Question

The complex power consumed by a constant – voltage load is given by (P₁ + jQ₁), Where, 1 kW ≤ P₁ ≤ 1.5 kW and 0.5 kVAR ≤ Q₁ ≤ 1 kVAR.

A compensating shunt capacitor is chosen such that |Q| ≤ 0.25 kVAR, where Q is the net reactive power consumed by the capacitor – load combination. The reactive power (in kVAR) supplied by the capacitor is__________.

Answer 1

Before connecting shunt capacitor:

Maximum reactive power consumed by the load from the source.

Q₁ = 1 kVAR.

After connecting shunt capacitor:

Maximum reactive power consumed by the capacitor-load combination from the source. 

Q = 0.25 kVAR

Net reactive power supplied by the capacitor to the load is

Q_c = Q1 - Q = 0.75 kVAR

Net reactive power supplied from source to load changed from 1 kVAR to 0.25 kVAR, remaining 0.75 kVAR is supplied by the shunt capacitor.