First electrical tests on a machine with an AC superconducting stator winding

The design of a three-phase superconducting stator winding, built using a low-loss NbTi wire for 50-Hz operation, is described, and results of electrical tests made on a three-phase superconducting armature winding are reported. The windings are formed on five concentric fiberglass cylinders with a thin impregnation of an epoxy film adhesive. The electrical tests have been performed using a normal iron rotor inside the superconducting stator. No-load and permanent-resistive-load tests have been completed up to a power of 13 kVA. The 18.5 kVA predicted value for this rotor was not realized because large inductances prevented the coils from becoming superconducting.