3-phase (was: Re: CDC 9766 Drive and packs)

From: Philip.Belben_at_pgen.com <(Philip.Belben_at_pgen.com)>
Date: Wed Feb 3 04:21:50 1999

> so don't get the idea that you can
> run it in your house or garage.

My parents have 3-phase electricity at home, but I don't (yet). But I
think it's more common in the UK than in the US. (BTW my parents have a
16th century farmhouse which they heat electrically during the winter.
Maximum load we've measured, 36kW.)

I am told (I think it was Toy Duell first pointed it out to me) you can get
reasonable 3-phase using a largeish induction motor (say a mechanical
rating 2 or 3 times the electrical load you want to connect), without a
mechanical load: wiring one phase to ground, a second to line, and the
third to line through a capacitor for an approximate 60 degree phase shift.
The induction motor will also act as a generator, and produce enough emf to
tidy up the phase relationships and voltage imbalance. But be warned - you
will not have the right voltage, and one of the phases (rather than the
star point) will be at ground potential. A bank of three single-phase
isolating transformers should do the trick if either of these is critical
(a single autotransformer, upstream of the converter, will also work if
only voltage is critical.)

Also be warned. I am confident that this works _in theory_ but I have
never tried it.

Philip.
Received on Wed Feb 03 1999 - 04:21:50 GMT