What is the maximum amperage of the auxiliary power unit generator above 30,000 ft?

What is the maximum amperage of the auxiliary power unit generator above 30,000 ft?

• A. 200 amps
• B. 400 amps
• C. 500 amps
• D. 300 amps

Answer: (D)

The APU generator is not allowed to deliver unlimited current; its output is limited by the generator’s rating and protection systems, especially at higher altitudes where cooling and voltage regulation become more challenging. Above 30,000 ft, the APU is limited to a maximum of 300 amps to keep the 400 Hz electrical system within voltage limits and to prevent overheating or overloading the wiring and protective devices. If more current were drawn, voltage would sag or protections would trip, compromising essential systems. So, the highest safe current the APU can supply at that altitude is 300 amps. Higher or lower values would either overtax the APU or underutilize its capacity, respectively.

The APU generator is not allowed to deliver unlimited current; its output is limited by the generator’s rating and protection systems, especially at higher altitudes where cooling and voltage regulation become more challenging. Above 30,000 ft, the APU is limited to a maximum of 300 amps to keep the 400 Hz electrical system within voltage limits and to prevent overheating or overloading the wiring and protective devices. If more current were drawn, voltage would sag or protections would trip, compromising essential systems. So, the highest safe current the APU can supply at that altitude is 300 amps. Higher or lower values would either overtax the APU or underutilize its capacity, respectively.