In general, how does a voltage regulator control a generator's output?

In general, how does a voltage regulator control a generator's output?

• A. Increases the mechanical speed
• B. Controls the strength of the field
• C. Adjusts the stator windings
• D. Changes the load on the bus

Answer: (B)

Controlling the field strength is how the voltage is kept steady. The generator’s output voltage is mainly set by the magnetic field in the rotor: stronger field produces a higher EMF in the stator, and weaker field lowers it. The voltage regulator watches the terminal voltage and then adjusts the excitation current to the rotor field to maintain the desired voltage as the load on the bus changes. It does this through the exciter to vary the field current. The stator windings are fixed, so they aren’t adjusted by the regulator, and speed is managed separately by the engine governor. The regulator’s job is to keep voltage constant by changing excitation, not to alter mechanical speed or the load itself.

Controlling the field strength is how the voltage is kept steady. The generator’s output voltage is mainly set by the magnetic field in the rotor: stronger field produces a higher EMF in the stator, and weaker field lowers it. The voltage regulator watches the terminal voltage and then adjusts the excitation current to the rotor field to maintain the desired voltage as the load on the bus changes. It does this through the exciter to vary the field current. The stator windings are fixed, so they aren’t adjusted by the regulator, and speed is managed separately by the engine governor. The regulator’s job is to keep voltage constant by changing excitation, not to alter mechanical speed or the load itself.