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

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

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.

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.

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

"UCLAN" = Monkey's Uncle


** This arrogant IMBECILE has had his lesson.

But he didn't learn anything -

cos he is a congenital ****wit.




....... Phil

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

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.

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

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