Instead of the usual field winding fed with DC, and an armature winding where the generated electricity comes out, there are two three-phase windings, one stationary and one rotating, both separately connected to equipment outside the generator.
12.
Lectures given at Massachusetts Institute of Technology formed the basis of the books " Armature windings of electric machines ", and " Electric generators " ( later expanded as " Electric machine design " ) published between 1895 and 1906.
13.
DC machines may have leakage current from the armature windings that energizes the shaft . Currents due to shaft voltage causes deterioration of motor bearings, but can be prevented with a grounding brush on the shaft, grounding of the motor frame, insulation of the bearing supports, or shielding.
