[132884] in North American Network Operators' Group
RE: Want to move to all 208V for server racks
daemon@ATHENA.MIT.EDU (John van Oppen)
Thu Dec 2 14:20:54 2010
From: John van Oppen <jvanoppen@spectrumnet.us>
To: 'Ingo Flaschberger' <if@xip.at>, Kevin Day <toasty@dragondata.com>
Date: Thu, 2 Dec 2010 19:20:39 +0000
In-Reply-To: <alpine.LFD.2.00.1012021858270.2841@filebunker.xip.at>
Cc: NANOG list <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
It is probably worth nothing that a 3-phase input in Europe is actually 240=
/415 volt Y (for every panel I have seen in Germany at least, even the plac=
es I have lived there had 240/415 three phase). The normal 240v single ph=
ase outlet circuits were the phase to neutral voltage. Obviously Europe a=
lso runs at 50 hz vs 60 in the US as well but the three phase still works t=
he same way.
A Europe 64 amp 240/415 circuit is pretty close to equivalent in to a 277/4=
80 Y configured 60 amp circuit in the US. The biggest notable difference =
is that equipment that runs on two different service voltage ranges where E=
urope has far less need for in-building step-down transformers since even s=
mall loads work on the phase-to-neutral voltage of the big services. I al=
ways find it interesting in the US to note how many 480v to 120/208Y step-d=
own transformers one can find in a big building or datacenter.
John
-----Original Message-----
From: Ingo Flaschberger [mailto:if@xip.at]=20
Sent: Thursday, December 02, 2010 10:08 AM
To: Kevin Day
Cc: NANOG list
Subject: Re: Want to move to all 208V for server racks
> I was just recently trying to explain this to a European friend who thoug=
ht I was hallucinating this system, so I took a picture.
>
> http://dl.dropbox.com/u/230717/temp/208YPanel.jpg
>
> That's a picture of one of the breaker boxes in our office, showing what =
you described. There are 3 phases coming into the panel, each a different =
coil off a Y transformer, as well as a "neutral". Those are the 4 black wir=
es you see at the bottom. You can see how the three hot phases are staggere=
d as they go up the breaker rails.
>
> For standard 110V service, you use a single-wide breaker and send one hot=
phase + neutral and you get 110V. The difference between two phases is 208=
volts though, so you use a double wide breaker and can send to device with=
out using a neutral wire. Just 2 hots and a ground. If that's all you're do=
ing (you don't need legacy 110V service anywhere) you skip the ground wire =
going into the panel entirely.
that one looks dangerous.
In europe:
http://img406.imageshack.us/i/verteilerkasten.jpg/
64A 240V 3-Phase input.
Out to Servers single phase, output to airconditioners with 3 phase (not=20
at this picture).
Kind regards,
Ingo Flaschberger
