[114808] in North American Network Operators' Group
Re: Why choose 120 volts?
daemon@ATHENA.MIT.EDU (Seth Mattinen)
Tue May 26 21:24:55 2009
Date: Tue, 26 May 2009 18:24:20 -0700
From: Seth Mattinen <sethm@rollernet.us>
To: "nanog@nanog.org" <nanog@nanog.org>
In-Reply-To: <200905270019.n4R0Jl0Z010462@aurora.sol.net>
Cc: Joe Greco <jgreco@ns.sol.net>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Joe Greco wrote:
>> Once upon a time, Joe Greco <jgreco@ns.sol.net> said:
>>> And I don't like not having anywhere to plug in my power screwdriver's
>>> recharger... I suppose I should see if I can find someplace that has
>>> a transformer of an appropriate size, or does anyone already have the
>>> part number for something that can provide a few hunderd milliamps of
>>> 120V from 208? :-)
>> Isn't 208V usually provided as a connection across two phases of a 3
>> phase circuit? In that case, you get 120V by going between one phase
>> and neutral (no transformer required).
>
> Yes, but this doesn't imply that you have access to those other phases.
> It is easy enough to be delivered 208V single phase service in a data
> center environment.
>
> ... JG
Correct. I have a Smart-UPS RT connected across two legs of 3 phase for
208. The unit does not have a neutral, only ground, so it's 3 wires in
and 3 out. The output is only 208 L-L with odd voltages on L-G. Since
there's no neutral, it can only be used to drive 208 loads or a
transformer for 120.
~Seth
