From: dxmm@albury.nospam.net.au   
      
   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   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)