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#21
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Power Conversion Electronics
Nobody wrote: On Sun, 26 Apr 2009 13:09:30 +0100, Eeyore wrote: I just purchase a Silverstone Power Supply Unit (PSU) for my PC. I am amaze with the PFC (Power Factor Correction) rating of over 0.96, which, according to some indicators, means it's 96% efficient. (4% wastage as heat). Incorrect. It has nothing to do with efficiency. It has *some* effect upon efficiency, but not much. Yes, it decreases the overall efficiency of the PSU but increases the efficiency of the grid ! Graham |
#22
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Power Conversion Electronics
Tim Williams wrote: On Apr 26, 11:33 am, MooseFET wrote: It also tries not to draw any current at harmonics. It is unfortunate that one term is now used for two effects but we are stuck with it. Displacement Factor is the fudamental only. Never heard that term. Can you explain ? Graham |
#23
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Power Conversion Electronics
John Larkin wrote:
"Phil Allison" wrote: .... snip ... ** TOTAL ******** !!! They are not capacitive, there is no phase angle. Active PFCs correct WAVEFORM distortion. Take you meds and lie down for a while. What he said was perfectly reasonable. Also, kindly give a complete description about how you determine that an isolated waveform is distorted? -- [mail]: Chuck F (cbfalconer at maineline dot net) [page]: http://cbfalconer.home.att.net Try the download section. |
#24
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Power Conversion Electronics
Phil Allison wrote:
"John Larkin" .... snip ... Take you meds and lie down for a while. ** Drop dead. What he said was perfectly reasonable. ** It was totally FALSE , you insane ****head. I suspect he failed to follow your advice, above. It doesn't appear to have improved his language, either. -- [mail]: Chuck F (cbfalconer at maineline dot net) [page]: http://cbfalconer.home.att.net Try the download section. |
#25
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Power Conversion Electronics
On Apr 27, 1:44*pm, Eeyore
wrote: Displacement Factor is the fudamental only. Never heard that term. Can you explain ? http://en.wikipedia.org/wiki/Power_f...dal_components It's mentioned in a paragraph or two. Apparently it's a fairly new term, IEEE or NEMA probably have something about it. The power meters in the power electronics lab here read three phase V, I, P, Q, PF, DF, etc. directly. Scary expensive Fluke 434. Tim |
#26
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Power Conversion Electronics
"UCLAN" = Monkey's Uncle ** This arrogant IMBECILE has had his lesson. But he didn't learn anything - cos he is a congenital ****wit. ....... Phil |
#27
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Power Conversion Electronics
Tim Williams wrote: On Apr 27, 1:44 pm, Eeyore wrote: Displacement Factor is the fudamental only. Never heard that term. Can you explain ? http://en.wikipedia.org/wiki/Power_f...dal_components It's mentioned in a paragraph or two. A search couldn't find it. Graham |
#28
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Power Conversion Electronics
On Sun, 26 Apr 2009 22:48:56 -0700, UCLAN put
finger to keyboard and composed: There is a big 400vdc capacitor (or two 200vdc caps in series) just after input rectifiers on the AC input. Note C5 and C6 on: http://www.pavouk.org/hw/en_atxps.html They charge to the peak value of the input AC voltage, or 1.414 times the RMS value. Since the cap(s) draw their maximum current when at lowest charge (zero cross-over point), and draw their least amount of current when charged to their highest point, the current waveform *leads* the voltage waveform by 90 degrees. [Maximum current is at the same time as minimum voltage; minimum current is at the same time as maximum voltage.] As much as I dislike the man, he's right. Look at Fig 6 on page 2 of the application note you linked to elsewhere in this thread. PA could easily put at end to this argument by enlightening everyone with his own example ... http://groups.google.com/group/aus.e...e=source&hl=en .... but instead he chooses to elevate himself by demeaning others. - Franc Zabkar -- Please remove one 'i' from my address when replying by email. |
#29
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Power Conversion Electronics
On Apr 27, 9:43*pm, Eeyore
wrote: It's mentioned in a paragraph or two. A search couldn't find it. Second paragraph from link, "In circuits having only sinusoidal currents and voltages, the power factor effect arises only from the difference in phase between the current and voltage. This is narrowly known as "displacement power factor". The concept can be generalized to a total, distortion, or true power factor where the apparent power includes all harmonic components." Tim |
#30
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Power Conversion Electronics
Franc Zabkar wrote: On Sun, 26 Apr 2009 22:48:56 -0700, UCLAN put finger to keyboard and composed: There is a big 400vdc capacitor (or two 200vdc caps in series) just after input rectifiers on the AC input. Note C5 and C6 on: http://www.pavouk.org/hw/en_atxps.html They charge to the peak value of the input AC voltage, or 1.414 times the RMS value. Since the cap(s) draw their maximum current when at lowest charge (zero cross-over point), and draw their least amount of current when charged to their highest point, the current waveform *leads* the voltage waveform by 90 degrees. [Maximum current is at the same time as minimum voltage; minimum current is at the same time as maximum voltage.] As much as I dislike the man, he's right. He is. Actually, from modelling, I've found a big hulky inductor between the rectifier and storage caps is pretty good at correcting harmonics. Trouble is, they're big, heavy and expensive. Sadly active PFC produces even more RF 'hash' that needs to be dealt with. Look at Fig 6 on page 2 of the application note you linked to elsewhere in this thread. PA could easily put at end to this argument by enlightening everyone with his own example ... http://groups.google.com/group/aus.e...e=source&hl=en ... but instead he chooses to elevate himself by demeaning others. Sadly so. Graham |
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