Which component supplies the DC field current in an AC generator?

• A. Exciter generator
• B. Stator windings
• C. Main rotor
• D. Load resistor

Answer: (A)

The thing that creates the magnetic field in the generator’s rotor is energized with direct current. That DC field current comes from the excitation system, typically an exciter generator, which delivers the required DC to the rotor windings (often via brushes and slip rings, or through a brushless rectifier in modern systems). The stator windings are where the AC voltage is produced as the rotor’s magnetic field rotates past them. The main rotor itself simply carries the field winding; it doesn’t supply the field current by itself. The load resistor is just part of the external circuit and does not supply the field.