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Re: [TCML] Dual MOT SGTC
Hi
I didn't measure the arc to ground. But the secondary is 52 cm, the strikerail is set at 5 cm above the bottom of the secondary and it never arcs to the strikerail, so I suppose that the lenght of the streamer would be around 40-45 cm. (the diameter of the toroid is 28 cm).
The schema is here:
http://www.geocities.com/livvasil/4kvtcsch.html
As you see in the schema I used two ballast coils connected in parallel, and together in serie with the antiparalleled MOTs primaries.
The data inscriptioned on the ballast coils are:
P = 250 VA, Ic = 2.15 A (in normal use), cos (fi) = 0.56, f = 50 Hz
Measured DC resistence is 3.7 ohms. I can not measure the AC current.
>From the power triangle cos (fi) = resistive power/ total power
Total power is 250 VA
Resistive power = (I^2)*R
so the ballast will limit the current at value I = sqrt [(P/R)*cos (fi)] = 6.15 A, and for two identical ballast coil in parallel the avalaible current would be around 12.3 A. Of course the real current will be smaller because the load seen by the two MOTs, which is adding to the impedance of the inductive ballast.
Maibe it is wrong, I didnt make more calculus, the matching between the current limiting and the value of the primary cap was empirical.
Unfortunately I can measure only DC currents with my meter.
I am sure I can increase the primary cap for more bang energy, but I am happy as it is.
teslina
>
>
--- On Fri, 6/27/08, DC Cox <resonance@xxxxxxxxxxxx> wrote:
> From: DC Cox <resonance@xxxxxxxxxxxx>
> Subject: Re: [TCML] Dual MOT SGTC
> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> Date: Friday, June 27, 2008, 6:39 PM
> What was your maximum measured spark output length, toroid
> to ground?
>
> What was the current in the primary of the MOTs limited to
> (each MOT I
> assume had separate ballast)?
>
> Dr. Resonance
>
>
>
>
> On Thu, Jun 26, 2008 at 11:28 PM, Liviu Vasiliu
> <teslina@xxxxxxxxx> wrote:
>
> > 37.5 nF @ 16 kV MMC type, 3 strings, each string with
> 8 caps in serie (100
> > nF @ 2kv)
> >
> > teslina
> > >
> > >
> >
> >
> > --- On Thu, 6/26/08, DC Cox
> <resonance@xxxxxxxxxxxx> wrote:
> >
> > > From: DC Cox <resonance@xxxxxxxxxxxx>
> > > Subject: Re: [TCML] Dual MOT SGTC
> > > To: "Tesla Coil Mailing List"
> <tesla@xxxxxxxxxx>
> > > Date: Thursday, June 26, 2008, 5:42 AM
> > > What size capacitor did you use with the two
> MOTs?
> > >
> > > Dr. Resonance
> > >
> > > On Wed, Jun 25, 2008 at 3:05 PM, Liviu Vasiliu
> > > <teslina@xxxxxxxxx> wrote:
> > >
> > > > Hi list
> > > >
> > > > I built these days another dual MOT for a
> friend (he
> > > needs it for a
> > > > presentation or maibe to impress some other
> guys, who
> > > knows). I dont have
> > > > the time to set a web page, but I made a
> quick movie
> > > presentation (sort
> > > > of...) and some "action" movies.
> > > >
> > > > The power source is just two MOTs in serie
> (4-4.5 kV
> > > output), inductive
> > > > ballasted on the low voltage side. I still
> believe
> > > that it is the cheapest
> > > > solution for the eastern Europe where the
> NSTs are
> > > still rare. They give
> > > > enough power for a healthy streamer and if
> they are
> > > well ballasted they can
> > > > get some more voltage input (from a variac)
> without
> > > saturation (just more
> > > > voltage and lower current in the same power
> area). The
> > > gap is not set very
> > > > wide (to mantain the breakrate at resonable
> high
> > > level), so the streamer is
> > > > not the longest possible, but is still very
> good for a
> > > presentation. I wound
> > > > a bit longer secondary to prevent the
> strikes to the
> > > strikerail, allowing
> > > > the full lenght for the streamers. Because
> the low kV
> > > input the primary cap
> > > > cost is very low.
> > > >
> > > > The "presentation" movie:
> > > >
> > > > http://www.youtube.com/watch?v=scdu0BoxSaw
> > > >
> > > > 220 V from mains, multiple streamer output:
> > > >
> > > > http://www.youtube.com/watch?v=5IdWf83LNvw
> > > >
> > > > 250 V from variac, more like a single
> streamer output:
> > > >
> > > > http://www.youtube.com/watch?v=18yltrMa5AE
> > > >
> > > > Enjoy
> > > >
> > > > teslina
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
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> >
> >
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