RE: [TCML] SISG Repair

["caspina" <caspina@xxxxxxxxx>]

Ok, so here's some more info on my coil:

It's a 6" DC-Resonant Charging coil.
Power supply = 2 MOT secondaries in series bridge-rectified, and another
identical setup like this in parallel for more current (hence 4 MOT's).
Smoothing cap = 30uF (28 elco's 220uF / 450V), so I have clean 6kV dc.
Charging choke = 8 fluorescent ballasts wich are wired in such a way that I
can change from 4 in series (2.5H) to 8 in series (5H).
When I put 4 in series I can put the other string of 4 in parallel with the
first one (1.25 H).
This is the configuration I use most, it allows higher BPS.

>From here it goes to the SISG (wich is a triggered SISG).
IGBT = IRGPS60B120KD
SIDAC = K2401GRP
TVS = 1.5KE24CA (24V) and P6KE33CA (33V)
Because I absolutely wanted a triggerable version I designed the PCB's
myself: 1 Module has 4 250V sidacs, hence 1kV / Module.
To build a triggerable SISG I studied many posts on TCML by Finn Hammer and
Terry Fritz.

Tank Cap = 100nF (8x8 strings of 100nF / 1600V caps)
Resonant Frequency = 125kHz with smallest toroid (6" x 23.6") and 104kHz
with biggest (5" x 40").

In ideal case the primary peak current should be around 800A... maybe too
close to the limit of the IGBT's :0
The IGBT's get good warm if BPS is between 400 - 800, above that they will
go hot but I try not to do so too much/too long.
Since I can trigger the SISG I use the coil frequently with audio modulation
and it has been working fine for months, though I must say
I don't apply longer runs then 2 minutes.

The SISG may have been destroyed due to internal arcing of the fluorescent
ballasts: a lot of energy then can find a clean path to the SISG...
If the IGBT's are broke because of too much stress (current) during
operation then I would have expected them to have died earlier...

So in a way I am curious of other 'SISG'-users that have encountered
problems with theirs...

Cheers,

Michael.



-----Original Message-----
From: Quarkster [mailto:quarkster@xxxxxxx]
Sent: woensdag 6 juli 2011 21:09
To: Tesla Coil Mailing List
Subject: Re: [TCML] SISG Repair


Michael -
 
There hasn't been much information circulated about failure modes with SISG
coils, so would it be possible for you to provide some additional
information on your coil?
 
1. Are your SISG modules from Mark Dunn (4 modules per PCBA), copies of
Terry Fritz 2-module PCBA, or some other board design?
2. What IGBT P/N did you use?
3. What SIDAC P/N did you use?
4. What value capacitors are used in the charging/tank circuit?
5. Are you using a 1-MOT or a 2-MOT power supply, or something else?
6. Do you know the approximate resonant frequency of your coil?
 
It should be fairly easy to desolder the IGBT and determine if it has
failed, or if the SIDACs have failed.
 
Quarkster

--- On Wed, 7/6/11, caspina <caspina@xxxxxxxxx> wrote:


From: caspina <caspina@xxxxxxxxx>
Subject: [TCML] SISG Repair
To: "TCML pupman" <tesla@xxxxxxxxxx>
Date: Wednesday, July 6, 2011, 4:33 AM


Hi list


I have a SISG coil, SISG = 15 modules (15kV)

Now 6 Modules are shorted and need to be replaced.
I'm not sure what to do with the others...
Could they be 'partly damaged' but still work for a certain time ? Best to
replace all modules, maybe even everything?
Has anyone experience with this?

Michael.
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla


_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla