Question

What is the formula for the full load rotor mmf?

(a) 65% of stator mmf

(b) 75% of stator mmf

(c) 85% of stator mmf

(d) 90% of stator mmf

The question was posed to me during an online interview.

I want to ask this question from Design of Wound Rotor topic in section Three Phase Induction Motor of Design of Electrical Machines

Answer 1

Correct option is (c) 85% of stator mmf

Explanation: The full load rotor mmf is taken as 0.85 of stator mmf. Full load rotor mmf = 0.85 *

(stator current * no of stator turns) / no of rotor turns.