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

The primary function of the Generator Control Unit (GCU) and the APU GCU is to control and monitor the output voltage and current of the electrical systems in the aircraft. These units ensure that the generators produce a stable and appropriate electrical output, which is critical for the operational integrity of all onboard systems that rely on electrical power. The GCU achieves this by regulating the electrical parameters, providing fault protection, and enabling automatic load management. This functionality is essential for maintaining the reliability of the aircraft’s electrical systems, as fluctuations or improper voltage levels can lead to system malfunctions or failures.