Re: VDG's - dangerous

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

Original poster: "D.C. Cox by way of Terry Fritz <twftesla-at-qwest-dot-net>" <DR.RESONANCE-at-next-wave-dot-net>


The "average" 170 lb. man has a capacitance of 160 pF.

Dr. Resonance




----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, July 19, 2002 7:13 AM
Subject: Re: VDG's - dangerous


> 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
> >
> >
> >
> >
> >
>
>
>
>