noobie question - what's PFC?

I think the numbers are like active is capable of up to or over 99% pf, while passive is capable of like 75-85%. Now I dont have anything to back that up but I do remember reading that some where (probably jonny's site.)
 
robman_rob said:
is active better then passive?
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To the home user, you won't notice a difference.

Passive PFC supplies are slightly more efficient.
 
Stinkfist said:
I think the numbers are like active is capable of up to or over 99% pf, while passive is capable of like 75-85%. Now I dont have anything to back that up but I do remember reading that some where (probably jonny's site.)
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can you explain a little more?

I don't know what pf stands for
 
gee said:
Passive PFC supplies are slightly more efficient.
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For the utility company, yeah. ;)

robman_rob said:
can you explain a little more?

I don't know what pf stands for
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Why not read the link Spectre supplied for you? It's all right there.

PF is Power Factor. Power Factor = True Power (Watts) / Apparent Power (VA).

VA is Volts * Amps. You'd think that's the same as Watts, but due to inductance and capacitance the VA is typically 60% of actual wattage. But with active PFC (Power Factor Correction) the VA is improved to nearly 100% of the wattage so the Power Factor would be "1."
 
robman_rob said:
can you explain a little more?

I don't know what pf stands for
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It's hard to explain without going deep into electronics theory, but here's the best I can do...

If your PSU has a power factor of 1.00, then 100% of the power that comes out of the wall socket is used by the supply. But if your supply has a power factor of 0.8, then only 80% of the power that comes out of the wall socket is actually used by the power supply - 20% "bounces off" the supply and goes back into the socket.

This "bouncing power" (called reactive power) causes extra current to flow though the lines in your house. Your electricity meter on your house only measures real power (not reactive power) so this doesn't affect your electricity bill or anything, but the extra current in the wires of your house does cause some power loss and it can cause circuit breakers to trip earlier if you have a bunch of non-PFC power supplies all on the same circuit.

In big office buildings where there are thousands of computers, this reactive power can cause transformer fires, big voltage varations and other bad things. But for joe blow at home, it's no problem.
 
jonnyGURU said:
For the utility company, yeah. ;)
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The extra DC-DC boost converter in a PFC PSU lowers the efficiency a bit.
 
Never mind the heat the extra circuitry gives off.

Heat = Watts and heat increases the de-rating curve of the PSU. Therefore, PFC = Heat X 2!!! (ok.. Not really times two, but you know what I mean.)
 
So you're not actually reading any of the information anyone is providing, right?
 
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