Application of active quenching of second generation wire for current limiting

• Quench triggered in the second generation wire by application of a short burst of RF field via an inductively coupled flexible coil.
• The normal zone propagation speed is measured.
• A small-scale superconducting fault current limiter with the active trigger comprised of a co-wound flexible coil.
• The fault current limiter is tested under a DC load, shown to have several times faster response when the triggering RF field pulse is applied.

Superconducting fault current limiters (SFCLs) are increasingly implemented in the power grid as a protection of substation equipment from fault currents. Resistive SFCLs are compact and light, however they are passively triggered and thus may not be sufficiently sensitive to respond to faults in the distribution grid. Here, we explore the prospect of adding an active management feature to a traditional resistive SFCL. A flexible radio-frequency coil, which is an integral part of the switching structure, acts as a triggering device. We show that the application of a short, 10 ms, burst of ac magnetic field during the fault triggers a uniform quench of the wire and significantly reduces the reaction time of the wire at low currents. The ac field burst generates a high density of normal zones, which merge into a continuous resistive region at a rate much faster than that of sparse normal zones created by the transport current alone.