Question

Calculate the active power in 56 μF capacitor if the VRF value is 5.1%.

(a) 6 W

(b) 0 W

(c) 9 W

(d) 2 W

This question was addressed to me during an internship interview.

This intriguing question comes from Traction Drives topic in division Traction Drives of Electric Drives

Answer 1

Correct choice is (b) 0 W

To explain I would say: The capacitor 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 capacitor so the angle between V & I is 90°. P = VIcos90° = 0 W.