On Friday, September 13, 2019 at 10:22:46 AM UTC-4, Ralph Mowery wrote:
In article ,
says...
Simple fact, the example Ralph provided is two phase power. And phase
is not limited to 90 deg, you can make it anything you want, just
rotate the second winding. Of course in physics and engineering, we
don't need to create it physically at all to analyze it, we can do
that on a piece of paper. We take two voltage source
Your simple fact is wrong.
What fact is wrong? I used your example of a two phase power source.
For the reason as you take one of the
windings and rotate it say 45 deg as you say. I don't know what it will
look like or what to call it,
Then if you don't know, maybe you should just stop right there?
but during part of the cycle you will have
one winding 45 deg out of phase and the other 135 deg out of phase
during parts of the cycle.. Really a weard wave form. You would have
to add extra windings to get things to even out and may not wven be able
to do that if you just give it a slight rotation of say 5 deg.
Why is it not weird at 90 deg? You said that was two phase power,
right? Why is it so hard to understand that I can simply rotate the winding
and get whatever phase angle I want? Is it weird at 89 deg? 95 deg?
That's what logical people do, it's a question a curious student trying
to learn would ask a science teacher. Why is it that 90 deg is so special?
Does it have to be 90? The answer of
course is that it's not, it's just that was one implementation of two
phase power. The general case is two power sources:
sine(wt)
sine (wt+O) where O can be 0 to 359 deg
Your Philly case of 100 years ago, used O=90. That's all there is too it.
Three phase
sine(wt)
sine(wt+O)
sine (wt+P)
If O=P=120, then you have the three phase that's actually implemented today.
But that does not mean that's the only phase angles allowed, that we can't
analyze what happens at all the other possible phase angles. It's
no different than the cases with differing voltages or frequencies.
Yes, 72 volts, 450Hz or whatever are not implemented, but that doesn't
mean that 3 voltage sources, per the above, would not have 3 phases,
that it can't exist, that we can't analyze it.
The argument is useless as there is a definition of two phase power and
the split phase power as in power distribution circuits.
Again, like the other poster tried to explain to you, *one implementation*
of two phase power does not make that the definition of it. That is
like saying an airplane was defined by the bi-plane, no other airplane
can exist.
It may very
well be something else or even called something else in other countries
or areas of electricity. Just as if yo go to the local lumber store and
ask for a 2x4 8 feet long. The board you get will not measure 2 inch or
4 inches in any direction. Standard iron pipe will not measure what it
is called either . But it is what it is by definition.
We're not talking about what it's called, we're talking about analyzing
in electrical engineering terms, what is actually there. Again, this
is like insisting that Kleenex is only Kleenex, that Kleenex is the
definition and to analyze it and describe it as a soft paper product made
from trees incorrect.