Question

If induction motor rotor power is 157.5 KW and gross developed power is 79.9 KW, then rotor ohmic loss will be _________ KW.

(a) 77.5

(b) 77.6

(c) 76.9

(d) 77.1

The question was posed to me by my college director while I was bunking the class.

Enquiry is from Induction Motors in division Speed Control of Direct Current Motors & Induction Motors of Electric Drives

Answer 1

Right answer is (b) 77.6

For explanation: Rotor ohmic losses are due to the resistance of armature windings. Net input power to the rotor is equal to the sum of rotor ohmic losses and mechanically developed power. Rotor ohmic losses=Air gap power-Mechanical developed power=157.5-79.9=77.6 KW.