Two-rotor alternators with superconductor field winding

A two rotor construction was proposed for synchronous a.c. machines with superconductor field windings, as a means of physically separating hot components from cold components and thus minimizing the heat leakage to the cold component with a resulting more efficient cryogenic cooling of the latter. The two rotors are mounted on the common shaft, coaxially in separate bearings. A hot working rotor with shorted winding or field winding and freely running cold rotor with superconductor field winding and a cold working rotor with superconductor field winding and freely running hot rotor, usually in the form of a hollow conducting cylinder are described and comparatively evaluated here for starting and running performance.