Question

If induction motor air gap power is 48 KW and gross developed power is 28 KW, then rotor ohmic loss will be _________ KW.

(a) 10

(b) 20

(c) 30

(d) 40

This question was posed to me by my school principal while I was bunking the class.

Question is from Speed Control of Shunt or Separately Excited Motors in division Speed Control of Direct Current Motors & Induction Motors of Electric Drives

Answer 1

Right option is (b) 20

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=48-28=20 KW.