Question

What is the average coil emf generated in a 4-pole DC machine having flux/pole equal to 0.1 wb rotating at 1500 rpm? (No. of coil sides = 100)

(a) 19 kV

(b) 1.9 kV

(c) 190 V

(d) 19 V

This question was posed to me in an online interview.

Enquiry is from EMF and Torque Production topic in chapter Circuit Model, Emf and Torque of DC Machines

Answer 1

The correct option is (a) 19 kV

To explain: Average coil emf generated= ∅ωNP/π.

E= 0.1*1500*100*4/3.14

E= 60000/3.14

E≅ 19 Kv.