# UPS output calculation

Discussion in 'General Electronics Chat' started by shahnawaz, May 21, 2012.

1. ### shahnawaz Thread Starter Active Member

Dec 30, 2008
37
0
Hi all,

i am cofuse about the calculation of Output of my UPS with cosθ of my UPS.
my ups is 6KVA at 230VAC. so my boss is calculating the cosθ as below

P= VI Cosθ
6000= 230 X I X .8
6000/230 X .8 = I
6000/184 = I
I= 32.60.
but i am saying as read is
6000 X 0.8/230 = 20.8

PLEASE TELL ME WHY THE HUGE DIFFERENCE BETWEEN MY AND MY BOSS CALCULATION.

Please tell me in detail of how i can calculate my output power in amperes and what is the farmula.

thanks

2. ### #12 Expert

Nov 30, 2010
16,655
7,293
You're going at it wrong. The power factor does not change the amps that will be provided. It changes the actual power that the load absorbs when the full amperage is flowing. Power = EI cos theta
not I = power/E cos theta

3. ### t_n_k AAC Fanatic!

Mar 6, 2009
5,448
783
Yes indeed. The UPS will be capable of delivering a maximum load current of around 26.1A.

A supplementary question might for instance be - Could this UPS service a predicted power load of 4kW at pf=0.6?