USCG Exam PracticeMotors and generators
According to 46 CFR §183.320, a generator or motor designed for a 40 °C ambient may be installed in a space where the ambient temperature reaches 50 °C, provided which condition is met?
- A. The machine is fitted with an additional cooling fan and the overcurrent device is increased by 20%
- ✓ The machine is derated to 80% of full-load rating and overcurrent device ratings are reduced accordinglyCorrect
- C. The machine is derated to 90% of full-load rating and a temperature alarm is installed
- D. The machine is replaced within 12 months with one rated for 50 °C ambient
Why B is correct
46 CFR §183.320(b)(2) permits a 40 °C-rated machine in a 50 °C ambient location only if 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