Study on the Quench Current of YBCO Thin Film FCL

We present the result of a theoretical analysis on the quench current of YBCO thin films for the superconducting resistive fault current limiter. Generally, a transport current exceeds a critical current without quenching and the quench current is usually more than 1.5 times of the critical current. The quench current is calculated theoretically by considering the effects of a small temperature rise DeltaT_p. The temperature rise produces the Joule heat increase because the critical current density decreases by the temperature rise. If this Joule heat can not be removed completely by the heat transmission (hDeltaT_p) from the superconductor surface to liquid nitrogen, the superconductor quenches. It is shown that the theoretically calculated quench currents accord with the experimental results.