TRANSIENTS IN SUPERCONDUCTING ALTERNATORS WITH TORQUE COMPENSATING SHELLS

ABSTRACT

In this machine the torque is not transmitted mechanically to the field winding but by an asynchronous link. The field winding is free to rotate inside the driving shaft, which acts as the squirrel cage of an induction motor. In the steady state the field winding turns at synchronous speed and the driving shaft slightly faster. During a transient the shaft acts as an electromagnetic shell protecting the low temperature parts of the cryostat from high torques and the superconducting coil from varying magnetic fields. In this paper the steady-state running, the fault torques, the critical clearing time, the steady state stability, and the losses in cold metallic parts, are compared with those of a classical superconducting alternator.