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Re: Transformers

> Mr. Quick has indicated , and rightly so , that neon light transformers 
> are simply not designed for as heavy a load as a TC places upon 
> them, nor to wirhstand the counter EMF generated upon the colapse 
> of the field around the secondary of the coil. What type of HV 
> transformers are available with the head room to withstand the 
> beating of a TC?

The ideal bullet-proof transformers for medium to high-powered, 
multi-kVA Tesla coil work are pole (distribution) transformers with 
potential transformers probably running a close second.  These, 
however, are extremely dangerous and are generally not as easy to get 
hold of as neon sign transformers.  They will also require external 
current limiting unless you want to drag the neighborhood into your 
adventure, and will need a more sophisticated (i.e. - rotary)  gap 
system to be effective.

Other more available alternatives are plate transformers (typically on 
the order of 5kV with mucho mA), or even microwave oven transformers 
(you can get 4kV or 5kV units).  To use them, you can hook them in 
series to get a higher voltage, but from what I've heard, I probably 
wouldn't run more than 2 or 3 in series to prevent arc-over to the low 
voltage wiring.  Also, these transformers are not current limited like the 
neons, so external current limiting is a must.  I had three 4kV 
microwave oven transformers hooked up in series, and they were 
sucking about 70 (yep, 70!) AMPS from the wall when I was playing 
around and pulling an arc with them.  The arc caught at about 1/4" but 
didn't let go until it was an inverted 'V' shape with about 7 inches of 
total arc length.


Steven Roys (sroys-at-radiology.ab.umd.edu)