JPH02158018A - Optical fiber composite insulator - Google Patents

Abstract

PURPOSE:To equalize the mechanical strength to that of a solid insulator by making the ratio of the diameter of the bore to the diameter of the core part less than a specified value. CONSTITUTION:In a composite insulator having an inner port passing optical fibers through and sealed by an organic material, the ratio of the diameter d of the bore to the diameter D of the core part is made d/D<0.25. Hence, the mechanical strength is largely reduced and made equal to that of a solid insulator having the same core diameter.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention has mechanical strength equivalent to that of a conventional solid insulator,
This invention relates to an optical fiber composite insulator with improved 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 JP-A-60-158402, 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 entire through hole to seal it.

Furthermore, a technique is known in which only the center portion of the through hole in the axial direction is filled with an organic insulating material such as silicone rubber, and the end portion is sealed with glass.

The optical fiber composite insulators used in these systems not only have built-in 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 mechanical strength equivalent to that of the solid support insulator.

(Problem to be solved by the invention) Conventionally, the mechanical strength of an insulator has been limited even if the body diameter is the same.
It is known that the guaranteed strength is different between a solid type and an insulator type that has a through hole in the axial direction of the insulator, and that the mechanical strength of the insulator type is lower. Furthermore, in the case of optical fiber composite insulators, materials having different coefficients of thermal expansion are filled and solidified to form an integrated structure, which generates residual stress, which further reduces mechanical strength.

Therefore, it is important to maintain the mechanical strength of the optical fiber composite insulator to the same level as that of a conventional solid support insulator of the same diameter. Conventionally, no consideration was given to the relationship with the diameter of the part.

An object of the present invention is to solve the above-mentioned problems and to improve the diameter d of the inner hole.
By investigating the relationship between the diameter of the insulator body and the diameter of the insulator body, we aim to provide an optical fiber composite insulator that has the same mechanical strength 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 is an optical fiber composite insulator in which an optical fiber is inserted into an inner hole penetrating the central part of the insulator, and the central part of the inner hole is sealed with an organic material. The insulator is characterized in that d/D is 0.25 or less, where d is the diameter of the inner hole and D is the diameter of the insulator body.

(Function) The present invention provides an optical fiber composite insulator that uses an organic material such as silicone rubber as a sealing material for hermetically sealing the entire or part of the optical fiber and the insulator through hole, and is equivalent to the conventional solid supported insulator. This is because we have found a relationship between the diameter d of the inner hole and the diameter of the body that can maintain the mechanical strength of the same shape.

This makes it possible to replace solid supporting insulators for disconnectors in power substations with optical fiber composite insulators that use silicone rubber as the sealing material for the inner holes that the fiber optic composite insulators penetrate. A failure point detection system can be easily configured at any location.

Here, in the relationship between the diameter d of the inner hole penetrating the central portion and the diameter of the insulator body, d/D was limited to 0.25 or less, as is clear from the examples described later. /D
This is because when the value exceeds 0.25, the mechanical strength becomes lower than that of a solid product of the same shape, and the heat resistance limit also becomes low.

Note that the diameter d of the inner hole is preferably 3 mm or more in order to allow the optical fiber to be inserted therein and to maintain sufficient airtightness after sealing.

(Example) An actual example will be explained below.

Various types of perforated insulators 3, whose shapes are shown in FIG. 1, each having an inner hole 1 passing through the axis of the porcelain insulator were prepared. The porcelain material was the same as the solid support insulator used for the support stand of the switch in the substation. The diameter d of the inner hole 1 passing through the center of the insulator shaft is 2~
60 mm, the diameter of the insulator body 2 is varied in the range of 80 to 145 mm, and the ratio (d/D) xloo of the penetrating inner hole diameter to the insulator body diameter is 2.8 to 50.0%. I prepared 3 open insulators.

Incidentally, a tapered part 4 was provided at the open end of the perforated insulator 3, the diameter of which was 1Q mm larger than the diameter of the inner hole passing through, and which formed an angle of 30° with the axis. The reason for providing the tapered portion 4 is to relieve internal pressure generated due to changes in environmental temperature after the silicone rubber is cured. Further, the surface of the inner hole 1 at the center of the insulator shaft was glazed with the same glaze as the surface of the insulator.

Optical fiber composite insulators were fabricated by sealing optical fibers to these insulators with silicone rubber, and performance tests were conducted. As the optical fiber used for the test specimen, an optical fiber with only a secondary coating and a buffer layer was used, taking into consideration the airtightness of the optical fiber itself and ease of handling during the sealing process. Furthermore, the surface of the buffer layer, which is the outermost layer of the optical fiber, was treated with a primer such as a silane coupling material to ensure airtight adhesion with silicone rubber. The silicone rubber used was a high-temperature curable, anti-core type silicone rubber, and a material with high tensile strength and elongation at break was selected. Table 1 shows the material properties of the buffer layer and silicone rubber that coat the optical fiber used in the test specimen.

The test specimens in Table 1 were prepared by inserting two optical fibers into the through holes of a porcelain insulator, and filling the periphery with silicone rubber while each optical fiber was pulled under a tension of 1 kg.

The silicone rubber was degassed and stirred for 30 minutes at a vacuum pressure of less than I Torr, and then press-fitted at a pressure of 5 kg/cm. Degassing is preferable because it prevents air bubbles from getting caught between the bonding surfaces of silicone rubber and porcelain, and the bonding surfaces of silicone rubber and optical fiber.After filling with silicone rubber, store it in a constant temperature bath at 80℃ for 6 hours to harden the silicone rubber. This resulted in an optical fiber composite insulator.

The optical fiber composite insulator produced in the above process was subjected to a bending strength test, a heat resistance limit test, and an airtightness test after sealing as a product.

The test method is shown below.

For the bending strength test, 10 specimens were prepared, the flange fitting at one end was fixed, and a load perpendicular to the insulator axis direction was applied using the unfixed end as the point of application. The test results were expressed as a relative value of the average strength of the 10 test specimens, with the average bending strength of insulators having the same body diameter and no through holes being lOO.

In addition, 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 appearance was inspected.

The test results are ◎, 1/1 if there are no problems with all test specimens.
A case where an abnormality such as destruction of the insulator or silicone rubber popping out occurred in the test specimen of 10 was indicated by △, and a case where an abnormality occurred in the test specimen of 2710 or more was indicated by X. The first exam was 9
Testing was carried out at 0°C, and test specimens with a sound testing machine were subsequently tested at 100°C, 110°C, and 120°C.

Regarding airtightness after sealing, we prepared 10 test specimens.
An AC withstand voltage equal to the external flash voltage of each insulator was loaded.

The test results were indicated by an X if internal electrical penetration or tracking traces were observed in the test specimens of 1710 or more after disassembly.

The test results are shown in Table 2.

From the results in Table 2, regarding bending strength, the inner hole diameter (d
), the ratio (d/D)xloo of the insulator body diameter (D) is 25
% or less, the strength is equivalent to that of a normal solid support insulator, and it was found that the strength is compatible with a normal support insulator.

Furthermore, regarding the heat resistance limit test, (d/D) xlo
If o is 25% or less, there is no difference in the temperature range up to 120°C. On the other hand, if (d/D)xloo exceeds 25%, the insulator will break or the silicone rubber will crack.

In addition, when an optical fiber composite insulator of the same shape was manufactured with a penetrating inner hole diameter d of less than 3 mm,
When the diameter d of the inner hole was less than 3 mm, internal electrical penetration occurred in the insulator in the AC withstanding voltage test.

As a result of dismantling and investigating the optical fiber composite insulator that had fallen outside, it was found that there were parts of the optical fiber that had passed two types of water that were not sealed with silicone rubber because they were in contact with each other or with the wall of the through hole. It was found that the airtight performance had deteriorated.

These results are believed to be due to the fact that the thermal expansion coefficient of silicone rubber is about 30 times larger than that of porcelain. That is, when the volume of the silicone rubber exceeds a certain value, internal pressure is generated due to the thermal expansion of the silicone rubber at high temperatures, causing the insulator to break or the silicone rubber itself to break.

Therefore, below a certain (d/D), preferably d is 3 mm.
It was found that in the case of a larger through hole, there was no reduction in the inherent mechanical strength of the insulator, and there was no problem with the airtight sealing of the optical fiber.

(Effects of the Invention) As is clear from the above description, according to the optical fiber composite insulator of the present invention, by limiting the relationship between the diameter d of the inner hole through which the optical fiber is inserted and the diameter of the body of the insulator. , can maintain the same mechanical strength as conventional solid support insulators in the same shape, and maintain reliability even when replaced with solid support insulators used in conventional power substation switchgears, etc. It is possible to easily configure a failure point detection system at a location or the like.

[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.

Claims (1)

[Claims] 1. In an optical fiber composite insulator in which an optical fiber is inserted into an inner hole that passes through the center of the insulator and the center of the inner hole is sealed with an organic material, the diameter of the inner hole is d, and the diameter of the insulator body. An optical fiber composite insulator characterized in that d/D is 0.25 or less, where D is d/D.