From: dxmm@albury.nospam.net.au   
      
   On 23/04/14 07:01, Uncle Peter wrote:   
   > On Tue, 22 Apr 2014 11:00:36 +0100, Daniel    
   > wrote:   
   >   
   >> On 22/04/14 04:26, Uncle Peter wrote:   
   >>> On Mon, 21 Apr 2014 12:22:39 +0100, Daniel    
   >>> wrote:   
   >>>   
   >>>> 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:   
   >   
   >>>   
   >>>>>   
   >>>   
   >   
   >>>>>> 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??"   
   >>>   
   >>> When you immediately answered yourself, with two shriek marks, I assumed   
   >>> you were telling me.   
   >>   
   >> What part of the world are you from?? In some parts of the world, the   
   >> first thing people might think when they hear "PFC" would be "Private   
   >> First Class"!!   
   >   
   > Only if they're military.   
   >   
   >>>>>> 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.   
   >>>   
   >>> But surely if it's not adjusted, then it's overcompensating when the   
   >>> supply is not fully loaded.   
   >>   
   >> No, in a Switched Mode Power Supply, as the load varies, it is *Switched   
   >> On* for more of less of the Alternating Cycle. If the supply's output   
   >> (Current/Voltage) is falling below the required (Current/Voltage), the   
   >> Switching element/transistor is switched on for more of the input cycle,   
   >> not the input voltage!!   
   >   
   > I see.  So this is seperate from the yellow one connected across the   
   > mains input?   
      
   Yes, the "yellow one connected across the mains input" is a bridge   
   rectifier, which converts the AC Sinewave input into single polarity   
   pulses at twice the mains supply frequency.   
      
   >>>>>> 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!!   
   >>>   
   >>> You said "very little effect on the phase angle of your homes mains   
   >>> supply!!"  It's probably 90% of my home's supply.   
   >>   
   >> At some particular moment, you might be correct that the power supply is   
   >> having this great effect, but over a day/week I doubt it would be   
   >> anything like 90%!   
   >   
   > It is.  Those things run 24/7.   
      
   Do you switch on lights at night?? That'll effect the mains supply current.   
   Do you have a refrigerator that turns on and off?? That'll effect the   
   mains supply current.   
   How about a heater/electric blanket, etc., etc.,  etc.   
      
   >>>>>> 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!!   
   >>>   
   >>> Yes, I was just pointing out I have a ridiculous freezer.   
   >>>   
   >> Wacko!!   
   >   
   > It hasn't got food in it.   
   >   
   So what's it doing "On", apart from wasting energy??   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)