OT question for electronics wizards

From: Allison J Parent <allisonp_at_world.std.com>
Date: Mon Dec 21 21:36:22 1998

<Hi. Just a quick question which is kind of off topic - with switched powe
<supplies like those in modern PCs, when it says the input current is 7 amps
<115 volts, is that the constant no matter how much the computer itself draw

7A_at_115V... an 800w PS???

<or the maximum, no matter what? If it's the latter my computer room is
<going to need more circuits in a big hurry...

The input current is load dependant above a minimum current. If that 7A
PS is real I'd expect a minimum of .5A-1.5A at near minimum load.

Plain english, input current is proportional to load current plus some
internal losses.

If it helps I have 6 vaxen on the same 15A line. Three 3100/M10E, one
3100/M76, two VS2000, BA123 MicrovaxII and one BA23 MicrovaxII. Worse
case numbers would have me using a 25-30A line. Real numbers are far
lower. Also the 3100 PS is only some 160W but if the aux outlet is present
for say a monitor then there is +3-5A added to the input current for that
outlet. So it's easy to have a spec for 7A but it's likly allowing 3A for
a monitor or somesuch.

Allison
Received on Mon Dec 21 1998 - 21:36:22 GMT