20 Mar
2011
20 Mar
'11
12:58 a.m.
On Sat, 19 Mar 2011 16:08:07 -0700
Eric Smith <eric at brouhaha.com> wrote:
Jochen Kunz wrote:
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.
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. 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
to spreed load. Biger loads like electric stoves, water heaters, big
motors, ... are allways three phase. So we have three phase in every
household.
--
\end{Jochen}
\ref{http://www.unixag-kl.fh-kl.de/~jkunz/}