High temperature superconductors as current limiters-an alternative to contacts and arcs in circuit breakers?

Abstract

Nowadays in circuit breakers from the low voltage level to the highest transmission voltages, contacts to carry the current and arcs established at contact opening to break it are utilized. Of the various possible but scarcely used alternatives to this principle, the transition between the superconducting and normal-conducting state has gained new attention since the high T/sub c/ superconductors (HTSCs) have been discovered. This paper assesses the technical possibilities and problems of resistive current limiters with such superconductors. Based on results of experimental investigations of HTSC samples, simulations of the behavior of fictive HTSC limiters in electrical power networks are carried out. Assuming a homogeneous conductor, the self-quench initialized by exceeding the critical current is calculated for conductors with different critical current densities. Furthermore, questions of inhomogeneity along the conductor, current pulse triggering, transient overvoltages and the effect of parallel elements are discussed.