Question

What is the relation between the number of poles and pole pitch with power factor?

(a) number of poles increases, pole pitch increases, bad power factor

(b) number of poles increases, pole pitch decreases, good power factor

(c) number of poles increases, pole pitch decreases, good power factor

(d) number of poles increases, pole pitch increases, bad power factor

I had been asked this question during an interview.

Question is taken from Dispersion Coefficient in chapter Three Phase Induction Motor of Design of Electrical Machines

Answer 1

Correct option is (c) number of poles increases, pole pitch decreases, good power factor

Explanation: As the number of poles increases, the pole pitch decreases and the number of slots per pole per phase also decreases. This increases the dispersion coefficient and it leads to poor power factor.