Seiji Numata

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.

EFFECTS OF POLE NUMBER AND STATOR CORE ON THE PERFORMANCE OF SUPERCONDUCTING MACHINE

Various superconducting machines, which have 2, 4 or 6 Pole numbers, and iron or conducting stator cores, were evaluated. Effects of pole number on damper electromagnetic stress and field airgap flux density were significant, as are effects of the material and position of the stator core on maximum and effective field flux density. From the comparison of the size and performance of various machines having the same output power, it was found that not only machines with an iron stator core but 4 pole machines without a stator core are of potential use.

MANUFACTURE OF A 50MVA SUPERCONDUCTING ROTOR

A rotor suitable for a 50MVA superconducting generator was constructed as the first stage in the development of a large scale superconducting generator. This paper reports on the design and construction of the rotor, rotor component tests, static excitation tests and dynamic balancing of the rotor.