How is the voltage of a DC generator primarily controlled?

The voltage of a DC generator is primarily controlled by varying the field current strength. The generator operates based on electromagnetic induction, where the rotor spins within a magnetic field to induce voltage in the stator windings. The strength of the magnetic field is directly influenced by the amount of current flowing through the field windings.

When the field current is increased, the magnetic field strength intensifies, resulting in a higher induced voltage in the generator's output. Conversely, reducing the field current will decrease the strength of the magnetic field and, correspondingly, lower the output voltage. This principle allows for effective regulation of the generator’s voltage to meet operational demands.

While changing the generator's rotor speed can affect the output voltage, it is not the primary method of control since operating conditions may limit the ability to adjust speed effectively. Adding external resistors could be used to manage current flow in certain applications, but it does not directly control voltage in the manner that altering field current does. Incorporating capacitors in the circuit is generally related to filtering or smoothing voltage rather than controlling it directly.