GCU stands for Generator Control Unit. What does it regulate?

• A. Currency, Frequency, and Voltage
• B. Current, Frequency, and Voltage
• C. Voltage, Current, and Temperature
• D. Pressure, Temperature, and Humidity

Answer: (A)

The Generator Control Unit regulates the generator’s electrical output by actively managing three key quantities: current, voltage, and frequency. It does this by controlling the generator’s excitation, which adjusts the strength of the generated EMF to keep voltage within the required range as loads change. Frequency is maintained at the aircraft standard by coordinating with engine speed and load, ensuring all systems that rely on the 400 Hz electrical supply stay in sync. The current is monitored and limited to prevent overcurrent faults, protecting the generator and wiring; the GCU can trip or reduce output if a fault is detected. Environmental factors like temperature or humidity aren’t directly controlled by the GCU; those are separate considerations, while the GCU focuses on keeping electrical output stable. Currency isn’t a relevant electrical parameter—the valid set is current, voltage, and frequency.