JPH0235131Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to the improvement of a composite overhead line in which an optical fiber is combined with an overhead power transmission line or an overhead ground wire.

(Prior Art) For the purpose of system protection and control of overhead power transmission lines, optical fiber composite overhead lines in which optical fibers are housed in overhead power transmission lines or overhead ground wires are used.

FIG. 1 shows a cross-sectional view of a generally known optical fiber composite overhead line. This optical fiber composite overhead line consists of an optical fiber unit 1 located at the center and a conductor strand layer 6 formed by twisting together a large number of conductor strands 6' such as aluminum-coated steel wires, aluminum wires, etc. on the outer periphery of the optical fiber unit 1. It is completed.

The optical fiber unit 1 has a plurality of helical grooves 3 on its circumference, and a spacer 2 made of, for example, aluminum, with an optical fiber 4 housed in the helical groove 3.
It is formed by an aluminum optical fiber protection tube 5 that houses this spacer 2. As shown in FIG. 3, the optical fiber 4 accommodated in the spiral groove 3 of the spacer 2 has a primary coating layer 8 of silicone resin or the like as a cushion layer on the optical fiber glass 7. The optical fiber glass 7 and the primary coating layer 8 are provided with a secondary coating layer 9 formed by extrusion of a heat-resistant resin, such as a fluororesin, to protect the optical fiber glass 7 and the primary coating layer 8 from external damage.

(Problem to be Solved) In the optical fiber overhead line having the above structure, the optical fiber 4 is housed in the spiral groove 3 of the spacer 2, and the spacer 2 is housed in the optical fiber protection tube 5. It has sufficient mechanical strength. However, when considering replacing the existing overhead line, the outer diameter must be approximately the same as the conventional overhead line, but in the optical fiber composite overhead line of this structure, the optical fiber can be accommodated by the cross-sectional area of the spacer 2. Since the available space is reduced and the number of grooves is limited with respect to the outer diameter, this is disadvantageous in terms of increasing the number of optical fibers. By the way, the outer diameter is 0.4 mm by providing a silicone resin primary coating layer 8 on the optical fiber glass 7 with an outer diameter of 125 μmφ.
When the optical fiber 4 is extruded and coated with a secondary coating layer 9 made of fluororesin or the like, the minimum thickness considering the manufacturing conditions is 0.15 mm and the outer diameter is 0.7 mmφ. When storing in the spiral groove 3, a total of 5
It could only hold up to my heart.

In addition, optical fiber composite overhead ground wires are constantly exposed to high temperatures of 100 to 150°C due to the current flowing through the conductor, and the temperature can reach nearly 300°C when a short circuit occurs. There is a problem in that the increase in transmission loss is caused by microbending caused by shrinkage of the secondary coating layer at high temperatures.

(Means for Solving the Problems) The present invention solves the above-mentioned problems and provides an optical fiber composite overhead line that can accommodate multiple optical fibers without increasing the outer diameter of the optical fiber unit. The feature is that an optical fiber is housed in the spiral groove of the spacer, which is made by twisting multiple optical fibers with a primary coating layer on them and applying a heat-resistant thin tape on top of them. There is a particular thing.

(Embodiment) FIGS. 2A and 2B show perspective views of an embodiment of the optical fiber 4 housed in the helical groove 3 of the spacer 2 in the optical fiber composite overhead line of FIG. 1.

Figure 2A shows, for example, an optical fiber glass 7 with an outer diameter of 125 μmφ and a silicone resin primary coating layer 8 on which a plurality of optical fiber wires 10 with an outer diameter of 0.4 mmφ are twisted together and a thickness of 0.075 mm. A thin heat-resistant tape 11 such as a tetrafluoride resin tape having a width of 6 mm is wound vertically, and the overlapping portions of the side edges of the tape 11 are bonded with an adhesive. In addition, the figure (B) is formed by winding a heat-resistant thin tape 11' such as a polyimide tape with a thickness of 0.0125 mm in a spiral shape on the twisted optical fiber wires 10 similar to the figure (A). The method may be lap winding, butt winding, or open spiral winding.

Note that the material of the heat-resistant thin tape is not limited to the above-mentioned examples, and may be made of thin-walled engineering plastics such as trifluoride resin, difluoride resin, polyphenylene sulfide, etc., depending on the desired heat resistance requirements. Any tape is fine.

Further, in order to reduce microbending of the optical fiber due to shrinkage of the coating at high temperatures and from the viewpoint of bending properties, the thickness of the tape is preferably 0.1 mm or less.

(Effects of the invention) The optical fiber composite overhead line of the invention described above provides the following effects.

It becomes possible to make the diameter of the optical fiber smaller and increase the number of fibers. In other words, in the present invention, an optical fiber wire (outer diameter 0.4 mm) with only a primary coating on the optical fiber glass
Since we use optical fibers that are made by twisting φ) and applying heat-resistant thin tape all at once, the optical fiber itself to be housed is The optical fiber shown in Figure 3 could only accommodate up to 5 fibers in a spacer with an outer diameter of 4.0 mmφ, but by using the optical fiber shown in Figure 2, up to 18 fibers can be accommodated with the same spacer outer diameter. It is now possible to store it.

The silicone resin of the primary coating layer has a large coefficient of friction, so when such an optical fiber wire is housed in the groove of the spacer, the frictional force is reduced depending on the degree of contact between the inner wall of the groove and the silicone resin coating layer. Because it is uniform, when an external force such as contraction or vibration is applied to the optical fiber composite overhead wire, local stress is likely to be applied to the optical fiber, and microbend loss is likely to occur. On the other hand, in the present invention, since a heat-resistant tape is applied to a collection of optical fiber strands, the spacer slides well against the inner wall of the groove, and the transmission loss is not affected.

Figure 4 shows the results of continuous measurement of changes in optical fiber transmission loss while applying vibrations with an amplitude of ±5 mm and a frequency of 35 Hz to an optical fiber unit with a length of 10 m. polyimide tape on the optical fiber and tape,
These are the results of an optical fiber using polyphenylene sulfide tape, and an optical fiber using polyphenylene sulfide tape and tetrafluoride resin tape as the optical fiber and tape in Figure 2 (b).
The dotted line shows the result of assembling the optical fibers and then storing them in the groove of the spacer without applying heat-resistant tape.The present invention shows that the increase in transmission loss due to vibration is improved from 0.6 dB/m without loss change. was completed.

As mentioned above, the increase in transmission loss of optical fibers at high temperatures is caused by microbending due to shrinkage of the secondary coating, but the optical fiber used in this invention has a thickness of heat-resistant tape that corresponds to the conventional secondary coating. It is possible to use a thin tape with a thickness of 1/2 or less or close to 0.15 mm, which is the minimum thickness considering the manufacturing conditions obtained by conventional extrusion molding, so the secondary coating can be The shrinkage stress applied to the optical fiber due to shrinkage can be reduced.

An additional advantage is that the secondary coating is much easier to remove when the optical fibers are spliced than in conventional extruded optical fibers.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an example of an optical fiber composite overhead line, FIG. 2 A and B are both perspective views of an embodiment of the optical fiber according to the present invention, and FIG. FIG. 4 is a characteristic diagram of an optical fiber vibration test. 1... Optical fiber unit, 2... Spacer,
3... Spiral groove, 4... Optical fiber, 5... Optical fiber protection tube, 6... Conductor twisted wire layer, 7... Optical fiber glass, 8... Primary coating layer, 9... Secondary coating layer, 10... Optical fiber wire, 11, 11'...
Heat resistant thin tape.

Claims (1)

[Claims for Utility Model Registration] (1) An optical fiber unit having an optical fiber protection tube on a spacer in which optical fibers are housed in a plurality of spiral grooves provided on the periphery, and a twisted conductor provided on the outer periphery of the optical fiber unit. In the optical fiber composite overhead wire consisting of a wire layer, a plurality of optical fiber wires each having a primary coating layer of resin on the optical fiber glass are twisted together in the spiral groove, and the thickness is An optical fiber composite overhead line that houses optical fibers coated with heat-resistant thin tape of 0.1 mm or less. (2) The optical fiber composite overhead line as set forth in claim 1 of the utility model registration claim, characterized in that a heat-resistant thin tape is longitudinally attached to the twisted optical fiber wires and the joints of the side edges are joined. . (3) The optical fiber composite overhead wire according to claim 1, which is characterized in that a heat-resistant thin tape is wound around the twisted optical fiber wires. (4) Utility model registration claim 1 characterized in that the heat-resistant thin tape is a tetrafluoride resin tape, a trifluoride resin tape, a difluoride resin tape, a polyimide tape, or a polyphenylene sulfide tape. The optical fiber composite overhead line according to items 1 to 3.