Re: [CAD_CAM_EDM_DRO] Power Supply Question - a bit OT

Brian Walsh wrote:

>
> I have a requirement to deliver 2000 Amps or so at about 30 or 40 volts AC
> or DC into a load. The load is made of stainless steel wire and is basically
> resistive with a 'smallish' positive temperature coefficient.

That's 60 - 80 KW! Do you have that much power available?

> At this stage the precise current requirement is unknown, so the ability to
> adjust the current is desirable. There may also be a need to control the
> current / time profile, as the particular requirements of the process become
> apparent.
>
> My immediate solution to this is to take ten 200 amp, cheap, arc welding
> units and connect their outputs in parallel. This is clearly not their
> intended mode of operation, so I don't imagine that the manufacturers will
> be prepared to comment on their suitability to this use.

If the units are identical, and you can be sure they are wired exactly the
same, it should sort of work, but it sounds like a nightmare. At least, the
arc
welders won't explode when short circuited.

> Is anyone here willing to venture an opinion as to whether or not simple
> (reluctance controlled - I assume) arc welders can be combined in parallel
> to achieve high current outputs? Will they current share, current hog,
> trip-out, explode?

As long as they are all phased the same way, they pretty much HAVE
to current share. If one of them has the phase wired backwards, all bets
are off. This also means every outlet for the 10 welders has to be wired
with the same phase, which the electricians would not do unless you
tell them is has to be that way.

Jon