In article , Robert Swinney says...

The only way the two 3-phase motors could be connected in parallel is if
they are both fed from a 3-phase source.

Ah, this *is* a semantic minefield. I think I see your point finally.

They're not, and cannot be in parallel, if one thinks that being
in parallel means they each have that extra wire there. The
third leg doesn't, it's missing the extra external connection that
the line wire represents.

From a rough electrician's standpoint consider what the wiring
looks like when I have my drum switch turned on at the lathe, but
the converter is not energized at the knife switch on the wall.

L1 and L2 are missing. There's no external current source so
the third leg is now identical to all the others. At that point
then they truly are in parallel - from an electrican's view as
well as a EE's view.

When the converter is operating of course there is one special lead
that breaks the symmetry - it's missing the line connection. An
electrican would say that the absence of that line connection does
not change the fact the two sets of windings are in parallel. A
EE looks at the entire network as a system, including the incoming
power. He says parallel means all nodes have the same number of
connections.

Jim


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