JPH064505Y2 - Optical fiber composite overhead ground wire - Google Patents

Description

[Detailed Description of the Invention] The present invention is a composite overhead ground wire having a structure in which an optical fiber is housed in an overhead ground wire that is installed on the top of a transmission line tower so that system protection and control of the overhead power transmission line can be performed accurately and with high accuracy. Related to the improvement of.

The inventors have designed the optical fiber in the structure shown in FIG. 1, that is, in the groove of the aluminum spacer (3) having the spiral groove (1) on the outer circumference.
(2) is accommodated, and the optical fiber (2) is placed in the groove of the spacer (3).
Developed a composite overhead ground wire with a structure in which an aluminum covered steel wire (6) is twisted around the outer circumference of an optical unit (5) with a structure in which the outer circumference of the spacer (3) is provided with an aluminum jacket (4) did. Aluminum covered steel wire
(6) has a structure in which the outer circumference of the steel wire (7) is coated with aluminum (8) of uniform thickness.The aluminum layer contributes to the electrical resistance and the steel wire contributes to the mechanical strength. It has excellent performance as a conductor for electric wires. However, in the above structure,
When the aluminum-covered steel wire (6) is closely twisted around the optical unit (5) and tensile stress is applied to the composite overhead ground wire after the overhead wire, the aluminum-covered steel wire (6) will Since the tensile strength is larger than that of 5), the tensile stress is absorbed, so that the force to crush the optical unit (5) acts in the direction of decreasing the twist radius. Therefore, in order to give the optical unit (5) sufficient rigidity, the aluminum outer cover (4) that constitutes the outer cover needs to have a sufficient thickness.

The present invention improves on the above points, and FIGS. 2 and 3 show an embodiment of an optical fiber composite overhead ground wire according to the present invention.

In FIG. 2, the optical fiber (2) is housed in a groove of an aluminum spacer (3) having a spiral groove (1) on the outer circumference, and an aluminum jacket (4) is applied to the outer circumference of the spacer. And constitutes an optical unit (5). On the outer circumference of the optical unit (5),
The aluminum-covered steel wire (6) is twisted so as to have a gap (11) between the optical unit and the aluminum-covered steel wire (6). Also,
As shown in FIG. 3, the optical fiber unit (5) is made by twisting the optical fiber (2) and applying heat-resistant coating (9) of silicon or fluorine on the outer periphery, and then placing it inside the aluminum pipe (10). The structure is such that a space (11) is provided between the optical unit (5) and the aluminum-covered steel wire (6).

Table 1 shows one optical unit (5) and seven aluminum covered steel wires (6)
It shows an embodiment in the case where there is a close contact with and a case where there is a gap.

Now, a case where tensile force is applied to an overhead ground wire having a gap of 0.2 mm in Table 1 is shown.

If the aluminum-covered steel wire has a tensile strength sufficiently larger than that of the optical unit, the optical unit undergoes elongation corresponding to the tensile stress, but the aluminum-covered steel wire absorbs the tensile stress by reducing the twist radius. At this time, assuming that the aluminum coating covering the outer circumference of the aluminum-covered steel wire is soft enough to prevent a decrease in the twisting radius at all, the twisted diameter of the aluminum-covered steel wire is easily reduced, and The collapsing force is not applied to the optical unit until is equal to the outer diameter of the optical unit.

As shown in Table 1, assuming that the aluminum-clad steel wire has an outer diameter of 3.8 mφ and the optical unit has an outer diameter of 4.5 mmφ and a spacing of 0.2 mm, and the aluminum-coated steel wire has a twist pitch of 150 mm, When the elongation ε of the overhead ground wire is ε <0.4% tensile stress, the twist diameter of the aluminum-covered steel wire can be reduced within the range where no crushing force is applied to the optical unit.

Further, when considering the elongation of the aluminum-covered steel wire itself or the steel wire of the aluminum-covered steel wire of the aluminum-covered steel wire, the elongation ε of the overhead ground wire is further increased.

If the size of this gap is too large, the aluminum-covered steel wires gathered around the optical unit will be irregularly arranged. Therefore, the upper limit is preferably 1 mm or less.

In this way, the optical fiber composite overhead ground wire of the present invention has a gap between the aluminum-covered steel wire and the optical unit, so that even when tensile stress is applied to the overhead ground wire, the crushing force applied to the optical unit is mitigated. Therefore, there is an effect that communication reliability is extremely high.

[Brief description of drawings]

FIG. 1 is a sectional view of an optical fiber composite overhead ground wire showing a conventional embodiment. FIGS. 2 and 3 are sectional views of an optical fiber composite overhead ground wire showing an embodiment of the present invention. The numbers in the figure are commonly used. (2) indicates the optical fiber (5), the optical unit (6) indicates the aluminum-covered steel wire (11), and the gap indicates.

Claims (1)

[Scope of utility model registration request] 1. An optical fiber composite overhead ground wire in which a fiber protection tube is arranged at the center of a stranded wire made of aluminum-covered steel wire having a circular cross section, and a plurality of optical fibers are accommodated in the protection tube. An optical fiber composite overhead ground wire, characterized in that there is a gap of 1 mm or less between the protective tube and the stranded wire.