Preliminary Design of a High Tc Superconducting Persistent Mode Current Switch

Persistent Mode Current Switches (PMCS) are made from coils of superconductor that in theory will provide zero conduction losses when closed. By causing a section of the superconductor to leave its superconducting state and become resistive, the switch is effectively opened. There are currently 3 methods to open a PMCS; 1) applying heat, 2) applying a magnetic field or 3) application of current above the critical current (Ic) of the tape. The first two methods are not suitable for power applications as the switching time is too slow. Recent work at the University of Wollongong and in literature has shown that by careful design, a switch using High Temperature Superconductors (HTS) and applying a high frequency current pulse can potentially achieve a switching time of less than 50μs.