JPH0287427A - Optical fiber composite insulator and manufacture thereof - Google Patents

Abstract

PURPOSE:To make glass sealing of an optical fiber over the whole internal hole of an insulator by sealedly protecting the optical fiber with a glass tube made of an appropriate material, and by sealing the glass tube penetrated by the optical fiber in a porcelain internal hole with a sealing glass. CONSTITUTION:An optical fiber 1 is cut into specified lengths, and the ends of each piece is covered with heat resistant resin 3-1, 3-2. A specified number of optical fibers 1 are installed inside this glass tube 4 with low thermal expansion. After the glass tube 4 with optical fibers 1 is heated to a temp. 700-800 deg.C, metal dies 5-1, 5-2 in specific shape apply a pressure. Thereby the optical fibers 1 are sealed in the glass tube 4. Finally heat resistant resin 6 seals, if necessary, the gaps between the heat resistant resin and glass tube or between optical fibers and glass to be produced at the ends of glass tube 4 after being welded. These optical fibers 1 after completion of anti-heat treatment are installed in an internal hole 12 of an insulator 11, and the gap between the side wall of glass tube 4 and the inner hole 12 is filled with glass powder for sealing or mixture liquid, and an organic glass flow stopper 13 is provided in the internal hole 12 at the bottom.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical fiber composite insulator that is mainly used in forming a fault point detection system in a power transmission line network and a substation, and a method for manufacturing the same.

(Prior Art) Optical fiber composite insulators that have a function of transmitting a signal from an optical sensor on the power supply side to a detector on the ground side have been used for automatic detection of failure points in power systems.

Various kinds of these optical fiber composite insulators are known. For example, in Japanese Patent Application Laid-Open No. 60-158.402, the insulator has a through hole in the axial center of the shaft part, and an optical fiber is inserted into this through hole. A technique for sealing an optical fiber by filling the whole or part of the through hole with an organic insulating material such as silicone rubber or epoxy resin to prevent surface leakage of the insulator from reducing the insulation distance, and an insulator. A technique is known in which the entire porcelain is heated and molten glass is poured into the whole or part of the through hole to seal the optical fiber.

(Problem to be solved by the invention) However, in the above-mentioned sealing using an organic substance,
Since the thermal expansion coefficients of the organic sealing material and porcelain are significantly different, the sealing material may jump out of the through hole when heated.
There was a problem of cracking the porcelain from inside.

In addition, in the case of sealing with an inorganic material as described above, the optical fiber with the coating removed or the optical fiber whose coating has been peeled off due to heating will be inserted into the inner hole of the insulator, so the sealing glass is used. There was also the problem that the optical fiber was likely to break inside the insulator when heated to melt it. In other words, when the coating is removed from an optical fiber coated with silicone rubber or the like using a jacket stripper or the like,
Slight scratches on the surface cause a significant drop in strength, and when an optical fiber with such reduced strength is used for sealing inorganic glass, there is a problem that the optical fiber may break after sealing.

The purpose of the present invention is to solve the above-mentioned problems and to produce a product that is simple and reliable! The present invention aims to provide an optical fiber composite insulator with high resistance and a method for manufacturing the same.

(Means for Solving the Problems) The optical fiber composite insulator of the present invention has an optical fiber welded to the inner hole of a glass tube installed in the inner hole penetrating the central part of the insulator, and the inner hole of the insulator and the glass It is characterized by having a structure in which the side walls of the tube are sealed with sealing glass.

Furthermore, in the method for manufacturing an optical fiber composite insulator of the present invention, an optical fiber whose both ends are coated with a heat-resistant resin is installed in the inner hole of a glass tube, and the optical fiber is heated to a predetermined temperature and pressurized. The optical fiber is sealed inside the tube, and the optical fiber is installed in the inner hole that passes through the center of the insulator. After filling sealing glass between the inner hole of the insulator and the side wall of the glass tube, it is heated to seal the inside of the insulator. It is characterized by sealing between the hole and the side wall of the glass tube.

(Function) In the above-described configuration, the optical fiber composite insulator of the present invention can solve problems in conventional organic sealing by using inorganic glass, which has a coefficient of thermal expansion close to that of the porcelain of the insulator, as a sealing material. When sealing the optical fiber into the inner hole of the insulator with inorganic glass, the optical fiber is coated with a low thermal expansion glass tube such as Pyrex glass, so the optical fiber is highly reliable and does not break. Composite insulators can be obtained.

In addition, the coefficient of thermal expansion of porcelain is α2. When the thermal expansion coefficient of the glass tube is α1 and the thermal expansion coefficient of the sealing glass is αg,
0.4≦αt/αg≦1.0.0.5≦αg/α≦1
．． If each member is configured to satisfy the relationship 0 and 0.5≦αg/αp≦1.5, an optical fiber composite insulator with better reliability can be obtained, as is clear from the examples described later. This is preferable because it can be done.

Furthermore, in the manufacturing method of the present invention, after a low thermal expansion glass tube is sealed to the optical fiber, the gap between the glass tube and the insulator inner hole is sealed with sealing glass, so that even during heating, The optical fiber does not deteriorate and breakage of the optical fiber can be prevented.

Moreover, as an optical fiber used in the manufacturing method of the present invention,
If you use an optical fiber that is protected by an organic sheet to prevent damage to the optical fiber without forming a protective coating or directly adhering it to the optical fiber during manufacturing, the problems that occur when removing the coating from conventional optical fibers. This is preferable because deterioration of the optical fiber can be completely eliminated by eliminating the step of removing the coating.

Furthermore, if heat-resistant resin is sealed at both ends of a used glass tube (optical fiber), the optical fiber can be welded to the glass tube, or the optical fiber welded to the glass tube can be placed in the inner hole of the insulator using sealing glass. Even after being sealed, the optical fiber can be bent and deformed, which has advantages such as ease of connection with other optical fibers.

Furthermore, by heating the insulator while cooling the optical fibers exposed to the outside during sealing and heating, it is possible to prevent deterioration of the parts of the insulator that are not heat-resistant and are exposed to high temperatures due to the glass tube. preferable.

(Example) FIGS. 1(a) to 1(f) are diagrams for explaining a heat-resistant treatment process when manufacturing an optical fiber composite insulator according to the present invention. FIG. 1(a) shows a preferred example of producing an optical fiber for use in the optical fiber composite insulator of the present invention, and shows steps to be carried out as necessary. Figure 1 (a
), the surface coating is done by protecting the pulled optical fiber I with an organic sheet 2 and winding it up, without applying the surface coating with heat-resistant resin such as silicone rubber or polyimide resin, which is applied during the production of ordinary optical fibers. This makes it easy to handle the optical fiber 1 without any cracks.

First, as shown in FIG. 1(b), the optical fiber 1 obtained as shown in FIG. 1(a) or obtained by peeling off the W is cut into a predetermined length, and the In order to protect the protruding parts, both ends are covered with heat-resistant resin 3-1.3-2 such as polyimide or silicone rubber. At this time, the optical fiber 1 is coated with a heat-resistant resin in advance, and the coating on the part where the glass tube is welded is peeled off by heating or chemical treatment so as not to damage the optical fiber 1. .3-2 can be formed. Next, as shown in FIG. 1(c), heat-resistant resin 3-1.
A predetermined number of optical fibers l, both ends of which are coated with 3-2, are installed in a low thermal expansion glass tube 4 such as Pyrex glass, two in this embodiment.

Next, as shown in FIG. 1(d), an optical fiber l is inserted inside.
After heating the glass tube 4 equipped with the above to a temperature of 700 to 800'C, it is pressurized using a mold 5-1.5-2 having a predetermined shape. Thereby, 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 sealing. Furthermore, heating the optical fiber exposed outside the glass tube (the part coated with heat-resistant resin) while cooling it is effective in protecting the heat-resistant resin. Finally, as shown in FIG. 1(e), if necessary, a heat-resistant resin 6 The optical fiber 1 is heat-resistant treated by enclosing it.

Note that instead of sealing the optical fibers by heating and pressurizing as shown in FIG. 1(d), the glass tube 4 is locally sealed with a burner 7-1, 7-2, as shown in FIG. 1(f). The optical fiber 1 can also be sealed in the glass tube 4 by heating it in a softened state and applying pressure while pulling it with the rollers 8- and 82.

The optical fiber 1 that has been heat-resistant treated is installed in the inner hole 12 that passes through the center of the insulator 11, as shown in FIG.
Glass powder or slurry for sealing is filled between the inner hole 12 and the side wall of the glass tube 4, and an inorganic glass 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, the sealing glass is particularly preferably formed into a shape that fits into the inner hole of the glass tube and the insulator, and then calcined. In addition, when replenishing the sealing glass that decreases in volume due to melting and degassing, sealing glass formed into beads (300 to 2000 μm in diameter) is used to improve fluidity. This is effective for uniformly sealing. Thereafter, as shown in FIG. 2, the heater 14. The insulator 11 is installed in a heating device 16 consisting of a hot air inlet 15a and an outlet 15b, and hot air is blown from the hot air inlet 15a and exhausted from the outlet 15b, and the heater 13 is used to heat the insulator 11 from around it. to melt the low melting point sealing glass. At that time, if the molten glass moves to the lower part and there is no glass in the upper inner hole, it is necessary to add molten inorganic glass from the upper part of the insulator 11 during heating. Note that during sealing and heating, the optical fiber in the portion exposed to the outside of the insulator 11 is cooled by a cooling section 17-1゜1 consisting of inorganic fibers and a metal pipe for water cooling.
It is preferable to protect the optical fiber by 7-2 and heat it while cooling, since this can prevent the optical fiber from breaking. Finally, if necessary, the glass tube 4 is 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.

An actual example will be explained below.

First, optical fibers used in each of the following examples.

The specifications of the glass tube, sealing glass, and porcelain are listed in Table 1.

In order to confirm the effectiveness of the heat insulation pretreatment for the n■ upper optical fiber, the insulator shape was: outer diameter 60 mmφ, inner hole diameter 15+nmφ.

Length 200mm, Sealing firing schedule: 480°C,
Under conditions of holding for 1 hour, insulator test pieces within and outside the scope of the present invention as shown in Table 2 were prepared using the optical fiber, glass tube, sealing glass, and porcelain shown in Table 2, and after sealing. The appearance and loss of one member of optical transmission after sealing were investigated. The appearance is
After sealing and firing, the porcelain was impregnated with a dyeing paint, and the presence or absence of cracks was observed based on the state of color development.The porcelain was also cut to observe the filling state of the sealing glass. Those marked with a circle indicate that no cranking was observed and the sealing glass had no large bubbles and had a good appearance. Optical transmission loss is determined by measuring the amount of light transmitted before and after sealing and firing, and if the loss of one member is 3 dB or less, there is no problem.

The results are shown in Table 2.

From the results in Table 2, it can be seen that A-1 to A-8-3 of the present invention had a good appearance after sealing, and the optical transmission loss after sealing was all 3 db or less, causing no problems, whereas Comparative Example A-1 to A-8-3 had no problem. -4゜8-5: Judging from the appearance after sealing, A-4 was insufficiently sealed, and A-4
, A-5 both had optical fibers broken during insulator manufacturing.

From this result, the effectiveness of the coating treatment using the glass tube of the present invention was confirmed.

Practical Blood I Based on the fact that the effectiveness of the glass tube coating treatment was confirmed in Example 1, the following experiment was conducted in order to find the optimal combination of thermal expansion coefficients of each member.

First, cut the optical fiber shown in Table 6 to 400 mm, and cut both ends of the cut optical fiber that are not welded with a glass tube.
00 mm was coated with polyimide, which is a heat-resistant resin. This optical fiber has the composition shown in Table 3, has an inner diameter of 0.8 mmφ,
It was inserted into the inner hole of a glass tube with an outer diameter of 2.0+nmφ and a length of 220 mm. Thereafter, when the glass tube was heated to a state where it could be deformed, pressure was applied using a mold to seal the optical fiber into the inner hole of the glass tube.

The optical fiber sealed in the glass tube in this way was prepared with the composition shown in Table 3 and had an outer diameter of 60 mmφ and an inner hole diameter of 15 II 1 m.
By inserting the insulator into the inner hole penetrating the central part of the insulator with φ, length 200 mm, filling the space between the glass tube and the side wall of the porcelain inner hole with the sealing glass powder shown in Table 3, and heating it. Sealed. The sealing firing schedule is 480°C for 1 hour if the sealing glass has composition B, and 450°C if the sealing glass has composition B.
C, held for 1 hour; in the case of C composition, held at 460°C for 1 hour. After the insulator has cooled, the portions of the glass tube and optical fiber that have not been welded with the sealing glass and are exposed to the outside from the inner hole of the insulator and have been burned out by heating are covered with resin or rubber-like elastic material, and test No. B-1 to B-39
An optical fiber composite insulator was obtained. The appearance of the obtained optical fiber composite insulator after sealing was examined in the same manner as in Example 1, and the optical transmission loss after sealing was also examined. Furthermore, we conducted a cold/thermal test at each temperature difference using a glycol solution tank that had been heated to a specified temperature and a water tank at 20°C.
This was carried out by holding the sample for each time and repeating the operation three times. The results are shown in Table 3.

From the results in Table 3, it is clear that among the optical fiber composite insulators of the present invention that satisfy the appearance after sealing and optical transmission loss, and also satisfy the thermal test with a temperature difference of 70°C, the coefficient of thermal expansion of porcelain is α2. ．． When the thermal expansion coefficient of the glass tube is αt and the thermal expansion coefficient of the sealing glass is αg, 0.4 ≦ αg/α2≦1.0 0.5 ≦ αg/α2≦1.0, and 0.5 It can be seen that the optical fiber composite insulator that satisfies the relationship ≦αg/αp≦1.0 has even better thermal test results.

Disaster ■1 Coat each 100 mm of both ends of an optical fiber with a length of 400 mm with polyimide resin, and have an outer diameter of 2 mmφ and an inner diameter of 0.8 mm.
The optical fiber was inserted into a glass tube B having a fence φ and a length of 210 mm, and was heated and pressurized to seal the optical fiber inside the glass tube. This optical fiber was installed in the center of an inner hole having an inner diameter of 10 mm in an insulator made of porcelain A, and the outer part thereof was filled with sealing glass A powder listed in Table 1 above.

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

Insert the insulator arranged in this way into an electric furnace and heat it to a maximum temperature of 4.
It was heated and sealed by holding it at 80°C for 1 hour. A tensile test was conducted on the obtained optical fiber composite insulator to measure the tensile strength of the optical fiber. The results are shown in Table 4.

Table 4 From the results in Table 4, when heating and sealing the optical fiber into the inner hole of the insulator, if 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 section, It can be seen that high optical fiber tensile strength can be obtained, which is preferable.

Senkepan ↓ Length 200 mm to assemble and evaluate as an actual product
Each 500 mm of both ends of the 0 mm optical fiber A were coated with polyimide resin. Outer diameter 5mmφ, inner diameter 3.4m
Glass tube B with mφ and length of 1020 mm was placed in an electric furnace at 850 mφ and 1020 mm in length.
It was heated at °C and then pressurized to form an elliptical shape with an inner diameter of 1 mm in breadth. Optical fiber 2 is inserted into the inner hole of this glass tube.
Insert a book, cover both ends of the optical fiber with inorganic fiber,
Heat to 850°C in an electric furnace while cooling and heat at 10k.
The glass tube was pressurized with a load of g to seal the optical fiber into the inner hole of the glass tube.

Body made of porcelain A, diameter 105 mmφ, equal diameter 190 m
mφ.

An optical fiber protected and sealed with a glass tube is inserted into the inner hole of an insulator with a length of 1000 mm and an inner hole diameter of 10 mmφ, and a porcelain flow stopper is installed at the bottom of the inner hole to connect the glass tube and the side surface of the inner hole of the insulator. Powder of sealing glass B was filled in between. moreover,
The glass tube and optical fiber exposed to the outside through the inner hole of the insulator are covered with inorganic fiber, the outside is fixed with refractory material, and a metal pipe is installed inside the inorganic fiber to create a structure that 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 ends. Next, the portion of the glass tube exposed to the outside from the inner hole of the cooled insulator and in contact with the sealing glass was fixed together with the resin support by adhering with silicone rubber.

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. All the results in Table 6 were at a level that satisfied the specifications.

(Effects of the Invention) As is clear from the detailed explanation above, according to the optical fiber composite insulator and the manufacturing method thereof of the present invention, an optical fiber is protected and sealed with a glass tube made of an appropriate material,
By sealing the glass tube with the optical fiber inserted into the inner hole of the porcelain with sealing glass, it is possible to seal the optical fiber with glass over the entire inner hole of the insulator, resulting in an optical fiber with excellent long-term reliability. Composite insulators can be easily obtained with high yield.

[Brief explanation of the drawing]

Figures 1 (a) to (f) are diagrams for explaining the heat-resistant process when manufacturing the optical fiber composite insulator of the present invention, and Figure 2 is a heating process when manufacturing the optical fiber composite insulator of the present invention. FIG. 3 is a diagram showing the configuration of an example of the optical fiber composite insulator of the present invention. 1... Optical fiber 2... Organic material sheet 3-
1.3-2...Heat-resistant resin 4...Glass tube 5-1
．． 5-2...Mold 6...Heat-resistant resin 1゜2...Burner 8-1゜8-2...Roller 11...Insulator 12...Inner hole 13...Inorganic glass flow Stop 14...Heater 5a...Hot air inlet 5b...Discharge port 16...Heating device 17-1゜17-2...Cooling section

Claims (1)

[Claims] 1. An optical fiber welded to the inner hole of the glass tube is installed in the inner hole penetrating the central part of the insulator, and a sealing glass is installed between the inner hole of the insulator and the side wall of the glass tube. An optical fiber composite insulator characterized by having a sealed structure. 2. The coefficient of thermal expansion of each member constituting the optical fiber composite insulator is 0.4, where α_p is the coefficient of thermal expansion of porcelain, α_t is the coefficient of thermal expansion of the glass tube, and α_g is the coefficient of thermal expansion of the sealing glass. The optical fiber composite insulator according to claim 1, having the following relationships: ≦α_t/α_p≦1.0, 0.5≦α_g/α_p≦1.0, and 0.5≦α_g/α_t≦1.5. 3. An optical fiber whose both ends were coated with heat-resistant resin was installed in the inner hole of the glass tube, the glass tube was heated to a predetermined temperature and pressurized to seal the optical fiber inside the glass tube, and the optical fiber was inserted. A glass tube is placed in an inner hole that passes through the center of the insulator, and sealing glass is filled between the inner hole of the insulator and the side wall of the glass tube, and then heated to seal the inner hole of the insulator and the side wall of the glass tube. A method for manufacturing an optical fiber composite insulator, which is characterized by sealing a fiber insulator between the fibers. 4. The method of manufacturing an optical fiber composite insulator according to claim 3, wherein the optical fiber is an optical fiber that has been extracted while being protected with an organic sheet. 5. The method for manufacturing an optical fiber composite insulator according to claim 3, wherein both ends of the glass tube to which the optical fiber is sealed are sealed with a heat-resistant resin. 6. The method for manufacturing an optical fiber composite insulator according to any one of claims 3 to 5, wherein the sealed portion is heated while cooling the optical fiber in the portion exposed to the outside of the insulator during the sealing heating.