An improved design of an inductive fault current limiter based on a superconducting cylinder

This paper deals with basic designs of a fault current limiter of the transformer type which differ from each other by the mutual location of a primary winding and a superconducting short-circuited cylinder. Theoretical study of the main parameters of the different designs is performed in the framework of the critical state model and shows that the most effective is a design in which the primary winding is divided into two sections with equal turn numbers. The sections are placed inside and outside of the cylinder and connected in series. Such an arrangement of the windings leads to a substantial reduction of AC losses in the superconducting cylinder, an increase of the activation current and a decrease of the inductive reactance in the normal regime of a protected circuit. The experimental results obtained on the laboratory model with a BSSCO cylinder confirm the theoretical predictions.