Development of a High-Temperature Superconducting Gas-Insulated Power Cable
Superconducting gas-insulated transmission line (S-GIL) concept for high-temperature superconducting (HTS) power cables was developed with practical designs that use tubular insulator spacers. The implications of spacer materials and designs were studied in terms of electric field enhancement and its role in limiting the maximum withstand voltage. Three different tubular insulator materials and two different sizes were explored using the finite-element analysis of electric field enhancement. Model cables were fabricated and tested for their response to high-voltage tests at various pressures up to 2 MPa, with two different gas media and at two different temperatures. The experimental results were compared with the expected behavior based on the finite-element analysis. Implications of the designs on cryogenic gas flow and pressure drop along the length are also discussed. Maximum withstand voltage above 40 kV was achieved for designs suitable for gas-cooled HTS cables operating at 77 K.