Electrical insulation systems at cryogenic temperatures

High voltage superconducting power apparatus and systems have been developed in the world, e.g. a 275 kV high temperature superconducting (HTS) cable in Japan or a 220 kV HTS fault current limiter in Russia. CIGRE SC D1 have so far established WGs D1.15 and D1.38 for the state-of-the-art R&D on superconducting power apparatus and systems and published TBs No. 418 (June 2010) and No. 644 (December 2015), respectively. Especially in WG D1.38, HTS materials, electrical insulation and cryogenics were focused as the common and critical factors for successful R&D and practical development of superconducting power apparatus and systems.