On 21/04/14 05:03, Uncle Peter wrote:
On Sun, 20 Apr 2014 12:17:45 +0100, Daniel
wrote:

On 18/04/14 22:45, Uncle Peter wrote:
On Fri, 18 Apr 2014 12:48:36 +0100, Daniel
wrote:

On 17/04/14 23:46, Uncle Peter wrote:
On Thu, 17 Apr 2014 13:50:32 +0100, Daniel
wrote:

On 17/04/14 10:07, Uncle Peter wrote:

When I last dealt with this, power generator companies "assumed"
there
would be an average power factor and set up their generators to
handle
that. Your individual house (or, probably, even a small factory)
would
not cause much variation in that power factor, considering the
generators are probably supplying hundreds of thousands of homes
at the
same time!!

That won't apply to switched mode power supplies clipping off the
peaks
though.

Wouldn't cause a very big blip in the grander scheme of things.

And what SMPS clips off the peaks?? Usually they vary the switch on
point in the A.C. waveform.

You can get power supplies with "active PFC" which is presumably what
you just described. However the cheap ones have "passive PFC" or no
PFC, so presumably they just top up the bulk capacitors at the peak of
each waveform. A basic transformer and rectifier will do the same.

What's "PFC" when it's at home?? Power Factor Correction maybe!!

I know that.

But *I* didn't, which is why I asked "What's "PFC" when it's at home??"

To the mains supply, most things look like Inductors, which means the
voltage waveform and the current waveforms are not in phase. Power
Factor Correction simple means that capacitors are switched in to
counter-act the Inductance, so the Voltage and Current are more nearly
in phase.

And at different power level draws from the output of the power supply,
presumably a different capacitance is ended to correct it. Active PFC
probably changes it accordingly. Or adjusts the other type of power
factor which you haven't mentioned - wave clipping.

I'm guessing just one, very big, capacitor which can handle the
filtering task for all loads up to the Power Supply's rating.

Active PFC might be changing how a transistor "appears" (more capacitive
or less capacitive) to fix the phase angle.

And, as I typed earlier, your little power supply would have very little
effect on the phase angle of your homes mains supply!!

How about ten 850W power supplies?

10 x 850 watt power supplies, total 8.5kW, from a 240V supply takes
about 35Amps, .... and lets double that to allow for transformer and
other circuitry loses = 70Amps!! Whoopee!! from your regional Power
Company, which probably supplies THOUSANDS of Amps!!

Now, when your refrigerator's (inductive) motor switches on, now that
might have a noticeably affect, but, in the greater scheme of your
regional Power companies operations, zero effect!!

Or my industrial grade meat freezer.

What's that, another 10kW!! WOW!! or rather Whoopee!! And remember the
freezer motor is not working 24/7 (or at least it shouldn't be), so its
real power consumption would be much lower, maybe 1kW at most!!

Daniel