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



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 > > > > > > > > > > > > > > > > > > > > > > > > >