JP2514047Y2 - Optical fiber composite optical fiber for overhead ground wire - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber core wire for an optical fiber composite overhead ground wire which is used for a composite overhead ground wire in which an optical fiber is combined with an overhead ground wire. Is. 2. Description of the Related Art For the purpose of system protection and control of an overhead power transmission line, an optical fiber composite overhead line in which an optical fiber is housed in an overhead power transmission line or an overhead ground line is used. FIG. 1 shows a cross section of a commonly known optical fiber composite overhead wire. This optical fiber composite overhead wire is composed of a conductor stranded wire layer 6 formed by twisting a plurality of conductor element wires 6a such as an aluminum-coated steel wire and an aluminum wire on the outer periphery of the optical fiber unit 1 located at the center. Made of The optical fiber unit 1 is provided with a plurality of spiral grooves 3 on its circumference, and an optical fiber core wire 4 is housed in the spiral grooves 3, for example, a spacer 2 made of aluminum.
And an optical fiber protection tube 5 made of aluminum in which the spacer 2 is housed. Then, the optical fiber core wire 4 accommodated in the spiral groove 3 of the spacer 2 is
As shown in the cross-sectional view of FIG.
A primary coating layer 8 made of silicone resin or the like is provided as a cushion layer on the above, and a secondary coating formed by extrusion of a heat-resistant resin, for example, a fluororesin, which protects the optical fiber glass 7 and the primary coating layer 8 from the outer periphery thereof A layer 9 is used. [0005] In the optical fiber composite overhead wire having the above structure, the optical fiber core wire 4 is the spacer 2
Since the spacer 2 is housed in the spiral groove 3 and the spacer 2 is housed in the optical fiber protection tube 5,
It has sufficient mechanical strength. On the other hand, when considering replacement with an existing overhead wire, the outer diameter must be made almost the same as that of the conventional overhead wire. Since the space that can be stored is reduced and the number of grooves is limited with respect to the outer diameter, it is disadvantageous in terms of increasing the number of optical fibers. Incidentally, a primary coating 8 of silicone resin is provided on the optical fiber glass 7 having an outer diameter of 125 μm to have an outer diameter of 0.4 mm, and a secondary coating layer 9 made of fluororesin or the like is formed thereon.
In the case where the optical fiber core wire 4 is housed in the spiral groove of the spacer 2, the minimum thickness is 0.15 mm and the outer diameter is 0.7 mm in consideration of manufacturing conditions. Only a total of 5 cores could be stored in the spacer 2 of 0.0 mm. Further, the optical fiber composite overhead ground wire is constantly exposed to a high temperature of 100 to 150 ° C. due to the electric current flowing through the conductor, and particularly when a short circuit accident occurs, 300 ° C.
However, there is a problem that the increase in transmission loss of the optical fiber at high temperature is caused by microbending due to the shrinkage of the secondary coating at high temperature. SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and accommodates an optical fiber composite overhead wire in an optical fiber composite overhead wire without increasing the outer diameter of the optical fiber core wire. The present invention provides an optical fiber core wire for an optical fiber composite overhead wire, which can realize a multi-core optical fiber, by twisting multiple optical fiber element wires with a resin-made primary coating layer on the optical fiber glass. And the thickness of 0.1
It is characterized in that a polyimide tape of mm or less is applied. The polyimide tape may be vertically laid on the twisted optical fiber strands, and the seam of the side edges thereof may be joined, or the polyimide tape may be wound on the twisted optical fiber strands. . A plurality of optical fiber element wires provided with a primary coating on the optical fiber are twisted together, and a polyimide tape is applied on the twisted optical fiber element wires to form an optical fiber composite overhead wire ground optical fiber core wire. , The number of strands per unit cross section can be increased,
The number of optical fibers can be increased. 2 (A) and 2 (B) are perspective views of an embodiment of an optical fiber core wire 4 for an optical fiber composite overhead ground wire according to the present invention. FIG. 2B shows, for example, an optical fiber glass 7 having an outer diameter of 125 μm, a primary coating layer 8 of a silicone resin, and a plurality of optical fiber element wires 10 having an outer diameter of 0.4 mm, which are twisted together and the thickness of It is formed by spirally winding a 0.0125 mm polyimide tape 11a. The winding method may be lap winding, butt winding or open spiral winding. As shown by 11 in FIG. 2A, the polyimide tape is obtained by twisting the optical fiber strands 10 and then wrapping them vertically to form a tape 1
The overlapping portions of the side edges of 1 may be joined by an adhesive. The polyimide tape preferably has a thickness of 0.1 mm or less in order to reduce microbending of the optical fiber due to shrinkage of the coating at high temperature and from the viewpoint of bending characteristics. According to the above-described optical fiber composite optical fiber core wire for an optical fiber composite ground wire of the present invention, the following effects can be obtained. It is possible to reduce the diameter and the number of cores of the optical fiber. That is, in the present invention, since the optical fiber element wires (for example, 0.4 mm in outer diameter) having only the primary coating are twisted together on the optical fiber glass and the polyimide fibers are collectively applied, the optical fibers are used. The optical fiber itself to be housed becomes thinner than the conventional one in which the secondary coating layer is extrusion-coated on the primary coating layer. Since the silicone resin of the primary coating layer has a large coefficient of friction, when such an optical fiber element wire is housed in the groove of the spacer, a frictional force is generated depending on the degree of contact between the inner wall of the groove and the silicone resin coating layer. Because it becomes uneven,
When an external force such as contraction or vibration is applied to the optical fiber composite overhead wire, local stress is easily applied to the optical fiber, and microbend loss is likely to occur. On the other hand, in the present invention, since the optical fiber strands are assembled and the polyimide tape is applied, slippage with the inner wall of the groove of the spacer is improved, and when a short-circuit accident occurs, the temperature rises to near 300 ° C. However, microbending due to shrinkage of the secondary coating at high temperature does not occur, and transmission loss is not affected. FIG. 4 shows the result of continuous measurement of the transmission loss change of the optical fiber while applying vibration of amplitude ± 5 mm and frequency of 35 Hz to the optical fiber unit having a length of 10 m. The solid line in the figure shows This is the result of using the optical fiber core wire according to the present invention, and the dotted line is the result of assembling the optical fiber wires and storing them in the groove of the spacer as they are without applying the polyimide tape. The amount could be improved from 0.6 dB / m without loss change. As described above, the increase in transmission loss of the optical fiber at high temperature is caused by the microbend due to the contraction of the secondary coating, but the optical fiber core wire used in the present invention corresponds to the conventional secondary coating. Since the thickness of the heat-resistant tape is less than or equal to 1/2, which is the minimum thickness of 0.15 mm that takes into consideration the manufacturing conditions obtained by conventional extrusion molding, it is possible to use a thin-walled tape. The contraction stress applied to the optical fiber due to the contraction of the secondary coating can be reduced. As an additional advantage, the removal of the secondary coating at the time of connecting the optical fibers is extremely easy as compared with the optical fiber core wire in which the secondary coating layer is formed by the conventional extrusion molding.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of an example of an optical fiber composite overhead wire. FIG. 2 is a perspective view of different embodiments of an optical fiber core wire for an optical fiber composite overhead ground wire according to the present invention. FIG. 3 is a cross-sectional view of a conventional optical fiber. FIG. 4 is a characteristic diagram of a vibration test of an optical fiber. [Explanation of Codes] 1 ... Optical fiber unit, 2 ... Spacer, 3 ... Helical groove, 4 ... Optical fiber core wire, 5 ... Optical fiber protection tube, 6 ...
Conductor twisted wire layer, 7 ... Optical fiber glass, 8 ... Primary coating layer,
10 ... Optical fiber strands, 11, 11a ... Polyimide tape.

Claims (1)

(57) [Claims for utility model registration] (1) A plurality of optical fiber strands having a resin-made primary coating layer on the optical fiber glass are twisted together, and the thickness is 0.1 mm or less An optical fiber composite optical fiber core wire for an aerial fiber ground, characterized by being applied with the polyimide tape of. (2) The optical fiber composite aerial land according to claim 1, characterized in that the polyimide tape is vertically provided on a twisted pair of optical fiber strands, and the joints of the side edges thereof are joined. Optical fiber core wire. (3) The optical fiber core wire for an optical fiber composite overhead ground wire according to claim 1, wherein the polyimide tape is wound around a twist of optical fiber wires.