Re: PIRANHA-III Power control? (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Gerry Reynolds <greynolds@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Sun, 17 Dec 2006 15:59:51 +0900
From: Peter Terren <pterren@xxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: PIRANHA-III  Power control? (fwd)

You are concerned to avoid the near saturation wastefulness of the MOT's 
driven at mains voltage.  A dimmer switching at 90%  will be well past the 
peak of the half wave and hence past the point of near saturation I suspect 
but with the current being 90 degrees slow I am not sure what will happen. 
Switching a transformer on at zero crossing gives the biggest current surge 
(rather than at peak).  I'm sure the dimmer people have it all worked out 
but I'm not sure it will neccessarily work as expected to improve 
efficiency.

Peter

> ---------- 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
> 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
>
> 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