Question

Which of the following will not happen if one of the phases to the induction motor is not available?

(a) Motor will start but operate at lower speed

(b) It will hum but not start

(c) It will continue to operate below 57.7% of rated load

(d) External means are needed to make it run at rated speed

This question was addressed to me by my college director while I was bunking the class.

Question is taken from Power Factor Control of Three Phase Induction Motors in portion Induction Machines of Electrical Machines

Answer 1

Correct choice is (a) Motor will start but operate at lower speed

To explain: Motor will not start if one of the phases is missing.