Kaizer DRSSTC 3

[Mads Barnkob]

I started construction on my large DRSSTC on the 24th of December 2011. What followed was a long journey of building, sourcing materials, becoming a father and at some point reach first full power light on the 31st of March 2016. A 4++ year long journey!

Bridge	2x CM600DU-24FA IGBTs in a full bridge configuration
Bridge supply	4x 6000uF 350V filtering capacitors, two in series, two string in parallel for 6000uF at 700V.
Primary coil	Flat primary. Inner diameter 375 mm, Outer diameter 855 mm. 8 turns 10 mm copper tubing, turn spacing 20 mm tapped at 6.75 turns.
MMC	0.8uF at 15kV. Made from GTO snubber capacitors. 5 in series.
Secondary coil	315 mm diameter, 1500 mm long, 1800 windings, 0,75 mm enamelled copper wire.
Resonant frequency	Around 38 kHz.
Topload	7 rings of 25 mm aluminium tubing forming a 150cm diameter toroid.
Input power	3x400VAC 16A / 11kW
Spark length	3.6 meters

First full power light (31st of March 2016)

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Kaizer DRSSTC 3 - Test After 5 Years In Storage (6th of May 2022)

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[klugesmith]

Camera as time machine!   Nice work.
We share enthusiasm for transporting large things by bicycle.  In about 1994 I stopped at a garage sale an hour away from home. Found and bought more than 50 pounds of lead metal, and got it all home in panniers and taped onto the rear rack.

[Mads Barnkob]

We had a good session with trying out some different interrupters, targets and lighting around the coil, for filming. Darkness did however surprise us a bit and it was hard to adjust lighting and run the coil at once, so a bit noise filled videos.

It was most of the time pulling around 5-10 kW, peaked out at 19kW with a quite insane BPS that I quickly turned down again as the 3 meter sparks was turning into a flame, it had that flicking change in sound as when sparks goes into full plasma flame. The measurements in the video is from a Merlin Gerin PM700 power meter.

The coil was, the whole time, fed through the 3 Phase 400 VAC 6 A Variac Stack With Voltage/Current Meters ( https://highvoltageforum.net/index.php?topic=2015.0 ) which did not even get warm to the touch.

The future holds a collaboration with ChaosEngine https://www.chaosengine.dk/ and https://www.instagram.com/chaos.engine/ where we will combine art and electricity in some way

[davekni]

The coil was, the whole time, fed through the 3 Phase 400 VAC 6 A Variac Stack With Voltage/Current Meters ( https://highvoltageforum.net/index.php?topic=2015.0 ) which did not even get warm to the touch.

Variac wipers are often hot spots, causing the winding to fail at the wiper setpoint.  Not sure if checking overall Variac temperature is a good way to judge margin for short-term overload.

Impressive video and demonstration!  I'm wondering if you could achieve even longer arcs (at least a little bit) with further detuning and/or a shorter breakout point.  It doesn't seem to be struggling to break out initially as would be the case if detuned was close to the limit.  Of course, perhaps it is at the limit.  Hard to tell by viewing a video only.  In my case, an interruption sequence of ramped pulse widths also helped.  The ramp from short to long helped an arc form with slightly more detuning than otherwise worked.  Final enable pulse at the end of the ramp jumped to 2x longer, trying to get a tiny bit more length from an arc that had already reduced secondary frequency below primary.

[Hydron]

I spy a lot of tinfoil on the power cable, which looks like a pain in the ass to deal with - have you looked at using industrial control cable with shielding? That's what I moved to using (with the shield grounded) once I thought through the likely consequences of a hit on an unshielded mains cable.

Also, what controller is this currently running?

[Mads Barnkob]

The coil was, the whole time, fed through the 3 Phase 400 VAC 6 A Variac Stack With Voltage/Current Meters ( https://highvoltageforum.net/index.php?topic=2015.0 ) which did not even get warm to the touch.

Variac wipers are often hot spots, causing the winding to fail at the wiper setpoint.  Not sure if checking overall Variac temperature is a good way to judge margin for short-term overload.

Impressive video and demonstration!  I'm wondering if you could achieve even longer arcs (at least a little bit) with further detuning and/or a shorter breakout point.  It doesn't seem to be struggling to break out initially as would be the case if detuned was close to the limit.  Of course, perhaps it is at the limit.  Hard to tell by viewing a video only.  In my case, an interruption sequence of ramped pulse widths also helped.  The ramp from short to long helped an arc form with slightly more detuning than otherwise worked.  Final enable pulse at the end of the ramp jumped to 2x longer, trying to get a tiny bit more length from an arc that had already reduced secondary frequency below primary.

That is good point about the variac, since its even a enclosed unit IP44 I think, its impossible to inspect the wiper, unless the entire thing is split in atoms. With the soft start box which pre-charges DC bus through power resistors, the variac is really not needed. I just brought it on this first try after storage to be sure to nurse it a bit and give the DCbus capacitors a soft low voltage start.

You are properly right about the tuning. Since its over 4 years from last tuning, I forgot why and where, but there is only one hole made in the base plate. I think its tuned exactly where JavaTC predicted it to be tuned. But considering that I, at that time, knew about detuning, it most be tuned lower. that just resonance.

I spy a lot of tinfoil on the power cable, which looks like a pain in the ass to deal with - have you looked at using industrial control cable with shielding? That's what I moved to using (with the shield grounded) once I thought through the likely consequences of a hit on an unshielded mains cable.

Also, what controller is this currently running?

To avoid buying new cable, I am putting it all through some copper braided shielding harness that I already have. Got enough to cover enough of what is in the danger zone. Then I will add some kind of protective cloth sleeve outside of that. The tin foil is just a 2 minute job, but ends up costing a roll every time as it gets a little bump or kink and there is no more unwinding it in one piece

Its running with my own single side version of UD2.1b, double GDTs.