[TCML] Variac Overrating (1256's and others)

[<brianb@xxxxxxxxxx>]

Jim/all,

Attached is a link to the official word on how much you can push a variac (direct from the 
manafacturer).
 
http://www.brianb.org/Download%20Files/staco_Overload_graph.jpg

As you can see they will easily do 250% for a 5-min run with a 30-min cool-down between runs (this 
assumes the brushes and contact surfaces are in good shape)...
 
Hope this helps.
Regards,
 
Brian B. (back to lurking)

> >
> >
> >
> > On Wed May 27 21:25 , "Jim Mora" sent:
> >
> > Hi Tyler,
> >
> >
> >
> > It occurred to me that the Superior 1256 is rated at 28amps. So 28*
> > 240=6720VA. You will need 2 on a common shaft to run up to 12KVA. They can
> > take a bit more the 28amps but not that much!. Stacking two 1256's likes to
> > have a balancing choke. Check the archives on construction of one of these
> > from a small variac unless you get lucky and find a dual with a choke. Pig
> > coiling ain't cheap!
> >
> >
> >
> > Regards,
> >
> > Jim Mora
> >
> >
> >
> > I aquired all my stuff over time. I am just getting ready for first light.
> > Be sure you look at control cabinets and a BIG contactor say an Allen
> > Bradley Nema 5 for your needs. Also Ebay. Just check the contacts which can
> > be replaced. All the power going out goes through the contactor and you do
> > not want it to weld connected!!! A fused safety switch rated at 20HP or 60
> > amps is about 14400VA is also required if the contactor should fail closed
> > or the transformer has a fault or some other High Power failure occurs.
> >
> >
> >
> > Jim Mora
> >
> > _______________________________________________
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> > Tesla@xxxxxxxxxxxxxx
> > http://www.pupman.com/mailman/listinfo/tesla
> >
> >
> >
> >
> >
> 
> 




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