500 V/200 A fault current limiter modules made of large-area MOD-YBa2Cu3O7 thin films with high-resistivity Au–Ag alloy shunt layers

摘要: We developed 500 Vrms/ 200 Arms superconducting thin-film fault current limiter (FCL) modules that can withstand high electric fields (E>30 Vrms cm−1) by using large-area YBa2Cu3O7 (YBCO) thin films with high-resistivity Au–Ag alloy shunt layers. about 60 nm thick were sputter-deposited on YBCO/CeO2/sapphire (2.7 cm × 20 cm) prepared a fluorine-free MOD method. Each long Au–Ag/YBCO film was then divided into three segments (each ~5.7 long) four Ag electrodes deposited the layer, resulting in an effective length of 17 cm. The V/200 A FCL fabricated first connecting two segmented parallel Ag-sheathed Bi-2223 tapes and external resistor capacitor for each segment to protect from hot spots. Switching tests short-circuit generator revealed all carried ac ≥237 YBCO having relatively homogeneous critical Ic distribution successfully withstood ≥515 five cycles without any damage. These results demonstrate (a) here achieved rated voltage (b) total area sapphire substrates required (100 kV A) module less than one-third conventional use gold layers, leading significantly reduced cost FCLs. Film damage due spots depended difference between parallel-connected inhomogeneity film, is most probably nonlinear flows at moment quenching cause local overheating.