Don, now you are beginning to get the idea, my poor teaching technique not
withstanding. Take another look at your line below where you say, "but I
can see how one might regard them
as functionally in series, particuarly if neutral floats as it must
in an RPC." Yes, neutral *must* float in a RPC but it is still my
contention that the idler and load of a RPC are not truly connected in
parallel unless there is a solid connection between the 2 respective
neutral points. That satisfies the definiton of corresponding points being
connected, doesn't it?? Can we call your special definition of parallel
as applied to RPC's, maybe, huh, "quasi parallel"?

Bear with me for one more moment, please (courteously).

We have a 3-phase source and wish to connect n numbers of 3-phase loads
across it, in parallel. You'd have to agree there would be a "phase"
connected to each of the 3 input terminals (nodes ?) of the loads. In other
words, the connections looking into the loads would be in parallel, and
connected across the 3-phase source, would they not? OK, if you're with me
(I'm a poor teacher, I know), now disconnect the 3-phase source and look at
the loads, say, call one of them an idler and the rest of them loads. Now
the idler and load are not truly in parallel, by definition, because the
lead between star points (neutrals) is not there.

Now consider, a RPC (rotary phase converter) connected as in what I call
"quasi parallel" for want of a better description. You might agree, the
idler and load are not in true parallel because the solid lead between
neutrals is missing.
But they are connected as a RPC must be. Current from L1 to L2 "sees" the
RPC as a series load. Current flow via the 3rd leg and the 2 line legs into
the load, as connected in RPC fashion, results in circulating currents
throughout that appear to the load as 3 phases. (emulation?) As you've
said elsewhere, a RPC would not be possible if the neutrals were connected
as in what I deem to be a true parallel connection. Therefore, it seems
that in a RPC, the idler and load are not truly connected in parallel.

Bob Swinney


"Don Foreman" wrote in message
...
On Fri, 6 Jan 2006 22:05:02 -0600, "Robert Swinney"
wrote:

This may be going out on a limb, and if so, I'm quite sure Don is ready
with
a saw but here goes:

When I said: "Sorry, Don. The lead between the 3rd leg terminals does
not place them in
parallel with each other because it connects from one end of one winding
to
the *other* end of the other winding. "

This concept was immediatly poo-pooed by the "if its connected as a RPC,
then it is in parallel". Later, then a definition of parallel was given
as:
"By this definition, if there are wires connecting each terminal of one
device to a corresponding terminal of another device, they are in
parallel -- regardless of what else might be connected to those
terminals."

Consider 2 wye motors connected as a RPC, seemingly in parallel. It
appears
to me that 2 wye motors connected in parallel by the definition of
corresponding terminals, above, are not in parallel by that definition
unless the "star" or neutral points within each motor are connected by a
solid lead. Then, all corresponding points are connected.

RPC connected motors do not meet the criteria.

Kapeesh?

Poo-pooed? That connotes fluffy dismissal. I flat disagreed.

I do capish. Kapeesh indeed! Texas is obviously a long ways from
Brooklyn, Ol' Son. Roger thet, big ol' ten-four. Yer waltz ain't
quite in synch with mah foxtrot, but we ain't that fur apawrt.
See recent post. They're still topologically connected in parallel
per conventional definition,
In any case, my chainsaws are put away for the MN winter and I'm way
too lazy to pull a Swedesaw anymore.

Bob (getting tired of all this)Swinney

What, time for your nap? (ducking.....)