20 Apr
1999
20 Apr
'99
5:54 p.m.
At 10:14 PM 4/20/99 +1, Hans wrote:
To get 2 phases, you need more than 2 wires. (another reason for 3 phase).
In the US the final distribution transformer, at least in residential areas
has a primary of around 12kV (I remember this as some neon sign
transformers step the main voltage back up to this level) connected with 2
wires to one of the 3 phases. The secondary is about 230 to 240 volts
center tap, still single phase, of course as 180 degrees doesn't mean
another phase.
Buildings may have different intermediate voltages, as many require step
down transformers within the building as even 240 volts from an external
transformer(s) would be too much current for all the loads.
-Dave
> Since it is a simple transformer, the phases are
180 degrees out of phase
> (by definition). That's assuming a balanced resistive load. Of course,
that
could change
under a heavy inductive or capacitive load but, that's an
extreme and won't normally present a problem.
Still not an argument against 2 phases from an 3~ signal.