they almost consist of cylindrical rotor with field winding and cylindrical stater with armature winding.
The output power p is obtained as p ¼ k0D2lN, where k0
is called output coefficient, D is a diameter of air-gap
between rotor and stater, l is length of air-gap, that is,
length of armature conductor, and N is rotor-speed. The
output coefficient k0 is given as k0 ¼ k1BgAC, where k1 is
coefficient, Bg is magnetic induction in air-gap, and AC
is ampere-conductor per length of circumference of airgap.
The magnetic induction Bg is limited due to magnetic
saturation of material.