Terminal Voltage

DC generator output voltage is dependent on three factors that are as follows (recall equation 5-1):  

(1) the number of conductor loops in series within the armature,

(2) armature speed and

(3) magnetic field strength.

In sequence to modify the generator output, one of these three factors has to be varied. The number of conductors in the armature cannot be changed in a generally operating generator, and it is commonly impractical to modify the speed at that the armature rotates. The strength of the magnetic field, therefore, could be changed quite simply through varying

                                          Figure: Varying Generator Terminal Voltage

the current by the field winding.  This is the most hugely used method for regulating the output voltage of a DC generator (Figure).