Re: PIRANHA-III Power control? (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Gerry Reynolds <greynolds@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Sun, 17 Dec 2006 07:35:15 -0500
From: BRIAN FOLEY <ka1bbg@xxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: PIRANHA-III  Power control? (fwd)

Hi, lets see if i can offer a couple things about scr control. an scr is a
switch with a diode in its output. once the minimum gate voltage/current is
met, its just a big switch controlling 1/2 of the sine wave. now the real
difference i see about this inductive/non inductive load is couple things.
first a inductor and usuall a toroid core for small size limits inrush
current. second is a snubber cap on the output. i alsways used a mov as well
on output side. if running 130 volts use 240 volt mov. now for a better
control the 2 scr drive circuit is the one you want. it controls both
negative and positive cycles. my rule of thumb on an scr is if it runs 120
volts use 300 volts minimum, if 240 volts use 600 volt. if it needs a
current of 20 amps use a 45 amp scr and no worry about failure. if the load
is very inductive i use 1200 volt scr for 240 volt circuit. use brick scrs
from a invertor or large scr motor speed control. i have a pile of scrs up
to 1200 volts at 125 amps. find a circuit, make sure your delivering more
than minimum voltage and current to gate and your off and running....you
must always limit gate current/voltage maximum....use the plain 2 scr
circuit, dont want regenerative, or back emf sensing. a quick search of the
web will bring hundreds of circuits. cul brian f.
----- Original Message ----- 
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Sunday, December 17, 2006 1:03 AM
Subject: PIRANHA-III Power control? (fwd)


> 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
>
> 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
>
>
>
>
>
>
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