Since the new coil system we are building requires so much input power, we've decided that it would be much safer to use a power controller on the input side of things. Instead of the typical "plug and play" operation that is typical of small coils, large coils need some kind of device to accurately control the power input. If something goes wrong with a small coil (say 1kVA and below), you can always yank the plug out by hand. But if something goes wrong with a large coil system running upwards of 5kVA, jerking the plug isn't always quick enough to stop some major damage from happening. **UPDATE** Almost a year later: Over time, we have tried every form and fashion of current limiting available. The nice variac we modified roared 60Hz that could be heard down the block. Our homeade "coil on some big core" drew 3 million amps and always tripped the 60A breaker. 1000 feet of 14 gauge on a 6" x 30" PVC pipe (from old magnifier) was huge and heavy and got hot fast, but worked. A spool of 14 gauge got hot *really* fast, but worked. Of course the #14 stuff got hot - it's #14 for crying out loud! But FINALLY - Aron found an arc welder that solved our problems. We've used that welder externally (out of the cabinet) for some time now - and we've been keeping an eye out for a new welder to actually weld with (imagine that) and yank the transformer from the old one to use for limiting.
In just 3 days, Aron and I stuffed the following components into what was a meaningless, empty, metal box.
Aron cutting a place for the the 240V output connector
Aron with the cabinet, ready for painting.
Painting! Notice the cardboard taped over the vent holes
Main power variac, rated 30A 520VAC 60Hz
With all the components finally installed, we're now ready to begin wiring
The controller with some wiring installed...
Contactor and instrumentation wiring is complete
All wiring is installed...it's a done deal!
Top view of the completed front panel
The finished product, with the door open
Another shot of the finished product
The pig and cabinet together - ready for testing
