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Re: [TCML] primary voltage



makinglightning@xxxxxxxxxxx wrote:

What is the practical upper limit on the primary tank circuit?


What is the highest primary tank voltage that people have used?


When you start getting above about 30kV, things get a lot tougher. Consider that your radius of curvature for conductors needs to be >1cm/30kV, and to keep corona losses to a minimum at, say, 50kV, means that in air, you're looking at conductors that are a couple inches in diameter, spaced a foot away from other conductors, etc. Or, you plunge the whole thing in SF6 or oil.

You can get wire for 50kV that works pretty well, but then you have all the connections to worry about. You wind up with things like corona suppression donuts around terminals, globs of silicone potting material, etc.

And I guarantee that any system operating at 50kV, in air, will be accompanied by an evil hiss and the smell of ozone. With an electrostatic generator (e.g. Van de Graaff generator or Wimshurst), you can operate at 100-200kV without much trouble, but you'll smell the ozone, and when you inevitably take a discharge to you, the stored energy is low enough that you don't get fried.

An inadvertent flashover of a TC primary storing several tens of Joules at 50kV is going to be an exciting prospect. A flashover with a power supply capable of pushing several kilowatts is going to probably develop into a nice power arc.

I'm pretty blase about working at, say, 10-15-20 kV (NST voltages) with limited powers. One is careful, follows the rules, etc. But every time I've had to work with over 30kV with any real stored energy or power capability, it's scary. You're a LOT more careful, you do things very deliberately, and you tend not to just "lash things together". I've seen and experienced too many unexpected faults (oops, that plastic rod we are poking in there to adjust something disrupted the field just enough so that the corona on that conductor turned into a real spark). You can work at those voltages and higher (and people do, every day, for a living), but it's a qualitatively different sort of experience than the usual tesla coil work.
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