"' Critical field resistance "'is a term that is associated with a Armature "'V a "'is directly proportional to the Flux acting across it, The Flux in a DC Generator is directly proportional to the field current "'I f " '.
22.
The field may be " separately excited " by a source of DC, such as a battery, or " self excited " by being connected to the armature of the generator so that the generator also provides the energy required for the field current.
23.
Essentially, the relay ( s ) employed pulse width modulation to regulate the output of the generator, controlling the field current reaching the generator ( or alternator ) and in this way controlling the output voltage producing back into the generator and attempting to run it as a motor.
