Limitation of DC currents by YBa2Cu3O7-δ-Au superconducting films

The limitation of dc fault currents is one of the issues for the development of dc networks or links. This paper shows for the first time the high potential of YBa₂Cu₃O_7-δ-Au bilayers for the design of dc current limiters. Such devices are based on the transition into the normal state of the superconducting YBa₂Cu₃O_7-δ films above a current I^*>I_c, where I_c is the critical current at the onset of dissipation. The study of the transition under current pulses shows that a thermally driven transition into the normal state can occur after a delay t_trans. This duration is defined by the amplitude of the current pulse. For I^*≈3I_c, this delay is less than 10 μs. The abrupt transition into the normal state allows an efficient current limitation. A recovery of the superconducting state can also occur under current. This property can be extremely interesting for autonomous operation of a current limiter in an electrical network in case of transient over-currents coming from the starting of high-power devices.