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Original poster: Yurtle Turtle <yurtle_t@xxxxxxxxx>

Don't discount motor starters. That's exactly what you
want. High current, high inductive load. If your
heaters cause you grief (mine never have) then simply
bypass them.


--- Tesla list <tesla@xxxxxxxxxx> wrote:
> Original poster: David Speck <dave@xxxxxxxxxxxxxxxx>
> Drew,
> 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
> situation.
> HTH,
> Dave
> 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)???
> >
> >Thanks,
> >~Drew
> >