Question

What is the Relation between pole pitch and the core length in terms of the best power factor?

(a) pole pitch = (0.18 * core length)^3

(b) pole pitch = (0.18 * core length)^2

(c) pole pitch = (0.18 * core length)^1/2

(d) pole pitch = (0.18 * core length)^1/3

The question was posed to me in exam.

The above asked question is from Main Dimensions in section Three Phase Induction Motor of Design of Electrical Machines

Answer 1

Right option is (c) pole pitch = (0.18 * core length)^1/2

Easiest explanation: For the best power factor, the pole pitch is equal to the square root of the product of 0.18 and core length. This value however is not dimensionally correct and is valid for the values in meters.