JPH0664954B2 - Optical fiber composite insulator and method for manufacturing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical fiber composite insulator mainly used when forming a fault point detection system in a transmission line network and a substation, and a manufacturing method thereof.

(Prior Art) Conventionally, in order to automatically detect a failure point in a power system, an optical fiber composite insulator having a function of transmitting a signal from an optical sensor on a power application side to a detector on a ground side has been used.

Various types of these optical fiber composite insulators are known. For example, in JP-A-60-158,402, a through hole is formed in the shaft center of the insulator, and an optical fiber is inserted into the through hole. A technique for sealing the optical fiber by filling the entire or part of the through hole with an organic insulator such as silicone rubber or epoxy resin, and preventing the surface leakage edge distance of the insulator from being reduced, and porcelain of the insulator. A technique is known in which the entire body is heated and molten glass is poured into the entire or part of the through hole to seal the optical fiber.

(Problems to be Solved by the Invention) However, in the above-described organic substance sealing,
Since the thermal expansion coefficient of the organic substance that is the sealing agent and that of the porcelain are greatly different, the sealing material may jump out from the through hole during heating,
There was a problem of cracking the porcelain from inside.

Further, in the sealing by the above-mentioned inorganic material, even if there is a coated optical fiber or coating, the optical fiber whose coating is peeled by heating will be inserted through the inner hole of the insulator, so that the glass for sealing is used. There is also a problem that the optical fiber easily breaks inside the insulator when heated for melting. That is, if the coating is peeled off from an optical fiber coated with silicone rubber or the like with a jacket stripper,
There is also a problem that the optical fiber is broken after the sealing when the optical fiber having such a reduced strength is used for sealing the inorganic glass.

An object of the present invention is to solve the above-mentioned problems and to provide an optical fiber composite insulator having a simple manufacturing method and high reliability, and a manufacturing method thereof.

(Means for Solving the Problem) The optical fiber composite insulator of the present invention is configured such that an optical fiber fused to an inner hole of a glass tube is installed in an inner hole penetrating a central portion of the insulator, and the inner hole and the glass of the insulator are installed. It has a structure in which the side walls of the tube are sealed with a sealing glass, and the thermal expansion coefficient of each member is such that the thermal expansion coefficient of the porcelain is α _p , the thermal expansion coefficient of the glass tube is α _t , and the thermal expansion coefficient of the sealing glass is When the expansion coefficient is α _q , 0.4 ≦ α _t / α _p ≦ 1.0 0.5 ≦ α _q / α _p ≦ 1.0 and 0.5 ≦ α _q / α _t ≦ 1.5. is there.

Further, the manufacturing method of the optical fiber composite insulator of the present invention, the optical fiber whose both ends are coated with a heat-resistant resin is installed in the glass tube inner hole, the glass tube is heated to a predetermined temperature to press the optical fiber to the glass. The optical fiber is sealed inside the tube, the insulator is installed in the inner hole that penetrates the central part, and the sealing glass is filled between the inner hole of the insulator and the side wall of the glass tube. It is characterized by sealing between the hole and the side wall of the glass tube.

(Operation) In the configuration described above, the optical fiber composite insulator of the present invention can solve the problems in the conventional organic sealing by using an inorganic glass having a thermal expansion coefficient close to that of the porcelain of the insulator as a sealing material. Since the optical fiber is covered with a low thermal expansion glass tube such as Pyrex glass when sealing the fiber in the insulator inner hole with inorganic glass, there is no disconnection of the optical fiber You can get an insulator.

When the thermal expansion coefficient of the porcelain is α _p , the thermal expansion coefficient of the glass tube is α _t , and the thermal expansion coefficient of the sealing glass is α _q ,
In _{0.4 ≦ α t / α p ≦} 1.0,0.5 ≦ α q / α p ≦ 1.0, and
If each member is configured so as to satisfy the relationship of 0.5 ≦ α _q / α _t ≦ 1.5, it is possible to obtain an optical fiber composite insulator having higher reliability, as will be apparent from Examples described later.

Furthermore, in the manufacturing method of the present invention, after sealing the low thermal expansion glass tube to the optical fiber, since the glass tube and the insulator inner hole are sealed with the sealing glass, even during heating. The optical fiber does not deteriorate, and the disconnection of the optical fiber can be prevented.

Further, as an optical fiber used in the manufacturing method of the present invention,
When using optical fiber protected by an organic sheet to prevent damage to the optical fiber without forming a protective coating during optical fiber manufacturing and directly adhering to the optical fiber, it occurred when peeling the coating of the conventional optical fiber. The deterioration of the optical fiber can be eliminated by eliminating the stripping process, which is preferable.

Furthermore, if a heat-resistant resin is filled into both ends of the glass tube with the optical fiber welded, the optical fiber is welded to the glass tube, or the optical fiber welded to the glass tube is sealed in the inner hole of the insulator using sealing glass. Even after wearing, the optical fiber can be bent and deformed, and there is an advantage that connection with other optical fibers becomes easy.

Furthermore, during sealing heating, it is preferable to heat the insulator while cooling the optical fiber of the portion exposed to the outside of the insulator, because it is possible to prevent deterioration of the portion exposed to high temperature without being subjected to heat treatment by the glass tube. .

(Example) FIGS. 1 (a) to 1 (f) are views for explaining a heat-resistant treatment step when manufacturing the optical fiber composite insulator according to the present invention.
FIG. 1 (a) shows an example suitable for producing an optical fiber used for the optical fiber composite insulator of the present invention, and is a step performed as necessary. In FIG. 1 (a), the optical fiber 1 that has been pulled out is wound while being protected by the organic sheet 2 without performing surface coating with a heat-resistant resin such as silicone rubber or polyimide resin that is usually applied when manufacturing an optical fiber. This facilitates handling of the optical fiber 1 having no surface coating.

First, as shown in FIG. 1 (b), the optical fiber 1 obtained as shown in FIG. 1 (a) or obtained by peeling off the coating is cut into a predetermined length and protruded from the insulator to the outside. Both ends are covered with heat resistant resins 3-1 and 3-2 such as polyimide and silicone rubber to protect the parts. At this time, the optical fiber 1
Heat-resistant resin is coated in advance, and the heat-resistant resin 3-1 and 3-2 are formed by peeling off the coating of the portion where the glass tube is welded by heat or chemical treatment so as not to scratch the optical fiber 1. can do. next,
As shown in FIG. 1 (c), a predetermined number of optical fibers 1 whose both ends are coated with heat-resistant resins 3-1 and 3-2 are placed in a low thermal expansion glass tube 4 such as Pyrex glass in this embodiment. Then install two. Next, as shown in FIG. 1 (d), after heating the glass tube 4 in which the optical fiber 1 is installed to a temperature of 700 to 800 ° C., the mold 5-1 and 5-2 having a predetermined shape are used. Pressurize. As a result, the optical fiber 1 is sealed inside the glass tube 4. In this case, it is effective to apply a flux component to the inner surface of the glass tube and the surface of the optical fiber in order to facilitate the sealing. In addition, heating the optical fiber exposed to the outside of the glass tube (the portion coated with the heat resistant resin) while cooling is effective for protecting the heat resistant resin. Finally, as shown in FIG. 1 (e), if necessary, heat-resistant resin 6 generated in both ends of the glass tube 4 after welding and the heat-resistant resin 6 in the gap between the glass tube or the optical fiber and the glass. The heat treatment of the optical fiber 1 is carried out by enclosing it.

Instead of sealing the optical fiber by heating and pressurizing as shown in FIG. 1 (d), as shown in FIG. 1 (f), the glass tube 4
Is locally heated by the burners 7-1 and 7-2 and softened, and is pressed while being pulled by the rollers 8-1 and 8-2,
The optical fiber 1 can be enclosed in the glass tube 4.

The optical fiber 1 that has been heat-treated is installed in an inner hole 12 that penetrates the central portion of the insulator 11 as shown in FIG.
Glass powder or sludge for sealing is filled between 12 and the side wall of the glass tube 4, and an inorganic glass flow stopper 13 made of calcined porcelain or the like is provided in the inner hole 12 at the lower end. In order to improve the filling efficiency, it is particularly preferable that the glass for sealing is calcined after being formed into a shape that fits into the inner holes of the glass tube and the insulator. Also, when refilling the amount of sealing glass that melts and the volume decreases with degassing, use sealing glass molded in the shape of beads (diameter 300 to 2000 μm) to improve fluidity. Doing is effective for uniform sealing. After that, as shown in FIG. 2, the insulator 11 is installed in the heating device 16 composed of the heater 14, the hot air blowing port 15a and the discharge port 15b, and hot air is blown from the hot air blowing port 15a and exhausted from the exhaust port 15b. A heater (13) is used to heat the periphery of the insulator (11) to melt the sealing glass having a low melting point. At that time, when the molten glass moves to the lower part and the glass does not exist in the upper inner hole, it is necessary to add the molten inorganic glass from the upper part of the insulator 11 during heating. In addition,
At the time of sealing and heating, a portion of the optical fiber exposed to the outside of the insulator 11 is cooled by an inorganic fiber and a water cooling metal pipe.
Protecting with 17-1 and 17-2 and heating while cooling is preferable because it is possible to prevent breakage of the optical fiber. Finally, if necessary, the periphery of the glass tube 4 may be protected at both ends of the insulator 11 with silicone rubber or the like to obtain an optical fiber composite insulator as shown in FIG.

Hereinafter, an actual example will be described.

First, Table 1 shows the specifications of the optical fiber, glass tube, sealing glass, and porcelain used in each of the following examples.

Example 1 In order to confirm the effectiveness of thermal insulation pretreatment for optical fibers, insulator shape: outer diameter 60 mmφ, inner hole diameter 15 mmφ, length 200 m
m, sealing firing schedule: optical fiber, glass tube, sealing glass, shown in Table 2, under the condition of 480 ° C and 1 hour holding
Using a porcelain, insulator test pieces within and outside the scope of the present invention shown in Table 2 were produced, and the appearance after sealing and the optical transmission loss after sealing were examined. As for the appearance, the dyeing paint was impregnated after firing for sealing, and the presence or absence of cracks was observed depending on the coloring state, and the porcelain was cut to observe the filled state of the sealing glass. Those marked with ○ are not recognized as cracks,
This shows that the sealing glass had good appearance without large bubbles. Regarding the optical transmission loss, there is no problem if the amount of light transmission is measured before and after sealing and baking, and the amount of loss is 3 dB or less.

The results are shown in Table 2.

From the results shown in Table 2, A-1 to A-3 of the present invention had a good appearance after sealing and the optical transmission loss after sealing was 3 dB or less, which was no problem. -4 and A-5 are A from the appearance after sealing.
-4 was not sufficiently sealed, and the optical fibers of A-4 and A-5 were broken at the time of insulator production. From this result, the effectiveness of the coating treatment with the glass tube of the present invention was confirmed.

Example 2 Based on the fact that the effectiveness of the coating treatment with the glass tube was confirmed in Example 1, the following experiment was conducted in order to find the optimum combination of the thermal expansion coefficients of the respective members.

First, the optical fiber shown in Table 6 was cut into 400 mm, and 100 mm of both ends of the cut optical fiber which were not welded by the glass tube were covered with polyimide which was a heat resistant resin. This optical fiber has the composition shown in Table 3 and has an inner diameter of 0.8 mmφ, an outer diameter of 2.0 mmφ, and a length.
It was inserted into the inner hole of a 220 mm glass tube. After that, when the glass tube was heated so that the glass tube could be deformed, pressure was applied by a mold to seal the optical fiber in the glass tube inner hole.

The optical fiber sealed in the glass tube in this way has the composition shown in Table 3 and has an outer diameter of 60 mmφ, an inner hole diameter of 15 mmφ, and a length of 200 m.
It was inserted into an inner hole penetrating the central portion of the insulator of m, filled with the sealing glass powder shown in Table 3 between the glass tube and the side wall of the porcelain inner hole, and sealed by heating. The sealing and firing schedule was 480 ° C. for 1 hour when the sealing glass had the A composition, 450 ° C. for 1 hour when the B composition was used, and 460 ° C. for 1 hour when the C composition was used. After the insulator was cooled, the glass tube and the optical fiber exposed to the outside from the inner hole of the insulator, which were not welded by the sealing glass, were covered with resin or a rubber-like elastic body for the test, and the test was performed.
No. B-1 to B-39 optical fiber composite insulators were obtained. With respect to the obtained optical fiber composite insulator, the appearance after sealing was examined in the same manner as in Example 1, and the optical transmission loss after sealing was examined.
Further, a cooling / heating test at each temperature difference was carried out by using a glycol solution tank heated to a predetermined temperature and a water tank at 20 ° C., holding each tank for 1 hour, and repeating the operation three times. . The results are shown in Table 3.

From the results shown in Table 3, among the optical fiber composite insulators of the present invention satisfying the appearance after sealing and light transmission loss, and satisfying the cooling / heating test with a temperature difference of 70 ° C., the coefficient of thermal expansion of the porcelain is α _p , the glass tube. Where α _{t is} the thermal expansion coefficient of α and α _q is the thermal expansion coefficient of the sealing glass, 0.4 ≦ α _t / α _p ≦ 1.0 0.5 ≦ α _q / α _p ≦ 1.0, and 0.5 ≦ α _q / α _t It can be seen that the optical fiber composite insulator satisfying the relation of ≦ 1.0 has obtained a better thermal test result.

Example 3 100 mm at each end of an optical fiber A having a length of 400 mm is covered with a polyimide resin, and the outer diameter is 2 mmφ, the inner diameter is 0.8 mmφ, and the length is 210 mm.
The glass fiber was inserted into the glass tube B, and heated and pressed to seal the optical fiber in the glass tube. This optical fiber was placed at the center of the inner hole of an insulator made of porcelain A and having an inner diameter of 10 mmφ, and the outer portion thereof was filled with the sealing glass A powder shown in Table 1 above.

Next, the glass tubes and optical fibers at the upper and lower ends exposed to the outside from the inner hole of the insulator are covered with inorganic fibers as needed as shown in Table 4, and the outside is fixed with a metal to fix the inorganic fibers. Alternatively, it was surrounded by a refractory and a metal tube was installed inside the inorganic fiber.

Insert the insulator arranged in this way into the electric furnace, and
Sealing was performed by heating on a schedule of holding at 0 ° C for 1 hour. A tensile test was performed on the obtained optical fiber composite insulator to measure the optical fiber tensile strength. The results are shown in Table 4.

From the results shown in Table 4, when the optical fiber is heated and sealed in the inner hole of the insulator, the upper and lower glass tubes and the optical fiber exposed to the outside from the inner hole of the insulator are cooled by the cooling unit. It can be seen that tensile strength can be obtained, which is preferable.

Example 4 Length 2000 mm to assemble and evaluate as an actual product
Each of the both ends of the optical fiber A of 500 mm was coated with a polyimide resin. A glass tube B having an outer diameter of 5 mmφ, an inner diameter of 3.4 mmφ and a length of 1020 mm was heated in an electric furnace at 850 ° C. and then pressed to form an elliptical shape having an inner diameter of 1 mm. Insert two optical fibers into the inner hole of this glass tube, cover both ends of the optical fiber with inorganic fiber, heat to 850 ° C in an electric furnace while cooling, pressurize the glass tube with a load of 10 kg, and The fiber was sealed in the glass tube bore.

Body diameter 105mmφ made of porcelain A, umbrella diameter 190mmφ, length 1000m
m, insert the optical fiber protected and sealed with a glass tube into the inner hole of the insulator with a diameter of 10 mmφ, install a flow stop made of porcelain in the lower part of the inner hole, and place it between the inner side of the insulator of the glass tube The powder of glass B for sealing was filled. Further, the glass tube and the optical fiber exposed to the outside from the inner hole of the insulator are covered with inorganic fiber, the outside is fixed with a refractory material, and a metal pipe is installed in the inorganic fiber so that the structure can be cooled.

The insulator thus installed was inserted into an electric furnace and heated at a maximum temperature of 480 ° C. for 1 hour while cooling the end portion. Next, the portion of the glass tube exposed to the outside through the inner hole of the cooled insulator and contacting with the sealing glass was bonded and fixed with a silicone rubber together with a resin support.

The characteristics of the optical fiber composite insulator thus produced were measured by the method shown in Table 5. The results are shown in Table 6. The results in Table 6 were all at the level that satisfied the specifications.

(Effects of the Invention) As is apparent from the above description in detail, according to the optical fiber composite insulator and the manufacturing method thereof of the present invention, the optical fiber is protected and sealed by the glass tube made of an appropriate material,
By sealing the glass tube in which the optical fiber is inserted into the porcelain inner hole with the sealing glass, the glass of the optical fiber can be sealed over the entire inner hole of the insulator, and the optical fiber has excellent long-term reliability. A composite insulator can be easily obtained with a high yield.

[Brief description of drawings]

1 (a) to 1 (f) are views for explaining a heat-resistant step in manufacturing the optical fiber composite insulator of the present invention, and FIG. 2 is a heating step in manufacturing the optical fiber composite insulator of the present invention. And FIG. 3 is a diagram showing a configuration of an example of the optical fiber composite insulator of the present invention. 1 ... Optical fiber, 2 ... Organic sheet 3-1, 3-2 ... Heat resistant resin, 4 ... Glass tube 5-1, 5-2 ... Mold, 6 ... Heat resistant resin 7-1, 7-2 ... Burner, 8 -1,8-2 ... Roller 11 ... Insulator, 12 ... Inner hole 13 ... Inorganic glass flow stop 14 ... Heater, 15a ... Hot air blowing port 15b ... Exhaust port, 16 ... Heating device 17-1,17-2 ... Cooling section .

Claims (5)

[Claims] 1. An optical fiber fused to an inner hole of a glass tube is installed in an inner hole penetrating a central portion of the insulator, and a sealing glass is used to seal between the inner hole of the insulator and a side wall of the glass tube. In addition to having a structure, the thermal expansion coefficient of each member is 0.4 ≤ α _t , where α _p is the thermal expansion coefficient of the porcelain, α _t is the thermal expansion coefficient of the glass tube, and α _g is the thermal expansion coefficient of the sealing glass. / Α _p ≤1.0 0.5 ≤α _g / α _p ≤1.0, and 0.5 ≤α _g / α _t ≤1.5. An optical fiber composite insulator. 2. An optical fiber whose both ends are coated with a heat-resistant resin is installed in an inner hole of a glass tube, and the glass tube is heated to a predetermined temperature and pressed to seal the optical fiber in the glass tube. Place the glass tube through the inner hole of the insulator, and fill the sealing glass between the inner hole of the insulator and the side wall of the glass tube, and then heat it to remove the inner hole of the insulator and the glass tube. A method for manufacturing an optical fiber composite insulator, which comprises sealing between side walls of the optical fiber composite insulator. 3. The method for manufacturing an optical fiber composite insulator according to claim 2, wherein an optical fiber pulled out while being protected by an organic sheet is used as the optical fiber. 4. The method of manufacturing an optical fiber composite insulator according to claim 2, wherein a heat resistant resin is sealed at both ends of the glass tube sealed with the optical fiber. 5. The sealing part is heated while cooling the part of the optical fiber exposed to the outside of the insulator at the time of heating the sealing part.
5. A method for manufacturing an optical fiber composite insulator according to any one of items 4 to 4.