# Re: how to calculate power factor?

Home Electrical Engineering Forum General Discussion how to calculate power factor? Re: how to calculate power factor?

#12129

on 1000 kw load our power factor is 0.85. how much kvar power is required to improve power factor up to 0.98. please tell me the formula to improve power factor by capacitors. thanks.

Dear Ikram ;

We have a very simple formula to calculate the Q ( kVAR ) that's :

Q = P ( tg φ1  –  tg φ2 )        where :

– Q : is the power of Capacitors in ” kVAR “

– P : is the real power load in ” kW “

– tg φ1 : tangent φ1 ( before compensation )     ( calculated from Cos φ1 )

– tg φ2 : tangent φ2 ( after compensation )     ( calculated from Cos φ2 )

– Cos φ1 = 0.85    →   tg φ1 = 0.619

– Cos φ2 = 0.98    →   tg φ2 = 0.203

Q = 1000 ( 0.619 – 0.203 ) = 416 kVAR

Noting that you should add at least 10-15% from the calculated Q, because if you have a drop voltage, then the real reactive power of capacitors is less than mentioned on.

Regards