What is Power Factor?

What is Power Factor?
Super. I’m ready to find out what power factor is.
To understand power factor, we’ll first start with the definition of some basic terms:
KW is Working Power (also called Actual Power or Active Power or Real Power).
It is the power that actually powers the equipment and performs useful
work.
KVAR is Reactive Power.
It is the power that magnetic equipment (transformer, motor and relay)
needs to produce the magnetizing flux.
KVA is Apparent Power.
It is the “vectorial summation” of KVAR and KW.
Let’s look at a simple analogy in order to better understand these terms….
Let’s say you are at the ballpark and it is a really hot day. You order up a
mug of your favorite brewsky. The thirst-quenching portion of your beer
is represented by KW (Figure 1).
Unfortunately, life isn’t perfect. Along with your ale comes a little bit of
foam. (And let’s face it…that foam just doesn’t quench your thirst.) This
foam is represented by KVAR.
The total contents of your mug, KVA, is this summation of KW (the beer)
and KVAR (the foam).
Figure 1
So, now that we understand some basic terms, we are ready to learn about power factor:
Power Factor (P.F.) is the ratio of Working Power to Apparent Power.
Looking at our beer mug analogy above, power factor would be the ratio
of beer (KW) to beer plus foam (KVA).
P.F. = KW
KW + KVAR
. = Beer
Beer + Foam
P.F. = KW
KVA
Thus, for a given KVA:
• The more foam you have (the higher the percentage of
KVAR), the lower your ratio of KW (beer) to KVA (beer
plus foam). Thus, the lower your power factor.
• The less foam you have (the lower the percentage of
KVAR), the higher your ratio of KW (beer) to KVA (beer
plus foam). In fact, as your foam (or KVAR) approaches
zero, your power factor approaches 1.0.
Our beer mug analogy is a bit simplistic. In reality, when we calculate
KVA, we must determine the “vectorial summation” of KVAR and KW.
Therefore, we must go one step further and look at the angle between
these vectors.