JPH0343621Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to optical fiber-containing metal stranded wires such as optical fiber composite overhead ground wires and optical fiber composite overhead power transmission lines.

[Conventional technology]

Figure 3 shows an example of a conventional optical fiber composite overhead ground wire (hereinafter abbreviated as OPGW).
Reference numeral 1 in the figure is an optical fiber unit. This optical fiber unit 1 includes a long spacer 2 made of metal, reinforced plastic (FRP), etc., and an optical fiber receiving groove 3 formed in a helical shape on the outer peripheral surface of the spacer 2 for signal transmission. It is composed of optical fibers 4 and so on. Such an optical fiber unit 1 is housed in a protection pipe 5 made of aluminum alloy, reinforced plastic, or the like, and is mechanically and thermally protected. Around the protective pipe 5, a plurality of metal wires 6 are twisted around the protective pipe 5 to form a stranded wire 7. Here, an aluminum-coated steel wire is used as the metal strand 6, and particularly for the inner stranded wire 7, an aluminum-coated steel wire with a irregular cross section is used as the strand 6.

According to the OPGW having such a structure, the optical fiber unit 1 is housed in the protection pipe 5 placed at the center of the stranded wires 7, so the OPGW as a whole can be compactly assembled with a circular cross section, and its It is characterized by easy handling.

[Problem that the invention attempts to solve]

By the way, in such an OPGW, a communication line network is constructed by the optical fibers 4 for signal transmission accommodated in the optical fiber accommodation grooves 3..., but the maintenance of the optical fiber communication line is・For management purposes, the tension applied to optical fiber 4, its elongation, etc.
It is necessary to know the status of the optical fibers 4 within the OPGW.

However, in the conventional OPGW, it is difficult to accurately maintain and manage the signal transmission optical fiber 4 because it is not possible to know the above-mentioned conditions (such as the magnitude of tension and the degree of elongation).

Such inconveniences are not limited to the OPGW having the above-mentioned structure, but also apply to optical fiber composite overhead power transmission lines, and it is desired to develop a means for detecting the above-mentioned situation.

[Means for solving problems]

In the optical fiber-containing stranded metal wire of this invention, a through hole is bored in the spacer and extends in the longitudinal direction of the spacer.
The structure has a sensor fiber wound in a helical shape inserted into the through hole, and the tension and elongation applied to the spacer are promoted as helical elongation (increase in helical pitch) of the sensor fiber, and this elongation causes the sensor fiber to By changing (decreasing) the transmission loss value, it is possible to detect the tension and elongation applied to the spacer, and by extension, the value of the tension and elongation applied to the signal transmission optical fiber.

(Example) Fig. 1 and Fig. 2 show an OPGW as an example of optical fiber-containing metal stranded wire of this invention.The difference between this example OPGW and the one shown in Fig. 3 is that the optical The point is that a sensor fiber 8 wound in a spiral shape is added to the fiber unit 1.

That is, a through hole 9 extending in the longitudinal direction of the spacer 2 is bored in the approximate center of the cross section of the spacer 2 constituting the optical fiber unit 1. A sensor fiber 8 is inserted. In this case, as shown in FIG. 2, if the void of the through hole 9 is filled with a resin 10 such as silicone resin, the spacer 2
The relative movement of the sensor fiber 8 against the sensor fiber 8 can be more reliably suppressed. Sensor fiber 8
A coating made of heat-resistant resin is provided on a bare optical fiber or an optical fiber (core wire), and this is wound into a cylindrical coil shape with a winding diameter of 2 to 3 mm and a winding pitch of 10 to 20 mm. . Since the winding pitch of this sensor fiber 8 has become small in this way, its transmission loss value is large. Therefore, when it is stretched, its winding pitch increases and its transmission loss value decreases. do. Further, as the resin 10, a relatively soft resin having good heat resistance and a Young's modulus of 5 kg/mm ² or less is preferable.

In such an OPGW, when tension is applied to the OPGW during or after erection, this tension is transmitted from the strands 7 to the spacer 2 via the protection pipe 5. The tension transmitted to the spacer 2 is transmitted to the signal transmission optical fibers 4 attached thereto, and simultaneously to the sensor fiber 8. The tension transmitted to the sensor fiber 8 causes the sensor fiber 8 to be elongated in proportion to the tension. As the sensor fiber 8 is extended, the transmission loss value of the sensor fiber 8 decreases as described above, so if this transmission loss fluctuation is monitored by a backscattering method (OTDR method, optical time delay refractometry), the presence or absence of tension can be detected. If the tension is locally applied to the OPGW, the location can also be determined. Thus,
It is possible to detect the tension applied to the signal transmission optical fiber 4 built into the OPGW.

Although the above explanation is about OPGW, it goes without saying that it can also be applied to optical fiber composite overhead power transmission lines if the optical fiber unit is a spacer type.

[Effect of idea]

As explained above, the metal stranded wire containing optical fiber of this invention has a through hole extending in the longitudinal direction of the spacer of the optical fiber unit in the metal stranded wire, and is wound in a spiral shape inside the through hole. Since the transmission loss fluctuation of the sensor fiber caused by the tension fluctuation of the metal stranded wire is monitored by backscattering method etc., it is possible to affect the signal transmission optical fiber of the optical fiber unit. It is possible to accurately detect the magnitude of tension (degree of elongation) and its location.
This makes it possible to easily maintain and manage optical fiber-containing metal stranded wires such as OPGW.

[Brief explanation of drawings]

Fig. 1 is a schematic cross-sectional view showing an example of optical fiber-containing metal stranded wire of this invention, Fig. 2 is a schematic longitudinal cross-sectional view showing the main part of Fig. 1, and Fig. 3 is a schematic cross-sectional view showing the conventional OPGW. It is a front view. 1... Optical fiber unit, 2... Spacer,
3... Optical fiber storage groove for signal transmission, 4... Optical fiber for signal transmission, 5... Protection pipe, 6... Metal wire, 7... Twisted wire, 8... Spiral-shaped sensor fiber, 9... ...Through hole.

Claims (1)

[Claim for Utility Model Registration] A protection pipe is provided inside the stranded metal wire, and an optical fiber unit consisting of a spacer and an optical fiber accommodated in the optical fiber accommodation groove of the spacer is housed within the protection pipe. An optical fiber-containing metal stranded wire, characterized in that a through-hole extending in the longitudinal direction of the spacer is formed in the spacer, and a sensor fiber wound in a spiral shape is fitted into the through-hole. twisted wire.