500 kV oil-filled cable installed on bridges

An outline of the Honshu-Shikoku interconnecting transmission line is given, along with some technical features concerning 500 kV cables. The 220 kV Chusi trunk line, now transmitting a maximum of 300 MW of electricity between the Chugoku area of Honshu and Shikoku island, is expected to be inadequate in the 1990s due to the rise in electrical demand. Therefore, to strengthen this interconnection, a new 500 kV transmission line was proposed. This project employs an AC 500 kV transmission line between the Higashi-Okayama substation of Chugoku Electric Power Company, the base of the Honshu side, and the Sanuki substation of Shikoku Electric Power Company, the base of the Shikoku side. It comprises an overhead power line portion of approximately 105 km and a cable portion of approximately 22 km in route length. The most significant feature of this transmission line is the installation of 500 m kV cables along the bridges which span the Inland Sea. Installation work on the interconnecting transmission line is described