20 Apr
1999
20 Apr
'99
11:03 a.m.
Realy 234V (strange) and 180 degree ? Where do you know ? By definition ?
Just remember, if you tap between 2 phases of a 3~ signal you still get
a perfect sinus and you can't decide if it is a single phase or part of
a 3 phase signal. Ok, I'm always learning new things on this earth :9
The numbers just saemed to fit well.
It's 230, 231, whatever it takes (from the movie "Mister Mom").
I'm sure the power company has a legal obligation to keep the voltage
within a certain range of values. Although, I don't know exactly what that
range is. I think 117 is probably the optimal value for each of the legs
giving 234 for the total. I've heard it referred to as 110, 115, 117, and
120. Since the actual voltage varies any of these could be correct.
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.
Steve Robertson - <steverob(a)hotoffice.com>
20 Apr
20 Apr
1:13 p.m.
New subject: Powerlines
> Realy 234V (strange) and 180 degree ? Where do
you know ? By definition ?
> Just remember, if you tap between 2 phases of a 3~ signal you still get
> a perfect sinus and you can't decide if it is a single phase or part of
> a 3 phase signal. Ok, I'm always learning new things on this earth :9
> The numbers just saemed to fit well.
It's 230, 231, whatever it takes (from the movie
"Mister Mom").
:))
I'm sure the power company has a legal obligation
to keep the voltage
within a certain range of values. Although, I don't know exactly what that
range is. I think 117 is probably the optimal value for each of the legs
giving 234 for the total. I've heard it referred to as 110, 115, 117, and
120. Since the actual voltage varies any of these could be correct.
Anybody out there knowing the US regulations ? AFAIR somewhen in the
late 70s the acording definitions have been worldewide standardized
on 115V/200V and 230/400V - the intention was to allow manufacturers
(especialy the ones for power transmission systems) to develop more
efiecently and to lower building costs, since within the lower power
range (up to some MW) designs could be standardized on a simple level.
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.
Gruss
H.
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Ich denke, also bin ich, also gut
HRK
1:54 p.m.
New subject: Powerlines
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.
9207
days inactive
9207
days old
2 comments
3 participants
participants (3)
-
ddameron＠earthlink.net -
Hans.Franke＠mch20.sbs.de -
steverob＠hotoffice.com