Simply stated, the Power Factor is the percentage of Apparent Power that does real work.
- kW – 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 – Reactive Power:- It is the power that magnetic equipment (transformer, motor, and relay)needs to produce the magnetizing flux.
- kVA – Apparent Power:- It is the “vectorial summation” of KVAR and KW.
Beer Mug Analogy
- The thirst-quenching portion of your beer is represented by KW. This is the usable power.
- Along with your beer comes a little bit of foam. (And that foam just doesn’t quench your thirst.) This foam is represented by KVAR. This part is the wasted power.
- The total contents of your mug, KVA, is this summation of KW (the beer) and KVAR (the foam).
Also Read: Horse Rail Analogy
Understanding Power Factor
- 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.
- KVAR would be very small (foam would be approaching zero)
- KW and KVA would be almost equal (more beer; less foam)
So, In order to have an “efficient” system, we want the power factor to be as close to 1.0 as possible.
A power factor of one or “unity power factor” is the goal of any electric utility company.
It is because if the power factor is less than one, they have to supply more current to the user for a given amount of power use. In so doing, they incur more line losses.