Question

Calculate the active power in a .154 H inductor.

(a) 22 W

(b) 14 W

(c) 45 W

(d) 0 W

This question was posed to me by my college director while I was bunking the class.

I would like to ask this question from Speed Control of Shunt or Separately Excited Motors in chapter Speed Control of Direct Current Motors & Induction Motors of Electric Drives

Answer 1

The correct choice is (d) 0 W

Easy explanation: The inductor is a linear element. It only absorbs reactive power and stores it in the form of oscillating energy. The voltage and current are 90° in phase in case of the inductor so the angle between V & I is 90°. P = VIcos90° = 0 W.