Fig. 4. has show stator and rotor of synchronous
generator. Stator part is installed armature winding. Rotor
part is installed field winding or using instead permanent
magnet. When rotor part is driven by prime mover, field
winding must be connected to dc. supply to build
magnetic flux but might be not if using permanent
magnet. Magnetic flux across the air gap and cut to
armature winding to induced voltage in armature winding