The submarine cable (submarine cable) is a wire wrapped in insulating material and laid under the seabed and river water for telecommunication transmission. Modern submarine cables use fiber optics as a material to transmit telephone and internet signals. The world's first submarine cable was laid between England and France in 1850. China's first submarine cable was completed in 1888, a total of two, one is the Fuzhou-Sichuan Shidao and Taiwan's Shanghai-tail (freshwater) between the length of 177 nautical miles from Tainan anping to Penghu, 53 nautical miles long.

Submarine cables are divided into submarine communication cables and submarine power cables. The submarine communication cable is mainly used for communication service, which is expensive, but has high degree of confidentiality. Submarine power cable is mainly used for underwater transmission of high-power electricity, and the role of underground power cable is equivalent, but the application of the occasion and laying different ways. Because the submarine cable project is recognized by the world as a complex and difficult large-scale project, from environmental detection, marine physical investigation, as well as cable design, manufacture andinstallation, the use of complex technology, so the submarine cable manufacturersin the world, mainly Norway, Denmark, Japan, Canada, the United States, Britain, France, Italy and other countries, These countries also provide laying technology in addition to manufacturing. At present, the application of submarine power cable in China still needs to be imported.

Submarine cable classification

Impregnated paper Package Cable: Suitable for 45kV AC and not less than 400kV direct current line. Currently confined to water depths of less than 500m.

Self-contained oil-filled cable: Suitable for up to 750kV DC or AC lines. As the cable is oil-filled, it can be laid in the sea area with a depth of 500m without difficulty.

Extruded insulation (XLPE insulated, ethylene-propylene rubber insulated) Cable: Suitable for up to 200kV AC voltage. Ethylene-propylene rubber than polyethylene can prevent the phenomenon of branch and partial discharge, so that the submarine cable more effective function.

"Hydraulic" pipe cable: Only for a few kilometers long cable system, because the very long cable to pull into the pipe, subject to a lot of mechanical restrictions.

Inflatable (pressure-assisted) Cables: Inflatable cables Using impregnated paper packages are more suitable for longer submarine cable networks than oil-filled cables, but because of the need for high pressure operation under deep water, the difficulty of designing cables and their accessories is increased, generally confined to a depth of 300m.

Submarine cable Use

Submarine communications cables are mainly used for long-distance communication networks, often used in remote islands, sea-crossing military facilities, and other more important occasions. Submarine power cable laying distance is much shorter than the communication cable, mainly used in the land island, across rivers or bays, from land-based connections between drilling platforms or drilling platforms and other connections. Under normal circumstances, the use of submarine cable transmission power is undoubtedly more expensive than the same length of overhead cable, but it is often more economical than using small isolated power stations for regional power generation, in the offshore area to apply more benefits. In countries with more islands and rivers, such cables are widely used.