Sumitomo Electric completes type approval test for 525kV DC GIS interface

Japanese cabling specialist Sumitomo Electric has completed the world’s first type approval test on its 525 kV direct-current (DC) cable system with a DC gas insulated switchgear (DC GIS) interface in accordance with CIGRE TB496 under the technical collaboration with Siemens Energy and German cable supplier Südkabel.


With more renewable energy penetration, multi-terminal DC interconnectors will be a desirable option for robust power networks, Sumitomo Electric claims.

DC GIS provide a compact solution, especially for connecting high-voltage direct-current (HVDC) cable lines to offshore converter platforms and onshore transition stations.

Sumitomo Electric has devised a 525 kV DC cross-linked polyethylene (XLPE) cable, while Siemens Energy has developed a DC GIS component.

These companies decided to carry out a collaborative type approval test at Mannheim laboratories of KEMA Labs, a CESI brand in Germany.

Südkabel supplied its DC XLPE cable using Sumitomo Electric’s DC XLPE compound materials and connected it to Sumitomo Electric’s XLPE cable and joints.

These cables plugged into Siemens’ DC GIS compartment via DC GIS terminations.

The collaborative test results showed the conformity of the 525 kV DC cable system and the DC GIS interface in accordance with CIGRE TB496.

Südkabel’s cables also proved compatible to Sumitomo Electric’s cable, while subsequent destructive tests, including polarity reversal condition tests, showed the both cable systems have sufficient design margins up to Uo = 640 kV level.

Sumitomo Electric has been leading the international power cable industry with its HVDC XLPE insulation technology.

In 2019, Sumitomo Electric was commissioned for the NEMO project, connecting UK and Belgium with 400 kV HVDC cable system.

The company has also secured the Corridor A-Nord Project, laying 525 kV HVDC underground cable in Germany.