CURRENT LIMITING LEVEL-TIME CHARACTERISTIC OF A SUPERCONDUCTING FAULTCURRENT LIMITER

A model superconducting fault current limiter (SE-FCL) has been develo ped. The adopted superconducting cable is composed of six strands insu lated from each other. The current limiting level of the SC-FCL is mea sured under two types of overcurrent, a sinusoidal and an inrush curre nt. The results show that the current limiting level of the SC-FCL I-q increases with an increase in the rate of rise of the overcurrent. By introducing a new parameter of time-to-quench t(f), it is found that I-q increases with decreasing t(f). This feature is taken as a current limiting level-time characteristic, i.e. the I-q-t(f) characteristic. The existence of the I-q-t(f) characteristic found in the SC-FCL is q ualitatively explained by measuring current distribution among the six strands. The superconducting cable is driven to the normal state stra nd by strand. Some delay in time is found from the quench of the first strand to that of the last and this is recognized as an I-q-t(f) char acteristic in its current limiting performance.