[Cialug] [omaha] Google Datacenters

[Daniel E Sloan]

As I recall from a power class...at this point many years ago...the electron flow is almost entirely on the outer skin of the cable.  This is why the main lines from the Hoover Dam are hollow.  (saves weight, while allowing maximum transfer)

My grandfather was an electrician at the Montgomery Wards building in Chicago when all the power transmission from the utilities was in DC. So power transfer through a DC bus in a server room should certainly be feasible. 

Dan Sloan


----- Original Message -----
From: "Daniel A. Ramaley" <daniel.ramaley at drake.edu>
To: "Central Iowa Linux Users Group" <cialug at cialug.org>
Sent: Friday, April 10, 2009 11:08:23 AM GMT -06:00 US/Canada Central
Subject: Re: [Cialug] [omaha] Google Datacenters

Possible? Of course. Practical? I don't know.

You need very thick wires (thick inch-thick bars of metal) to carry 
enough current at 12V if the distance spaned is very far. If the wires 
are too thin, they will have too high a resistance and drop too much of 
the potential. If the wires are really too thin, they will get hot and 
melt. Making thick enough wires out of copper might be prohibitively 
expensive. Cheaper metals that don't conduct as well would require even 
thicker wires. Of course, if you have a room temperature superconductor 
(presumably made of unobtainium), then it might be more feasible. But i 
don't know much about superconductors; they might have limits on how 
much current they can carry too.

People with more electrical knowledge please correct me if necessary.

On 2009-04-10 at 10:49:09, jrnosee at gmail.com wrote:
>I've often wondered if it would be possible to convert AC to 12VDC for
> the entire datacenter then run 12V lines to each server and only have
> a DC->DC 12V/5V/3.3V Point of Load power supply do the conversion. 
> Thus eliminating power loss in the multiple AC-DC conversions and
> running all the extra power supply fans, etc.

------------------------------------------------------------------------
Dan Ramaley                            Dial Center 118, Drake University
Network Programmer/Analyst             2407 Carpenter Ave
+1 515 271-4540                        Des Moines IA 50311 USA
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