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Newsletter "SEI NEWS" 2014

Home > Company Information > SEI WORLD > Back number > Vol.441

[Newsletter "SEI WORLD" Vol.441]

Submarine Cable Projects

The Sumitomo Electric Group, capable of providing comprehensive services from production to installation of submarine cables, contributes to power transmission infrastructure development in Japan and throughout the world.
Highly evaluated the engineering prowess that the Group has accumulated for many years, we have taken part in various large-scale projects as follows.

  In these projects, the following two types of cables are used.

■ XLPE Cable

This cable uses cross-linked polyethylene (XLPE) insulation, which has a network molecular structure with improved softening property at high temperatures. Due to the high thermal insulation property, XLPE can be used at high temperatures compared with other insulation materials, and thus contributes to the downsizing of the cable.

■ MI Cable

This cable uses insulating paper mass-impregnated (MI) with high-viscosity insulating oil. While exhibiting excellent DC characteristics, MI cables, unlike oil-filled (OF) cables, require no oil feeding equipment, and they can therefore be used for long-distance power transmission.


±250 kV XLPE DC Submarine Cables Connecting Hokkaido and Honshu

Cable installation (at landing point in Hakodate)

J-Power Systems (JPS) Corporation, a subsidiary of Sumitomo Electric, won a contract in 2009 from Electric Power Development Co., Ltd. for an approximately 43 km long submarine cable installation between Hokkaido and Honshu. The cable selected for this project was an XLPE DC cable jointly developed by JPS and Electric Power Development. Use of a conventional XLPE AC cable for DC applications involves a problem that the cable decreases in insulation performance at the time of polarity inversion (positive and negative poles of the voltage are inverted depending on the operating situation) due to space charge accumulation. JPS successfully developed an insulating material with the world’s highest performance and versatility and used it in the XLPE submarine cable project. The voltage rating of the XLPE cable supplied to the project is 250 kV, the world’s highest in its class of cables. Its feature that allows for polarity inversion is also the world’s first as an XLPE DC cable. After successful cable installation and testing, the project entered its operation phase in December 2012. The world paid attention to the commercial use of the XLPE DC submarine cable that featured the world’s highest voltage rating. This cable is expected to be adopted in future power transmission projects in Japan and abroad.


161 kV XLPE AC Submarine Cables between Islands of Taiwan and Penghu

In 2011, JPS jointly with Sumitomo Corporation was awarded a subcontract from the Taiwan Power Company for a project launched to manufacture and lay six submarine power cables between the island of Taiwan and the Penghu Islands, approximately 60 km off the southwest coast of the island of Taiwan.

The Penghu Islands are a beautiful archipelago blessed with nature including coral reefs. The islands’ main industries are fishery and tourism. Taiwan is promoting redevelopment of the Penghu Islands to conserve the natural environment and to build a low-carbon society called “Low-Carbon Islands.” The redevelopment program intends to facilitate shifting towards the use of renewable energy by discontinuing diesel power stations and constructing windfarms as a source of power on the islands.

In that process, this cable installation project plays an important role of providing stable power from the island of Taiwan to the Penghu islands until renewable energy becomes available in the islands. It is considered to be an essential project to implement the Low-Carbon Islands initiative on the Penghu Islands.

This cable-laying project features a total length of 350 km or more and a cable-laying depth of approximately 150 m at the deepest. It is the world’s largest in its class of projects. JPS is working on the manufacturing of cables to complete the project.


500 kV MI DC Submarine Cables Connecting Montenegro and Italy

In January 2014, Sumitomo Electric won a subcontract from Italian wire manufacturer Prysmian Group for the manufacturing of MI submarine cables for use in a submarine power cable project connecting Montenegro and Italy. This project is being planned by Terna Rete Italia S.p.A, a subsidiary of the Italian company Terna S.p.A. It involves two poles of the interconnection (about 415 km of submarine route covering depths of up to 1,200 m) made of an 500 kV DC submarine cable system with a rated power of 500 MW per pole (1,000 MW per two poles).

This project will promote and facilitate the development of the next-generation power interconnections among European countries (the Supergrid). The Supergrid is intended to rejuvenate the European power market by introducing large-scale renewable energy systems, balancing electricity demand and supply, and enhancing power transmission efficiency.

Sumitomo Electric will manufacture 115 km of MI 500 kV DC submarine cable to complete this project on time. The manufacturing of the cable will start in 2014 in Sumitomo Electric’s Osaka Works for delivery in 2016. The winning of this subcontract marks the Company’s entry in the market of international 500 kV long-distance large-capacity interconnecting lines.


230 kV XLPE AC Submarine Cable in San Francisco Bay

In February 2014, Sumitomo Electric U.S.A., Inc., a subsidiary of Sumitomo Electric in the USA, was awarded a contract by Pacific Gas and Electric Company, a firm based in San Francisco, for supply and installation of a 230 kV XLPE submarine cable project.

This project involves laying power cables in San Francisco Bay with a route length of 4.5 km and total installation distance of 13.5 km.

Submarine power cables manufactured by JPS were selected for this project, and will be exported from Japan. Cable-laying will start in January 2015 and be completed in July 2015. This project will improve the power network in San Francisco and will achieve more stable energy supply.

The Sumitomo Electric Group will continue to actively promote submarine power cable installation projects.
Installing submarine cable   Loading on barge
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