can pf=1? be a possibility

[electronist]

Is it true that a power factor of 1 cannot be achieved?
To what extent can the power factor be improved. Was just thinking about it? can PF=0.999999999999999 be possoble

 

[Optikon]

Is it true that a power factor of 1 cannot be achieved?
To what extent can the power factor be improved. Was just thinking about it? can PF=0.999999999999999 be possoble

Theoretically, If I recall correctly PF = 1 is possible. One can choose a reactive network to perfectly align the phase of V & I.

But don't even worry about it. From a practical standpoint, one cannot control circuit parameters & parasitics to such an extent as to make PF = 1 but there are systems that can get very close.

 

[John Sorensen]

Ever heard of the intermediate value theorem*? If power factor passes from anything lagging to anything leading, it must have passed through 1.0.

It's not impossible. Hard to do if that's what you're striving for, but certainly not impossible.

Maybe they were talking about efficiency, or some other physical impossibility.

j.

*The only possible argument is that the power factor is discontinuous as theta passes through zero, but it's not hard to show that it is continuous.

 

[Dean Huster]

If you're talking about real, live industrial electricity where you're dealing with big motors, solenoids, transformers and all that rot, it ain't never gonna happen. You can correct the PF, but no one tries to pull it to 1.000; they just try to minimize it on one side of 0° or the other. If one did make the PF perfect, all it would take is a motor being loaded or unloaded a bit differently than it was when the PF was corrected to 1.000 and it would shift off again. So trying to achieve perfection isn't the least bit practical.

On the other hand, if you're just toying with simple electronics, a simple 1K ohm carbon composition resistor slapped across the 60Hz mains will exhibit a PF so close to 1.000 that to argue that it's anything but cannot be proved with any measurement equipment known to mankind.

If we insisted that all our water be as pure as that pure of a power factor, we'd be dehydrated in a matter of a couple of days.

Dean

 

[Styx]

Have a look at "Active Rectifiers".

Their aim is to draw sinusoidal current from the utility no matter what the load is.

With a fast enough loop for the control as well as high enough switching freq (for the input stage converter) you can get it very close to PF=1 (well it hovers around it very closely).

However, that is dependant on your reference SIN wave from the VCO being of extreamly good form (very low harmonic content). Any distortion will be transposed back onto the supply (as the control will try and shape voltage and current to follow the reference SIN wave)

 

[Glyph]

This answer is just for kicks so have a good laugh :lol: :

If you want pf=1 hook up the line to a resistor and let it heat up. Using the heat from the resistor run an internal generator (stirling engine comes to mind due to its small size and efficiency). Then use the energy from THAT generator to run whatever non-resistive loads you have.

In theory this setup would give you a PF=1 because the line really IS driving a resistive load (the heating resistor).

Best of all, if you use a resistor with a positive temperature coefficient it would be current limiting, self-regulating, in-rush limiting, heat capacity would closely emulate electrical capacity, soft-starting and still be fully isolated.

Efficiency would be jack though.

Don't forget plenty of ventilation!

 

[Styx]

very nice, unfortunetly to do that you would need a high wattage resistor to get enough power, high wattage resistor tend to be inductive, thus your power factor goes down.

Best and only way is to convert the grid to HV-DC, lots of generators everywhere outputting silly-high voltage.

NO PF loss or anything

 

[John Sorensen]

high wattage resistor tend to be inductive

You can buy low inductance wire wound resistors. I believe they're wound ambihelically.

j.

 

[Styx]

high wattage resistor tend to be inductive

You can buy low inductance wire wound resistors. I believe they're wound ambihelically.

j.

doesn't matter still going to be inductive especially at any decent power levels (that industry would use). you are still going to get inductance - fact of life.

DC all the way...

 

[Nigel Goodwin]

ambihelically.

Now THAT'S a really nice word, my spell checker doesn't like it, but I do!.