Question

For self-excited DC generator, field circuit curve in the OCC will be __________

(a) Straight line not passing through the origin with +ve slope

(b) Straight line passing through the origin

(c) Straight line not passing through the origin with -ve slope

(d) Increasing curve

I had been asked this question in an online interview.

Asked question is from Characteristics of Self Excited Generator in chapter DC Generator of DC Machines

Answer 1

The correct choice is (b) Straight line passing through the origin

The best I can explain: Field is connected such that this current increases the field mmf and therefore the induced emf, the machine will continuously build up. For the field circuit V = If *Rf, which is a straight-line relationship, called the Rf -line, in V-If plot.