To provide a ceramic high-temperature superconductor used for a current limiter on an alternating current line.
A ceramic high-temperature superconductor 1 has a bypass layer 2 having electrical resistance larger than decuple of that of a pure noble metal. The noble metal bypass layer 2 (preferably, silver) of the high- temperature superconductor 1 is allayed with a base metal (preferably, Pb, Bi, Ga) by heat treatment. The ratio of thickness d2 of the noble metal bypass layer to thickness d1 of the superconductor 1 is set to be less than 1/5. A steel base metal bypass layer 3 has electrical resistance between 10 μΩ×cm and 100 μΩ×cm at 77 k and it is soldered or welded with static pressure to the noble metal containing bypass layer 2. The thickness d2 of the noble metal bypass layer and a thickness d3 of the base metal bypass layer are set to be ρ2/d2>0.5×ρ3/d3. Here, the ρ2 and the ρ3 are respectively electrical risistivities of the noble metal containing bypass layer 2 and the base metal bypass layers 3, 3'.
LAKNER MARTIN DR
PAUL WILLI DR