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

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

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

Answer: (C)

The question tests the APU generator’s current capability within the altitude range used for operations. The ERJ-145’s auxiliary power unit provides a significant amount of 400 Hz AC power, and its generator is rated for about 40 kVA. When you translate that power rating to current on the aircraft’s 115 V AC electrical system, the allowable load is limited to a practical maximum around 400 amperes up to the altitude of 30,000 ft. This derating keeps voltage and frequency within limits and prevents overloading the electrical distribution. Therefore, the maximum amperage you can rely on from the APU generator up to 30,000 ft is 400 amps. Lower values would underutilize the APU, while a higher value would exceed the generator’s rating and risk system instability.

The question tests the APU generator’s current capability within the altitude range used for operations. The ERJ-145’s auxiliary power unit provides a significant amount of 400 Hz AC power, and its generator is rated for about 40 kVA. When you translate that power rating to current on the aircraft’s 115 V AC electrical system, the allowable load is limited to a practical maximum around 400 amperes up to the altitude of 30,000 ft. This derating keeps voltage and frequency within limits and prevents overloading the electrical distribution. Therefore, the maximum amperage you can rely on from the APU generator up to 30,000 ft is 400 amps. Lower values would underutilize the APU, while a higher value would exceed the generator’s rating and risk system instability.