On Wed, 04 Jan 2006 21:59:47 -0600, Don Foreman
wrote:

On 4 Jan 2006 13:22:13 -0800, jim rozen
wrote:



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

He does? In circuit analysis, a set of two-terminal networks are
regarded as "in parallel" if they are each connected to the same pair
of nodes so the voltage across them is identically the same.
Similarly, a set of n-terminal networks are in parallel if they are
connected to the same set of n nodes so the various inter-terminal
voltages on each n-terminal network are identically the same for
corresponding pairs of terminals. This is regardless of whatever
else might be connected to, between or among those nodes and
regardless of any external symmetry or lack thereof. Some nodes may
well have more connections than other.

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.


Just to stir things up a bit further I register my support for
BOTH the parallel and non parallel camps - it just depends on how
you look at the circuit operation.

If we regard the idler plus load motors as two connected
passive three terminal networks the there can be no doubt that
this is a straightforward parallell connection. No playing with
words on the way any further conections are made (e.g single
phase power input) can alter this.

However,when the motors have rotating rotors, BOTH motors
accept input power on two of their terminals and BOTH try to
deliver output power to the third linked phantom phase
connection.

The direction of the power flow through the phantom phase
link then depends on the relative mechanical loading on the two
rotors. In the two limiting conditions of both motors idling or
both motors loaded to the same fraction of their rated HP, each
motor is self sufficient and little or no third phase power flows
through the link. In the normal case of one idling and one
loaded, the power flow is from idler to load motor.

It is equally valid to regard this current as a circulating
current within a parallel connected system or as the current
developed in the series connection of an idler generator to its
load motor


Jim