Want to move to all 208V for server racks

Sat Dec 4 19:45:08 UTC 2010

----- Original Message -----
> From: "Michael Loftis" <mloftis at wgops.com>
> 
> On Fri, Dec 3, 2010 at 10:33 PM, Jay Ashworth <jra at baylink.com> wrote:
> > And in fact, much carrier class equipment can be had with -48V
> > power, there are ATX and similar power supplies for PCs that are -48, and I
> > *think* I've seen commercial small UPSs (<3kVa) that give with -48 
> > as well... using 48V battery strings, obviously.
> 
> Take a look at the Solar/Renewable energy systems, Xantrex (Schneider
> actually) makes the XW series inverter/chargers which use 48V battery
> strings and can be paralleled up to a rated total of about
> 18kW at 120/240. This is done by paralleling 3x 6kW inverter/chargers.
> They've an integrated transfer switch, load shaving/sharing (IE if
> you've got say 6kW of generator, but 12kW of Inverter, the system
> capacity is up to 12kW, with battery assist).
> 
> And that's just one option, Magnasine makes parallel inverter/charger
> and inverter systems up to around 12kW, also using 48VDC (or 24VDC)
> strings.
> 
> Both of these are sinewave inverters.
> 
> There's also a telco oriented 48V inverter rack system thats escaping
> my mind at the moment. It can be setup with A/B 48V strings, and you
> plug in inverter modules up to IIRC around 8kW. Not parallel capable
> between racks AFAIK.

I phrased my comment poorly, which mislead you.  I was suggesting a UPS which 
took 208VAC on on the charge side, and charged 48VDC batteries with it,
providing -48 to a rack full of equipment which took that.

People actually call those "48VDC UPSs", though in fact they're just
Little Teeny Battery Plants.  :-)

Cheers,
-- jra