Question

A 3-phase, 5 kW induction motor has a p.f. of 0.75 lagging. A bank of capacitors is connected in delta across the supply terminals and p.f is raised to 0.9 lagging. The kVAR rating of capacitor connected in each phase is ____ kVAR.

• A. 0.66

Answer 1

The correct option is A 0.66


Reactive power before compensation $=5\times {10}^3\times \tan \left({41.41}^{\circ }\right)$

$=4.409kVAR$

Reactive power after compensation $=5\times {10}^3\times \tan \left({25.84}^{\circ }\right)$

$=2.421kVAR$

$\therefore$ Reactive power supplied by capacitor bank,

$=1.988kVAR$

kVAR rating of capacitors connected in each phase $=\frac{1.988}{3}=0.662kVAR$