Question

Calculate the compensator rating required for sin(Φ)=.8.

(a) 0.9 P.U

(b) 0.8 P.U

(c) 0.7 P.U

(d) 0.2 P.U

I had been asked this question in final exam.

Asked question is from Motors Rating and Heating topic in section Rating and Heating of Motors of Electric Drives

Answer 1

Correct choice is (b) 0.8 P.U

To explain I would say: The compensator rating can be calculated using the relation QP.U=√1-cos^2(∅)=sin(∅)=.8. This per unit value VAR compensator is required to improve the power factor of the system.