Question

Calculate the active power in a .56 F capacitor.

(a) 37.8 W

(b) 0 W

(c) 15.4 W

(d) 124.5 W

The question was asked by my school teacher while I was bunking the class.

Question is from Methods of Starting Electric Motors topic in division Starting of Electric Drives

Answer 1

Correct option is (b) 0 W

To explain: 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. Current leads the voltage in case of the capacitor.