Quench behaviors of QMG current limiting elements under the influence of magnetic field

The superconducting fault current limiter (SFCL) is a very attractive device for power networks, therefore, a lot of research and development has been conducted for several types of SFCLs. We have studied quench properties of QMG (quench melt growth) YBCO bulk elements for a resistive type SFCL. The bulk element has a high critical current density J/sub c/ exceeding 10000 A/cm/sup 2/ at 77 K and could carry 2 kA transport current. In order to protect the element from burn-out during quenching, the element has not only coatings such as Ag and solder but also a magnetic field applied to the element simultaneous with the quench. The magnetic field helps the quenching by decreasing the J/sub c/ for the whole element. Quench behaviors of the QMG bulk elements under pulsed magnetic fields up to 0.43 T generated by a magnet with copper windings were studied in liquid argon whose boiling point is 87.3 K. Successful quench of the entire element was observed.