Generic power factor
- Thread starter arnettda
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Given the formal definition of power factor as the instantaneous power integrated over time divided by the product of the RMS voltage and the RMS current, you can prove mathematically (just a little algebra and a little calculus) that PF cannot be greater than 1.
And that you get 1 only when the current waveform is an exact match to the (not necessarily sinusoidal) voltage waveform.
That corresponds to a linear resistive load.
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You can use a PF of 1.0 if the load is purely resistive with no reactive components and zero harmonics. Not altogether common, at least in my experience, to get that.
And, as GD has said, you can't have a PF greater than 1.0.
kwired
Electron manager
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- NE Nebraska
You can have a power factor that is leading instead of lagging though.
A circuit with a capacitor only would have a leading power factor.
A circuit with a capacitor only would have a leading power factor.
Yes, but close to zero.
kwired
Electron manager
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That depends on the KVAR of the capacitor just like power factor of a motor depends on KVAR of the motor.
If you have a motor with KVAR of 10 and apply 20KVAR correction capacitor - you still end up with a net of 10 KVAR in your circuti - but it went from lagging power factor to leading power factor.
I was responding to your
comment.
kwired
Electron manager
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- NE Nebraska
Ok. I was assuming a circuit with a voltage source though
PFC has a voltage source.............Ok. I was assuming a circuit with a voltage source though
kingpb
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Mathematically it would be impossible. Power is a vector which has magnitude and direction. The power factor is derived by taking the cosine of the angle (direction). The cosine of 0deg is = 1.0 In this case the KW = KVA, The cosine of 90 deg = 0; thus KW is zero and KVAR = KVA. At 91 deg, the value will take on a negative value which means it is now leading instead of lagging; and all the way until 180 deg, but never more than -1.
Basically, it's a whole bunch of trigonometry thus the range will always be between 0 to 1.0 which is termed lagging, and between 0 to -1 which is termed leading.
Basically, it's a whole bunch of trigonometry thus the range will always be between 0 to 1.0 which is termed lagging, and between 0 to -1 which is termed leading.
pf = active power P / total power S
active power = perform work
total power S = active power + reactive power = P + jQ
|S| = sqrt(P^2 + Q^2), even if Q = 0 then S = P and pf = P/P = 1
if pf > 1 that means you are getting out more active power/work than the total you put in
not happening
active power = perform work
total power S = active power + reactive power = P + jQ
|S| = sqrt(P^2 + Q^2), even if Q = 0 then S = P and pf = P/P = 1
if pf > 1 that means you are getting out more active power/work than the total you put in
not happening
ggunn
PE (Electrical), NABCEP certified
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As others have said, PF cannot be >1.00. PF is a measure of how well AC voltage and current are aligned in the time domain. If they are perfectly aligned, PF = 1.00. If the current waveform shifts either way relative to the voltage waveform, PF < 1.00.
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