  Numerous proposed and developed superconducting fault current limiters and
self-limiting transformers limit successfully fault currents but do not provide
uninterrupted supplying of consumers. A design investigated in the work
combines the functions of a conventional transformer with the functions of fast
energy redistribution and fault protection. The device constitutes a
transformer containing an additional high-temperature superconducting (HTS)
coil short-circuited by a thin film HTS switching element. Fault current
limitation and redistribution of the power flow to a standby line are achieved
as a result of a fast transition of the superconducting switching element from
the superconducting into the normal state. Transient and steady-state
characteristics were experimentally investigated. A mathematical model of the
device operation was proposed, and the calculated results were found to be in
good agreement with the experimental data. The application field and basic
requirements to such devices were discussed and it was shown that the proposed
device meets these requirements.
