Stupid Powersupply question

From: Jerome Fine <jhfine_at_idirect.com>
Date: Sun Sep 2 13:19:13 2001

>Zane H. Healy wrote:

> Subject says it all. If I've got a StorageWorks shelf with a 150W
> Powersupply, I don't draw 150W do I? I simply draw the sum of the number
> of disks in the shelf. Trying to see if I've got this down right as I need
> to add some disks and the cost of power is going up again.

Jerome Fine replies:

I don't know if this will help.

Let us assume that (electrical) energy cost $ US 1.00 per kilowatt hour.
That is the same as a power supply which draws 100 Watts for 10 hours
or 500 Watts for 2 hours.

If you run the StorageWorks shelf and it draws even 100 Watts (usually the
ratting is the maximum and it will normally draw much less), then in one day
that it runs 10 hours, it will end up costing $ US 1.00 for that day.

So an Air Conditioner (funny name for a cooling device) that draws 4000 Watts
(a circuit of 220 Volts and 18.18 Amps on each of the 110 Volt phases) will
cost $ US 4.00 an hour to run. Of course, the circulating fan in the house or
the apartment will add to that cost, but probably only by about 10%.

The formula: Power (Watts) = Voltage (Volts) * Current (Amps)
Also: Energy (WattHours) = Power (Watts) * Time (Hours)
Note also that my example price was $ US 1.00 per KiloWattHour,
NOT just WattHour. It is the difference between speed and distance
and time. You can't go a speed of just 10 miles and your distance
is never in 20 miles per hour.

Sincerely yours,

Jerome Fine
Received on Sun Sep 02 2001 - 13:19:13 BST