On Sat, 08 Apr 2006 20:35:17 GMT, the renowned "Siggy"
wrote:

A while back there was a discussion about why wall wart transformers that
were not under load would draw no current. Anyone recall that thread? As I
recall there were some references to the induced currents created by
collapsing magnetic fields etc.

Anyway, I'm trying to either prove or disprove the statement that unplugging
wall warts when not actually using them to power or re-charge your device
will save electricity. My recollection is that it doesn't matter. Right or
wrong?

It does matter. Just put your hand on an energized wall-wart which
isn't plugged into anything and you'll feel warmth- losses which are
typically in the 1-4W range. The Asian wall-wart sweatshops use about
the cheapest of materials, particularly the laminations, and push them
to the limits of saturation (meaning they don't use any more material
than absolutely necessary), so there is substantial loss. Using better
magnetic alloys would push the cost up perhaps 10-20%, so it's not
done.

California is supposed to be enacting a regulation mid-this year wot
prohibits sale of new gadgets with losses of more than 500mW, which
will knock out most linear AC adapters (also the active mode losses
are limited). It's already voluntary in China, Canada and the EU, and
mandatory in Oz. Manufacturers will probably more go to switchers
rather than improving the linear adapters**, which has advantages in
shipping weight and size, and allowing 'universal' input voltage which
can be used anywhere in the world, from 100VAC in Japan to 240VAC in
Europe etc. Also less losses in regulation.

Anyway, if the losses are 2.5W and you're running it 24/7, you're
wasting 22kWh/year, which is probably worth more than the adapter cost
to make, but it's still only a couple dollars, so not really a big
deal for one. But if you made all of them in the US twice as efficient
you could save energy equivalent to the output of a nuclear power
plant or two, IIRC.

http://energyefficiency.jrc.cec.eu.i...tinez%20PS.pdf

** Or maybe just hire lobbyists..


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
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