Submarine power cable

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Submarine power cables are cables for electrical power running through the sea, below the surface.

A DC system may use the ground and seawater as a return path for current. However, this cannot be always practiced because of disturbances to magnetic compass systems on vessels crossing the cable and because of ecological effects of electrochemical reactions at the electrodes. Also, the impedance of the water and other things in the return path might be high.

The length of undersea AC cables is restricted by the capacitance between the active conductors and the surrounding metallic shield. If the cable were to be made long enough, the reactive power produced by an AC cable would take up the entire current carrying capacity of the conductor, so no usable power would be transmitted. Therefore, for transmission of large amounts of electric power through long submarine cables, direct current (DC) is preferred over AC, because DC cables require no reactive power. As well, for three phase AC-cables three conductors are necessary, while for DC only 1 or 2 conductors are required.

Submarine cables for AC

Nelson Island - Texada Island - Vancouver Island (500kV)
Sweden-Bornholm (110kV)
Spain-Morocco (380 kV)
Öresund (380 kV)
Strait of Messina (380kV), replaced overhead line crossing (Pylons of Messina)
Isle of Man to England Interconnector (90kV) - World's longest
New Brunswick - Prince Edward Island(200 MW)
Cebu - Negros, Philippines(138 KV)
Negros - Panay, Philippines(138 KV)
Leyte - Bohol, Philippines(138 KV)

Submarine cables for DC

Baltic-Cable (between Germany and Sweden)
Basslink (between Victoria, Australia and Tasmania, Australia) (500kV DC) (with a length of 290 km underwater)
Cross-Skagerak (between Norway and Denmark)
Cross Sound Cable (between New York's Long Island and Connecticut, USA)
Estlink (between Estonia and Finland)
Fenno-Skan (Powerline between Sweden and Finland)
HVDC Cross-Channel (Submarine cable between UK and France)
HVDC Gotland (the first commercial HVDC submarine cable installation)
HVDC Hokkaido-Honschu (between Hokkaido and Honshu)
HVDC Inter-Island (Power line between the islands of New Zealand)
HVDC Italy-Corsica-Sardinia (SACOI, Submarine cable link between Italy, Corsica and Sardinia)
HVDC Italy-Greece (between Italy and Greece)
HVDC Leyte - Luzon (between Leyte and Luzon)
HVDC Moyle (between Scotland and Northern Ireland)
HVDC NorNed (between Eemshaven and Fedafjord)
HVDC Vancouver Island (link between Vancouver Island and the Canadian mainland)
Kii Channel HVDC system (through Kii-channel, Japan)
Kontek (between Germany and Denmark)
Konti-Skan (Powerline between Sweden and Denmark)
Swepol (between Poland and Sweden)

Longest

Basslink (between Victoria, Australia and Tasmania, Australia) (500kV DC) (290km underwater)

Submarine power cable

Submarine cables for AC

Submarine cables for DC

Longest

See also