Quench characteristics of resistive superconducting fault current limiters based on YBa2Cu3O7 films

We investigated the quench characteristics of resistive superconducting fault current limiters (SFCLs) based on YBa2Cu3O7 (YBCO) films. The SFCL consists of meander-type YBCO stripes covered with 200 nm Au layer grown in situ for current shunt and heat dispersion at hot spots. The SFCL quenched in a 100 V-rms circuit to produce resistance of 29 Ohm at 55 ms. This resistance indicates the gold film temperature of about 200 K. The SFCL showed reproducible characteristics during m more than a hundred times of repeated experiments. Two nearly identical SFCLs were connected in series to investigate simultaneous quench. A slight difference in the rate of voltage increase between two SFCL units produced significantly unbalanced power dissipation between units. The imbalance of power was matched by a shunt resistance connected in parallel. The appropriate values of shunt resistance here were 80 Ohm at 75 V-rms 100 Ohm at 100 V-rms and 110 Ohm at 120 V-rms, respectively. Increased power input at high voltages also tends to balance the power dissipation, but with increasing in film temperature to higher than 200 K. (C) 2001 Elsevier Science B.V. All rights reserved.