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RE: [TCML] Primary Grounding was [Control Cabinet ...]
If his cap were charged to a greater voltage than usual, resulting in a larger than usual bang, resulting in a longer than usual secondary streamer, wouldn't that then save the cap from over-voltage? I mean, if a cap survives a "charge cycle" long enough to "bang", then the voltage would only go down at that point, right? If a cap dies, wouldn't it simply discharge internally, rather than ending by discharging all its energy in a final bang? I guess it may depend on whether it really died due to over-voltage. Does it make sense that it would go out in a bang, or a whimper?
Adam
--- On Wed, 12/17/08, Lau, Gary <Gary.Lau@xxxxxx> wrote:
> From: Lau, Gary <Gary.Lau@xxxxxx>
> Subject: RE: [TCML] Primary Grounding was [Control Cabinet ...]
> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> Date: Wednesday, December 17, 2008, 10:22 AM
> 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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