Design, fabrication and test of superconducting field winding modules for a 2 MVA synchronous generator

In the course of the Austrian development program for superconducting generators, upgrading of the field winding was undertaken. While the first exciter winding in the main sections was a copper dummy winding, the next step was a fully superconducting field winding with 150% of the ampere turns of the preceding winding. This superconducting winding occupies only a very small part of the available cross section of the rotor. In an upgraded modification, a field winding was designed, manufactured and tested which fully occupies the available space. This exciter winding, its principal features, the trial manufacturing, and some fabrication problems due to the stiffness of the NbTi conductor are described. The test rig for the individual modules of the field winding and the test procedure which each coil has to pass is outlined. Test results of different element coils are reported.