Re: [CAD_CAM_EDM_DRO] Home shop power for a big machine

gcode fi (hanermo) wrote:

> All good comments.
> There is an issue with the sheer capacity ... ? can you get, in the US,
> for a nominal cost, that much power ?
>
>

Power, yes. For instance, just as the mains happen to be wired, we have
our own 50 KVA transformer, and a 200 A service.
This is just the luck of the draw, what the power company had on their
truck last time the transformer needed to be replaced, exactly how the
utility drops ran to the poles due to the alignment of the lots on both
sides of the street, etc.

200 A at 240 V is 48 KVA, or 48 KW, if your power factor is optimum.
Sometimes the power co. will put a 25 KVA transformer on a 200 A
service, or share a 50 KVA transformer among several houses with 200 A
service. These transformers can handle substantial overloads for a good
while, but if everybody has a giant welder, mill, electric heat, etc.
and they all try to run them at the same time, the lights are going to
go out. One big problem is rotary phase converters without power factor
correction caps draw very large reactive currents, as I mentioned in my
previous response. This doesn't represent real power draw, but is a lot
of current on the lines. This reduces the available real power you can
draw.

Jon