On Jul 28, 6:24*pm, "Ed Huntress" wrote:


Right. Except, perhaps, for Dan's Australian friends. g That's why I said
that most single-phase motors do not run with an induced, second phase that
is in quadrature. The second phase can be at a wide variety of phase angles,
and many single-phase motors are made specifically to produce a second phase
that is NOT 90 degrees out of phase with the primary phase. It has to do
with producing better starting torque, but I forget the details.

I said this was a "partially shifted" phase, or something like that, in our
original discussion. That's exactly what it is. And you jumped all over me
for being an ignorant writer. g

--
Ed Huntress

You and Don are really saying the same thing. Don is saying that
there is an in phase current and a quadrature current, which is
exactly the same thing as saying the current lags the voltage, or
saying that the current is not in phase with the voltage, but is
shifted.

Don did not say all the current was in quadrature. He said there was
quadrature current. Don was using cartesian coordinates and you are
using polar coordinates. Engineers tend to think in cartesian
coordinates because it makes solving problems easier. It is somewhat
like thinking in terms of frequency or in terms of time.

If he jumped on you and called you an ignorant writer, it was because
you were saying there was no quadrature current, but the current was
not in phase with the voltage. And if the current is not in phase
with the voltage, there is quadrature current.

In what you say above about a second current in addition to the in
phase is true. And one could use a convention of say a current that
is 60 degrees out of phase with the voltage and in phase current. But
it would make the math very complicated. The usual convention is
either the current is xx amps lagging the voltage by yy degrees. Or
the current is ww - j v v amps. Where j is the same as i. ( i^2 =
1 ).

Dan