USCG Exam PracticeElectrical basics — generators, motors, and safety
A motor designed for a 40 °C ambient temperature must be used in a space where the ambient temperature reaches 50 °C. Under what condition is this permitted?
- ✓ Provided the motor is derated to 80 percent of its full load rating and overcurrent devices are reduced accordinglyCorrect
- B. Provided the motor is derated to 90 percent of its full load rating
- C. Provided additional ventilation is installed to maintain the space below 45 °C
- D. This is never permitted; the motor must be replaced with one rated for 50 °C
Why A is correct
46 CFR §183.320(b)(2) expressly permits a 40 °C-rated generator or motor to be used in a 50 °C ambient location, provided it is derated to 80 percent of full load rating and the rating or setting of the overcurrent devices is reduced accordingly.
Cited:46 CFR §183.320