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