Re: PIRANHA-III Power control? (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Gerry Reynolds <greynolds@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Mon, 18 Dec 2006 10:25:39 -0700
From: resonance <resonance@xxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: PIRANHA-III Power control? (fwd)




At present we are working on a similar circuit to eliminate variacs.

We plan on using a series choke with the MOT primary.  We are winding up 
some 2 inch ID x 18 inch long PVC pipe filled with cut 1/8th inch dia. steel 
rods to add a small inductance to clip off the harshest peaks on the inrush 
current.  We plan on using one in each MOT primary.  Unlike Terry's circuit, 
we our using a single MOT running around 16-18 Amps each running off a 
separate 120 VAC circuit --- shooting for a 4.0 to 4.4 kVA total input into 
the system.  We are shooting fgor 7-7.5 ft long sparks on a portable coil 
that can run on two separate 120 VAC circuits and not require 220 volts for 
portable operation at schools, etc.

Brian V. is working together with us on this project.  I also want to 
eliminate the necessity of using heavy variacs for current control.

This posted opto-isolated circuit might prove to be the best answer as it is 
totally independent of the AC line for triggering.

I will advise on how it works out.

Dr. Resonance


>
> Here is a "A High-Resolution Digital Dimmer" based on the 555 timer.  It
> looks very nice.  I'm inspired!
>
> http://archive.chipcenter.com/analog/tn046.htm.
>
> Again the TRIAC driver stage is opto isolated(MOC3022), which is aways a
> benefit in HV systems, but in reality how much is this going to help 
> defend
> against a 1MV strike?
>
> Of course the challenge would be adapting the output stage to cope with
> inductive loads.  The consensus seems to be the use of a snubber circuit
> (cap + mov), other filters and a healthy amount of capacity over-kill i.e.
> TRIAC rating of *5 voltage and *2 current of values seen.
>
> I cant really see the EM switching emissions being a problem in this case 
> :)
>
> Chris R
>
>
>
> On 12/17/06, Tesla list <tesla@xxxxxxxxxx> wrote:
>>
>> Original poster: Gerry Reynolds <greynolds@xxxxxxxxxx >
>>
>>
>>
>> ---------- Forwarded message ----------
>> Date: Sun, 17 Dec 2006 14:16:41 +0000
>> From: Chris Rutherford <chrismrutherford@xxxxxxxxxxxxxx>
>> To: Tesla list <tesla@xxxxxxxxxx>
>> Subject: Re: PIRANHA-III Power control? (fwd)
>>
>> Hi All,
>>
>> Having briefly looked on the Internet the system described at the link
>> below
>> looks like it might be useful.  Although it has 4 channels, you could use
>> one channel for each of your 2 MOTs, or even a parallel series 
>> combination
>> using 4 MOTs.
>>
>> http://www.epanorama.net/circuits/dimmer4.html
>>
>> I think the key to these designs is the linking the PWM ramp voltage
>> timing
>> to the mains phase.  i.e. The ramp starts when the mains is at 0v and
>> allows
>> the output stage to conduct until the ramp voltage reaches the trigger
>> voltage and then stops conducting, that way you basically allow the mains
>> to
>> conduct for x% of each cycle.  This may help minimise 'distortion' on 
>> your
>> power line feeding the MOTs.  You could probably use a 555 circuit or a
>> digital counter/comparator/ ADC circuit to produce the ramp.
>>
>> Thanks
>>
>> Chris R
>>
>>
>>
>> On 12/17/06, Tesla list <tesla@xxxxxxxxxx> wrote:
>> >
>> > Original poster: Gerry Reynolds < greynolds@xxxxxxxxxx>
>> >
>> >
>> >
>> > ---------- Forwarded message ----------
>> > Date: Sat, 16 Dec 2006 19:08:32 -0700
>> > From: Terrell Fritz < terrellfone@xxxxxxxxxxxxxxxxxxxxxxx>
>> > To: Tesla list <tesla@xxxxxxxxxx>
>> > Subject: PIRANHA-III  Power control?
>> >
>> > Hi,
>> >
>> > I am working on PIRANHA III issues today.  A dual MOT system that runs
>> off
>> > a 120VAC 20A circuit with ease.  It is in the 8 foot arc to ground
>> > range...  About 2kW input at ~90% efficiency.
>> >
>> > These coils like to run with the MOT input voltage at about 95-105 
>> > volts
>> > to
>> > stay out of the MOT saturation range which just waists precious
>> > current.  Normally that is done with a 15 -20 amp variac...
>> >
>> > http://drsstc.com/~piranha/PIRANHA/PIRANHA-3/PIRANHA-III-001.gif<http://drsstc.com/%7Epiranha/PIRANHA/PIRANHA-3/PIRANHA-III-001.gif>
>> >
>> > Variacs are very nice, but they are real heavy and not real "modern" or
>> > solid state.  The charging circuit (MOT / Primary Cap loop) is resonant
>> > too
>> > to drive up to a 15000 volt firing voltage...  But the waveforms are
>> > pretty
>> > "tame" and the power factor is excellent without any fiddling.
>> >
>> > http://drsstc.com/~piranha/PIRANHA/PIRANHA-3/PIRANHA-III-002.gif<http://drsstc.com/%7Epiranha/PIRANHA/PIRANHA-3/PIRANHA-III-002.gif>
>> >
>> > It would be super cool to use a beefy lamp dimmer circuit or some
>> similar
>> > cheap but very reliable solid state thing to control power other than
>> the
>> > variac.  The PIRANHA input section is very forgiving of sloppy input
>> wave
>> > forms and all so no big deal there.  Ceiling fans are made for 
>> > inductive
>> > loads...
>> >
>> > I don't know much about dimmer circuits and such so I can't guess at
>> what
>> > to do and feed the computer models well.  0:-|
>> >
>> > If anyone knows what to do to make a cheap hardy dimmer type circuit
>> that
>> > could run two MOTs (~2kW)  I am all ears ;-))
>> >
>> > Cheers,
>> >
>> >         Terry
>> >
>> >
>> >
>> >
>> >
>>
>>
>>
>
>
>