What is the primary function of the GCU (Generator Control Unit)?

• A. Power distribution
• B. Frequency regulation
• C. Battery charging
• D. Voltage regulation

Answer: (C)

The Generator Control Unit is there to keep the generator delivering the right voltage and to protect the generator and system. It monitors the generator’s output, current, and temperature, and then adjusts the generator’s field to hold the bus voltage within safe limits. It also trips or isolates the generator if faults or overloads occur. Battery charging happens because the system voltage is kept at the level that allows the battery to be charged, but charging itself isn’t the primary job—the main task is voltage regulation and protection. Frequency regulation isn’t controlled by the GCU (that depends on engine speed and generator design), and power distribution is handled by the distribution system, not the GCU. So, the core function is maintaining proper voltage and protecting the generator, with charging as a secondary effect.