kW kVA pf


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An alternating current circuit with a power factor (electrical efficiency pf) of less than 1.0 needs some of the input electricity to build magnetic fields in components. So not all of the electrical energy put into a circuit can do work. kVA is 1000 volt amperes or input. kW is 1000 watts or output. The comparison of these two values is known as the power factor. For starters pf=kW/kVA or even pf=W/VA or even kW = kVA pf

So by multiplying the kVA by the power factor, a calculation will produce the amount of work that is produced kW. Neat, eh?

Sure pf is also the cosine of the phase angle (theta) of the circuit.

There are many formulas for each of these values. The formula to use in a calculation is the one with will give you what you want based on what you have. This sounds like a great recipe for life. Physics in life. Yeah, baby.

So here are a few formulas. Note where the circuit under consideration is single phase, leave out the 1.732 factor

W watts

W=IE 1.732 pf/ eff
W=pf VA
W=I squared Z 1.732 pf / eff
W=VAR Z pf / X sub L

VA volt amperes

VA=P /(eff pf)
VA= HP 746 / (eff squared pf)
VA=E squared 1.732 / (Z eff)
VA= W/pf

pf power factor

pf=W eff / (I E 1.732)
pf=P/(VA eff)
pf=cos theta

Find practice problems HERE for single phase.

Find practice problems HERE for single phase.

Find audio support HERE for single phase.

Find audio support HERE for three phase.

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