One of the mysterious metrics that may appear on your electric bill is power factor. You might wonder, what is power factor and how does it affect utility costs?
Power factor is determined by the difference between real power, which is measured in kilowatts (kW) and apparent power, measured in kilovolt-amps (kVA). What does that mean? A train track analogy will help explain.
When a train engine pulls a car from point A to point B, it's using power to do real work. This is called real power. Some equipment however, such as an induction motors, requires an induction field to operate. This requires additional power to do the same amount of work.
Imagine we replace the train engine with a horse. The horse can't run on the track, so it's off to the side pulling the cart. The horse is doing real work moving the cart forward, but it's also using extra effort pulling the cart sideways. This extra effort or power beyond what's needed to move the cart toward point B is called reactive power, which is measured in kilovolt-amp reactive (kVAR).
The side of the triangle between the cart and the horse is apparent power. This is the power that is actually supplied by the energy company to get us from point A to point B.
Now we have all the information we need to calculate power factor. Just divide real power (kW) by apparent power (kVA). This will give you a number between 1 and 0. A power factor of 1 means a closely in sync system. The closer you get to 0, the more power your energy company has to provide.
What does this mean to you. If you have low power factor, you may be charged a penalty. This is because facilities with low power factor draw more apparent power, causing additional strain on the electric grid.
To improve power factor, you have to reduce your reactive power. The best way to do that is by adding capacitors to your electric system. When you reduce reactive power, you minimize the difference between real and apparent power, increasing your power factor. This won't reduce your energy consumption, but it can reduce power factor charges in your energy bills.
