, if the inner surface of the inner hole was a glazed surface, a decrease in AC withstand voltage was observed after 3,000 cycles due to a decrease in internal insulation. It was done. A.C.
As a result of dismantling and investigating an optical fiber composite insulator that had undergone the same number of heat cycles as the low-withstand-voltage destroyed product, cracks were found in the seal between the glass and the inner surface of the inner hole, and moisture was found in the cavity at the center of the inner hole's axis. Infiltration was observed. Further, when the optical fiber and the inner hole surface are sealed with an inorganic material, the heat cycle resistance performance is better when the inner hole surface is a polished surface than when it is an unglazed surface. Furthermore, an adhesive strength test was conducted using test pieces. A test piece measuring 20 mmφ x 10 mmH was prepared from the same porcelain material as the insulator used for the optical fiber composite insulator. The surface of the test piece to be bonded to glass was an unglazed surface, a polished surface, and a glazed surface. After the test piece was fired, the end face was polished to the specified shape, and the adhesive surface was spray-coated with glass and heated to 350°C.
After calcining for 1 hour at
Glued. Adhesive strength is determined by 20 test pieces at each level.
Prepare each piece and use a tensile tester to test the tensile speed.
It was carried out at 0.5 mm/min. The adhesive strength was calculated by dividing the load at which the adhesive part broke by the adhesive cross-sectional area. The cohesive failure rate is the number of tensile failures of the glass itself in all test pieces expressed as a percentage. Test results in the 6th
Shown in the table.

[Table] (Note) However, the glazed surface was a white glaze that is used for the surface of insulators.
As a result of the adhesive strength test shown in Table 6, the adhesive strength of the test pieces in which the unglazed or polished surface was the adhesive surface to the glass was high, and the starting point of failure was not the adhesive surface.
It turned out to be inside the glass. On the other hand, all of the test pieces with glazed surfaces showed failure starting from the adhesive surface, indicating that the adhesive strength between glass and glaze was low. (Effects of the Invention) As is clear from the above description, according to the optical fiber composite insulator of the present invention, by adjusting the surface of the inner hole through which the optical fiber is inserted in accordance with the sealing material, each sealing A sealing material suitable for the material is obtained, the airtight performance of the bonded part is improved, and electrical insulation properties equivalent to those of conventional solid support insulators can be maintained in the same shape. As a result, reliability can be maintained even when replacing solid support insulators used in conventional switches in power substations, etc., so that a failure point detection system in a substation, etc. can be easily configured.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the shape of an insulator used in the optical fiber composite insulator of the present invention. 1...Inner hole, 2...Insulator, 3...Tapered part.

Claims (1)

[Scope of Claims] 1. An optical fiber composite insulator in which an optical fiber is inserted into an inner hole penetrating the central portion of the insulator, and the optical fiber and the inner hole surface are sealed with silicone rubber. An optical fiber composite insulator characterized by having a glazed and fired surface. 2. An optical fiber composite insulator in which an optical fiber is inserted into an inner hole penetrating the central portion of the insulator and the optical fiber and the inner hole surface are sealed with an inorganic material, characterized in that the inner hole surface is a polished surface. Optical fiber composite insulator.