Re: SISG Coil question... (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Sun, 19 Aug 2007 16:03:25 -0500
From: resonance <resonance@xxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: SISG Coil question... (fwd)



IGBTs like lower switching frequencies, especially below 75 kHz --- max most 
are rated for, so keep the inductance large to keep the res frequency lower 
which results in more energy transfer efficiency and reduces heating.

Also, as you increase the inductance (lowering the sec res freq) by 
increasing the sec coil radius, the inductance goes much higher as it 
depends on the SQUARE of the radius of the sec coilform, so larger is better 
in most all cases.

Lower res freq for the IGBTs and more output voltage (better air ionization) 
due to larger inductance.  Output Vsec = 75% x Vpri x SQR (Lsec / Lpri). 
Keeping the sec inductance high is almost always better.

Small 1-3 kVA coils use 6, 8, 10 inch dia. coilforms which 3 kVA to 7 kVA 
favor large dia sec coils, typically 12 to 24 inch diameter.  4 inch can be 
used for small coils but you lose a lot of efficiency and stresses your 
IGBTs to the breaking point.

Resonance Research Corp.
www.resonanceresearch.com


----- Original Message ----- 
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Saturday, August 18, 2007 5:11 PM
Subject: Re: SISG Coil question... (fwd)


>
> ---------- Forwarded message ----------
> Date: Fri, 17 Aug 2007 23:50:33 +0200
> From: Finn Hammer <f-h@xxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Re: SISG Coil question... (fwd)
>
>
>
> Tesla list skrev:
>> ---------- Forwarded message ----------
>> Date: Fri, 17 Aug 2007 10:52:45 -0400
>> From: Daniel Kline <daniel_kline@xxxxxxxxxxx>
>> To: Tesla list <tesla@xxxxxxxxxx>
>> Subject: SISG Coil question...
>>
>> Hello,
>> Does the operating frequency of a Tesla-coil system using a SISG matter?
>> Is there a frequency that's too low or too high?
>
> I don`t think that there is a lower limit to the resonant frequency due
> to the sisg components. I have run as low as 40kHz.
> There may well be an upper limit determined by the IGBT and the
> freewheeling diode, but I am no solid state expert, so others should
> answer that.
>>
>>
>> Is it possible to over-current a SISG?
>
> Absolutely. This is determined by the current handling ability of the
> IGBT. When I grew tired of the 600Amps limit imposed by the
> IRG4PSH71KDPBF`s originally specified for the job, I switched over to
> the CM600HA and successfully ran them at 4.5kA
> You can see one such brick doing 1,5 meters here:
> http://www.youtube.com/watch?v=vK17-CoB7LE
>> How do I calculate current through a SISG?
>
> You need to calculate the surge impedance of the tank, and combined with
> the voltage, you have the current.
>
> Z=sqrt(L/C)
>
> I=V/Z
>
> Hope this helps.
>
> Cheers, Finn Hammer
>>
>> Thanks,
>> Dan K.
>>
>>
>>
>>
>>
>
>
>
>