JPH05264824A - Optical fiber-combined insulator and its production - Google Patents

Abstract

PURPOSE:To improve the light transmission performance at the time of a low temp. of the optical fiber-combined element and to improve the insulation performance thereof. CONSTITUTION:A through-hole 1a having an approximately circular shape in a transverse direction is provided in the insulator body. Plural pieces of optical fibers 2A, 2B (2A, 2B, 2C, 2D)are inserted into this through-hole 1a. These optical fibers are hermetically sealed by an org. insulator. The diameter of the through-hole 1a is specified to <=13mm. The optical fibers 2A, 2B (2A, 2B, 2C, 2D) exist on the inner side of a virtual circle C having the diameter of about 95% the diameter of the through-hole 1a. All of the spacings l (lAB, lBC, lCD, lDA, lAC, lBD) between the optical fibers are specified to >=0.1mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber composite insulator and a method for manufacturing the same.

[0002]

2. Description of the Related Art Transmission and distribution lines or electric power substations require a system for promptly detecting and restoring a fault point that has occurred in the transmission and distribution lines or substation due to a lightning accident or the like. For this reason, an abnormal current / abnormal voltage detection device using an optical sensor having the Faraday effect and the Pockels effect is used. In these devices, it is necessary to insulate the transmission voltage and the transmission current between the sensor attached to the distribution line and the failure point detector. Therefore, in order to transmit only an optical signal and maintain electrical insulation, an optical fiber composite insulator containing an optical fiber is used.

As such an optical fiber composite insulator, it is general that an insulator main body is provided with an elongated through hole, an optical fiber is inserted into the through hole, and sealed with an organic insulating material such as silicone rubber or epoxy resin. .. However, at low temperatures in winter, the organic insulator contracts greatly, causing the optical fiber to distort.
There is a problem that the optical transmission loss increases. Further, in the manufacturing process of the optical fiber composite insulator, if the injection condition of the organic insulating material is impaired, the organic insulating material does not wrap around the optical fiber, which may easily cause defective adhesion and deteriorate the insulating performance. ..

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to improve the optical transmission performance and insulation performance at low temperature in an optical fiber composite insulator.

[0005]

According to the present invention, a through hole having a substantially circular cross section in the width direction is provided in an insulator body, and a plurality of optical fibers are inserted into the through hole, and these optical fibers are made of an organic insulator. In the optical fiber composite insulator hermetically sealed by, the diameter of the through hole is 13 mm or less, inside the virtual circle concentric with the through hole and having a diameter of 95% of the diameter of the through hole. The present invention relates to an optical fiber composite insulator, wherein the optical fibers are located and a distance between the optical fibers is 0.1 mm or more.

Further, according to the present invention, an insulator body having a through-hole having a substantially circular cross section in the width direction and having a diameter of 13 mm or less is prepared, and a plurality of optical fibers are inserted into the through-hole. Position each optical fiber so that the optical fiber is located inside a virtual circle that is concentric with the through hole and has a diameter of 95% of the diameter of the through hole, and that the distance between any of the optical fibers is 0.1 mm or more. Fixing, filling the inside of the through hole with an organic insulating material, and then heating and curing the organic insulating material to hermetically seal the optical fiber, thereby producing an optical fiber composite insulator. It relates to the method.

[0007]

EXAMPLE FIG. 2 is an enlarged sectional view showing the vicinity of an end face of an optical fiber composite insulator. The insulator main body 1 has an elongated cylindrical shape, is provided with a large number of shades on the outer peripheral surface thereof, and has a through hole 1a having a substantially circular cross section in the width direction formed in the central portion. Through hole 1a
For example, two optical fibers 2A and 2B are inserted therein. The upper end outer peripheral surface and the lower end outer peripheral surface of the insulator body 1 are attached to the flange 6 via the cement layer 5. The organic insulator 3A is filled in the through hole 1a. Further, at the upper end and the lower end of the insulator body 1, the organic insulator 3A rises from the end face 1c to form a raised portion 4A. In the example shown in FIG. 2, the raised portion 4A has a flat disk shape. The optical fibers 2A and 2B are disc-shaped raised portions 4A.
It is taken straight out from the center of.

A cross-sectional view of the through hole 1a taken in the width direction is shown in FIG. 1 (a). However, in FIG. 1 (a), the organic insulator 3A is not shown for the sake of clarity. The diameter of the through hole 1a is 13 mm or less according to the present invention. The center of the virtual circle C is made to coincide with the center O of the through hole 1a, and the diameter of the virtual circle C is set to 95% of the diameter of the through hole 1a. The optical fibers 2A and 2B are positioned inside the virtual circle C. Optical fiber 2
The distance l between A and 2B is 0.1 mm or more.

The following effects can be obtained by adopting the above configuration. That is, the present inventor obtained the following findings as a result of various studies on the cause of the increase in optical transmission loss at low temperatures. The organic insulator 3A is specifically silicone rubber, urethane rubber, epoxy resin, or the like, but silicone rubber is particularly preferable because of its excellent stress relaxation property. They are,
Compared with the insulator body, it has a coefficient of thermal expansion of several times to several tens of times, so that the organic insulator in the through-hole largely shrinks at low temperature. However, since the organic insulator 3A in the through-hole 1a is firmly bonded to the wall surface of the insulator body 1, its movement is restricted and it hardly shrinks in the radial direction and the circumferential direction. Large contraction only in the axial direction near the part. Due to the displacement (dent) of the organic insulating material 3A near the end of the through hole 1a, the optical fiber 2A sealed to the organic insulating material 3A,
2B shrinks, causing optical transmission loss.

According to the present invention, if the diameter of the through hole 1a is 13 mm or less, the displacement (dent) of the organic insulator near the end portion of the through hole 1a at a low temperature is small, and the optical transmission at a low temperature is achieved. It turns out that the loss can be reduced. The reason for this is considered as follows. First, the organic insulator 3A has the through hole 1a.
Since it is adhered to the wall surface of the organic insulator 3A, it has the effect of restraining the contraction of the organic insulator 3A in the axial direction.
The stronger the wall surface of the through hole, the weaker it gets closer to the center of the through hole. Therefore, as the through hole becomes thinner, the effect of restraint extends to near the center of the through hole. As described above, the contraction of the organic insulator 3a sealed in the through hole 1a is restricted by the movement in the radial direction and the circumferential direction in the through hole, so that the shaft near the end of the through hole 1a is restricted. As the diameter of the through-hole 1a is larger, the axial displacement (dent) is larger even if the contraction rate of the organic insulator is the same.
The size (maximum value) of becomes large. It is considered that the magnitude of this axial displacement is approximately proportional to the 1.5 to the square of the diameter of the through hole 1a. Therefore, the thinner the through hole, the smaller the displacement (dent) near the end.

Further, according to the present invention, by locating the optical fibers 2A and 2B inside the virtual circle C, the optical fiber 2
It is possible to eliminate contact between A and 2B and the wall surface of the through hole 1a, and allow the organic insulator 3A to sufficiently wrap around in the meantime.
Further, by setting the distance l between the optical fibers 2A and 2B to be 0.1 mm or more, the organic insulator 3A can be made to sufficiently wrap around between the optical fibers 2A and 2B. As a result of both of these limitations, the organic insulator 3B wraps around the respective optical fibers 2A and 2B uniformly, so that defective adhesion sites are less likely to occur. This improves the insulation performance of the optical fiber.

The same applies to the case where three or more optical fibers are inserted into the through holes. For example, 4 optical fibers
The case of a book will be described with reference to FIG. The optical fibers 2A, 2B, 2C, 2 are placed in the through holes 1a.
D is inserted. At this time, the optical fibers 2A, 2B, 2C and 2D are positioned inside the virtual circle C. Also, the distance between the optical fibers 2A and 2B is set to l _AB ,
The distance between the optical fibers 2B and 2C is 1 _BC , the distance between the optical fibers 2C and 2D is 1 _CD , and the optical fibers 2D and 2A are
The distance between the l _DA, the distance between the optical fiber 2A and 2C and l _AC, the distance between the optical fiber 2B and 2D and l _BD. l _AB , l _BC , l _CD , l _DA , l _AC , l _BD are all
It should be 0.1 mm or more.

Next, a preferred method of manufacturing the optical fiber composite insulator as shown in FIGS. 1 and 2 will be described with reference to FIG. The mold 7 is installed on each of the upper and lower end surfaces 1c of the insulator body 1. Each of the molds 7 is formed with a raised portion forming space 7a, and a through hole 7b communicates with each raised portion forming space 7a. A material injection pipe 9A is attached to the lower mold 7, a material discharge pipe 9B is attached to the upper mold 7, and the insides of the pipes 9A and 9B communicate with the through hole 7b. The mold 7 is fixed to the flange 6 with bolts 10, and an O-ring 13 hermetically seals between each mold 7 and the end face 1c. An insertion hole 7c for inserting an optical fiber is provided at the center of each mold 7. When setting each die 7, the center of the die 7 and the center of the through hole 1a are aligned with each other.

In order to prevent the optical fibers 2A and 2B from coming into contact with each other and the optical fiber through hole wall surface from coming into contact with each other in the through hole 1a, the spacer 12 made of the same material as the organic insulator 3A is used. Therefore, it is preferable to fix the optical fibers 2A and 2B in advance at three or more locations. Optical fiber 2
The geometry of A, 2B is according to the invention.

The optical fibers 2A and 2B are inserted through the insertion hole 7c and the through hole 1a. Packing 8 in the insertion hole 7c of the mold 7
Attach. The optical fiber 2A near the end of the through hole 1a
And 2B and the optical fiber through hole wall surface are prevented from coming into contact with each other.
It is preferable to provide two insertion holes having a diameter substantially equal to the outer diameter of B and adjust the positions of these insertion holes so that the positions of the optical fibers 2A and 2B are not displaced.

Further, it is preferable to apply a tensile load to each of the optical fibers 2A and 2B and pull each of the optical fibers 2A and 2B straight. As a result, even when the organic insulating material 3B is filled, the contact between the optical fibers and the contact between the optical fibers and the through hole are reliably prevented. Further, it is possible to prevent the optical fibers 2A and 2B from being slightly bent by the pressure when the organic insulating material 3B is filled.

When the organic insulating material 3B is filled, the inside of the through hole 1a may be depressurized to about 1 to 3 torr in order to prevent air bubbles from being trapped inside the organic insulating material 3B being injected. preferable. Then, the organic insulating material 3B is injected from the material injection pipe 9A. The material 3B rises in the through hole 1a and reaches the material discharge port 9B. The space 7a for forming the raised portion and the through hole 1a are filled with the organic insulating material 3B and heated to cure. Then, the mold 7 is removed. At this time, the injection pressure of the organic insulating material 3B is 3 to 10 kgf / cm ²
Then, it is easy to uniformly inject the material 3B into the through hole 1a.

Specific experimental results will be described below. (Experiment 1) An optical fiber composite insulator as shown in FIGS. 1 (a) and 2 was manufactured by the method shown in FIG. The insulator body 1 had a total length of 1150 mm, a body diameter of 105 mm, and a cap diameter of 205 mm. In this experiment, the height h of the raised portion 4A was set to 3 mm, and the size of the depression of the organic insulator in the central portion was measured. As the optical fibers 2A and 2B, silica optical fiber strands were used.
As the organic insulating material 3B, a liquid silicone rubber having a viscosity before curing of 500 to 1000 poise was used.

The diameter of the through hole 1A of the insulator body 1 was variously changed as shown in FIGS. 4 and 5, and the average end face displacement (dent) of the organic insulator 3A at −20 ° C. 20 ° C
The optical transmission loss of the optical fiber was measured. The results are shown in FIGS. The optical transmission loss at −20 ° C. was obtained as a ratio of the amount of light transmitted at −20 ° C. divided by the amount of light transmitted at room temperature (25 ° C.). In the experiment, the optical fibers 2A and 2B were positioned on the circumference of an imaginary circle that was concentric with the through hole 1a and had a diameter of 30% of the diameter of the through hole 1a. Then, the optical fibers 2A and 2B are arranged point-symmetrically about the center O of the through hole. Therefore, when the diameter of the through hole 1a is 4 mm, the distance between the optical fibers 2A and 2B is 1.2m.
It becomes m.

As can be seen from FIG. 5, the diameter of the through hole is 13 mm.
At that point, the optical transmission loss at −20 ° C. has sharply improved. Further, as the diameter of the through hole increases, the dent of the organic insulating material also rises.

(Experiment 2) An optical fiber composite insulator as shown in FIG. 2 was manufactured by the above method shown in FIG. The insulator main body 1 has a length of 1150 mm, a body diameter of 105 mm, and a cap diameter of 205 mm. As the optical fibers 2A and 2B, those having an outer diameter of 0.4 mm in which the periphery of quartz glass which is a light guide portion is covered with an ultraviolet curable resin were used. The organic insulating material 3B is liquid silicone rubber and has a viscosity before curing.
A poise of 100 to 1000 was used.

Then, the arrangement of the optical fibers 2A and 2B was variously changed, and the insulation performance of the optical fiber composite insulator was evaluated.
Specifically, the distance between the optical fibers 2A and 2B was changed as shown in Table 1. At the same time, the optical fibers 2A and 2B
For an optical fiber farthest from the center O among the above, consider a virtual circle passing through the farthest optical fiber centered on the center O of the through hole, and Table 1 shows the ratio of the diameter of the virtual circle to the diameter of the through hole. Changed as shown. For each example shown in Table 1, the diameter of the through hole 1a is 6 mm and the insulator body is 10 mm.
The insulator body and the insulator body were prepared for every five pieces and subjected to the test. That is, for each example, there are 10 specimens.

Further, as a standard product, a test piece in which only one optical fiber is directly sealed at the center of the through hole 1a so as not to come into contact with the through hole wall is provided with the through hole 1a as in the above-mentioned examples. Insulator body with a diameter of φ6 mm and insulator body with a diameter of φ10 mm were prepared for each five pieces, for a total of ten pieces. The insulation performance is measured by measuring the flashover voltage of each optical fiber composite insulator, and averaging 10 of each,
The relative value was evaluated with the average value of the standard product as 1.0. As a reference, we prepared 10 test pieces in which two optical fibers, which are considered to have the lowest insulation performance, were brought into contact with each other, and those optical fibers were brought into contact with the through-hole wall. The relative value of was measured to be 0.70. In Table 1,
The relative values of the flashover voltage of the standard product, each example, and the reference product are shown.

[0024]

[Table 1]

As can be seen from Table 1, the ratio of the diameter of the virtual circle on which the distant optical fiber is located to the diameter of the through hole is 97.
When it becomes%, the insulation performance deteriorates. Also, the optical fiber 2
The same applies when the distance between A and 2B is 0.05 mm. Also,
It can be said that the ratio of the imaginary circle where the distant optical fiber is located to the diameter of the through hole is 70% or less.
It can be said that the distance between the optical fibers is more preferably 0.2 mm or more.

[0026]

As described above, according to the present invention, since the diameter of the through hole is 13 mm or less, the displacement (dent) of the organic insulator near the end of the through hole becomes small at low temperature, and The optical transmission loss can be reduced. Moreover, since the optical fibers are positioned inside the virtual circle having a diameter of 95% of the diameter of the through hole, the contact between each optical fiber and the wall surface of the through hole is eliminated, and the organic insulator is sufficiently circulated between them. Can be made. And the distance between any optical fibers
Since the thickness is 0.1 mm or more, it is possible to sufficiently wrap the organic insulator between the optical fibers. As a result, since the organic insulating material uniformly wraps around the entire circumference of each optical fiber, a defective contact point is less likely to occur, and the insulating performance of the optical fiber is improved.

[Brief description of drawings]

1 (a) and 1 (b) are schematic cross-sectional views of a through hole 1a taken along a width direction for explaining the configuration of the present invention.

FIG. 2 is an enlarged cross-sectional view showing the vicinity of an end face of an optical fiber composite insulator.

FIG. 3 is a cross-sectional view showing a state in which a mold 7 is installed on the end surface 1c of the insulator main body 1 and the organic insulating material 3B is filled.

FIG. 4 is a graph showing the relationship between the diameter of a through hole and the dent of an organic insulating material.

FIG. 5 is a graph showing a relationship between a diameter of a through hole and an optical transmission loss.

[Explanation of symbols]

1 Insulator body 1a Through hole 1c End face 2A, 2B, 2C, 2D Optical fiber 3A Organic insulator 3B Organic insulator material 7 Type 8 Packing C Virtual circle O with 95% diameter of through hole O Center of through hole l , L _AB , l _BC , l _CD , l _DA , l _AC , l _BD Distance between optical fibers

Claims (2)

[Claims] 1. An insulator body is provided with a through hole having a substantially circular cross section in a width direction, a plurality of optical fibers are inserted into the through hole, and these optical fibers are hermetically sealed by an organic insulator. In the optical fiber composite insulator, the diameter of the through hole is 13 mm or less, the optical fiber is located inside a virtual circle concentric with the through hole and having a diameter of 95% of the diameter of the through hole, and The distance between all the optical fibers is 0.1 mm or more,
Optical fiber composite insulator. 2. The cross section in the width direction is substantially circular and has a diameter of 13 mm.
Prepare an insulator body having the following through holes, and insert a plurality of optical fibers into the through holes, at this time, a virtual circle that is concentric with the through holes and has a diameter of 95% of the diameter of the through holes. The optical fibers are located inside and each optical fiber is fixed such that the distance between any of the optical fibers is 0.1 mm or more, and in this state, the through hole is filled with an organic insulating material, and then this A method for manufacturing an optical fiber composite insulator, characterized in that an organic insulating material is heat-cured to hermetically seal the optical fiber.