Re: single to three phase conversion

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Ed Phillips <evp-at-pacbell-dot-net> 

 >I seem to remember a post some time about being able to get three
phase
 > >power from single phase power by wiring up 3 or 4 transformers in some
 > >fashion. I have looked high and low but can not seem to find it. maybe i'm
 > >just out of my mind? can someone please point me in the correct direction?
 >
 >     Offhand, not doable.
 >     If Tesla-two-phase is available a 'funny three phase
 >     can be faked (check for 'Scott t"')
 >
 >     IF one has a large single phase supply,
 >       AND a large three phase induction motor
 >          AND a way to start the motor
 >     one can power the motor from SINGLE phase and
 >     get SOME three phase.
 >
 >     Details are on the web, usually  on woodworking/machine tool sites,
 >     As cheap 3 phase tools can be used 'at home'.
 >
 >     best
 >      dwp

	The gadgets described are capacitor-start arrangments for the three
phase motor, generating enough torque to get it running after which it
runs on a single phase with accordingly reduced power.  On inspection
they contain a large ELECTROLYTIC starting capacitor, a resistor, and a
relay.  I assume the Lindsay book gives construction details.  Both my
lathe and my mill have three-phase motors which I run this way and they
are noticeably deficient in torque.  There is another technique which is
sometimes used, but not at all convenient.  A large three-phase motor is
started single phase that way and, once it's running three phase power
can be drawn from its three connections, only two of which are connected
to the single phase input line.  No magic really, the three-phase motor
is operating as a three-phase induction generator.  Cumbersome and not
very efficient, but can be used.

Ed