Dielectric properties of 22.9 kV class prototype high-Tc superconducting cable

Based on the increasing power demands of power transmission in major cities, high-T-c superconductivity (HTS) power cables which have high current capacity and low power loss will be demanded. Electrical insulation is required to realize the HTS cable system with low power loss as well as high current capacity of cable. For this reason, we manufactured a 22.9 kV class prototype HTS cable and measured the dielectric loss tangent (tan delta) which is one of the parameters of electrical insulation. From the experimental results, the tan delta of the prototype cable was 1.16 x 10(-3) when the electric stress was low. However, when the electric stress was high, the tan delta suddenly increased because partial discharge occurred inside the butt gap of prototype cable.