Who's rewired their house for this hobby?

Jon Elson elson at pico-systems.com
Mon Nov 24 12:12:23 CST 2014

On 11/23/2014 03:15 PM, Holm Tiffe wrote:
> but sine you already have 240V outlets, it should be 
> possible to change the distribution slowly to 3 phase 
> power.. it's a matter of time and the only needed thing 
> for compatibility are the transformers with modified 
> secondaries. I don't think that this would ever happen 
> since the US is the biggest US of the world and other 
> people are just dumb aliens, aren't they? :-) But with 
> that stone age power system you are stumbling over your 
> own feet all the time.. Regards, Holm 
Well, we only have single phase 7200 V running down our 
street. This 7200 V run goes a LONG way,
so an entire region that may be about a mile square is 
running off a single phase HV line, that
branches over and over again into the neighborhood.  Many of 
these feeds that go back
into subdivisions are buried, and have pad-mount 
transformers placed every few homes.
Our house has a pole-mount 50 KVA transformer that supplies 
just our one house, although
that is kind of an accident of the layout.  We are on the 
corner lot, and otherwise probably
would have shared that transformer with a neighbor.  Our LV 
drop is buried.

So, what I'm saying here is there is a lot of high-cost 
infrastructure that would have to be
ripped up (literally out of the ground) to go to 3 phase 
into the homes.  Not to mention
all the meters, service entry gear and breaker panels.

I have a small machine shop in my basement, and some years 
ago it seemed like 3-phase
would be real nice for that.  Now that VFDs can run 3-phase 
motors so nicely off single
phase power, it is no longer of much interest.

Unless you desire to run a Cray 1 in your home (yeah, keep 
dreaming) there really isn't
that much need for 3-phase power.  Most machines that 
"require" 3-phase can actually
be rewired internally to run off single-phase.  One I can 
think of that won't is the
KL-10B, which had a totally insane power system starting 
with a 3-phase transformer
and rectifier.  A mid-scale 370 like the 145 had a 
motor-generator set, which could be
run off a large VFD.  Or, replace the stupid MG and 415 Hz 
power supplies with
off-the-shelf large power supplies running off single-phase 
240 V.


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