Question

A three phase, 50 Hz induction motor has a full load speed of 1440 rpm. Speed of the stator field revolving rotor structure is?

(a) 157 rad/s

(b) 150 rad/s

(c) 6.28 rad/s

(d) 145 rad/s

This question was addressed to me in an online quiz.

The origin of the question is Rotor Frequency in division Induction Machines of Electrical Machines

Answer 1

Right choice is (c) 6.28 rad/s

For explanation I would say: Speed of the stator field revolving rotor structure = 1550-1440 = 60 rpm = 6.28 rad/s.