Re: getting three phase power

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

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-uswest-dot-net>" <jimlux-at-earthlink-dot-net>

>
> Hi Jim,
>     A thought comes to mind. I have a shed full of MOT's ( no two the same
> of course) and a three
> phase supply 415 volts 50 hz 30 amps per phase.  Could I run three pairs
of
> MOT's (2 in series
> across each phase) feeding into a 3 phase rectifier. Don't know where to
go
> after that.  Help.

It certainly would work... You'd kind of want to find pairs of MOTs that are
roughly the same to series (otherwise the voltages on the primary won't
divide evenly.).

How to do the bridges..  Hook your secondaries in Wye (i.e. all the cold
ends of the mot secondaries are hooked together and grounded.  Now, create a
couple of buses, one for positive and one for negative.  The hot end of the
Mot goes through a diode to the positive bus and through another diode,
oppositely oriented to the negative bus.  You can use the MOT rectifiers.
For your configuration, you'll have 6 hot ends (2 per phase) and so, you'll
need 12(!) diodes.  Fire it up and stand back... (or is the the other way
around... )

Sure, the voltages won't be the same on all MOTs, but it'll certainly be no
worse, and will probably be a lot better than a single phase scheme.  I
cringe to even think about trying to figure out the ripple or output
waveform under load, as each MOT has varying amounts of leakage inductance
limiting the current, etc.  But, hey, all it is is wire and time, and it
might work real well.

There are also all sorts of voltage multiplier schemes for polyphase
circuits.  They work much better than single phase ones, because for most
multistage multipliers, the output ripple and regulation is directly related
to the "number of pulses per time" going into the stack, and with three
phase power you can easily get 6 pulses per cycle, as opposed to 1 or 2 with
single phase.  These might be real attractive for a MOT system with varying
transformers, because the multiplier doesn't really care about the
uniformity of the pulses, especially at light loads.

You could probably also come up with a variety of static gap schemes,
hooking them in wye and delta and actually play songs on your TC by running
the different phases up and down in level, causing some gaps to fire, and
others not.   (this is a bit far fetched......)

> Does this look as if it might go somewhere?
>
> cheers
> bob golding
>
> Tesla list wrote:
>