USCG Exam PracticeMotors and generators
A generator rated for 40 °C ambient is installed in a space where the ambient temperature regularly reaches 50 °C. Under 46 CFR §183.320, what corrective action is required?
- A. The generator must be replaced with one rated for 50 °C; no derating is permitted
- ✓ The generator may be used if derated to 80 percent of full load rating and overcurrent devices are adjusted accordinglyCorrect
- C. The generator may be used at full rating provided additional ventilation is supplied
- D. The generator must be derated to 50 percent of full load rating to account for the temperature difference
Why B is correct
46 CFR §183.320(b)(2) permits a generator designed for 40 °C to be used in a 50 °C ambient location provided it is derated to 80 percent of the full load rating and the rating or setting of the overcurrent devices is reduced accordingly.
Cited:46 CFR §183.320