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Re: [TCML] Series Transformers



I have seen a bunch of sidacs is parallel used as a solid state spark gap.
Lok at tesladownunder.com i think he talks about it on his website.

On Wed, Jun 18, 2008 at 6:47 PM, Phillip Slawinski <pslawinski@xxxxxxxxx>
wrote:

> Has anyone made a spark gap tesla coil with such a low voltage and high
> current?  Is there a way to make a sort of solid state spark gap?  Of
> course
> without all the complicated circuitry of a DRSSTC.
>
> On Wed, Jun 18, 2008 at 7:37 PM, bartb <bartb@xxxxxxxxxxxxxxxx> wrote:
>
> > It probably could be done with a rotary, but it would certainly be an
> > unconventional rotary. A sucker gap is good, but at the large cap size
> > discharge energy, it's likely to be a problem. And due to the low
> voltage,
> > increasing electrodes within the sucker gap has the same problem as the
> > rotary. This is also not a good system for a standard hyperbaric gap.
> > Hmmm..... Well, maybe a large surface area quench gap would work?
> >
> > An interesting problem! SISG comes to mind for some odd reason  ;-) .
> >
> > Bart
> >
> >
> > Lau, Gary wrote:
> >
> >> My experience to date has been strictly with NST's, so take what I say
> >> with a grain of salt.  But the experience of others as reported on this
> List
> >> is that static gaps perform poorly with high current transformers.  Yes,
> I
> >> suspect that quenching will be the issue.
> >>
> >> I would fear that a rotary gap would need its electrodes set
> precariously
> >> close, especially since the total gap needs to be divided into two
> segments.
> >>  But you didn't hear me say that it can't be done!
> >>
> >> Regards, Gary Lau
> >> MA, USA
> >>
> >>
> >>
> >>> -----Original Message-----
> >>> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> >>> Behalf Of Phillip Slawinski
> >>> Sent: Wednesday, June 18, 2008 8:11 AM
> >>> To: Tesla Coil Mailing List
> >>> Subject: Re: [TCML] Series Transformers
> >>>
> >>> I have already built a sucker gap, and it seemed to do a decent job
> >>> quenching.  This of course was with a .013 mfd cap.  I suppose when the
> >>> full
> >>> 1mfd + cap is hooked up the quenching will worsen?  Why do you say a
> >>> rotary
> >>> gap is probably not advisable, electrode spacing has to be too close
> for
> >>> comfort?
> >>>
> >>> On Wed, Jun 18, 2008 at 6:41 AM, Lau, Gary <Gary.Lau@xxxxxx> wrote:
> >>>
> >>>
> >>>
> >>>> 2970V @800mA will be challenging.  Despite many who thought 4kV is too
> >>>> low
> >>>> for a coil, I built a very efficient coil using a 4kV/20mA NST, using
> a
> >>>> single static cylinder gap.  While it may be possible to get a static
> >>>> gap to
> >>>> work at 2970V, the 800mA part may be difficult to quench.  At that low
> a
> >>>> voltage, an RSG is probably not advisable.  You would also need a very
> >>>> large
> >>>> cap to utilize the full potential of that power supply.
> >>>>
> >>>> Regards, Gary Lau
> >>>> MA, USA
> >>>>
> >>>>
> >>>>
> >>>>> -----Original Message-----
> >>>>> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> >>>>> Behalf Of Phillip Slawinski
> >>>>> Sent: Tuesday, June 17, 2008 9:21 PM
> >>>>> To: Tesla Coil Mailing List
> >>>>> Subject: Re: [TCML] Series Transformers
> >>>>>
> >>>>> I have a nice variac 20A rated and 0-270V output with 120V in.  I was
> >>>>>
> >>>>>
> >>>> able
> >>>>
> >>>>
> >>>>> to wire them in series and ran them up to 2970V @ 800mA.  Is 2970V
> too
> >>>>>
> >>>>>
> >>>> low
> >>>>
> >>>>
> >>>>> to run a TC efficiently?
> >>>>>
> >>>>> On Tue, Jun 17, 2008 at 5:13 PM, David Speck <Dave@xxxxxxxxxxxxxxxx>
> >>>>>
> >>>>>
> >>>> wrote:
> >>>>
> >>>>
> >>>>> OK, Phil,
> >>>>>>
> >>>>>> Looks to me like you want to step 110 VAC to perhaps 1100 VAC.
> >>>>>>
> >>>>>> If they are identical transformers, then their internal polarities
> are
> >>>>>> probably the same.  (But you can't count on that!)
> >>>>>>
> >>>>>> Wire the two primaries in parallel.  Connect the high voltage output
> >>>>>>
> >>>>>>
> >>>>> end of
> >>>>
> >>>>
> >>>>> one transformer secondary to the low voltage end of the other
> >>>>>>
> >>>>>>
> >>>>> secondary.
> >>>>
> >>>>
> >>>>>  Power up the pair with a Variac set on a very low voltage, say one
> >>>>>>
> >>>>>>
> >>>>> volt.
> >>>>
> >>>>
> >>>>>  Measure the voltage from the low end of the first transformer
> >>>>>>
> >>>>>>
> >>>>> secondary to
> >>>>
> >>>>
> >>>>> the high end of the second transformer secondary.  If you have the
> >>>>>> connection right, then you should see something like 11 volts.  You
> >>>>>> can
> >>>>>>
> >>>>>>
> >>>>> then
> >>>>
> >>>>
> >>>>> crank up the Variac voltage slowly to confirm that you see a
> >>>>>>
> >>>>>>
> >>>>> corresponding
> >>>>
> >>>>
> >>>>> increase in the output voltage at the high end.  Remember that
> Variacs
> >>>>>>
> >>>>>>
> >>>>> do
> >>>>
> >>>>
> >>>>> not provide any line isolation, and even at a one volt output, the
> >>>>>>
> >>>>>>
> >>>>> "hot" end
> >>>>
> >>>>
> >>>>> of the Variac output is still at line potential and can deliver a
> >>>>>>
> >>>>>>
> >>>>> lethal
> >>>>
> >>>>
> >>>>> shock.
> >>>>>> If you don't see any voltage, check the output across each of the
> >>>>>> transformers, to make sure that one of them is not open.  If both
> are
> >>>>>> putting out about 5.5 volts individually, then you have the
> >>>>>> secondaries
> >>>>>> connected wrong.  Just swap the link between the two secondaries to
> >>>>>> the
> >>>>>> opposite secondary pin on one transformer (with the power off!) and
> >>>>>>
> >>>>>>
> >>>>> recheck.
> >>>>
> >>>>
> >>>>> A small word of warning -- many digital voltmeters (both cheap and
> >>>>>> expensive) can give spurious readings when used to measure unloaded
> >>>>>> transformers.  You may get much more sensible readings if you
> parallel
> >>>>>>
> >>>>>>
> >>>>> a 1K
> >>>>
> >>>>
> >>>>> to 10K ohm power resistor across the inputs to your voltmeter.  I
> once
> >>>>>> wasted a half a day trying to figure out the transformer of a
> bandsaw
> >>>>>>
> >>>>>>
> >>>>> blade
> >>>>
> >>>>
> >>>>> welder with a good Fluke DVM.  The readings were all over the map,
> and
> >>>>>>
> >>>>>>
> >>>>> often
> >>>>
> >>>>
> >>>>> inconsistent and unrepeatable.  Putting a load resistor on the meter
> >>>>>>
> >>>>>>
> >>>>> made
> >>>>
> >>>>
> >>>>> everything work out sensibly.
> >>>>>> 1100 VAC isn't going to help you a lot for TC work.  You might be
> able
> >>>>>>
> >>>>>>
> >>>>> to
> >>>>
> >>>>
> >>>>> get away with seriesing 4 transformers for 2200 volts, but at this
> >>>>>>
> >>>>>>
> >>>>> point,
> >>>>
> >>>>
> >>>>> you will begin to stress the insulation between the windings and the
> >>>>>>
> >>>>>>
> >>>>> cores.
> >>>>
> >>>>
> >>>>>  I've read of 4 and 6 MOT series strings, but the outer transformers
> on
> >>>>>>
> >>>>>>
> >>>>> the
> >>>>
> >>>>
> >>>>> 6 MOT strings had to be run under transformer oil to prevent winding
> to
> >>>>>>
> >>>>>>
> >>>>> core
> >>>>
> >>>>
> >>>>> voltage breakdown.  OTOH, the power output of a 6 MOT string (~12
> KVAC
> >>>>>>
> >>>>>>
> >>>>> at
> >>>>
> >>>>
> >>>>> 500 mA, if you use big MOTs), can compare favorably with a 5 KVA pole
> >>>>>>
> >>>>>>
> >>>>> pig,
> >>>>
> >>>>
> >>>>> just not so nice and compact, but nearly free, if you can find the
> >>>>>>
> >>>>>>
> >>>>> MOTs.
> >>>>
> >>>>
> >>>>> HTH,
> >>>>>> Dave
> >>>>>>
> >>>>>>
> >>>>>> Phillip Slawinski wrote:
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>> Step Down transformers run in reverse.  The transformers have taps
> >>>>>>> for
> >>>>>>> neutral 100V 110V on the primary.  On the secondary neutral  420
> 480
> >>>>>>>
> >>>>>>>
> >>>>>> 550.
> >>>>
> >>>>
> >>>>> On Tue, Jun 17, 2008 at 1:39 PM, David Speck
> >>>>>>>
> >>>>>>>
> >>>>>> <Dave@xxxxxxxxxxxxxxxx>
> >>>
> >>>
> >>>> wrote:
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>> Phil:
> >>>>>>>>
> >>>>>>>> What kind of transformers?
> >>>>>>>>
> >>>>>>>> You can't series NSTs, 'cause they are center tap grounded.  You
> can
> >>>>>>>> parallel them for more current, though.
> >>>>>>>>
> >>>>>>>> Dave
> >>>>>>>>
> >>>>>>>> Phillip Slawinski wrote:
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>> Does anyone know of a way to wire two transformers so that they
> are
> >>>>>>>>> oppositely phased?
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>  _______________________________________________
> >>>>>>>
> >>>>>>>
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> >>>>>> Tesla@xxxxxxxxxxxxxx
> >>>>>> http://www.pupman.com/mailman/listinfo/tesla
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>> _______________________________________________
> >>>>> Tesla mailing list
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> >>>>> http://www.pupman.com/mailman/listinfo/tesla
> >>>>>
> >>>>>
> >>>> _______________________________________________
> >>>> Tesla mailing list
> >>>> Tesla@xxxxxxxxxxxxxx
> >>>> http://www.pupman.com/mailman/listinfo/tesla
> >>>>
> >>>>
> >>>>
> >>> _______________________________________________
> >>> Tesla mailing list
> >>> Tesla@xxxxxxxxxxxxxx
> >>> http://www.pupman.com/mailman/listinfo/tesla
> >>>
> >>>
> >> _______________________________________________
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> >>
> >>
> >>
> > _______________________________________________
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> >
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