RE: [TCML] BIG solid state

["Phil Tuck" <phil@xxxxxxxxxxx>]

No Vasil, you were not in any rude, nor was my 'tongue in cheek' reply meant
to be. Spark gap technology is cheap and simple which is how I like things,
but it is generally fair to say they can beat SS stuff regarding spark
length to power input.  [Don't let's start a war of postings on this]
Hats off to Steve and others for creating these electronic marvels, I
struggle working out which way round a resistor goes [wink]

Regards
Phil Tuck

www.hvtesla.com




-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of Liviu Vasiliu
Sent: 15 June 2011 19:54
To: Tesla Coil Mailing List
Subject: Re: [TCML] BIG solid state

Did I was rude? Sorry Phil. It was not intended. I include myself in the
gapper category as I have limited electronic knowledge, so the phrase was
directed to me more than to the others.
Do not be offended. It is not related with the age too.

vasil
>
>
>An excellent build and infinitely more complex than a lot of us could 
>manage.
>A YouTube video to see the 'type' of streamer it produces would be 
>great. >I say 'type' as I like the lazy wandering sort as produced by 
>the Biggg one, rather than the more frantic output of some SS types.

>There are many I am sure who want to know about the fire Dept. issues, 
>>which were briefly mentioned as a teaser.


>PS:    I can't say I agree with Vasil's rather cheeky comment of >>  " and
>they win compared with "those old spark gappers" 

>Regards
>Phil Tuck  (an old spark gapper)

>www.hvtesla.com
>
>
--- On Wed, 6/15/11, Steve Ward <steve.ward@xxxxxxxxx> wrote:

> From: Steve Ward <steve.ward@xxxxxxxxx>
> Subject: [TCML] BIG solid state
> To: "Tesla list" <tesla@xxxxxxxxxx>
> Date: Wednesday, June 15, 2011, 6:35 AM Hi Everyone,
> 
> Just a post about a recent project of mine.  Many hands involved on 
> this one (see credits later).  So far its just a prototype, but 
> results are
> promising:
> 
> http://www.flickr.com/photos/kickermagnet/5811280440/in/photostream
> 
> This is, as far as im aware, the largest Double Resonant Solid State 
> Tesla Coil built and working as intended.  The machine stands 15 foot 
> tall (to the top of the toroid).  With breakout point at 16 foot above 
> the ground, its made some 25 foot sparks.  Power input at 200bps was 
> measured at 33kVA (480VAC 3 phase, about 40.5A RMS).  I estimate a 
> power factor of .92 given the line reactor used to smooth the current 
> peaks charging the 2kJ of DC bus storage.  The secondary is 24" 
> diameter and wound to just over 8 feet length.  The toroid is 96" by 
> 16", and is indeed very ugly.
> 
> For now, i dont have many photos of the detailed construction (this is 
> something i should get to soon) but you can sorta see whats going on 
> here:
> 
> http://www.flickr.com/photos/kickermagnet/5487415037/in/photostream
> 
> <http://www.flickr.com/photos/kickermagnet/5487415037/in/photostream>O
> n
> the
> lower level, you can see banks of white electrolytic DC capacitors, 
> 3300uF 400V X 16 total, wired in series parallel banks, one per each 
> of the 4 IGBT inverters.  The inverters consist of a full-bridge of 
> CM300DY-24H transistors.  So each pair of half-bridge bricks (there 
> are 8 total, 4
> H-bridges) drives its own .625uF 20kVAC capacitor, and 2-turn primary 
> coil.
>  There are 4 MMCs and 4 primaries.  The mutual inductance between 
> primaries and equal MMCs force current balancing of the 4 drives (each 
> drive sees the same load impedance).  This was chosen to avoid some 
> possible issues with directly paralleling modules, such as, what 
> happens if 1 device fails?  Does it take out all the rest?  In this 
> scheme, there is DC isolation between inverter outputs, so one 
> inverter failure should not take out the other 3.
>  And, in fact, if i did lose an inverter, i should be able to short 
> its tank circuit (using its energy storage of the MMC to maintain
> tuning) and
> continue operating at 3/4 power.  Hopefully it never comes to this!
> 
> The coil has a natural resonance of about 45khz, but i found that 
> de-tuning the drive down to 40khz or so was best to keep it in tune 
> with large streamer loading.  The primary current peaks at 6000A after 
> about 6 cycles of excitement.  The coupling coefficient of the system 
> is fairly high, at about .19 (estimated by a 5 cycle beat period that 
> didnt quite notch).  So detuning the primary seemed to work well at 
> efficiently transferring energy to the secondary in the event of being 
> detuned by streamers.
> 
> The primary copper is 3/8" diameter to keep the surface area down 
> (which happens to reduce AC losses as the eddy currents are lessened).  
> I pump tap water through the primary to keep it cool, as the RMS 
> current is something like 80-100A per primary coil!  Me (tall guy) and 
> friend Mike working on the primary coils:
> 
> http://www.flickr.com/photos/kickermagnet/5487414563/in/photostream
> 
> The MMC is made out of giant polypropylene snubber capacitors, rated 
> 5uF, 2500VAC pk, 3600Apk and 80A RMS each.  They make the CDE MMC caps 
> look very small indeed.  I think the whole MMC bank (32 of these
> caps) weighs
> something like 150lbs.  Total bank is 4 strings of 8 in series, 2.5uF 
> 20kVAC effectively.
> 
> RF grounding was primarily a 4x20 foot sheet of metal "cloth" (1/2" 
> square steel mesh) laid on the parking lot, and also clipped to the 
> building ground rod (about 40 feet away).  Would have preferred an 
> even larger sheet of metal down there, but this was available and 
> quick, and seemed to do the trick!
> 
> Spark performance ended up being right on target, at 25 feet, with 
> extrapolations from smaller DRSSTCs (that make 10-12 foot sparks).
> 
> I gotta thank the help of many friends, Jeff Larson for his use of 
> materials and labor on the secondary coil for this beast.  Big thanks 
> to the guys in Arcattack, who stayed at my house for a week this 
> january to help me crank out this prototype (we actually got it 
> running by the end of a week!).
>  Terry Blake has been supportive in helping setup and teardown of this 
> system, which isnt trivial, and for being the guy in the suit.  And 
> recently Jimmy Hynes (who got me working with DRSSTCs originally) who 
> visited and instigated the testing of this machine, and helped tune it 
> up to almost perfectly match our expected outputs. And Dave (who isnt 
> on the TCML) for being such an awesome host, letting us run and store 
> this machine at your shop, and dealing with the city and fire 
> department on issues that really dont concern them, thats a story for 
> another time.
> 
> Steve
> _______________________________________________
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> 
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