Protection of superconducting field windings for electrical machines by the use of an inertial free electromechanical shield

This new machine has two independent rotors, the driven inner rotor with the superconducting field winding and the free rotor which serves as the electro-mechanical shield. At steady state both rotate at synchronous speed, but during a fault transient the shield acts as a low-pass filter protecting the field from the large pulsations in torque and magnetic field. The new machine is described and its steady state and transient performance are outlined.