Help with power factor calculations, how to find KW from KVA and KVAR
A single line feeds 2 separate loads. The first load is 1200kw at .80 pf. The second load is 800kva and 300 kvar. What is the total load on the single line feeder?
I have been racking my brain trying to figure out this question that someone else said was on the Level 4 exam. My answer is 1702kW, can anyone let me know if I am right? Here is how I figured it out:
Load 1: Easy, just correct kW for power factor. 1200 * 0.8 = 960kW
Load 2: This is where it got tricky but this is how I was able to calculate kW from kVA and kVAR, I think:
(800kVA)2 = 640000
(300kVAR)2 = 90000
640000 - 90000 = 550000
Square root (550000) = 742kW
Load 1 (960kW) + Load 2 (742kW) = 1702kW
Just looking to know if this is correct. Thanks in advance.
kva kvar kw calculation
The equation is: KW = KVA x pf, therefore KVA = KW/pf
1200 kW = KVA x 0.8 ..... KVA = 1200/0.8 = 1500 KVA,
In other words, the 1200 kW, with pf 0.8, needs to have available 1500 KVA.
For the second question we have:
(KVA)2 = (KVAR)2 + (KW)2 .... (800)2 = (300)2 + (KW)2 (This is you got it right)
Observe that you can use the above equation to calculate the KVAR for the first question:
(1500)2 = (KVAR)2 + (1200)2
KVAR = Square root ( 2250000 - 1440000) .... KVAR = Square root(810000) = 900
Load: 1500 + 800 = 2300 KVA
1200 + 742 = 1942 KW
900 + 300 = 1200 KVAR
how to find kvar
doh! thats what i get for not double checking my work. thanks for clearing this up for me!
Originally Posted by joaogemal
kva to kw
No calculation is necessary for load 1, you are given the kW.
Originally Posted by veracon0700
i found this power factor triangle to be helpful in understanding these kind of calculations
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