PPI power sample exams

[saw]

Hi there,

I have a new delema, what is the equation for Reactive power with respect to voltage and reactance? There are two question in PPI power sample exams (P10, P12) which the Q is calculated and the book used (Q=(sqrt3)x(Vsquare/Xc). I think the formula should be Q= (Vsquare/Xc). Please some one explain if I am wrong and why. Thank you

 

[KatyLied P.E.]

I agree with you. Did a quick Google search also and you appear to be correct. Assuming there's nothing in the problem that could change that.

 

[saw]

KatyLeid,

Here is problem 10: A 60HZ, three phase, 208V system carries a total load of 200+j150VA. What is the most nearly the total capacitance required to correct the power factor?

The PPI answer is:

to find Xc

Q=sqrt3 X(V2 /Xc)

to find C

C = (-1/2 x pi x 60 x Xc)

It is so confusing when our study books do mistake. we do not know if the book is wrong or we are doing some wrong calcualtions.