JP3037815B2 - Optical fiber composite insulator and its manufacturing method - Google Patents

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 In transmission lines and power substations, there is a need for a system for quickly detecting and restoring a fault point occurring in a transmission line or a substation due to a lightning strike or the like. For this purpose, an abnormal current and abnormal voltage detecting device using an optical sensor having a Faraday effect and a Pockels effect is used. In these devices, it is necessary to insulate the transmission voltage and transmission current between the sensor attached to the distribution line and the fault point detector. For this reason, an optical fiber composite insulator having a built-in optical fiber is used to transmit only an optical signal and maintain electrical insulation.

In an optical fiber composite insulator proposed in Japanese Utility Model Application Publication No. 64-31620, a through hole is provided in an elongated insulator main body, an optical fiber is inserted into the through hole, and the through hole is filled with an organic insulator. Further, the organic insulator is raised from the end face of the insulator body. This is for the purpose of absorbing the expansion of the organic insulator by the raised portion of the organic insulator, and preventing the organic insulator itself from jumping out and the optical fiber being disconnected due to this. Since the amount of expansion of the organic insulator is large at a high temperature, the expansion of the organic insulator is usually large and raised to absorb the expansion as much as possible.

[0004]

However, such an optical fiber composite insulator has a problem that optical transmission loss increases particularly at low temperatures. In addition, there has been a problem in that the adhesive force is reduced at the adhesive interface between the raised portion made of an organic insulator and the end face of the insulator main body due to a long-term temperature change.

An object of the present invention is to reduce optical transmission loss at low temperatures in an optical fiber composite insulator in which an optical fiber is sealed with an organic insulator. Another object of the present invention is to prevent peeling at the bonding interface between the raised portion made of an organic insulator and the end face of the insulator main body. Another object of the present invention is to efficiently produce such an optical fiber composite insulator without adversely affecting the transmission characteristics of the optical fiber.

[0006]

According to the present invention, there is provided an insulator body provided with a through hole, and at least one optical fiber inserted into the through hole, wherein the through hole is filled with an organic insulator. An optical fiber composite insulator in which a raised portion protruding from an end face of the insulator main body is formed of an organic insulator, and wherein the optical fiber is hermetically sealed by the organic insulator, wherein the raised portion is protruded from the end face of the insulator main body. The height to the tip of the optical fiber composite insulator is 5 mm or more and 40 mm or less.

The present invention also includes an insulator main body provided with a through hole, and one or more optical fibers inserted through the through hole, wherein the through hole is filled with an organic insulator.
In an optical fiber composite insulator in which a raised portion protruding from an end face of the insulator main body is formed of an organic insulator, and the optical fiber is hermetically sealed by the organic insulator, the through hole at the end face of the insulator main body is provided. The optical fiber composite insulator according to claim 1, wherein a bonding length from an outer peripheral edge to an outer peripheral edge of a bonding portion of the raised portion to the end face is 1 mm or more and 35 mm or less.

Further, according to the present invention, a mold having a space for forming a raised portion is prepared, and the mold is attached to each of a pair of end faces of an insulator body provided with a through-hole. Inserting one or more optical fibers, applying a tensile stress to the optical fibers, and pulling the optical fibers straight and filling the space for forming the ridges and the through holes with an organic insulating material; The method according to the present invention relates to a method for manufacturing an optical fiber composite insulator, characterized in that the optical fiber is hermetically sealed with an organic insulator by curing the composite.

[0009]

1 is an enlarged sectional view showing the vicinity of an end face of an optical fiber composite insulator, and FIG. 2 is a sectional view showing the entire optical fiber composite insulator. The insulator body 1 is in the shape of an elongated column,
The outer peripheral surface is provided with a number of shades 1b, and a circular through hole 1a is formed in the center. For example, two optical fibers 2 are inserted into the circular through hole 1a. The upper end outer peripheral surface and the lower end outer peripheral surface of the insulator main body 1 are attached to the flange 6 via the cement layer 5. The through hole 1a is filled with the organic insulator 3A. Furthermore, at the upper end and the lower end of the insulator main body 1, an end face 1c
From there, the organic insulator 3A rises to form the raised portion 4A.

In the example shown in FIG. 1, the raised portion 4A has three parts. That is, a truncated conical portion 4a is formed concentrically with the circular through-hole 1a, and a columnar top 4c is formed at the center of the truncated conical portion 4a. A relatively thin extending portion 4b is formed at the skirt portion of the outer peripheral edge of the truncated conical portion 4a. The optical fiber 2 passes through the truncated conical portion 4a and the cylindrical top 4c, and is taken out from the distal end surface of the cylindrical top 4c.

The present inventor has made various studies on the cause of the increase in optical transmission loss at low temperatures, and has obtained the following findings. That is, the organic insulator is specifically a silicone rubber, a urethane rubber, an epoxy resin, or the like, and has a coefficient of thermal expansion several times to several tens times that of the insulator main body. Things shrink significantly. On the other hand, since the organic insulator in the through hole is firmly bonded to the wall surface of the insulator main body, the movement is restricted, and the organic insulator does not contract much even at a low temperature.

As described above, it has been practiced to increase the height of the raised portion to absorb the expansion at high temperatures.
On the other hand, when the temperature is low, the protrusions shrink greatly, and strain is generated inside the organic insulator near the end openings of the through holes. As a result, microbending occurs in the optical fiber sealed in the vicinity of the end opening, which causes optical transmission loss.

Based on such new knowledge, the present inventor has found that when the height H from the end face 1c of the insulator main body 1 to the tip of the protruding portion 4A is set to 40 mm or less, the optical transmission loss at low temperatures is greatly reduced. We found that we did. That is, it is considered that such a limitation significantly reduced the strain inside the organic insulator near the end opening of the circular through hole 1a even at a low temperature, thereby preventing microbending of the optical fiber in this portion.

The inventor of the present invention has conducted various investigations on the cause of a decrease in the adhesive force during long-term use at the adhesive interface between the raised portion made of an organic insulator and the end face of the insulator main body. It has been found that the bonding length l from the outer peripheral edge A to the outer peripheral edge B of the bonding portion of the raised portion 4A to the end face 1c is important. Specifically, the bonding length l is 1 mm
As described above, it was found that when the thickness was 35 mm or less, peeling did not occur.

The reason will be described in more detail. When the bonding length 1 is small, the end of the bonding interface between the circular through hole 1a and the organic insulator 3A is directly exposed. When the ambient temperature changes, the organic insulator 3A expands and contracts. Organic insulator 3A
In the circular through-hole 1a, since it is firmly restrained in the radial direction by the wall surface of the insulator main body 1, it expands and contracts only in the axial direction.
For this reason, near the end opening of the circular through hole 1a, a large tensile stress is generated along the axial direction of the circular through hole 1a. If the end of the adhesive interface between the circular through-hole 1a and the organic insulator 3A is directly exposed to the vicinity, the adhesive strength at this portion is likely to be reduced.

On the other hand, in the raised portion 4A, the circular through hole 1a
Unlike the inside, there is room for the organic insulator 3A to expand and contract freely to some extent in both the radial direction and the axial direction. Accordingly, if the bonding length 1 is 1 mm or more, the stress applied to the outer peripheral edge B of the bonded portion is much smaller than the stress applied to the outer peripheral edge A of the circular through hole 1a. This makes it difficult for the adhesive portion to peel off from the end.

According to the study of the present inventor, when the bonding length 1 is too long, the bonding strength tends to decrease. this is,
This is because when the ambient temperature changes, the absolute amount of expansion and contraction in the radial direction of the raised portion 4A increases. As a result, the end face 1c
, A large tensile stress is generated in the radial direction.

In this regard, according to the present invention, the bonding length 1 from the outer peripheral edge A of the circular through hole 1a to the outer peripheral edge B of the bonding portion is 35 mm.
With the following, the absolute amount of expansion and contraction in the radial direction of the raised portion 4A due to the temperature change can be reduced, and as a result, the tensile stress generated on the outer peripheral edge B of the bonding portion is also reduced. Thereby, even if the organic insulator 3A expands and contracts due to a change in the ambient temperature, the adhesive strength at the adhesive interface is hardly reduced, and an optical fiber composite insulator excellent in long-term insulation performance can be obtained.

FIG. 3 is a sectional view schematically showing an entire optical fiber composite insulator obtained by stacking the insulator main bodies 1 in multiple stages.
1 and 2 are denoted by the same reference numerals. Two or more insulator bodies 1 are prepared, and the flanges 6 of the insulator body 1 are connected to each other with bolts 10 to be integrated. The present invention can be applied to such a multi-tiered composite insulator, and the raised portion 4A can be formed on the end face 1c.

The shape of the raised portion can be changed to the raised portions 4B, 4C and 14 shown in FIGS. FIG.
In the example, as in FIG. 1, an extended portion 4b is formed at the bottom of the outer peripheral edge of the truncated conical portion 4a. Frustoconical part 4a
A flat top 4d having a circular shape is formed at the center. In the example of FIG. 5, an extended portion 4b is also formed at the skirt portion of the outer peripheral edge of the truncated conical portion 4a. Frustoconical part 4a
Is provided with a flat circular concave portion 4e as the top. In the example of FIG. 6, the raised portion 14 includes a disc-shaped portion 14a centered on the through hole 1a, and a column-shaped top portion 14b formed at the center of the disc-shaped portion 14a.

The following effects can be obtained by forming the main body of the raised portions 4A, 4B, 4C into a truncated cone shape. That is, expansion and contraction of the organic insulator due to a change in ambient temperature escapes uniformly in the radial direction, and expansion and contraction in the axial direction decreases. Therefore, an optical fiber composite insulator having good optical transmission performance can be obtained without distortion of the optical fiber.

Also, the truncated conical portion 4a or the disc-shaped portion 14a
If the top of the cylinder is cylindrical, at low temperatures the cylindrical top 4
c and 14b shrink equally in the radial and axial directions. However, the truncated conical or disc-shaped portion other than the columnar tops 4c and 14b is adhered to the insulator end face 1c, so that it does not easily contract in the radial direction and easily contracts in the axial direction. Therefore, the contraction in the axial direction at the cylindrical tops 4c and 14b is smaller than the contraction in the axial direction at the other truncated conical or disk-shaped portions. Strain is generated in the organic insulator near the roots of the columnar tops 4c and 14b by the amount of the contraction difference. Here, when the step height h between the cylindrical tops 4c and 14b is set to 5 mm or less, the above-described shrinkage difference becomes extremely small, and it is found that no distortion occurs inside the organic insulator near the base of the cylindrical tops 4c and 14b. did. As a result, microbending does not occur in the optical fibers near the roots of the cylindrical tops 4c and 14b, so that the optical transmission loss at low temperatures is further reduced. When the top is a flat surface 4d, the step h at the top is 0 mm, and this kind of problem does not occur.

When the top of the truncated conical portion 4a or the disc-shaped portion 14a is formed as the concave portion 4e, the radial expansion of the organic insulator is restrained by the side surface of the concave portion 4e near the bottom surface of the concave portion 4e at a high temperature. . As a result, the vicinity of the bottom surface of the recess 4e swells. For this reason, distortion occurs at the base of the optical fiber protruding from the bottom surface of the recess 4e. Also in this case, the step h of the recess 4e is 5 mm.
In the following, expansion in the radial direction near the bottom surface of the concave portion 4e is not restrained, no distortion occurs at the root of the optical fiber, and optical transmission loss at high temperatures is further reduced.

In FIGS. 1 and 6, the tops 4c, 14b
Is cylindrical, the radius of the surface of the top is preferably 3 mm or more. As a result, the drawn-out portion of the optical fiber is reinforced by the top portions 4c and 14b, and even if the optical fiber protruding outward from the sealing portion is shaken due to force majeure during work and vibrations such as earthquakes, the optical fiber in the drawn portion is not affected. Will not be damaged.

Next, a preferred method of manufacturing the optical fiber composite insulator as shown in FIGS. 1 to 6 will be described with reference to FIG. The molds 7 are installed on the upper and lower end faces 1c of the insulator main body 1, respectively. Each of the molds 7 has a space 7a for forming a ridge, and a through hole 7b communicates with each space 7a for forming a ridge. 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 holes 7b. Each type 7
Is fixed to the flange 6 with bolts 10, and the space between each mold 7 and the end face 1 c is hermetically sealed with an O-ring 11. The optical fiber 2 is inserted into the optical fiber insertion hole 7c of each mold 7 and stretched into the circular through hole 1a. The vacuum packing 8 is set in the optical fiber insertion hole 7c of each mold 7 respectively.

An appropriate tensile stress is applied to the optical fiber 2 and the optical fiber 2 is pulled straight, the inside of the circular through-hole 1a is vacuum sucked, and the organic insulating material 3B is injected from the material injection tube 9A. This material 3B
Rises in the circular through-hole 1a and reaches the material discharge port 9B.
The organic insulating material 3B is formed in the protrusion forming space 7a and the circular through hole 1a.
And cured by heating. Thereafter, the mold 7 is removed.

According to such a method, an optical fiber composite insulator as shown in FIGS. 1 to 6 can be efficiently manufactured. In addition, it is effective that a tensile stress is applied to the optical fiber 2 at the stage of filling, heating, and curing the material 3B, whereby the transmission characteristics of the optical fiber are maintained well before and after the heat curing process. You.

Hereinafter, specific experimental results will be described. [Experiment 1] An optical fiber composite insulator as shown in FIG. 1 was manufactured by the method shown in FIG. The addition type silicone rubber was used as the organic insulator, and the heat curing temperature was 70 to 90 ° C. The dimensions of the insulator body were 950 mm in total length, 105 mm in body diameter, and 205 mm in shade diameter. The bonding length 1 is 20 mm, and the step of the cylindrical top 4c is 3
mm. The height H of the raised portion 4A, as shown in FIG. 8 5-
The light transmission loss at a low temperature was measured by changing the thickness to 100 μm . FIG. 8 shows the results.

FIG. 8 shows the optical transmission loss at 0 ° C. and the optical transmission loss at −20 ° C. 0 ℃ or -20 ℃
Was determined as a ratio obtained by dividing the amount of light transmission at 0 ° C. or −20 ° C. by the amount of light transmission at 25 ° C., respectively. As can be seen from FIG. 8, when H exceeds 40 mm, the optical transmission loss at a low temperature sharply increases. This tendency is -20 even at 0 ° C.
It looks almost the same at ° C.

[Experiment 2] An optical fiber composite insulator was manufactured in the same manner as in Experiment 1. However, the height H of the raised portion 4A is 40 mm
The step of the cylindrical top 4c was 3 mm. Adhesion length l
Was variously changed as shown in Table 1, and the adhesion between the organic insulator and the end face of the insulator was evaluated. More specifically, three optical fiber composite insulators having the bonding length 1 shown in Table 1 are prepared for each dimension and for each predetermined cycle, and are repeated a predetermined number of times. A heat cycle was given between.
Next, the adhesive strength between the organic insulator and the end face of the insulator was evaluated.
The adhesive strength was examined by pulling the organic insulator in the raised portion upward to determine whether cohesive failure occurs in the organic insulator or peeling occurs between the organic insulator and the insulator end face.

In each of the three samples, the case where the cohesive failure was caused by the organic insulator in all three samples was evaluated as “◎”.
In addition, when one or more of the three samples peeled off between the organic insulator and the end face of the insulator, the sample was evaluated as “○”. In all three, the case where peeling occurred between the organic insulator and the end face of the insulator was evaluated as “×”. Table 1 shows the results. As will be understood from the above, when the bonding length 1 is 1 to 35 mm, the bonding strength is large.

[0032]

[Table 1]

[Experiment 3] An insulator body having a total length of 950 mm, a body diameter of 105 mm, and a shade diameter of 205 mm was stacked in two stages, and silicone rubber was used as an organic sealing material. The optical fiber composite shown in FIG. 1, FIG. 4 or FIG. Insulators were manufactured. However, ridges 4A, 4B or
4C height 25mm, diameter of bottom of frustoconical part 4a is φ60
mm. Then, the shape of the top and the step were changed as shown in FIG. 9, and the optical transmission loss at 80 ° C. and −20 ° C. was measured. The result is shown in FIG. Each optical transmission loss was expressed as a ratio of the amount of light transmission at 80 ° C. or −20 ° C. to the amount of light transmission at 25 ° C.

As can be seen from FIG. 9, the optical transmission loss when the step h is 5 mm or less is greatly reduced. In particular, in the case of having a concave top, if the step h exceeds 5 mm, the optical transmission loss at 80 ° C. increases. In addition, in the case of having a column-shaped top (FIG. 1), when the step h becomes large, the optical transmission loss particularly at −20 ° C. increases.

[0035]

As described above, according to the present invention, since the height from the end face of the insulator main body to the tip of the raised portion is set to 40 mm or less, the inside of the organic insulator near the opening at the end of the through hole is reduced. Can be greatly reduced, and microbending of the optical fiber in this portion can be prevented. Thereby, the optical transmission loss at a low temperature can be greatly reduced. In addition, by setting the bonding length from the outer peripheral edge of the through hole to the outer peripheral surface of the bonding portion of the raised portion to the end surface to be 1 mm or more and 35 mm or less,
It is possible to prevent a decrease in the adhesive strength of the raised portion and to obtain an optical fiber composite insulator excellent in long-term insulation performance.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view showing the vicinity of an end face 1c of an optical fiber composite insulator.

FIG. 2 is a sectional view schematically showing the entire optical fiber composite insulator.

FIG. 3 is a cross-sectional view schematically showing the entire optical fiber composite insulator.

FIG. 4 is a sectional view showing the vicinity of an end face 1c of another optical fiber composite insulator.

FIG. 5 is a sectional view showing the vicinity of an end face 1c of still another optical fiber composite insulator.

FIG. 6 is a sectional view showing the vicinity of an end face 1c of still another optical fiber composite insulator.

FIG. 7: A mold 7 is attached to the insulator body 1, and an organic insulator material is used.
It is sectional drawing which shows the state which is injecting 3B.

FIG. 8 is a graph showing a relationship between a height H of a protruding portion and an optical transmission loss at 0 ° C. or −20 ° C.

FIG. 9 is a graph showing a relationship between a top step h and an optical transmission loss at 80 ° C. or −20 ° C.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulator main body 1a Circular through hole 1b Cap 1c End face of insulator main body 2 Optical fiber 3A Organic insulator 3B Organic insulator material 4A, 4B, 4C, 14 Raised part 4a Frustoconical part 4c, 14b Cylindrical top 4d Flat top 4e Recessed part 7 type 7a Raised portion forming space 14a Disc-shaped portion A Outer peripheral edge of circular through hole 1a at end surface 1c B Outer peripheral edge of raised portion bonded to end surface 1c H Height of raised portion h Step l Adhesive length

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tadashi Sugiura 26-1, Hikuhigashi, Higashimakinai-cho, Okazaki-shi, Aichi 1 (JP, U) Japanese Utility Model Hei 1-90006 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B 6/00 H01B 17/00

Claims (6)

(57) [Claims] 1. An insulator body provided with a through hole, and at least one optical fiber inserted through the through hole, wherein the through hole is filled with an organic insulator and rises from an end face of the insulator body. The raised portion is formed of an organic insulator, and the optical fiber is hermetically sealed with the organic insulator, wherein the height from the end face of the insulator main body to the tip of the raised portion is increased.
An optical fiber composite insulator having a length of 5 mm or more and 40 mm or less. 2. The optical fiber composite insulator according to claim 1, wherein the raised portion has a disk-shaped portion or a truncated cone-shaped portion and a top provided at the center thereof, and a step of the top is 5 mm or less. . 3. The optical fiber composite insulator according to claim 2, wherein the top is cylindrical, and a radius of a tip surface of the top is 3 mm or more. 4. A concave portion having a step of 5 mm or less is provided in said raised portion.
2. The optical fiber according to claim 1, wherein
Iva composite insulator. 5. An insulator body provided with a through-hole, and one or more optical fibers inserted through the through-hole, wherein the through-hole is filled with an organic insulator and rises from an end face of the insulator body. The raised portion is formed of an organic insulator, and the optical fiber is hermetically sealed with the organic insulator in an optical fiber composite insulator.From the outer peripheral edge of the through hole at the end face of the insulator main body,
An optical fiber composite insulator, wherein an adhesion length of the raised portion to the end face to an outer peripheral edge of an adhesion portion is 1 mm or more and 35 mm or less. 6. A mold having a space for forming a ridge is provided,
The molds are respectively attached to a pair of end faces of the insulator main body provided with through holes, and one or more optical fibers are inserted into the pair of molds and the through holes, and a tensile stress is applied to the optical fibers to straighten them. By filling an organic insulating material in the raised portion forming space and the through hole in a pulled state and curing the organic insulating material, the optical fiber is hermetically sealed with an organic insulating material. A method for producing an optical fiber composite insulator.