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

From: Stephen Dauphin <ai705_at_osfn.org>
Date: Thu Feb 4 10:00:21 1999

Reason I'm posting this is that other list members may find themselves in
similar straits. The situation is not necesarily as difficult as you
might think it is.

On 4 Feb 1999, Eric Smith wrote:

> The equipment I want to run will need about 45A per phase. If I had
> an 85% efficient converter, I'd need an 80A 240V circuit. The entire service
> entrance to my house is only 100A,

So upgrade the breaker box and the service entrance cable or
wire-in-conduit. The rest of the house is going to stay the same. Get a
box that uses the same brand of breakers that you currently use. Then you
can add wiring, some of it surface if necessary, to key portions of the
house.

The electric company wire from your pole to your house can probably
already carry the current. Most people do not realize that they use a
"one size fits all" for the task. Plus it is a wire in free air and the
rules about current capacity are far less stringent. You would be
surprised at how small a wire can carry service entrance current from the
pole to your house, when it is not enclosed in a jacket or tube.

Of course, it is a little more complicated than that but still...


> and I use more than 20A of that for

Is that 2400KW or 4800? If you are only rating that at 120V, then you are
only using 10% of your incoming power.


>
> Normal US homes are not wired for big old computers and their peripherals.
>
>

So you can do it after the fact and leave the legacy of its strangeness
for the next owner.

Seriously, you also get another possibility by a 2x upgrade. You now have
the ability to isolate machinery, appliances, kitchen gadgets, your tools
on one 120V leg and put all the sensitive electronics on the other (plus
balance everything else loadwise across the two).

Think of it as less of a drag and more of a real opportunity.


                                                      -- Steve
Received on Thu Feb 04 1999 - 10:00:21 GMT