Transient stability of AC multi-strand superconducting cables

AC application, it is necessary to estimate the stability of multi-strand s uperconducting cable. Therefore, we have been studying the transient stabil ity of non-insulated multi-strand cable when one strand in a cable turns in to the normal state locally. In the quench process, local temperature rise produced by current redistribution among strands is not desirable for stabi lity. In a previous work, we discussed the effect of Cu matrix allocated to each strand on the transient stability and showed that the Cu matrix alloc ation can improve the stability of non-insulated multi-strand cable through mainly numerical simulations. In this paper, we carried out experiments on three kinds of non-insulated three-strand cables; one consists of NbTi/CuN i strands and the others consist of NbTi/Cu/CuNi strands having different c ross-sectional arrangement. These sample strands have almost the same diame ter, the same matrix to superconductor ratio and the same B-J characteristi cs to evaluate the effect of Cu allocation quantitatively, We choose to def ine the transient stability in terms of the minimum quench energy (MQE) at each DC transport current. We also investigated the transient stability of sample cables when quench is initiated in two or three (all) strands simult aneously. (C) 1998 Elsevier Science B.V. All rights reserved.