# Three phase and IBM

Jochen Kunz jkunz at unixag-kl.fh-kl.de
Sun Mar 20 02:58:24 CDT 2011

On Sat, 19 Mar 2011 16:08:07 -0700
Eric Smith <eric at brouhaha.com> wrote:

> Jochen Kunz wrote:
>  > No. If you have a symetrical load like a motor you can wire it Y
>  > without connecting neutral. So the presence of netral is no indication
>  > of Y or D.
> If the power plug or cable has a neutral lead, you cannot assume that it
> doesn't need a neutral connection.
That is exactely what I wrote: It depends on the equipment if it needs
netral or not. The cable may have a neutral, but the equipment may not
need it.

> Note that neutral is NOT the same thing as ground.
I am verry aware of this. I was an electrician in a former live... :-)

> Here in the US, the most common commercial three-phase power
> configurations are:
>
> *  120/208 wye   - 120V RMS phase-to-neutral, 208V RMS phase-to-phase
> *  208 delta         - 208V RMS phase-to-phase
Ahhh, I forgot about the insanity of US three phase distribution.
This caused the confusion on my end of the transformer. ;-)

In Germany, well, most if not all of Europe, the entire power grid is
three phase. The power that gets distributed to a house is always three
phase 230 / 400 V in Y configuration. Single phase loads like ordinary
power outlets are wired from one phase to neutral. The single phase
circuits in a house (apartment, flat, ...) are spreed across all phases
motors, ... are allways three phase. So we have three phase in every
household.
--

\end{Jochen}

\ref{http://www.unixag-kl.fh-kl.de/~jkunz/}