5 replies to this topic

[will]

how do you calculate power factor.Say if your load is
120VAC
0.6Amps

Is this the correct way to calculate it?

120Vx0.6A=72Watts

0.6Ax120V=72VA

72W/72VA=1 PF=1 Is this right?

[marke]

Hello Will

Welcome to the forum.

Power factor is the ratio of KW to KVA. i.e. pf = KW/KVA.
V x I = VA
V x I x PF = Watts

You can calculate the power factor provided that you know the volts, Amps and KW. You can not calculate PF from volts and amps only.

There are two forms of power factor, one is displacement power factor, caused by reactive loads (typically inductive) and the other is harmonic power factor caused by solid state loads such as computers and VSDs.
If you have an inductive load such as a motor, you can use an oscilloscope to measure the phase angle between the voltage and the current and calculate the displacement power factor from the cosine of the displacement angle.
Unfortunately, you need more measurements than just a voltmeter and ameter.

Best regards,

[marke]

PF = Cos (Phi) is true for displacement power factor only. It does not give an indication of distortion power factor.

PF = KW/KVA is more correct.

Best regards,

[marke]

Actually, it is pf = w / VA by definition.
This is true for displacement power factor and distortion power factor.
Displacement power factor can also be expressed as pf = cos(thi) where thi is the angle between voltage and current.

Best regards,