JPH01142513A - Optical fiber submarine cable - Google Patents

Abstract

PURPOSE:To protect an optical fiber submarine cable against fish bites by sharks, etc., by covering the outside of a metallic pipe contg. optical fibers with a material layer contg. high-hardness particles at a high content ratio to enhance the hardness thereof. CONSTITUTION:This submarine cable is constructed by housing the optical fibers 2 into the metallic pipe 3 and insulating the outside thereof with polyethylene (PE) 6, etc. The outside of the metallic pipe 3 is coated with the layer 8 consisting of the material contg. the particles having high hardness at a high concn. Metallic tapes 7 are wound in the PE jacket 6 in order to protect the cable against the fish bites. This material layer 8 is the layer which has the high hardness and high impact absorbing power cable of finally stopping the penetrating force of the teeth of the sharks, etc., weakened by the metallic tapes 7. The outside is further protected by the PE jacket 6 to prevent dislodgment of the high-hardness particles and, therefore, the content thereof can be increased. The internal structure of the cable is thereby effectively protected.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to fiber optic submarine cables, and more particularly to improvements in their physical structure.

[Conventional technology]

Conventionally, for optical fiber submarine cables laid to the deep sea, for example, "Design and evaluation results of deep sea optical submarine cables"
Journal of the Institute of Electronics and Communication Engineers, '85/1, Vol, J68-B
, No., pp. 1.85-92)" or "Undersea optical fiber cable intended for application in deep sea areas ("Facility J38-4.
79-85), it is necessary to house the optical fiber in a pressure-resistant tube made of copper, aluminum, etc., and to give it tensile strength as a cable, in order to protect the optical fiber from the water pressure of the deep seabed. The center part is made up of a large number of piano wires wrapped around each other, and a pipe made of copper, aluminum 14, etc. is placed on the outside. Furthermore, in order to prevent this central part from coming into direct contact with seawater, the outside is covered with a jacket made of polyethylene or the like.

FIG. 2 is a sectional view showing an example of a conventional optical fiber submarine cable.

An optical fiber 12 is wound around a central steel wire 11 and housed in a metal pipe 13. In this example, the metal pipe 13 is made of steel and is divided into three parts. A required number of turns of piano wire 14 are wound on the outside to provide the necessary tensile strength. Further, on the outside, a copper pipe 15 is covered by drawing so as to tighten the whole part. polyethylene jacket 16
is extrusion coated onto the outermost layer to form an insulating layer. In a cable having such a structure, the outermost polyethylene jacket 16 is required to serve as insulation and at the same time protect the submarine cable from external forces.

In particular, the outermost polyethylene jacket 16 is
High-density polyethylene, which has high hardness, is usually used.

[Problem that the invention seeks to solve]

Optical fiber submarine cables with the conventional structure described above have recently been put into practical use, but in some areas the cables have been bitten by sharks, etc., and the outer polyethylene jacket has been torn, causing damage to the inner metal pipes (which carry high-voltage direct current). An accident occurred in which a person (whose equipment was in contact with seawater) came into contact with seawater. This is called a fish bite. This accident was caused by the fact that the outside of the metal pipe was made of soft polyethylene (even though it was made of high-density polyethylene), so it could not resist the strong teeth of sharks and other animals, and it must be said that this was a structural flaw.

[Means for Solving the Problems] The optical fiber submarine cable of the present invention has a 1fI4 structure in which an optical fiber is housed in a metal pipe and the outside thereof is insulated with polyethylene or the like, and the outside of the metal pipe is It is coated with a layer of material containing a high concentration of hard particles.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view of an embodiment of the present invention. In this embodiment, the optical fiber 2 is wound around the w4 wire 1,
The internal structure is the same as that of the conventional example, in which a piano wire 4 is wound around a metal pipe 3 divided into three parts, and the outside is closed with a copper pipe 5.

Furthermore, in this embodiment, the material layer 8 containing high concentration of highly hard particles directly covers the copper pipe 5, and the polyethylene jacket 6 is extruded to the outside to cover the copper pipe 5. In order to protect the cable from the aforementioned fish bite, it has been proposed to wrap a metal tape inside the polyethylene jacket 6, and in FIG. The material layer 8 containing particles, together with the metal tape 7, has the function of protecting the internal structure of the cable.

Here, the material layer 8 added according to this embodiment will be described in detail. This material M8 ultimately stops the penetrating force of the teeth of sharks, etc., which has been weakened by the metal tape 7, and has high hardness and high shock absorbing power.

Specifically, particles with high hardness, such as silicon carbide ( Hereinafter, it is considered that a material mixed with 5iC) particles is applied to the outside of a metal pipe to a certain thickness, and then heated and baked. By heating, Pv
The C resin swells with the plasticizer, and the resins fuse together.
Firing is completed by gelation, and a layer of material containing highly hard particles is completed. This plastisol processing containing SiC is applied to the exterior iron wire of submarine cables.
This process improves its wear resistance on the seabed. In the present invention, impact resistance and crush resistance are more important than improvement of abrasion resistance, so as high hardness particles, for example, particles of SiC coated with silicone rubber may be effective, especially SiC Since particles are somewhat conductive, it is effective to coat each particle with an insulating substance so that the whole particle has insulating properties. Furthermore, any particles of highly hard, non-conductive substances can be used in the present invention.

In the case of the above-mentioned SiC-containing plastisol for submarine cable armored steel wires, the content of SiC particles is kept low to prevent the SiC particles from falling off, as the plastisol containing SiC is fired into the outermost layer of the steel wire, and the content of SiC particles is kept low, about 15% by weight. It had been. On the other hand, when coating and firing on the outside of a metal pipe as in the present invention, the outside is further protected by the polyethylene jacket 6, which prevents the high hardness particles from falling off, so the content should be high (for example, 25 to 50 weight%). In other words, the apparent hardness can be increased.

This makes it possible to protect the internal structure of the cable more effectively.

〔Effect of the invention〕

As explained above, the present invention coats the outside of a metal pipe containing an optical fiber with a layer of material containing a high content of highly hard particles to increase its hardness, thereby making it possible for optical fiber submarine cables to be fished by sharks and other animals. It has the effect of being able to protect you from bites.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is a sectional view of an example of a conventional optical fiber submarine cable. 1.11...Steel wire, 2,12...Optical fiber, 3゜13...Metal pipe, 4.14...Piano wire, 5.
15...Copper pipe, 6,16...Polyethylene jacket, 7...Metal tape, 8...Material layer.

Claims (1)

[Claims] In an optical fiber submarine cable having a structure in which an optical fiber is housed in a metal pipe and the outside is insulated with polyethylene, etc., the outside of the metal pipe is coated with a layer of a substance containing a high concentration of particles having high hardness. An optical fiber submarine cable characterized by: