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Accident Handling Of Submarine Cables

Jul. 04, 2020

It is learned from China Submarine Pipe Installation Providers that submarine optical cables have many advantages over terrestrial optical cables: one is that laying does not require digging tunnels or supported by brackets, so there is less investment and the construction speed is fast; second, except for landing areas. In addition, most of the cables are on the bottom of the sea at a certain depth, and are not affected by the damage of natural environments such as wind and waves and the interference of human production activities. Therefore, the cables are safe and stable, with strong anti-interference capabilities and good confidentiality.


However, after Subsea Cable Laying, it will inevitably be damaged. There are generally two major reasons for submarine cable breaks. One is force majeure such as earthquakes and tsunamis, and the other is man-made causes. Once the cable is disconnected, not only will it have a huge impact on international communications, so the losses caused will not be estimated.


Cables are often vulnerable to trawler fishing, anchor damage, and even shark bites. Cables are sometimes destroyed by enemy forces during wartime. The Newfoundland Earthquake of 1929 caused a large-scale seafloor collapse that caused damage to the trans-Atlantic cable.


Once multiple submarine cables are damaged at the same time (eg, damaged by an earthquake), it may lead to the interruption of regional Internet and long-distance telephone services, causing losses that are difficult to estimate. For example, the 2006 Hengchun earthquake was just one example.


The Submarine Optical Cable Repairing and the damaged part is brought to the water for repair. The cable in the deep water zone must be cut off the damaged part, and then brought to the water surface for repair. The part to be repaired will be longer than the original one.

Accident Handling Of Submarine Cables

Some important cable lines near the port have established repair ships with special repair cables. There are several restoration companies like CS Cyrus West Field near Nova Scotia Halifax. Some large telecommunications companies such as France Telecom and Japan Telecom have their own submarine cables.


Submarine cable is usually buried 1-2 meters deep under the seabed. Because the seabed is not very regular, sometimes the cable will inevitably be exposed. Both the anchoring of a fishing boat and the use of trawl nets may damage the optical cable. Therefore, the place where the optical cable passes through the seabed is classified as a prohibited anchorage area, and the ship is not allowed to dock. This principle is the same as the optical cable on land. We often see such signs on the road as "There are optical cables underground. Construction is prohibited." Submarine optical cables need to be protected, and technology needs to be strengthened to improve their own tensile strength.


The first step in the repair work is to find the breakpoint. Submarine cable engineers can find the approximate location of the breakpoint through telephone and Internet interruptions. The shore terminal can emit light pulses, and normal fiber can always transmit these pulses in the sea, but if the fiber is broken, the pulse will bounce back from that point, so the shore terminal can find the break point. After that, ships need to ship new optical cables for repair, but the first step is to catch the broken fiber.


If the optical cable is deeper than 2000 meters underwater, the robot can be used to salvage the optical cable. Generally, it is located in the sea area of about 3000 meters to 4000 meters deep. Only one grapple can be used. It takes more than 12 hours to retract the grapple once. After the broken optical cable is caught on the ship, it needs to be added in the middle. This work is done by a highly skilled technician.


1. After the robot dives into the water, it will find the precise position of the damaged submarine optical cable by scanning and detecting.

2. The robot digs out the submarine optical cable shallowly buried in the mud and cuts it with cable scissors. The rope was laid down on the ship, and the robot was tied to the end of the optical cable, and then pulled it out of the sea. At the same time, the robot places a wireless transponder at the cut-off point.

3. Use the same method to pull another section of optical cable out of the sea. Just like repairing the telephone line, the instruments on the ship are connected to the two ends of the optical cable, and the landing station is detected through the submarine optical cable in both directions to detect which end of the optical cable is blocked. After that, a longer part of the submarine optical cable with a blocking portion is recovered and cut off. The other section was equipped with buoys and allowed to float on the sea temporarily.

4. Next, manually connect the spare submarine cable to the two breakpoints of the Shanghai submarine cable. Connecting optical fiber cable connectors is a very "technical" task, which is not suitable for ordinary people. It must be specially rigorously trained and obtained a license from an international organization before it can be put into operation.

5. After the spare submarine optical cable is connected, after repeated testing, after the communication is normal, it is thrown into the sea water. At this time, the underwater robots have to "come into battle" again: "buried" the repaired submarine optical cable, that is, use a high-pressure water gun to flush the mud on the seabed out of a ditch, and "place" the repaired submarine optical cable into it.


At the same time, bad weather such as strong winds and waves on the sea may cause slow repair work.