Influence of Self-magnetic Field on the Quench of Superconducting Fault Current Limiter

Abstract

×The quench current level of a superconducting power apparatus may be decreased by the self-magnetic field induced by its own current. As the self-magnetic field is spatially distributed in the apparatus, each section of the superconducting cable is exposed to the different magnetic field in the magnitude as well as in the direction. In this paper, the quench current level and quench initiation position are discussed for a 6kV-200A class superconducting fault current limiter(SC-FCL) which has been developed by us. We calculated spatial profile of strength and direction of self-magnetic field in the SC-FCL. As a result, the self magnetic field is applied to almost section of the superconducting cable in transverse direction (maximum value : 6.42×10^-4T/A), but the connection section between coils suffers the magnetic field with longitudinal component of 3.34×10^-4T/A.
On the other hand, quench current levels of a short sample of superconducting cable which was used for the SC-FCL were measured for the different magnetic field externally applied in the same, transverse and opposite direction to that of the transport current of the cable. The quench current level decreases at the rate of 100A par OAT in same direction magnetic field and 40A per OAT in transverse direction. However, in the case of opposite direction of magnetic field, the quench current level did not change with the magnitude of the magnetic field.
Taking these results into consideration, it can be pointed out that the quench may be initiated in the connection section between coils where the self-magnetic field is applied in the same direction. Furthermore, we discuss the configuration of the SC-FCL coils to suppress the decrease of the quench current level.