AA-EDF superconducting generator development program

AA-EDF collaboration in this field began in 1971. 250 to 3000 MW superconducting generators have been studied. Tests have been performed on parts for machines of more than 1000 MW. A large cryogenic rotor model (outer diameter : 1,06 m, length between bearings : 5 m with superconductor winding) is undergoing initial tests. Concerning a prototype, the existing turbines impose speeds of 3000 rpm; 250 MW power (47 existing turbines) allows rotor diameter characteristic of machines of more than 1 GW, the field winding could be constructed as in the rotor model; an important technical problem is the ambient temperature damper, a serious concern is to obtain a 250 MW power plant for the tests. The required availability and principal modes of operation in a large system - and, above all, resynchronization without quenching led us to the principal technical options : low-loss superconductors, no low temperature damper and supercritical helium.