Superconducting coaxial turn transformer

Abstract

The concept of a superconducting coaxial turn transformer is presented. The turns enclose each other like hoses and the circularly wound warm iron core encloses the coils outside the cryostat. This concept promises some remarkable advantages over other geometries. The potentials of this concept as well as of existing superconductor technology are demonstrated by design studies on various actively short circuit protected and inherently short safe 400 MV A, 400/21 kV, 50 Hz, three phase coaxial turn generator transformer banks. Based on an experimental NbTi superconductor it is shown that actively switch-protected transformers which quench at certain overcurrents exhibit losses and weights which are only fractions of those of corresponding conventional transformers. These types could also serve as current limiters with fast recovery times. It is further demonstrated that even inherently short safe varieties with losses and weights less than those of normal conducting transformers are possible.