Fault current limiting characteristics due to winding direction between coil 1 and coil 2 in a flux-lock type SFCL

Abstract

The flux-lock type high- T c superconducting fault current limiter (SFCL) has different fault current limiting characteristics according to the winding direction between coil 1 and coil 2. In this paper, the fault current limiting characteristics and the resistance of high- T c superconducting (HTSC) element in the flux-lock type SFCL without the 3rd winding due to the winding direction were analyzed based on the equivalent circuit with the magnetization branch. In addition, we investigated the fault current limiting characteristics of it along the number of turns of coil 2 with the fixed number of turns of coil 1 through the fault current limiting experiments. In case that coil 1 was wound to the same winding direction as coil 2, or, subtractive polarity winding, the more the number of turns in coil 2 for the fixed turns of coil 1, the higher the resistance of HTSC element and the limited line current. On the other hand, the additive polarity winding case, which coil 1 was wound to the reverse winding direction of coil 2, showed the opposite operational characteristics to the case of the subtractive polarity winding. The experimental results for each winding direction were well coincided with the analyzed ones from the equivalent circuit.