May 16 2019
Sumitomo Electric Industries, Ltd.

Sumitomo Electric Completes HVDC Cable Projects inEurope & Japan
Sumitomo Electric Industries, Ltd. is pleased to announce the completion of two
high-voltage direct current (HVDC) interconnector cable projects using
crosslinked polyethylene (XLPE) insulated cables:-400-kV NEMO Link connecting the United Kingdom and Belgium, contractedwith NEMO Link Limited through J-Power Systems Corporation,*1 a subsidiaryof Sumitomo Electric.

-250-kV Hokuto-Imabetsu HVDC Link connecting Hokkaido and Honshu,
contracted with Hokkaido Electric Power Company (HEPCO).

With the increasing capacity of renewable energy sources and the necessity of longdistance power interconnectors for efficient use of such renewable energy between
countries and regions, HVDC cable technology, which is suitable for long-distancepower transmission, has been gaining significant attention in international markets.
In support of this trend, Sumitomo Electric has recently completed the construction of a400-kV HVDC XLPE cable system, the highest voltage in the world for an HVDC-XLPE
cable system, for NEMO Link, which connects the UK and Belgium.
Sumitomo Electric has also completed construction of the Hokuto-Imabetsu HVDC Linkwith 250-kV HVDC XLPE cable, which will increase transmission capacity between
Honshu (Japan’s main island) and Hokkaido (Japan’s northern island) along with theexisting circuit for the Hokkaido-Honshu DC Interconnector that commenced
commercial operation in 2012. The route length of this HVDC cable system is thelongest in the world for an inter-strait tunnel.
In addition to these recently-completed HVDC projects,

1/5Sumitomo Electric is currently constructing the first HVDC cable system in India.
Sumitomo Electric will continue its endeavour to lead the global market

by utilizing theCompany’s state-of-the-art HVDC cable technologies and experience in large-scale
projects.
Construction of 400-kV HVDC XLPE cable system connecting the UK andBelgium
In Europe, with the aim of achieving efficient use of energy and security of energy
supply, electricity interconnectors connecting countries are playing significant roles.
NEMO Link, a joint venture between National Grid in the UK and ELIA in Belgium,
initiated a project to connect Kent in the UK and Zeebrugge in Belgium with an HVDC
cable system. Sumitomo Electric secured an Engineering, Procurement andConstruction (EPC) contract for the interconnector project in June 2015.

▲ Construction route of HVDC Subsea Interconnector Cable

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This project was the first in the world to adopt 400kV DC XLPE insulated cable.*2 Production andinstallation of the cable system was completed inDecember 2018, and since the end of January 2019the system has been in commercial operation. InApril 2019, Sumitomo Electric announced that allnecessary procedures toward completion of theproject have finished. The commencement of operation of the system marks thesuccessful installation of the world’s first 400-kV HVDC XLPE cable system.
Project outline
Transmission capacity

1,000 MW

Total route extension

141.5 km (submarine: 130 km, land: 11.5 km)

Type of transmission line

Cable (no OHL)

AC-DC conversion

Voltage-sourced convertor (VSC)

Pole structure

Symmetrical monopole*1 J-Power Systems Corporation is a subsidiary of Sumitomo Electric. It transferred thetransmission cable and conductor business to Sumitomo Electric in 2016. All new
contracts since then have been directly handled and executed as Sumitomo
Electric.
*2 XLPE stands for crosslinked polyethylene. Conventionally, mass impregnated cables
using highly viscous insulation oil have been utilized for HVDC projects. In recentyears, XLPE insulated cables have been commonly adopted due to their highallowable operating temperature and growing environmental concerns. Until thecompletion of this project, the maximum voltage for commercially used HVDCXLPE insulated cables was 320 kV.

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Installation of the 250-kV HVDC XLPE cable system for a new

Hokuto-Imabetsu

HVDC Link
To secure a stable power supply between Hokkaido and Honshu , HEPCO hasconstructed the new Hokuto-Imabetsu HVDC Link (300 MW), connecting Hokuto
Converter Station in Hokkaido and Imabetsu Converter Station in Honshu, in addition tothe existing Hokkaido-Honshu Interconnection Line. The commercial operation started
on March 28, 2019, increasing the total transmission capacity between Hokkaido andHonshu from 600 MW to 900 MW.

▲ Construction site of the Hokuto-Imabetsu HVDC power trunk line

This interconnector features voltage-sourced converters (VSC) and cable installation inthe Seikan Tunnel (a subsea railway tunnel). Among 122 km of overall transmissionline, Sumitomo Electric supplied and installed about 24 km of 250-kV HVDC XLPE
cables, which were connected to the overhead transmission lines that were also
supplied by the Company at both onshore ends.
Although there were challenging situations
during cable installation inside the subsea
tunnel, Sumitomo Electric delivered the system
on time. This HVDC cable system is the longest
in the world for a strait tunnel. For the HVDC
link, Sumitomo Electric also supplied 98 km of
overhead conductors and provided technical

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Power cablessupport for the overall transmission line installation.
Project outline
Transmission capacity
Route extension

300 MW
122 km（24 km in subsea tunnel, 98 km outside of tunnel）

Installation route

In the Seikan Tunnel

AC-DC conversion

Voltage-sourced convertor (VSC)

Pole structure

Asymmetric monopole

References
High voltage cable and overhead conductor:
https://global-sei.com/power-cable-business/
Press release, June 8, 2015: “J-Power Systems Wins Contract with NEMO LINK for
HVDC Subsea Interconnector Cable System between UK and Belgium”
https://global-sei.com/company/press/2015/06/prs044.html
Press release, March 27, 2017: “Siemens and Sumitomo Electric win order for HVDC
link and agree on cooperation”
https://global-sei.com/company/press/2017/prs031.pdf
Sumitomo Electric Group e-magazine id, July 2017: “International Submarine Cable
Project: Installing the world’s highest voltage DC XLPE insulated cable across theEnglish Channel”
https://global-sei.com/id/2017/07/project/index.html
Sumitomo Electric Group e-magazine id, July 2017: “Contribution to Stable
Interregional Electricity Supply”
https://global-sei.com/id/2017/07/quarterly/file001.html■ Reference
Sumitomo Electric's Website
https://sumitomoelectric.com/5/5