[ExI] Power factor

Keith Henson hkeithhenson at gmail.com
Thu Nov 26 03:26:25 UTC 2009

 Eugen Leitl <eugen at leitl.org> wrote:

On Wed, Nov 25, 2009 at 06:26:18AM -0500, Brent Neal wrote:

>> Really good point about power factor. That's been my largest concern
>>> about the push for CFLs, since most manufacturers don't spend the half-
>>.penny necessary for an inductor that would correct the power factor in
>> those things. :(

>Don't forget switching power supplies either. Get a lot of them
>together, and interesting (as in: possibly expensive) things
>start to happen.

I designed power factor corrected switching power supplies using the
MC33262 See page 13 and 37 here:

and I don't understand what Brent is talking about.  Can you explain?

Re  Eugen's comment, the problem is not switching, but capacitor
input, (see page 13 of the above document) and yes those cause
problems when a whole bunch of PC's are plugged in.  Company I worked
for felt they had to replace a big 480 dry step down transformer that
was overheating due to the high peak currents from 100 PC power
supplies.  (My approach was to take the top off and put a big
cardboard chimney on the transformer.)


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