500-kV long-distance cable completed in Japan

The first 500-kV long-distance cable line is described. This oil filled self-contained cable has been installed along the Seto-Ohashi bridge connecting Shikoku, the fourth largest of the four major islands that constitute Japan with Honshu, the main island. The power flow will generally be from Shikoku where there is a surplus of power to Honshu, the main island. The technical features of the cable and its installation are described. Polypropylene laminated paper (PPLP), a low-loss insulation paper with high dielectric performance, was adopted, allowing the cable to carry the required transmission capacity of 1200 MW per circuit without forced cooling. The number of splices is also reduced by approximately 40%, resulting in further economy.<>