JP2999112B2 - Optical fiber composite underwater long body with wound detection line - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber composite underwater elongate body capable of detecting damage such as a power cable or a water pipe laid underwater.

[0002]

2. Description of the Related Art With respect to the prior art for detecting a trauma of an electric power cable or the like laid on the water bottom, Japanese Utility Model Application Laid-Open No. 56-117427 (Prior Art 1), Electronology B, Vol. 112, No. 10 (Heisei 4)
Years) pp. 921-926 (prior art 2).

[0003] In the prior art 1, an optical fiber is inserted into a gap between armored wires provided on the outer periphery of a cable body, and a cable damage is detected based on a break in the optical fiber.

In the prior art 2, a unit in which an optical fiber is housed in a shallow groove provided on the outer periphery of a spacer is inserted into a gap for twisting a power core. By monitoring the increase in loss of the optical fiber. This is to detect cable damage.

[0005]

However, in the prior art 1, since the optical fiber is inserted into the gap between the armor wires, the optical fiber is bent by bending the armor wire or laying the cable. In some cases, the armored wire may get on and damage the optical fiber.

Further, the prior art 2 uses a spacer type optical fiber unit, so that the unit outer diameter becomes large.
For this reason, a cable with a multi-core twisted power core can insert a unit into the gap between the twists, but a single-core cable, etc. cannot take such a structure and the outer diameter is considerably larger than that of the main body cable. There was a problem that it became larger.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made to solve such a problem, and a metal having a plastic coating on the outer periphery of a plastic sheath provided on the outer periphery of a long body such as a power cable. An optical fiber unit in which an optical fiber is accommodated in a pipe is provided, and an optical fiber composite underwater elongated body provided with iron wire armoring on the outside thereof is provided with a damage detection line having the same configuration as the optical fiber unit.
The wound detection line is wound on a plastic sheath. Then, the following three features are characterized so that the external pressure can be detected with high sensitivity.

The thickness of the metal pipe of the damage detection line is made thinner than the metal pipe of the optical fiber unit. The coating of the damage detection line is made harder than the coating of the optical fiber unit. When a plastic string spacer is used together with the optical fiber unit, the material of the plastic string spacer is softer than the coating of the damage detection wire. Of course, each of these three configurations can be used alone,
They may be combined.

[0009]

By monitoring the increase in the transmission loss of the optical fiber, it is possible to detect a trauma at a minor stage before the function of a long body such as a power cable is lost.

First, regarding the above-mentioned configuration, as a result of examining the crushing force of the metal pipe and the increase in the loss of the optical fiber, it is found that the increase in the loss is more susceptible to the difference in wall thickness than the outer diameter of the metal pipe. It is based on the findings of

This test method will be described with reference to FIG. As shown in the figure, an optical fiber 22 housed in a metal pipe 21 is placed on an iron plate 20, and an armored iron wire 23 is placed in a direction orthogonal to the optical fiber 22, and a crushing force is applied to the metal pipe 21. At this time, light was incident from the light source 24 at one end of the optical fiber, and the light intensity was measured by the optical power meter 25 at the other end to monitor the change in transmission loss.
FIG. 2 shows the results of tests conducted by changing the outer diameter and wall thickness of the metal pipe. As shown in the graph of the same figure, it can be seen that the increase in loss is affected by the wall thickness rather than the outer diameter of the metal pipe.

FIG. 3 shows the results of examining the crushing force at which loss starts to increase for metal pipes having the same inner diameter and different wall thicknesses according to the test method shown in FIG. 1. Again, there is a close contact between the wall thickness and the crushing force. It can be seen that there is a relationship.

Accordingly, if the thickness of the metal pipe of the damage detection line is made smaller than that of the optical fiber unit, the sensitivity to the external pressure can be increased. Of course, if it is made too sensitive to the external pressure, the external pressure will be detected even in the normal state of installation or the like, so that the metal pipe thickness of the damage detection line must not be too thin. Usually,
The material of the metal pipe of the damage detection line and the metal pipe of the optical fiber unit may be the same, but the same effect can be obtained even if different materials are used, as long as the metal pipe of the damage detection line is more easily crushed. Can be expected.

The following configuration is also a configuration for detecting the external pressure with high sensitivity. That is, if the coating of the damage detection line is soft, the coating will be deformed by the external pressure, and it will be difficult for external force to act on the metal pipe, so that it will not function effectively as a damage detection line.

Further, even with the above configuration, the external pressure can be detected with high sensitivity. When the optical fiber unit is applied on a plastic sheath, a plastic string spacer having the same diameter or a slightly larger diameter is disposed in a portion without the optical fiber unit. Here, if the plastic string spacer (especially the string spacer adjacent to the damage detection line) is made softer than the metal pipe covering of the damage detection line, when an external force is applied, the plastic string spacer is deformed, and the external force is applied to the damage detection line. Since it is easy to apply, the sensitivity to the external pressure can be increased.

[0016]

An embodiment of the present invention will be described below with reference to FIG. (A) As shown in the figure, this power cable is provided with a conductor 1, an insulator 2, a lead sheath 3, a stainless steel tape 4, and a polyethylene sheath 5 in order from the center, on which an optical fiber unit 6, a damage detection device is provided. A wire 7 and a plastic string spacer 8 are wound, and an armoring wire 9 is further provided thereon. The number of the optical fiber unit 6 and the number of the damage detection lines 7 are four, and the positions are shifted by 90 °.
Also, the plastic string spacer 8 is used for the optical fiber unit 6.
The optical fiber unit 6 has the same diameter as that of the optical fiber unit 6 and is closely arranged to protect the optical fiber unit 6 from being tightened by the armoring wire 9.

Here, the wound detection wire 7 is a stainless steel pipe 11 having a coating 10 and an optical fiber wire 12 housed in a stainless steel pipe 11 as shown in FIG. Configuration. However, the stainless steel pipe 11 of the damage detection wire 7 has an outer diameter of 1.0 mm and a thickness of 0.1 mm.
Whereas the optical fiber unit 6 has an outer diameter of 1.
The thickness is 0 mm and the thickness is 0.15 mm.

Further, while the coating 10 of the damage detection line is made of polyester, that of the optical fiber unit 6 and the plastic string spacer 8 adjacent to the damage detection line 7 are made of softer polyethylene. The other plastic string spacers 8 were made of polyamide fiber (nylon).

[0019]

As described above, the sensitivity to external pressure is increased by reducing the thickness of the metal pipe of the damage detection line or by making the coating harder than the coating of the optical fiber unit or the plastic string spacer. In addition, it is possible to detect a trauma in a long body such as a cable at the smallest possible stage. In addition, since a damage detection line in which an optical fiber is housed in a metal pipe having a coating is merely disposed on a plastic sheath such as a cable, an increase in the outer diameter of the cable can be minimized. Therefore, it is suitable for a single-core cable as well as a multi-core stranded cable.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a test method for examining a relationship between a crushing force of a metal pipe and a transmission loss.

FIG. 2 is a graph showing the relationship between crushing force and transmission loss in various metal pipes.

FIG. 3 is a graph showing the relationship between the thickness of a metal pipe having the same inner diameter and the transmission loss.

FIG. 4 shows a submarine cable according to an embodiment of the present invention.
(A) is a sectional view thereof, and (B) is a sectional view of a damage detection line.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conductor 2 Insulator 3 Lead coat 4 Stainless steel tape 5 Polyethylene sheath 6 Optical fiber unit 7 Injury detection wire 8 Plastic string spacer 9 Armoring wire 10 Coating 11 Stainless steel pipe 12 Optical fiber wire 20 Iron plate 21 Metal pipe 22 Optical fiber 23 Armor Wire 24 Light source 25 Optical power meter

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshiaki Hara 3-2-2, Nakanoshima, Kita-ku, Osaka-shi Kansai Electric Power Co., Inc. (72) Inventor Kazuo Yokota 3-2-2, Nakanoshima, Kita-ku, Osaka Kansai Electric Power Inside (72) Inventor Yoshikazu Murata 1-3-1 Shimaya, Konohana-ku, Osaka Sumitomo Electric Industries, Ltd. Osaka Works (72) Inventor Hideaki Nishima 1-3-1 Shimaya, Konohana-ku, Osaka Sumitomo Inside Electric Works, Osaka Works (72) Inventor Akiki Otsuki 1-3-1, Shimaya, Konohana-ku, Osaka Sumitomo Electric Works, Ltd. Osaka Works (56) References JP-A-58-204415 (JP, A) 55-100610 (JP, A) 5-11221 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01B 7/32 H01B 7/14

Claims (3)

(57) [Claims] 1. An optical fiber unit in which an optical fiber is housed in a metal pipe having a plastic coating on an outer periphery is provided on a plastic sheath provided on an outer periphery of a long body such as a power cable and a water pipe, and an outer side thereof is provided. In an optical fiber composite underwater elongated body provided with iron wire armor, the plastic
Trauma wound with an optical fiber unit on a sheath
A detection line, the wound detection line having a coating on the outer periphery
An optical fiber composite water bottom elongate body with a flaw detection line, wherein an optical fiber is housed in a metal pipe, and the metal pipe of the flaw detection line is thinner than the metal pipe of the optical fiber unit. 2. An optical fiber unit in which an optical fiber is housed in a metal pipe having a plastic coating on an outer periphery is provided on a plastic sheath provided on an outer periphery of a long body such as a power cable and a water pipe, and an outer side thereof is provided. In an optical fiber composite underwater elongated body provided with iron wire armor, the plastic
Trauma wound with an optical fiber unit on a sheath
A detection line, the wound detection line having a coating on the outer periphery
An optical fiber composite water bottom elongate body with a wound detection line , wherein an optical fiber is housed in a metal pipe, and the coating of the wound detection line is harder than the coating of the optical fiber unit. 3. An optical fiber unit in which an optical fiber is housed in a metal pipe having a plastic coating on the outer periphery, and a plastic string spacer are formed on a plastic sheath provided on the outer periphery of a long body such as a power cable and a water pipe. And an optical fiber composite underwater elongate body provided with iron wire armoring on the outside of the plastic sheath on the plastic sheath.
It is equipped with a wound detection wire wound around
The damage detection line is placed inside a metal pipe with a coating on the outer periphery.
An optical fiber composite underwater elongate body with a flaw detection line, wherein the elongate body is configured to house a fiber and the material of the plastic string spacer is softer than the covering of the flaw detection line.