[en] The development of large turbogenerators with superconducting exciter winding has moved into the area of considerable economic interest. The advantages and problems of superconductance are discussed. The problems of cooling the cold rotor are especially considered in detail. At the same time, discussions concern what thermal losses are to be expected and what effects occur with respect to coolant flow, heat transmission as well as the change of state of coolant in a rotating system as a result of centrifugal and Coriolis forces. A listing is made as to what formulations are available for solution of these problems and what investigations are to be carried out before a reliable design of a superconducting rotor can result