from the serious department...
KVAR Calculations
Engineering and workplace issues. topic
Posted by Rajan Mane on 23 February, 2005 - 5:31 pm
how to calculate kvar of any given load for unity power factor?

Posted by bill on 24 February, 2005 - 11:26 pm

Try this link.

Posted by Dave on 8 April, 2006 - 7:54 pm
I think this person is confusing KW and KVAR. It seems that he/she thinks that if KVAR's in a system = 0 then there is no power flowing. This person fails to understand that Real power and apparent power are not the same for a system operating with a no unity power factor. This apparent power is simply circulating power due to the phase shift etween the source and the loads. This additional power that appears to be flowing requires the equipment to be rated higher than that for a system operating at unity. Obviously these circulating currents while real....produce no usefull work. It is the job of the EE to correct the load reactance as close as possible to unity to increase efficiency and reduce operational costs.

To my learned collegues I will add that this argument is overly simplistic. And that great things have been done either using existing or inducing reactive power into a system for a myraid of usefull puposes far beyond the scope of my simple explanation of a simple power system.


Posted by Steve Myres on 24 February, 2005 - 11:34 pm
Maybe I don't understand the question. If the power factor is unity, is the reactive power not by definition zero?

Steve Myres, PE
Automation Solutions
(480) 813-1145

Posted by Anonymous on 24 February, 2005 - 11:49 pm
for a unity power factor there is no reactive power...

Posted by Ganesh on 25 February, 2005 - 4:40 pm
i donno whether u r serious or jokin...

kvar = kv * sin (phase)

for unity pf, sin (phase)=0
hence, kvar=0

Posted by DP on 27 February, 2005 - 2:02 pm
The calculation is the same for any other power factor, as cos phi is power
factor and the inverse cos of 1 is 0 you will find applying the calculation
that Kvar for unity power factor is................... 0

Do you know what the formula is????


for a unity power factor there is no reactive power...

Posted by Jose on 1 March, 2005 - 9:37 pm
If sion 0 is o and kvar is 0, how do we run motors?

What is then the use of a capacitive bank?


Posted by Meir Saggie on 3 March, 2005 - 11:50 pm
Hi guys - oversimplification kills.

A motor draws a certain amount of inductive KVARs. In order for the utility company to see Cos phi of 1 (zero KVAR), we add an equal amount of capactive KVAR's that hopefully cancels out the motor inductive KVARs.


1 out of 1 members thought this post was helpful...
Posted by Phil Corso on 6 March, 2005 - 12:42 am

Hopefully you meant SOME of the motors' kVAR. "Zero" should never be the goal!

Phil Corso, PE {Boca Raton, FL, USA}
[] (

Posted by armando on 13 May, 2005 - 8:44 pm
For unity power factor, there will be no angle displacement between voltage and current. Both are in phase. when we say unity, we are refering to resistive load. If the load is reactive, then power factor will come into picture which is less than unity.

Posted by mahesh on 28 January, 2012 - 8:22 am
how to calculate kvar of any given load for unity power factor? & method of calculation mfd\hz\volt\kvar

Posted by Technical Assistant on 16 February, 2012 - 4:48 am
to calculate kVar, a very simple way for small power generating plants is to apply the principle of the right-angled Triangle for Known power factor and Load being generated by the system. By using the triangular formula VAR = sqrt(VA2- kW2),
where VA is Load(kW)/power Factor

Your use of this site is subject to the terms and conditions set forth under Legal Notices and the Privacy Policy. Please read those terms and conditions carefully. Subject to the rights expressly reserved to others under Legal Notices, the content of this site and the compilation thereof is © 1999-2014 Nerds in Control, LLC. All rights reserved.

Users of this site are benefiting from open source technologies, including PHP, MySQL and Apache. Be happy.

"In any world menu, Canada must be considered the vichyssoise of
nations -- it's cold, half-French, and difficult to stir."
-- Stuart Keate
Advertise here
164-page eBook free download - EtherCAT Applications Guide
View free setup and multi-vendor EtherCAT demo videos online
Servo, steppers, analog, digital & web HMI - Fully Integrated!
Time to incorporate data handling, web HMI and motion in one system! is the largest Automation community on the web. Learn how to advertise here now...
our advertisers
Help keep our servers running...
Patronize our advertisers!
Visit our Post Archive