If a D.C. motor designed for 40°C ambient temperature is to be used for 50°C ambient temperature, then the motor
A)of lower H.P. should be selected
B)of higher H.P. should be selected
C)can be used for 50°C ambient temperature also
D)is to be derated by a factor recom-mended by manufacturer and select the next higher H.P. motor

Question

Quizplus · Accepted Answer

Motors are rated for a specific ambient temperature, and using them in higher temperatures can lead to overheating and reduced efficiency. Derating by a factor recommended by the manufacturer and selecting a higher horsepower (H.P.) motor compensates for the reduced cooling and increased thermal stress at higher ambient temperatures.

If a DC Motor Designed for 40°C Ambient Temperature Is to Be