JPH0343619Y2 - - Google Patents

Description

[Detailed Description of the Invention] "Industrial Application Field" The present 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.

"Prior Art" 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, and the optical fiber unit 1 consists of a long spacer 2 made of metal, reinforced plastic (FRP), etc., and an optical fiber formed spirally on the outer peripheral surface of the spacer 2. It is comprised of optical fibers 4 for signal transmission accommodated in accommodation grooves 3.

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,
A twisted wire 7 is formed. Here, an aluminum-coated steel wire is used as the metal wire, and especially for the inner stranded wire 7, an aluminum-coated steel wire with a irregular cross section is used as the wire 6.

According to the OPGW with this structure, the optical fiber unit 1 is housed in the protection pipe 5 placed in the center of the stranded wires 7, so the OPGW as a whole can be compactly assembled with a circular cross section.
It is easy to handle.

"Problems to be solved by the invention" By the way, in the above-mentioned OPGW, various information is communicated through the optical fibers 4 for signal transmission housed in the optical fiber accommodation grooves 3. However, in order to maintain and manage the optical communication line, it is necessary to know the status of the optical fiber 4 within the OPGW, such as the tension applied to the optical fiber 4 and its elongation.

However, since the conventional OPGW cannot know the above-mentioned conditions of the optical fiber 4 (such as the magnitude of tension and the extent of stretching), it has been difficult to maintain and manage this accurately.

"Means for Solving the Problems" The present invention has been made to solve the above problems, and includes forming sensor fiber receiving grooves having bottom protrusions at appropriate intervals in the longitudinal direction in the spacer,
The sensor fiber is housed in this, and when the tension of the OPGW increases, the sensor fiber is pressed against the bottom protrusion and bends, which takes advantage of the fact that the transmission loss of the sensor fiber increases rapidly. This makes it possible to detect the amount of tension or elongation that has occurred in the signal transmission optical fiber.

"Embodiment" Fig. 1 is a cross-sectional view showing an embodiment of OPGW (optical fiber-containing metal stranded wire) according to the present invention, and Fig. 2 shows a spacer 2 connected to a spiral sensor fiber receiving groove 3.
1, and the same parts as those of the conventional OPGW shown in FIG. 3 are denoted by the same reference numerals, and the explanation thereof will be omitted.

The difference between the OPGW according to the present invention and the conventional OPGW is that in the present invention, a sensor fiber accommodating groove 31 is added to the spacer 2, and the sensor fiber accommodating groove 31 has a longitudinal direction as shown in FIG. Bottom protrusions 10 are formed at regular intervals, and sensor fibers 41 are placed in the sensor fiber accommodating grooves 31.
The reason is that it is accommodated.

The bottom protrusion 10 is designed such that when the tension of the OPGW is within an appropriate range, the sensor fiber 41 has almost no transmission loss, and when the tension of the OPGW is greater than the appropriate value, the sensor fiber 41 has a sufficient tension. It is believed that microbending can occur, causing a sharp increase in transmission loss.

For the OPGW with the above structure, now this OPGW
If the tension applied to the material increases abnormally and elongation occurs,
The optical fiber 4 for signal transmission is simply pressed flat against the bottom of its receiving groove 3, while the sensor fiber 41 has a bottom protrusion 10 in its receiving groove 31.
Therefore, a sufficiently small bending (microbending) occurs in the part pressed by this protrusion 10,
The transmission loss increases rapidly. Therefore, OPGW
By recording in advance the transmission loss value of the sensor fiber 41 at the appropriate tension, and then measuring the transmission loss value with an optical measuring device or the like at appropriate times and comparing it with the initial value, it is possible to detect signals that cannot be directly measured. The tension and elongation values of the transmission optical fiber 4 can be detected.

Note that the protrusion 10 in the sensor fiber accommodation groove 31
If... are formed at regular intervals, it is possible to identify even the location where the abnormal tension or elongation occurs by using OTDR (optical time delay refractometry) as a detection device.

Further, although the above embodiments are related to OPGW, it is of course applicable to optical fiber composite overhead power transmission lines as long as the optical fiber unit is of a spacer type.

"Effects of the Invention" As is clear from the above explanation, in the optical fiber-containing metal stranded wire of the present invention, the spacer of the optical fiber unit is provided with sensor fiber accommodating grooves having bottom protrusions at appropriate intervals in the longitudinal direction. Since the sensor fiber is accommodated in this accommodation groove, the transmission loss value of the sensor fiber changes sharply as the tension and elongation of the OPGW increases. Therefore, by measuring the transmission loss value of this sensor fiber and comparing it with the reference value, it is possible to detect and confirm the status of the optical fiber for signal transmission within the OPGW, that is, the degree of tension and elongation acting on it. This makes maintenance and management of OPGW easier.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a stranded metal wire containing an optical fiber according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing the optical fiber unit shown in FIG. FIG. Moreover, FIG. 3 is a cross-sectional view of a conventional optical fiber-containing metal stranded wire. 1... Optical fiber unit, 2... Spacer,
3... Optical fiber accommodation groove, 31... Sensor fiber accommodation groove, 4... Optical fiber for signal transmission, 41...
...Sensor fiber, 5...Protection pipe, 6...Metal element wire, 7...Twisted wire, 10...Bottom protrusion.

Claims (1)

[Scope of Claim for Utility Model Registration] An optical fiber unit comprising a protective pipe provided inside a stranded metal wire, a spacer inside the protective pipe, and an optical fiber for signal transmission accommodated in an optical fiber receiving groove of the spacer. The optical fiber-containing metal stranded wire is characterized in that the spacer is formed with a sensor fiber-accommodating groove having bottom protrusions at appropriate intervals in the longitudinal direction, and the sensor fiber is accommodated in the sensor fiber-accommodating groove. twisted wire.