Study on conditions to reuse quenched HTS coil

An HTS coil wound with insulated HTS wires quenches despite of the high quench margin. Main origins of unexpected quench of HTS coils are non-reversible local defects, and training effects as in LTS coils are not observed in HTS coils. Therefore, when an HTS coil is quenched before the required coil performance is met, the coil cannot be reused unless the coil is safely protected from quench damage and its operating conditions are readjusted. This paper studies on the conditions to readjust for the coil which was not damaged by the quench to meet the required performance. The study is conducted based on the temperature and current dependences of the coil stability measures of the maximum allowable defect (MAD) and minimum propagating zone (MPZ).