Re: VDG's - dangerous

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Daniel McCauley by way of Terry Fritz <twftesla-at-qwest-dot-net>" <dhmccauley-at-spacecatlighting-dot-com>


Yes, but the human body will itself act like another 10-20pF of capacitance.
Forget the actual average number here.

Dan



> > Yes, be careful.  Most people are under the impression that since a van
de
> > graaf generator is electrostatic, that it isn't dangerous.
> > However, if you have a powerful VDG, and you have someone standing on an
> > insulator (for hair raising) etc.., the body acts just like a capacitor
and
> > the same goes with those Leyden jars.  These discharges can provide
enough
> > current to be lethal, although very rare.
>
> The problem lies in the energy stored in the terminal.
> Consider a spherical terminal with 60 cm of diameter:
> Its capacitance is C = 33.36 pF
> It can sustain a maximum voltage of V = 900 kV, with maximum surface
> field of 30 kV/cm.
> The stored energy, 0.5*C*V^2, reaches 13.5 Joules.
> The accepted limit for a not very dangerous impulsive shock is 10
> Joules.
> This corresponds to a terminal with 27 cm of radius. After this,
> the stored energy grows quickly, with the cube of the radius.
> The stored energy can be calculated as Emax = 500.4*r^3 Joules,
> r in meters.
> Of course, the same applies for a Tesla coil with a terminal of
> equivalent capacitance and voltage giving single discharges, with
> the aggravation that a Tesla coil recharges the terminal much faster
> than a VDG.
>
> Antonio Carlos M. de Queiroz
>
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