New High Voltage Mutliplier Setup

[kilovolt]

Dear high voltage friends

Here I would like to present a high voltage project I already finished some time ago, a large bipolar cascade.

There are two cascades for bipolar operation, both as full wave designs. The cascades are fed by two 6kVA ferrite X-ray transformers, which in turn are fed by two IGBT full bridges. The setup is powered with two phases 230V and two Variacs on the same axis.

In total 126 Doorknobs TDK UHV10A with 560pF / 50kV each were used and 224 diodes if I remember correctly.

Here are some pictures of the setup:











Both bipolar setups in one pic:



And a video:

I look forward to your comments.

Best regards
kilovolt

[MRMILSTAR]

Great work there kilovolt! I thought about making a full-wave design but ultimately decided on a half-wave design to save on parts. One thing I really like about your full-wave design for operation in air is that, since it has 3 legs, the structure is much more stable especially if you want to move it.

[Mads Barnkob]

Wow those are some good looking towers!

What is your power consumption on those inverters? It might be 6KVA transformers, but what are you pushing through them?

What is the arc distance?

Do you have a calculated voltage output?

Do you have any problems with corona on the diode series? I have usually seen people put them in epoxy/oil filled hoses. As they are too far away from the very small minor diameter corona disks between the stages.

Just for long arcs or got a plan like lifters and experiments?

[kilovolt]

Hello Mads and MRMILSTAR 

Thank you for your interest and kind words. After experimenting with both, halfwave and fullwave setups I have to say I would rather go the halfwave way. Fullwave didn't show as much better performance as it needed more material.

@Mads:
Power draw was just about 8kVA for the whole setup, so about 4kVA for each fullbridge/transformer. The transformers could make a lot more. 6kVA is the continuous rating for each of them. For short periods they could make much more, but I have not much more power from the line and I'm not sure what the fullbridges really can perform. They get a bit warm after each run.

Arc distance was about 70cm in the shown video. There is not much more possible, because of arcing between the diode strings. About 80cm ignition distance is the absolute maximum and this is not a safe operation anymore.

I don't know the voltage. According to measurements in the first stage of one tower I estimate about 400kV max.

Just for long arcs or got a plan like lifters and experiments?

The setups were just for fun  The material was given to me by a friend who works in the x-ray industry. I just wanted to see, what's actually possible without using oil (of course for the transformers i needed oil baths, but no oil for the multiplier setups).

Wish you all a nice week.
Best regards
kilovolt

[Steve Ward]

Thanks for sharing this project!  Those long, ghostly, soft arcs are very nice for indoor demonstration!  Are you feeling the hair raise on your body, yet?  I put together a 5-stage (10X input multiplication) tower that could make 200kV and jump some 16" air gap, which agrees well with your 80cm for 400kV.  Even with 200kV, the ion streams could be intense, causing discharges several feet from the machine as "static" charge builds up on items nearby.

Is there any chance for recombining the parts from full-wave to half-wave to achieve higher voltages still? The high voltage DC corona plumes are fascinating, but very difficult to capture well on camera compared to the arcs, but at extremely high voltage it may be more interesting.

[Duane B]

Very impressive display kilovolt!! Thanks for sharing.

[abstruse1]

Very impressive work!

I've just now gotten 13" sparks from a 9 stage CW, and I'm wondering about the difference between our displays.  Yours is putting out what I'd refer to as "arcs," namely a flamelike phenomenon with a rather soft noise, like NSTs, where mine is putting out sparks -- very fine, discrete blue sparks that are really noisy.

I'd assume that you're putting out a lot more power -- e.g. amps -- than I am.

Is my thinking correct as to why the difference?  Thanx.