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Re: [TCML] Pulse capacitor grounding



Steve

I think I'd ground (bonding is more correct term) the capacitor case
through a 100k 10W metal oxide (not wirewound!!) power resistor to
apply a high impedance ground path.

I would use one rated for high voltage like this one from Dale Vishay (1.0
Meg-ohm, 10W, 22.5kV max working).  Not cheap at $15 ea but in stock
and proper part application/good design practice.

https://www.digikey.com/products/en/resistors/through-hole-resistors/53?k=metal+oxide+resistor&k=&pkeyword=metal+oxide+resistor&sv=0&pv2085=u1+MOhms&sf=0&FV=ffe00035%2C143300&quantity=&ColumnSort=0&page=1&stock=1&pageSize=25

http://www.vishay.com/docs/31033/rox.pdf

Be sure to use rubber gloves when handling, skin oil contaminates will
severely compromise voltage ratings.

Best Regards
Dave "Sparky" Sharpe

On Thu, May 9, 2019 at 11:38 PM David Rieben <drieben@xxxxxxx> wrote:

> This is just my opinion, but I would think that it would be wise to ground
> the outer metal case of the huge cap and if you decided to ground one of
> the terminals, I don't think it would matter which one. As much as the
> National Electrical Code manual harps on grounding and bonding (Article
> 250), I would be wary of leaving the outer case of such a huge capacitor
> ‘floating’, as I’m sure that it could pick up a significant charge from
> mere electrostatic induction from the internally charged plates in such
> close proximity to it.
>
> David Rieben,
> Memphis, TN
>
> Sent from my iPhone
>
> > On May 8, 2019, at 10:48 PM, Steve White <steve.white1@xxxxxxxxx> wrote:
> >
> > This is not strictly a tesla coil question but it is closely related and
> I can't find an answer elsewhere.
> >
> > I am building a quarter shrinker based on a large (100 uF, 22 KV, 24 KJ)
> Aerovox pulse capacitor. This is a 2-terminal unit. My question concerns
> grounding. I plan on grounding one of the terminals. Should I also ground
> the case or just leave it floating? My ohmmeter shows no connection between
> the case and either of the two terminals. My capacitance meter shows
> negligible capacitance (5 nF) between the case and either of the two
> terminals. My current thinking is just to let the case float and keep it
> away from any conductors.
> >
> > Steve White
> > Cedar Rapids, Iowa
> > _______________________________________________
> > Tesla mailing list
> > Tesla@xxxxxxxxxxxxxxxxxx
> > https://www.pupman.com/mailman/listinfo/tesla
>
> _______________________________________________
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>


-- 
Dave Sharpe, TCBOR/HEAS
Chesterfield, VA USA

Sharpe's Axiom of Murphy's Law
"Physics trumps opinion!"
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