Re: Luxtrol 45A 240V variac as ballast--cutting up core?

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "david baehr" <dfb25@xxxxxxxxxxx>


Where do ya live ? I got an ol' welder takin up space.


From:  "Tesla list" <tesla@xxxxxxxxxx>
To:  tesla@xxxxxxxxxx
Subject:  Re: Luxtrol 45A 240V variac as ballast--cutting up core?
Date:  Tue, 27 Sep 2005 13:38:21 -0600
>Original poster: "J. Aaron Holmes" <jaholmes@xxxxxxxxxxxxxxxxxx>
>
>Thanks all for the help!  I actually did put the thing
>in series with the resistor last night and was making
>ready to try it when I got called away and didn't end
>up coming back.  I'll try it (hopefully tonight) and
>see how it does as-is.
>
>As for getting an arc welder, I've always had an eye
>out for a good deal.  < $100 would be great! :))
>Getting a new one at Home Depot is not in the cards,
>I'm afraid.  Not, at least, if used purely as a
>ballast :)  Although, if used in series with a
>resistor, one of these newer Lincoln units with taps
>(that you can't change while it's running) would be
>ok, since you'd just be using the welder to establish
>the maximum current, and the resistor for soft
>starts/stops.
>
>Using a contactor to short across the resistor when
>it's at its lowest resistance setting is also a good
>idea.  I'll probably give that a shot, too (not that a
>little warm water is bad :))
>
>Thanks again,
>Aaron
>
>--- Tesla list <tesla@xxxxxxxxxx> wrote:
>
> > Original poster: "Barton B. Anderson"
> > <bartb@xxxxxxxxxxxxxxxx>
> >
> > Hi Aaron,
> >
> > Congrats on the variac! But, if it's a 45A variac, I
> > wouldn't
> > recommend cutting the core unless you actually begin
> > to run into
> > saturation (and then I'd recommend a double stack).
> > I did cut the
> > core in my variac, but only because it is a single
> > 28A variac
> > ballast. I did this early on, not realizing that I
> > should have just
> > picked up the other 2 variacs (which were only $45
> > ea). Yep, live and
> > learn. If I had it to do again, I wouldn't. You may
> > want to sell it
> > someday and it would be best to sell it without a
> > slit core.
> >
> > Take care,
> > Bart
> >
> > Tesla list wrote:
> >
> > >Original poster: "J. Aaron Holmes"
> > <jaholmes@xxxxxxxxxxxxxxxxxx>
> > >
> > >Hey folks!  I recently acquired a Luxtrol 45A 240V
> > >variac.  I'd like to make it a ballast for a pole
> > >transformer, and I'm wondering if somebody could
> > share
> > >an experience:  How shall I go about putting a gap
> > in
> > >the core?  About how wide should the gap be?  I'm
> > >thinking of trying to coerce a machinist friend
> > into
> > >helping me, since I'd like to avoid hours of hack
> > >sawing by hand! :)
> > >
> > >And one related question:  I recently built a water
> > >resistor (20 gallon garbage can full of doped water
> > >with copper rods immersed about 1/8th inch apart,
> > >sliding PVC sheath over one rod to control
> > resistance)
> > >and have used this to create some nice 20+kW
> > Jacob's
> > >ladders.  It's obviously quite lossy, but the nice
> > >thing is that I can ramp the current down to near
> > zero
> > >before cutting the power, thereby avoiding big
> > >inductive spikes.  To avoid forfeiting this
> > "feature"
> > >of the resistor while deliberately forfeiting most
> > of
> > >the losses, I thought perhaps that I'd put the
> > water
> > >resistor in between the modified variac and the
> > pig.
> > >The resistance can then be slowly brought down
> > until
> > >the majority of the limiting is being done by the
> > >variac (resistor varies down to about one ohm).
> > This
> > >would seem to offer the low losses of an inductive
> > >ballast while simultaneously allowing nice soft
> > stops
> > >and starts.  The variac would just be preset to the
> > >desired operating current and then left alone.
> > >
> > >Thoughts on this?
> > >
> > >Aaron
> > >
> > >
> > >
> > >
> > >
> >
> >
> >
> >
>
>