wrote in message
ups.com...

Grant Erwin wrote:
wrote:
Another possible solution than what has been mentioned:

Use a 220/440V motor as the phase converter. Wire for 440, and
drive
ONE HALF of the line connected phase. The converter will be working
as
a rotary step up, eliminating the need for the seperate
transformer. I
have a machine that uses this trick to avoid the need for a step
down.
Not all dual voltage motors can be used in this way.

Can you elucidate a little on "drive one half of the line connected
phase",
please? This is written in English and I know what every word means,
and
I once had quite a bit of electrical engineering knowledge, but I
unfortunately
have no idea what you're talking about.



Many 220/440 indution motors (I have several) are converted between
voltages by connecting the coils either in series or in parallel,
similarly to selection of the windings on dual voltage transformers
(such as the fairly comon 220/440 input on many welders) If the
connection is made for 440, then there are two series connected
windings on a common core and if ONE of these windings (half of the
series connected pair) is powered with 220, then 440 will be seen
across the pair (it is acting as an autotransformer in boost
configuration)

The same behavior is exhibited by the windings on many 220/440 three
phase motor-- each phase is two windings, either series connected, or
parallel connected. The motor must be designed for delta connection.

A motor designed for 220/440, why connected, would again need all three
phases series connected, but the line connection would be from the
center tie of one phase to the center tie of another, the 480 exhibited
at the outside of the three phases.


You got any 'scope pictures of that?

Bob Swinney