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Thursday, October 22, 1998
Question:
I met a guy from the power company who told me I needed to correct my power factor since it is 68%, what does 68% power factor mean and what do I do to correct it??
A
Answer:
The short answer, it is the percent of available energy that you have used. If you using 100 kVA and your power factor is 68%, then you are using 68 kW of real power. The power company has to build and/or maintain 100 kVA or transformation for you ... HMMM ... not a good deal, is it? That is why most power companies bill for poor power factor.
kVA is the vector sum of kW and kVAR. kW is true power whereas kVAR is either inductive or capacitive (positive or negative). kW is what is actually used but, kVA is used to calculate voltage drop, transformer and service sizes, it is read when you use a clamp-on ammeter, etc. You can lower the kVA by adding capacitive kVAR which is 180 degrees out of phase with inductive kVAR and is generally added with motor load.
This is a more complex subject than it appears, especially when non-linear loads and harmonics are thrown into the mix. If the harmonic distortion is high enough from non-linear loads, you can destroy the capacitors if inductance is not added with them to shift the resonance point. This is more properly addressed in an apprenticeship program (or in your old notes) or in the numerous trade magazines such as Electrical Contractor and the IAEI News.