SAPEI

SAPEI, is a high-voltage direct current power transmission system that connects Sardinia with the Italian mainland. The submarine cable from Fiume Santo to Latina runs at 1600 m below sea level in the Tyrrhenian Sea. It is the deepest submarine power cable in the world. The cable is owned and operated by Terna.

History
The project was launched in 2006. Scientific surveys and studies of the sea floor began soon after. The first submarine cable as also onshore cables was laid in 2008 and the first voltage tests were conducted. In 2009, the converter stations in Latina and Fiume Santo entered into operation. Laying of the second submarine cable was scheduled for the end of 2010. The submarine cable-laying activity was being carried out by the Cable Lay Vessel (CLV) Giulio Verne owned and operated by Prysmian Group. The cable was inaugurated on 17 March 2011.

Description
The system consists of a 420 km submarine cable and 15 km land cables. It has two poles, having a total capacity of 1,000 MW at 500 kV of voltage. The diameter of the submarine cable is 120 mm. It is connected to the alternating current grids through converter stations in Fiume Santo and Latina at 400 kV of voltage. The substation in Latina extends over a surface area of 35000 m2, the one in Fiume Santo of 48000 m2. The cable was manufactured by Prysmian and converter stations were manufactured by ABB. The project cost over €730 million.