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Re: HELP WITH TOROID
- To: tesla@xxxxxxxxxx
- Subject: Re: HELP WITH TOROID
- From: "Tesla list" <tesla@xxxxxxxxxx>
- Date: Sun, 27 Mar 2005 09:36:53 -0700
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Original poster: David Speck <dave@xxxxxxxxxxxxxxxx>
I can't offer any suggestions about the toroid, but I'd offer the following
on the power control switches.
For systems at power levels that you describe, you usually don't switch the
50 amp currents directly from the front panel.
Instead, you use low voltage front panel switches, typically 24 VAC, to
drive heavy duty relays, often called contactors, appropriately rated for
the current you intend to draw, and with a sizable safety margin to boot.
Look on eBay under Allen-Bradley, Cutler Hammer, or Square-D for industrial
front panel switches and pilot lights of many different configurations to
fit your needs. Prices for these can often get pretty high, but
frequently, pieces fall through the cracks and can be bought very reasonably.
A search for "contactor*" or "power relay*" will bring up what you need for
power handling. I'd avoid motor starter contactors, as they have heaters
to detect and shut off under overcurrent situations. They might produce
unanticipated results in TC use.
Check your local junkyard for scrapped industrial machinery, as the front
panels will frequently have switches like these, and you might get a better
deal that way. A 240 to 24 VAC industrial control transformer will provide
the low voltage you need to run the control circuitry.
Be sure to incorporate an emergency stop circuit with an easily accessed
big red mushroom button to kill everything in case of unanticipated
results. The most cautious coilers include a hand held pendant switch with
a button that has to be held in continuously to allow any operation of the
high voltage circuitry.
Your 10 kVA tranny would draw ~42 amps on 240V at max rating, and is
capable of at least twice that for short runs, so you'd want a contactor
rated at least 80 amps, if not 100. Using an overrated contactor will save
you from rebuilding when you move up to the next power level, and also
reduce the possibility of having your contacts weld shut in a major fault
Tesla list wrote:
Original poster: Teslamad@xxxxxxx
I've been coiling for years now and im about to complete my latest coil.
This coil was built for research purposes. It runs off a 14,400 10KVA
X-former, but unfortunately before it will be operational, it needs a
toroid. I have tried building it MANY times from Home Depot ducting with
unsuccessful (expensive) results!!! The ducting used by other coilers
appears more ridged than mine... hmm... Could you please tell me where to
get this other material or how to handle the ducting (dentable and
fragile) I've been getting from home depot? Also, one other thing, where
do you purchase heavy duty switches for control panels and how much are
they (240v 50A)???