"Owen Duffy" wrote in message
...
"Jerry" wrote in
news:s5Ivk.448$sq3.441@trnddc07:
...
I realize that you have asked this question to Richard, who is far
better
prepared to answer than I am. But, it seems that you are confused
about how two sine waves add. Maybe I am wrong, and you do know how
two sine wave voltages generated at different times and are connected
in series combine to being other than 180 degrees from terminal to
terminal.
All the 208 power lines I am familiar with *are* 208 from terminal
to
terminal when each leg is 120 "terminal to center". Where did you
get the "240"?

Jerry KD6JDJ



Jerry, in the three wire system with 180° phase difference between Line1
and Line2 wrt Neutral (the centre wire) the voltage Line1 wrt Line2 is
exactly twice the Line1 to Neutral voltage.

You probably don't use the word Neutral over there, it is the word used
for four wire three phase systems and it is equally applicable for a
three wire two phase system where the Neutral wire carries the
"imbalance" current.

None of this is a good analogy to a two wire open transmission line at
radio frequencies, principally because the length of conductors at power
frequencies is usually a very small part of a wavelength and can be
approximated well using a simpler analytical model than the traditional
'Telegrapher's' equations applied to transmission lines.

Those who resort to explaining radio frequency transmission lines and
transformers using 60Hz models need to justify the accuracy / limits of
the approximation. The low frequency model does not explain high
frequency roll-off in RF transformers and inductors, so it is clearly
incomplete.

Almost all of this discussion is using lumped circuit analysis (a low
frequency model) to explain not just transmission lines, but conductors
with significant mutual coupling (the nominal radiator and its feedline).

Owen

Hi Owen

My post to the other guy evidently read as though I was asking a question.
Actually I read the original post as to have errors and was expecting some
lanswer to justify how 120 degrees can be associated with a set of only 2
terminals. There is *no* 240 volt pair of terminals available in a 208/120
power system.
Here in "the states" 208/120 refers to a 3 phase system Y circuit. That
means there are 3 sets of single phase 120 volt circuits available at the
panel. Also available is a set of three terminals that are 208 volts 3
phase.

Jerry