Question

Calculate the useful power developed by a motor using the given data: Eb = 4V and I = 52 A. Assume frictional losses are 3 W and windage losses are 2 W.

(a) 203 W

(b) 247 W

(c) 211 W

(d) 202 W

This question was posed to me in quiz.

This key question is from Methods to Reduce the Energy Loss During Starting topic in section Starting of Electric Drives

Answer 1

Correct option is (a) 203 W

The explanation is: Useful power developed by the motor can be calculated using the formula P = Eb*I -(rotational losses) = 4*52 – (5) = 203 W. If rotational losses are neglected, the power developed becomes equal to the shaft power of the motor.