Re: PIRANHA-III Power control? (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Gerry Reynolds <greynolds@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Sun, 17 Dec 2006 17:57:46 +0000
From: Chris Rutherford <chrismrutherford@xxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: PIRANHA-III Power control? (fwd)

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
> >
> >
> >
> >
> >
>
>
>