# [TCML] Re: Breakdown voltages of toroids

```Hello All,

I know there was a long thread on this topic
several years ago, but the calculations seemed
to be based on the breakdown voltages Between
equally sized toroids rather than breakdown
to air.

Does anyone have this equation, a table, or
if the information  posted in 2003 is appropriate
also for breakdown to air, can someone extend these
values to larger toroid sizes ? ( 12" 15" 18" etc )

I attempted to extrapolate the data in Excel, but
the curves are too non linear for any useful accuracy.

Thanks,
Alex P

Date: Fri, 12 Dec 2003 19:56:24 -0700
Resent-Date: Fri, 12 Dec 2003 20:01:32 -0700
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--------------------------------------------------------------------------------

Original poster: "Antonio Carlos M. de Queiroz" <acmq-at-compuland-dot-com.br>

Tesla list wrote:
>
> Original poster: Peter Lawrence <Peter.Lawrence-at-Sun-dot-com>
>
> Antonio,
>          how about another table that gives the toroid capacitance relative
> to a sphere equal to the larger diameter of the toroid.

Ok. Instead of a 2 cm sphere, I will use a 20 cm sphere as start, to
avoid ridiculously small toroids. Anyway, the scaling mentioned in the
other post continue to be valid for other sizes. But what I said about
capacitance scaling was wrong. The breakdown voltage and the capacitance
are both directly proportional to the scaling factor of the dimensions.

20    cm sphere:    300 kV  11.1 pF
20x10 cm toroid:    226 kV  9.69 pF
20x9  cm toroid:    216 kV  9.50 pF
20x8  cm toroid:    205 kV  9.31 pF
20x7  cm toroid:    193 kV  9.09 pF
20x6  cm toroid:    180 kV  8.86 pF
20x5  cm toroid:    164 kV  8.60 pF
20x4  cm toroid:    147 kV  8.30 pF
20x3  cm toroid:    126 kV  7.92 pF
20x2  cm toroid:    99.9 kV 7.41 pF
20x1  cm toroid:    63.9 kV 6.62 pF

Antonio Carlos M. de Queiroz

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