ABSTRACTSwitching from superconducting (S) to normal (N) state was investigated using short rise time (∼ 10⁻¹⁰ s) electric pulses in MBE grown Bi-Sr-Ca-Cu-O and rf magnetron sputtered Y-Ba-Cu-O submicron thickness microstrips. It was found that two reversible processes: fast electronic (τ∼10∼⁻¹² s) and slow thermal (τ∼10∼⁻⁸s) one take place during switching. At high current densities (∼10⁷ A/cm²) irreversible changes in strip material induced by thermal runaway occurred. The use of a superconducting element as fast fault-current limiter or pulse sharpening device is pointed out.