"Don Foreman" wrote in message
...
On Fri, 30 Jul 2010 09:38:42 -0400, "Ed Huntress"
wrote:


"Joseph Gwinn" wrote in message
...
In article ,
"Ed Huntress" wrote:

"Don Foreman" wrote in message
...
On Tue, 27 Jul 2010 14:19:15 -0400, "Ed Huntress"
wrote:

But it was
apparent to me from the time you first commented that you must have
been
absent the day they explained internal phase relationships and force
in
single-phase motors. g You went so far off base, contending that
those
motors operate in quadrature and so on (most inentionally do *not*
operate
in quadrature; it's part of their design to have partially-shifted
phases)
that I didn't even respond to much of it.

Engineers refer to a quadrature component in any case where there is
phase difference. It's standard notation. However slight the phase
difference is, a quadrature component is necessary to develop torque.

The engineers I know, and the electronics I learned when studying for
both
my amateur and commercial radiotelephone licenses, mean a 90-degree
phase
shift -- pi/2. Anything else is a phase shift of different
proportions --
not quadrature.

What kind of engineers call any phase shift "quadrature"?
Mathematicians
use
different meanings for the term, referring to different processes of
integration, but I've never heard that usage in engineering
applications.

The critical word is "component". Any angle can be resolved into the
sum
of an
in-phase component and a quadrature component.

http://en.wikipedia.org/wiki/Phase_%...ature_.28I.26Q.
29_components

Joe Gwinn

Of course. But to be "in quadrature" means that the phases are displaced
by
90 degrees. Anything else is some other phase shift.

Any phasor can be expressed as the vector sum of an inphase component
and a quadrature component, wherein the quadrature component is
displaced from the inphase component by 90 degrees.

Of course. But you weren't talking about a complex phase relationship. You
were talking about a second phase that was "in quadrature." You can find
definitions for "in quadrature" in any technical resource. It means related
as per a quadrant of a cycle -- in other words, displaced by 90 degrees from
the reference phase.

I decribed the *real* phase relationship as a phase shift that wasn't "in
quadrature." You scoffed. d8-)


For example, in one of the most common types of single-phase motors, the
basic split-phase, the starting phase lags the primary phase by,
typically,
around 30 degrees.

In this instance, the starting phase could be expressed as the vector
sum (0.866 + j 0.5)M where M is its magnitude. The magnitude of
the inphase component is .866M or M cos (30) that of the
quadrature component is 0.5M or M sin(30).

Yes. But we were talking about relationships that were "in quadrature."

--
Ed Huntress