[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
RE: DC Resonance Charging Advice Sought
Original poster: "Chris Arnold by way of Terry Fritz <teslalist-at-qwest-dot-net>" <chris_arnold-at-msn-dot-com>
Dave,
If I were in your situation I would size the bleeder resistors to dissipate
much more power, and live with some higher losses. A time span of 30
seconds or so to get down to a "safe" voltage would be much more useful in
your situation IMO. I think in the 750 kOhm range would do this, but that
would result in 100 watts of power loss. I guess it all depends on how
long you're willing to deal with the capacitor storing a lethal
charge. From a little experience messing around with really big filter
caps like that, the discharge can be most impressive! Good luck and be safe.
Chris Arnold
>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: RE: DC Resonance Charging Advice Sought
>Date: Tue, 12 Aug 2003 08:52:15 -0600
>
>Original poster: "Dave Kyle by way of Terry Fritz <teslalist-at-qwest-dot-net>"
><dave-at-kyleusa-dot-com>
>
>Thanks for the feedback. Yours is the first advice I have seen that suggests
>the sizing of the smoothing caps. I admit the smoothing caps value was
>pretty much determined by finding a good deal on eBay and you may be right
>that it is over kill (pun intended) in this application.
>
>To be honest the DC supply scares me to death which is probably a good
>thing. Obviously it is certain death to contact almost any part of it while
>it is on with or without the caps. My main concern is to safe the caps after
>operation to ensure inadvertent contact does not result in tragedy.
>
>I have bleeder resisters (two 100 megaohm 3 watt -at- 15KV in parallel) in
>place on each cap that take the smoothing caps with a full charge to safe
>values in about 35 minutes.
>
>R*C=T 50,000,000 * .000,007 = 350
>Estimated full discharge =6*T 6 * 350 = 2100 seconds
>2100 seconds / 60 = 35 minutes
>
>I made the resistors redundant to get the value down and should one fail
>ensure discharge will still occur, albeit more slowly. This was the one of
>the critical elements I checked during my initial testing this weekend.
>
>I can easily reduce the capacitance by half should testing show it is
>unnecessary but I think this will only be a false sense of security since
>the two remaining caps will still present nearly the same danger as four.
>The key point is to ensure they are always safely discharged after use which
>I think I have done.
>
>=========================================
>Dave Kyle
>Austin, TX USA
>Email: dave-at-kyleusa-dot-com
>
>
>-----Original Message-----
>From: Tesla list [mailto:tesla-at-pupman-dot-com]
>Sent: Monday, August 11, 2003 10:39 PM
>To: tesla-at-pupman-dot-com
>Subject: Re: DC Resonance Charging Advice Sought
>
>Original poster: "S & J Young by way of Terry Fritz <teslalist-at-qwest-dot-net>"
><youngs-at-konnections-dot-net>
>
>Dave,
>
>I will comment on the need for PFCs. I found they did not help at all with
>my DC supply. The reason I believe is because the filtering capacitance
>gets reflected back as a much higher value across the primary, and so PFC is
>already in place.
>
>By the way, the 7 uF smoothing capacitor is highly dangerous and much more
>than you need. The smoothing cap need only be about ten times your tank
>capacitance.
>--Steve Y.
>----- Original Message -----
>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: <tesla-at-pupman-dot-com>
>Sent: Monday, August 11, 2003 12:12 AM
>Subject: DC Resonance Charging Advice Sought
>
>
> > Original poster: "Dave Kyle by way of Terry Fritz <teslalist-at-qwest-dot-net>"
><dave-at-kyleusa-dot-com>
> >
> > Several months ago after being inspired by Steve Conner's very impressive
>DC
> > coil http://www.scopeboy-dot-com/tesla/index.html I started my own DC coil
> > project. I was drawn to the very elegant power control permitted by DC
> > resonance charging. Richie Burnett's site offers an excellent explanation
> > and provided the designs rules that I have followed
> > http://www.richieburnett.co.uk/dcreschg.html#resonant. Of course for the
> > ultimate expression of DC resonance charging one only needs to look at
>Greg
> > Leyh's incredible Electrum http://www.lod-dot-org/index.html.
> >
> > I have now completed and tested to 8KVDC (without load) the DC power
>supply
> > which can be seen here:
> > http://home.austin.rr-dot-com/dkyle/images/temp/dc_tesla_ps.jpg. For scale
>the
> > base disk is two feet across. You will note the very large black power
> > transformer, full wave rectifier and de-Qing circuit, smoothing
>capacitors
> > with safety bleeders and grey charging inductor.
> >
> > Specifications are as follows:
> > 4.700KVAC 775VA transformer (6.65KVDC rectified)
> > 7uf -at- 10KVDC of smoothing capacitors
> > 20Henry -at- 15KVDC inductor
> >
> > Under construction:
> > ..02uf -at- 20KVDC cap
> > 0 to 500bps RSG
> > 4 inch x 25 inch secondary with 1400 turns of #26 gauge wire
> > 6x24 inch toroid
> > 15 turn primary (tuned at 11 turns)
> >
> > Advice needed on the following:
> >
> > 1.) I have yet to resolve the system grounding. Is it advisable to ground
> > the center point of the main transformer for safety (like an NST)? Or
>would
> > it be better to simply ground the negative side of the DC power supply?
>Or
> > let it all float and just ground the secondary?
> >
> > 2.) I am assuming this transformer is not shunted (current limited) but
> > short of dismantling it how can I tell? DC resonance charging is self
> > current limiting so that will not be an issue but I would like pull
>current
> > slightly higher than the transformer's rating.
> >
> > 3.) Assuming the transformer is not shunted would there be any benefit to
> > adding PFC caps?
> >
> > 4.) I have noticed in some of the very few DC coils documented on the net
> > that a clamp diode and air inductor are sometimes added to the charging
> > circuit presumably to protect the supply and caps from over voltage and
> > transients. Can anyone comment on the need for this?
> >
> > Dave
> >
> > =========================================
> > Dave Kyle
> > Austin, TX USA
> > Email: dave-at-kyleusa-dot-com
> >
> >
> >