JPS6349326B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a submarine cable line that can monitor the degree of damage to submarine cable armor and prevent insulation breakdown or disconnection accidents of submarine cables.

In general, submarine cables are subject to mechanical external forces, tension,
Although the cable is equipped with a sheathing that can withstand wear and tear, there is a risk that the submarine cable sheathing could be damaged due to the method used to propagate the submarine cable, the environment at the location, and other conditions, leading to a major accident.

The present invention has been made in view of the above-mentioned points, and is a submarine cable line that can monitor the damage state of the submarine cable armor, detect it before an accident occurs to the submarine cable itself, and prevent accidents from occurring. This is what we provide.

Next, a submarine cable line and armor damage detection method according to the present invention will be explained.

FIG. 1 shows a cross section of the submarine cable line, in which a plurality of detection lines are arranged at equal intervals on the cable sheathing.

Figure 3 shows the principle of the detection wire disconnection detection circuit. If there is a disconnection in the detection wire, the conductor resistance of the detection wire changes, which upsets the balance of the bridge, which was balanced in advance, and detects the disconnection. .

If the submarine cable is installed in a place where there is no conductive medium such as the air, the conductor resistance of the detection wire will increase dramatically due to the disconnection of the detection wire, and the bridge will become unbalanced. If the medium is installed in a conductive location such as the ocean, the conductor resistance of the sensing wire will not change significantly even if the sensing wire is disconnected. However, even in this case, when measured at a low voltage below the decomposition voltage of the conductive medium,
The conductor resistance of the detection wire changes greatly, and bridge imbalance appears greatly. In this way, even under the sea (seawater decomposition voltage...approximately 0.6V), a break in the detection line can be detected by measuring the change in the resistance of the detection line conductor due to a break in the detection line at a low voltage below the decomposition voltage.

An embodiment of the present invention will be described below with reference to the drawings.

Figure 1 shows a cross section of a submarine cable line, in which multiple insulated wire cores 1 are bundled around the outer periphery.
A seat floor 2 having a circular cross section is provided around these wire cores 1. A conductive lead wire 3 is inserted into the seat floor 2 close to the wire core 1, and the wire core 1 and the seat floor 2
The space between them is filled with interposition 4. The inside of this seat floor 2 is the cable core.

A plurality of armored iron wires 5 are connected and provided on the outer periphery of the seat floor 2, and a separator 6 is wound around the outer side of the armored iron wire 5.

A plurality of armored iron wires 7 and a plurality of detection wires 8 are continuously provided on the outer periphery of this separator 6, and the detection wires 8 are arranged every fourth of the armored iron wires 7. A corrosion protection layer 9 is provided around the outer periphery of the armored iron wire 7 and the detection wire 8. These, armored iron wire 7,
The detection wire 8 and the anti-corrosion layer 9 constitute an armored portion of the submarine cable.

Next, a method for detecting wear and tear on the submarine cable according to the present invention will be explained with reference to FIGS. 2 and 3.

FIG. 2 shows a state in which the outer periphery of the submarine cable is worn out due to wear, and at the same time as the armored iron wire 7 is worn out, the detection wire 8 is also worn out and is in a disconnected state.

FIG. 3 shows a disconnection detection circuit for the detection wire 8. One end of the lead wire 3 and one end of each of the detection wires 8 are connected in common, and the other ends of the lead wire 3 and the detection wire 8 are connected to the detector. It is connected to 10. The lead wire 3 is connected to the bridge circuit, and the detection wire 8 is connected to the selector 1.
1 to the bridge circuit. An ammeter 12 is connected to one pair of bridge circuits, and a battery 13 is connected to the other pair.

In this case, the battery voltage must be low enough to apply a voltage below the seawater decomposition voltage at the point where the detection line is broken.

Since the aforementioned lead wire 3 and detection wire 8 are connected in a loop, a resistance of several tens of ohms will occur, so adjust the resistance value of resistor R ₁ to set the deflection of ammeter 12 to 0. . Thereafter, the selector 11 measures the change in the ammeter 12 for each detection line 8 one by one.

If the detection wire 8 is not disconnected, the ammeter 12 will be 0.
refers to If the detection wire 8 is broken, the resistance of the detection wire 8 will be approximately several kiloohms because the broken part of the detection wire 8 is exposed in the seawater, and the ammeter 12 will swing significantly and the broken detection wire 8 can be known.

Next, FIG. 4 shows a locating circuit for locating the disconnected part of the detection wire 8. The other end of the detection wire 8, which is disconnected from the lead wire 3, is equipped with an ammeter 14 and a variable resistor. 15 is connected, and a battery 16 is connected between the contact of the variable resistor 15 and the ground.

In this circuit, a Wheatstone bridge is formed by the lead wire 3, the detection wire 8, and the variable resistor 15, so move the contact of the variable resistor 15 so that the ammeter 14 points to 0. adjust.

Since seawater is in contact with the disconnection part A of the detection line 8, the disconnection part A can be located by the position of the contact of the variable resistor 15. Further, this orientation can also be carried out by the Mahle loop method, pulse method, etc.

FIG. 5 shows another embodiment of the submarine cable line, in which two armored iron wires 7 are arranged between each detection wire 8.

FIG. 6 shows yet another embodiment of the submarine cable line, in which three armored iron wires 7 are arranged between each detection wire 8.

In the example shown in FIG. 5, since the armored iron wire and the detection wire are twisted, it is possible to detect wear at any position along the length of the submarine cable.

In addition, in the case of Figure 6, the twist pitch of the armored iron wire is
If it is 1300mm, then it will rotate next to one iron wire at a position 50mm forward in the length direction, so if you look through the cross section of the cable cut into rings with a width of 50mm, you will see the result shown in Figure 5. Because of this positional relationship, if the wear width is 50 mm, wear can be detected at any position along the length of the cable.

Similarly, in Fig. 2, the wear width is 100 mm and it can be detected at any position.

Therefore, the number of detection lines is determined by the wear width that can be detected.

Since the present invention is configured as described above, it is possible to easily and reliably detect the degree of damage to the armor and the location of the damage, and it is also possible to estimate the remaining lifespan of the steel wire against wear and tear, making it possible to take measures in a planned manner. .

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a submarine cable line showing an embodiment of the present invention, Fig. 2 is an explanatory diagram showing the state of wear of the submarine cable shown above, Fig. 3 is a circuit diagram showing the detection circuit shown above, and Fig. 4 5 is a sectional view showing another embodiment of the submarine cable line of the present invention, and FIG. 6 is a sectional view showing still another embodiment. 3...Lead wire, 8...Detection wire.

Claims (1)

[Claims] 1 A plurality of detection wires are arranged at equal intervals around the circumference of the submarine cable, a lead wire is provided at the core of the cable wire, one end of each of the lead wires and the detection wire is connected, and the other end of the lead wire is connected to the other end of the lead wire. and the other end of each detection wire at a low voltage below the seawater decomposition voltage to monitor the damage state of the cable sheathing. Submarine cable line with wire.