Superconducting Rotor Development for a 50 MVA Generator

A superconducting rotor for a 50 MVA generatoi with a superconducting field winding was developed. This paper describes rotor development, and field winding static and rotating rotor excitation tests. Two electromagnetic damper shields, one for ambient temperature and the other for low temperature (50 K), were used to protect the field winding from time varying flux. The thermal strain that occurs between field winding supports and outer parts of the rotor body when a winding is cooled was prevented by providing individual supports for the winding and rotor body at one end of the rotor. The field winding was a concentrated saddle-shape type, inpregnated by epoxy. The rotor was tested using a small stator with an air gap armature winding. An output of voltage of about 1.5 kV and current of about 1.5 kA was obtained when a generating test was carried out at 3000 rpm.