# how do i go about finding power factor and kva for questions like these

Discussion in 'Homework Help' started by Rance, Mar 26, 2016.

1. ### Rance Thread Starter New Member

Mar 26, 2016
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0
Im not sure how to get the answer for this question and cant find anything that helps. Any help would be apprecitied.

2. ### WBahn Moderator

Mar 31, 2012
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This is Homework Help, not Homework Done For You. You need to show YOUR best attempt at a solution. That gives us a starting point from which to help you identify where you are going wrong and help guide you toward the answer.

Hint: Just tabulate the real and reactive powers, add them up, and convert to apparent power and power factor.

3. ### Rance Thread Starter New Member

Mar 26, 2016
2
0
not sure how to go about this problem this is what i have tried don't know where im going wrong
real power = kva x pf
so i did 100kva x .9pf =90kw for the induction motor being added
and 400kva x .75pf =300kw
new kva is 100kw / .9 = 111.1kva + 400kva = 511.1kva
then 390kw / 500kva = .78 new power factor

4. ### WBahn Moderator

Mar 31, 2012
17,788
4,808
Note that the additional motor, in either case, is NOT 100 kVA -- it is 100 kW. They are giving you the real power load of the motor along with it's power factor.

5. ### WBahn Moderator

Mar 31, 2012
17,788
4,808
Also, note that you can't add kVA values together because kVA is apparent power that makes no allowance for phase angle.