[Discuss] Server Room Power

[gaf at blu.org (Jerry Feldman)]

On 10/11/2011 01:56 PM, Matthew Kowalski wrote:
> Does anyone have any experience with running server equipment (Dell Power
> Edges, HP Proliant DL G7s&  HP c7000 Enclosures) at 208 VAC instead of 120
> VAC?  Right now we're running 20 Amp circuits at 120 VAC but I've been
> reading some on the web about better efficiency at 208V along with
> additional power available.  The main issue we're having is getting enough
> power to the racks to run the power dense equipment.
>
> Given one form of Ohm's as Power (Watts) = Current (Amps) x Voltage (Volts):
>
> The max power out of a single phase 20A 120VAC circuit is 2400 Watts.
> The max power out of a single phase 20A 208VAC circuit is 4160 Watts.
>
> Since only 80% of the power should be utilized the max power would be
> reduced to 1920 Watts and 3328 Watts respectively.
>
> Am I missing something?  We've got a network power unit that can output
> various VAC voltages and up to 3 phases so this is really more of a
> distribution to the rack question.  I'm thinking all I need is an
> electrician to add additional circuits, am I right?
>
We are running 2 208VAC circuits. We have 7 old Intel Whitebox systems + 
1 ReadyNAS (2 power supplies), 1 HP DL380 G7 VMware ESX and a few other 
things. Before that on 120V, I had to split the power between two 
different circuits including running a power cord across the ceiling. I 
am now using a Metered C-24V Dual Input CDU 
http://www.servertech.com/products/metered-pdus/metered-pdu-c-24vd

One issue with computers is that while they are running normally, things 
should be ok, but on startup, you are spinning up all the drives and the 
fans.

-- 
Jerry Feldman<gaf at blu.org>
Boston Linux and Unix
PGP key id:3BC1EB90
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