Question

The generated e.m.f from 20-pole armature having 800 conductors driven at 30 rev/sec having flux per pole as 60 mWb, with 16 parallel paths is ___________

(a) 1900 V

(b) 1840 V

(c) 1700 V

(d) 1800 V

This question was posed to me in an interview.

The origin of the question is DC Motors Characteristics in chapter Characteristics of DC & AC Motors of Electric Drives

Answer 1

The correct choice is (d) 1800 V

To elaborate: The generated e.m.f can be calculated using the formula Eb = Φ×Z×N×P÷60×A, Φ represent flux per pole, Z represents the total number of conductors, P represents the number of poles, A represents the number of parallel paths, N represents speed in rpm. Eb = .06×20×1800×800÷60×16 = 1800 V.