Experimental analysis of bifilar pancake type fault current limiting coil using stabilizer-free coated conductor

YBCO coated conductors (CC) have actively been researched and manufactured these days. Recently, stabilizer-free (SF) CC with Hastelloy substrate has been developed for superconducting fault current limiter (SFCL). The SF CC has higher resistivity than other existing CCs with thick metallic stabilizer. Higher voltage per unit length applicable can be increased. In this research, the bifilar pancake coil using SF CC was manufactured and characteristic tests of the coil for SFCL were performed. Though the bifilar coil is supposed to have no inductance during normal operation, the transport current loss is be produced due to AC current flowing through the SF CC. AC loss was measured and short-circuit test was performed in liquid nitrogen. In order to develop large scale SFCL, it is indispensable to consider the dielectric characteristics of pancake module. Dielectric breakdown tests were carried out to find applicable maximum voltage in one pancake module. These results provided to suitable design parameters and showed technical feasibility of pancake type module as an SFCL.