A numerical investigation was carried out to assess the influence of ferromagnetic substrate on the transport losses in YBCO coated conductor. We used an improved version of the method that was proposed recently by A. Campbell to simulate the evolution of current and field distributions in wire from hard superconductor carrying ac. It was found that this technique is able to cope with field dependent critical current density in superconductor in the presence of ferromagnetic material with non-linear properties. Our results indicate that the magnetic substrate is a significant factor in the loss behavior.

We enhanced the performance of superconducting tapes during quenching by coating the tapes with various composites, with regards to the application of such coated systems in superconducting fault current limiters. In composition of the coating, we varied the type of epoxy matrix, the content of ceramic filler particles and the use of reinforcement in order to optimize the thermal and the mechanical stability of the coated tapes. By this way modified superconducting tapes were able to reduce the maximum temperature 170 °C of not modified superconducting tape to 55 °C during the quench with electric field up to 130 V m⁻¹.

The paper explores the idea of reducing the amount of REBCO conductor in Resistive Superconducting Fault Current Limiters (R-SCFCL) by reducing the temperature of liquid Nitrogen from 77 K to 66 K. Because of lower temperature, the critical current increase approximately two times, and instead of two parallel tapes, one can use only one tape in a 1000 A class R-SCFCL. However, recent experimental results on short samples show a frequent degradation of superconductors by DC current limitation at 66 K. The paper reports our investigation of this phenomenon by experiments complemented by extensive numerical modeling. We suggest that the primary cause of conductor degradation initially appearing at 66 K should be sought in the first sub-millisecond period of the limitation pulse. We observed that a reduced initial rate of the current rise during the limitation event can prevent the conductor damage.