1. Torque is placed directly on the windings.
2. Eddy current generates in them.
To solve the subjects, method to support the winding by
non-magnetic material, transposed fine wire, cooling
method and insulation have been developed. Air-gap
windings have feature such as flexibility of winding and
high voltage winding.
By developing superconducting wire of AC use,
generators with superconducting armature windings
have been tried to develop. However, the development is
stopped due to no wire of low loss at high field and to
disappearance of some feature as mentioned below.
The results of developments of design and manufacture including what are not introduced here give good
outcomes.