JPH0226444B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a grounding structure for supplying power to repeaters and the like used in optical submarine communications, and particularly to a grounding structure that facilitates installation.

It is well known that with the amazing development and progress of optical fibers, optical communications are being used extensively in the communications field, and that submarine cables are also being replaced by optical submarine cables.

This optical submarine cable uses, for example, a branching device to branch into two branches under the sea, and in addition to the power supply system on the main cable side, a power supply system is also required on the branch cable side, as shown in FIG. 3. In other words, in Fig. 3, a is a schematic diagram of the laying procedure, and b is a schematic diagram of the power supply system, to explain the procedure for laying the submarine cable.
Submarine cables 40, 41 between points A and B across the sea
When laying a submarine cable, as shown in FIG. 3b, (+) power is supplied to one of the repeaters 42 and 43 provided on this submarine cable, and (-) power is supplied to the other.

And a submarine cable 40 connecting points A and B,
When the submarine cable 44 laid from island C is connected to 41 using the branching device 46, the submarine cable 44
Power must also be supplied from island C to a repeater 45 installed in the middle of the island. If the branching device 46 is used only for connecting the submarine cables 4, 41, and 44, it is sufficient to perform underwater earthing near the repeater 45 in order to supply power to the repeater 45 from the island C. .

However, the underwater branching device 46 is equipped with a control unit for switching the power supply system and the connection relationship of the transmission signal system in order to enable communication between at least two points when the submarine cable 40 or 41 is disconnected. Built-in. For example, if the submarine cable 41 is cut at point E, the power supply line 47 will also be cut off, so the power supply to the repeaters 42 and 43 will stop, and this will cause power to be cut not only between points A and B, but also between point A and island C. Calls between calls will no longer be made.

For this reason, the underwater branching device 46 switches the power supply system to the relay 46 as shown by the dotted line in FIG.
Power will also be supplied to Island 2 to secure a line between point A and island C. For this switching, a power supply line 48 from island C is installed, and a repeater 45 and a branch device 46 are installed.
Undersea earthing will be conducted at point D via .

However, a current of about 1A flows through this underwater ground, and if there is a metal object near the underwater ground, that metal object will undergo electrolytic corrosion. For this reason, it is necessary to place the underwater grounding device far away from the branching device, so there is a demand for the development of a grounding structure that allows for easy underwater grounding.

(b) Prior Art FIG. 2 is a sectional view of a main part of a conventional earthing structure.

In the branching device 1, a first main cable 2, a second main cable 3, and a branch cable 4 are connected as shown in FIG. An electrode 6 is attached. A cable tie 10, 11, 12 and 13 is therefore required for each cable 2, 3, 4 and 5. The cable retaining parts 10 to 13, the hermetic sealing part 9, and the connecting part 8 will be explained in detail.

First, the structure of the main cables 2, 3 and the branch cable 4 will be explained using a cross section with reference to FIG.
A copper pipe 14 and a piano wire 16 are housed in a copper pipe 18, and a polyethylene coating 17 is provided on the outermost layer.

In the cable retaining portion 10, as shown in FIG. 2c, the piano wire 16 is sandwiched between the wedge 10b and the disc 10a, and the disc 10a is housed in the retaining fitting 10c by a known method. A copper pipe 1 insulated with a polyethylene coating 17 is attached to the spherical tip 10d of the retaining fitting 10c.
A hole is provided for 4 to pass through, and 2 pins 10g
It is coupled to the donut-shaped ring 10e so as to be rotatable in a direction perpendicular to the plane of the paper. ring 10
e is coupled to the casing 10f by a pin (not shown) in a direction perpendicular to the pin 10g so as to be rotatable in the vertical direction with respect to the plane of the paper, and each cable is mechanically and firmly coupled to the casing 10f.

Optical fiber 15 that has passed through cable retention section 10
The copper pipe 14 accommodating the is connected to the feedthrough 8a at the connecting portion 8.

The feedthrough 8a is hollow, and the optical fiber 15 passes through this hollow space. The feedthrough 8a is a hollow feedthrough 9 of the airtight sealing part 9.
a and a power supply line 8a. optical fiber 1
5 passes through the feedthrough 9a and is connected to the control section 7.
is combined with Further, the feed through 9a and the power supply circuit inside the control section 7 are connected by the power supply line 8b.

With this configuration, the main cable 2 and the housing 1
0f is coupled to supply power. The underwater earth cable 5 is also coupled to the casing 10f in a similar configuration and is also electrically connected. However, in this case, copper pipe 1
No optical fiber is housed within 4. The cable retaining portion 13 is covered with resin 19 or the like. The other end of the underwater earth cable 5 has a copper pipe 14 and a ground electrode 6 soldered to it, and its surroundings are covered with a resin 19 and a protector 3 is attached to the other end.
1 protects the soldered part.

(c) Problems to be solved by the invention However, since the branching device with this structure is composed of a total of four cables, two main cables, one branch cable, and one underwater earth cable, each has a high Strong cable retention part 10-1
3 is required, which poses a problem of complicating the structure.

(d) Means for Solving the Problems In order to solve the above problems, the present invention has a structure in which the feeder line 9a provided in the submarine cable branching device 1 is grounded via the main cable 2. , an outer conductor 20 that is insulated from seawater and connected to the power supply line 9b on the outer circumference of the main cable 2; This is accomplished by providing a grounding electrode 30 having an exposed portion for grounding the external conductor 20.

(e) Effect That is, in the present invention, the underwater earth cable 5
In order to integrate the transmission line cable and the first main cable 2, an outer conductor 20 is formed on the first main cable 2, and a ground electrode 3 in the sea is connected via the outer conductor 20.
It has a structure that connects to 0.

(f) Embodiments Hereinafter, embodiments of the branching device according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of essential parts for explaining one embodiment of a branching device according to the present invention, and the same parts as in FIG. 2 are given the same reference numerals.

One main cable 2 has an outer conductor 20 made of braided wire (copper), metal tape, etc. around the sheath 17.
The outer conductor 20 is covered with an insulator 21 made of polyethylene or the like.

An insulating layer 22 is also formed on the outer peripheral surface of the disk 10a and integrated with the sheath 17 of the main cable 2.

A metal layer 23 is formed on the outside of the insulating layer 22, and one end 23a of the metal layer 23 is electrically connected to the external conductor 20. The other end 23b of the metal layer 23 is electrically connected to an external conductor 25 provided around the outer periphery of the coating 17.

The outer periphery of the external conductor 20 is protected by an insulating layer 21, and the outer periphery of the metal layer 23 is protected by an insulating layer 24. Then, as shown in Fig. 2, hold the retaining fitting 1.
It is coupled to the housing 10f by 0c. The feedthrough in the connecting portion 8 is composed of feedthroughs 8c and 8d that are insulated from each other, the feedthrough 8c is electrically connected to the external conductor 25, and the feedthrough 8d is electrically connected to the copper pipe 14.

The optical fiber 15 is fed through 8d.
It passes through the inside of the feedthrough 9a and the inside of the feedthrough 9a, and is connected to the control section 7. Feed through 8d is feed line 8b
electrically connected to the feedthrough 9a,
Further, the feedthrough 9a is electrically connected to the control section 7 by a power supply line 9b. On the other hand, the feed through 8c is connected to the feed through 9c by the power supply line 8e,
Further, the feed through 9c is electrically connected to the control section 7 by a power supply line 9d.

A joint box 32 for exposing the outer conductor 20 into the sea is provided at a point located at the midpoint of the main cable 2 and at least about 50 meters away from the branching device 1. The distance between the branching device 1 and the joint box 32 is as follows when they are close to each other.
Electrical corrosion occurs in the metal parts of the branching device 1 due to the current flowing from the joint box 32 into the seawater, and the amount of corrosion is proportional to the current value and inversely proportional to the distance between the joint box 32 and the branching device 1.
For this reason, in an optical submarine cable system, a current of about 1.6 amperes flows, so if the cable is separated by about 50 meters, the amount of corrosion can be ignored.

This joint box 32 is constructed by inserting a piano wire (not shown) into a wedge 27 and
28 and the hollow metal box 26, the main cable 2 and the main cable 33 are mechanically coupled. Here, the main cable 2 and each copper pipe 14 of the main cable 33 are electrically connected through a path of a piano wire, a wedge 27, a metal box 26, and a wedge 28. The periphery of the metal box 26 is covered with an insulator 29 by molding, etc., and the outside thereof is covered with a ground electrode 3 made of a metal such as a titanium alloy.
0 is plated with platinum and connected to the external conductor 20. Protectors 31 are provided at both ends of the metal box 26 to prevent the main cables 2, 33 from being excessively bent.

In this configuration, when (+) power is supplied,
The current flows through the copper pipe 14 → feed through 8c → feed line 8 b → feed through 9 c → feed line 9 b → control unit 7 → feed line 9 d → feed through 9 c → feed line 8 e → feed through 8 d → outer conductor 25 → metal layer 23 → outer conductor 20 → The current flows through the path of the ground electrode 30, and when (-) power is supplied, the current flows through the opposite path as described above.

Note that the present invention is applicable not only to underwater branching devices but also to repeaters.

(g) Effects of the Invention As explained above, the earthing structure according to the present invention can be constructed with a single main cable compared to the conventional structure, making the structure simple, economical, and easy to install. Improves efficiency.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a main part to explain an embodiment of a grounding structure according to the present invention, Fig. 2 is a sectional view of a main part to explain a conventional grounding structure, and Fig. 3 is a sectional view of a submarine cable. FIG. 2 is a diagram for explaining the installation procedure, where a is a schematic installation procedure diagram, b is a schematic diagram of the power supply system,
It is. In Figures 1 and 2, 1 is a branch device, 2 is a first main cable, 3 is a second main cable, 4 is a branch cable, 7 is a control section, 8 is a connection section, and 9 is an airtight seal. 9a is a feed through, 9b is a feed line, 9c is a feed through, 9d is a feed line, 17 is a coating, 19 is a resin, 2
0 is an external conductor, 21 is an insulator, 23 is a metal layer, 2
4 is an insulating layer, 29 is an insulator, 30 is a ground electrode,
31 is a protector, 32 is a joint box,
shows.

Claims (1)

[Claims] 1. A structure in which a feeder line 9b provided in a submarine cable branching device 1 is grounded via a main cable 2, the outer periphery of the main cable 2 being insulated from seawater and coated. An external conductor 20 connected to the power supply line 9b
and a grounding electrode 30 connected to the tip of the outer conductor 20 and having a portion exposed to seawater on the outer periphery of the main cable 2 so that the outer conductor 20 can be grounded. An earth structure characterized by: