2 May
2005
2 May
'05
7:22 p.m.
As usual during initial power tests - pulled all
cards, and began to
power-up through variac and series light bulb - Bulb glows brightly
as power comes up, suggesting system is drawing far more power than
it should, [...]
Can anyone explain to me what is going on, and why the
unloaded power
supply is drawing so much on it's input?
One possibility comes to mind immediately.
Current flowing != power being drawn. A serial resistance will show
you, approximately, current drawn. But if the load is heavily
reactive, as may well be the case here, it's entirely possible for the
current drawn to be all out of proportion to the power consumed.
An ideal capacitor or inductor, for example, presents a purely reactive
load and consumes no power even though it draws current. (Of course,
real capacitors and inductors are not ideal; put a poorly chosen
capacitor or inductor across mains voltage and you will get a rather
forceful, and quite likely dangerous, lesson in how far from ideal they
can be.)
Mind you, that's not necessarily to say that that's what's going on in
your case. Just a possibility.
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