You can use 3 phase induction motors on single phase.  I have
three industrial quality machines in my shop that do very well.
Put the 240 V across two of the motor leads, and run the
third motor lead back to either of the 240 V supply through
a large (50 mfd or so) oil-filled AC capacitor rated to at least
380V.  The motor will begin turning in one direction or the
other depending on what side the cap is connected to.  Disconnect
the cap when the motor reaches about 75% speed, it is for
starting only.  You will get only about 65% of the torque that
the motor would give on 240V 3 Phase, but usually that is
plenty.  The 3 phase motor is almost indestructable, and
used industrial equipment is a much better bargain than new
single phase modern home shop equipment.

There is a company that markets a box that does the
automatic disconnect of the capacitor, called Phase-O-Matic,
but two switches and the capacitor does just fine.

John Shreffler.

-----Original Message-----
From:   Leo van Loon [SMTP:sbb.simpeltron@TIP.NL]
Sent:   Tuesday, July 21, 1998 5:15 AM
To:     PICLIST@MITVMA.MIT.EDU
Subject:        [OT] 240V in USA

Dear friends,

In another mailinglist a member told about a two-phase 120V net with 180
degrees phase difference in parts of the US. I do not understand how high
power induction motors can be used with such an electricity supply. Three
phase rotary currant was invented for this type of motors.
Can anybody from the States tell me about the finesses of this type of
electricity supply?

Leo van Loon
SBB simpeltronics
Netherlands
tel +31 (0481) 450034
fax+31 (0481) 450051
mail sbb.simpeltron@tip.nl
url http://www.sbb-simpeltronics.nl
SBB simpeltronics ontwikkelt technische projecten voor basisschool en
basisvorming.
SBB simpeltronics develops technical projects for children in primary and
secondary education.