RE: [TCML] Primary Grounding was [Control Cabinet ...]

["Lau, Gary" <Gary.Lau@xxxxxx>]

Hi Phillip,

I don't doubt that you saw a primary strike just prior to David's cap dying.  But I think it's not always easy to separate cause and effect.

Conservation of energy will not allow the primary cap to be recharged by a streamer-strike to a higher voltage than before the gap fired.  So I don't think that's what killed the cap, although certainly possible that I missed something.

Instead, let me propose this.  What if through RSG misfiring or some other conspiracy of events, the cap was able to charge to a higher-than-normal voltage.  When the gap did fire, it would be a bigger than normal bang, resulting in a longer secondary streamer, and able to strike something (primary) normally out of reach?  The over-charging of the cap as a result of gap miss-fire may be the cause of the cap's demise, rather than the primary strike.

I don't know, just an arm-chair perspective.  Corrections, discussion, and alternate theories are very welcome!

Regards, Gary Lau
MA, USA


> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of Phillip Slawinski
> Sent: Wednesday, December 17, 2008 8:54 AM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] Primary Grounding was [Control Cabinet ...]
>
> I was there when David fried his Hipotronics cap.  I know for a fact that I
> saw a streamer hit the primary right before the cap went short.
>
> We also tried running my 6" coil on his Green Monster control panel.  It was
> running very well, and fortunately the sucker gap was not overheating.  Of
> course it was just above freezing outside, so this is somewhat
> unsurprising.  What was surprising was then number of primary strikes my
> coil was taking.  I've never had a problem with primary strikes until I ran
> it with a grounded primary.  I do not run my coil with the strike rail
> grounded, I just leave it floating because the primary will arc to it.  I
> ran my 6" coil on Cameron Prince's pole pig this summer and did not have a
> single primary strike.  This was not because the streamers could not reach
> the primary either.  Cameron's pig has two ears, and neither ear is
> grounded.
>
> http://www.flickr.com/photos/pslawinski  I've got some pictures of the run
> at David's home, and on the second page there is a video of the run at
> Cameron's home.
>
> On Tue, Dec 16, 2008 at 21:39, David Rieben <drieben@xxxxxxxxxxx> wrote:
>
> > Hi Bart, Jim,
> >
> > If I'm not mistaken, I was the one who originally turned you on
> > to the grounding one of the ears of the pig to allow a single HV
> > transmission line from the pig to the primary circuit ;^) However,
> > after some recent discussion with one or two members, I am be-
> > ginning to wonder if this is the best configuration in light of suppres-
> > sing primary coil strikes. I have been running my Green Monster in
> > this fashion but have noticed rather excessive primary strikes. As a
> > matter of fact, I smoked my beloved Hipotronics pulse cap during
> > a recent firing of the beast for a mini-Teslathon ;^( (3 of us). I'm
> > not sure but it was mentioned that a large primary strike was seen
> > right before the Hipotronics caps gave up the ghost. Of course I
> > have an RF grounded strike shield ring and I was figuring that this
> > may be the main culprit for primary bound strikes. Do you guys think
> > that leaving the primary coil "floating" with not connection to RF
> > (mains ground) will suppress primary bound strikes from the
> > topload or is this a sure recipe for distruction of the primary circuit
> > components? Of course, I realize that one of the best methods of
> > suppressing primary strikes is to add an extra corona shield toroid
> > underneath the main topload. I have not done this in my design main-
> > ly due to the shear size of my main topload (12x56") in comparison
> > to the outer diameter of my primary spiral (about 40"). It seems to
> > me though that the RF grounded strike ring (which is about the same
> > diameter as the outermost primary turn - ~40", and sits on a horizon-
> > tal plane about 4" above the primary coil's plane, is the main culprit
> > at drawing the strikes toward the primary coil, regardless of whether
> > the primary coil is "floating" or grounded. What do you think?
> >
> > Fortunately, I had a spare Plastic Capacitors BNZ custom made pulse
> > cap that I got as a spare from list member Bill Limeaux (Gomez
> > Addams), that was of the same capacitance as the now defunct Hipo-
> > tronics cap (.1 uFd) that I was able to swap out to get the Monster
> > breathing fire again ;^)
> >
> > Anyway, sorry for the rather lengthy post but I am really curious
> > about this issue and thank you all in advance for your responses.
> >
> > David Rieben
> >
> > PS - I, too, have been tying the external tank of my pig to RF
> > ground via the transmission line from the tank circuit assembly
> > and if I disconnect the primary coil from the RF ground, then
> > the pig's external tank will also be floating (that just doesn't
> > sound good to me!)
> >
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