THE 345 KV UNDERGROUND UNDERWATER LONG-ISLAND SOUND CABLE PROJECT

A high voltage underground/underwater cable system was installed to in crease the transmission capacity from the mainland of New York to Long Island. In terms of weight and diameter, the self-contained, fluid-fi lled (SCFF) cable used for the underwater portion of the project is th e largest underwater cable in the world. The use of high-pressure, flu id-filled (HPFF) pipe-type cable on the land portion represents the La rgest appLication of paper-polypropylene-paper (PPP) insulated cable i n the United States. State-of-the-art technologies were implemented in the use of fiber optic cables for relay protection and SCADA/RTU, tem perature monitoring and teak detection systems, SF6 gas-insulated subs tations, and underwater cable Laying and embedment techniques. This pa per discusses the design and installation of a 750 MVA, 43 km (26.6 mi ), 345 kV underground/underwater electric transmission system installe d by the New York Power Authority (NYPA).