Submarine cable cathodic protection

Corrosion is a significant problem for underwater structures, particularly in environments where there are conditions that accelerate corrosion such as stray electrical currents. The New York Power Authority (NYPA) is concerned about corrosion on their 345 kV submarine cable that runs across Long Island Sound and brings 690 MW of power to the 2.6 million people on Long Island, New York. In 1994, a team of NYPA engineers and consultants was formed to analyze the effects of corrosion on the power circuit. Ultimately, a specially designed corrosion protection system was installed to mitigate corrosion on the cables. The corrosion protection system includes a unique monitoring and control system that regulates the protection and provides feedback for the corrosion system performance. A system of reference electrodes and a current density sensor in the water is used. The system self-corrects for the voltage shift between the land-based drainage point and the location where protection is applied. Features of the computer-controlled corrosion protection system are described in this article.