On Friday, September 13, 2019 at 2:35:30 PM UTC-4, Mark Lloyd wrote:
[snip]

You three guys are something else. You all must have had a difficult
time with algebra word problems. Problem 1, one train leaves city A
at noon, headed for City B, traveling at 50 MPH. A second train
leaves City B at 1:30PM, traveling at 70 MPH headed for City A.
The cities are 500 miles apart, where do they meet?
I always liked word problems (and have no problem with 100-degree phase
angles).

There were always some kids in school who hated word problems. Maybe
arithmetic was hard enough without having to think too.


But in the beginning, word problems really throw you a curve, at least
they did for me. You understand equations, solving them, but then
when you have to come up with the actual equations for something like
the train example, when you're first exposed to it, it's like starting
all over. The only similar experience was probability and statistics,
which is worse. It's deja vu all over again. You know the various
formulas for probablility too, but trying to figure out which ones
to use, how to approach a problem, that's another thing.


Another thought came to mind with the center-tapped transformer issue.
Those that say it's just one transformer, one source, have they
considered what happens when there is a load with reactance on one
side of that secondary, different from the load on the other side?
Then the voltage and current waveforms are not necessairly going to
be zero and 180. You could have a phase difference, say 175 deg phase
difference instead of 180 between the voltages or currents one
either side with respect to the other.
Treating them as two 120V voltage sources allows for that. And that
kind of analysis was the point of the paper by the professor.