Jan,
That is one very interesting coil with great potential. Nice to see a
robust rotary, but a I'm not too sure on the choice of MMC size though,
as you will never get a full charge into 300nF with an ARSG, or even
with an SRSG unless you connect to the grid direct :-). You may have
been better off going smaller and arranging things so you have a higher
voltage rating, this would also allow more turns on the primary. Some
people don't like a low turns primary as they give more losses with the
increased current, but personally I don't mind the losses as it often
results in brighter streamers, rather than the weaker ones that a single
current starved NST tends to give. (10Kv max in the UK and 50mA
generally)
I don't know about costs in your country, but I found winding my own HV
tranny to be an expensive undertaking, and when a pig did come along the
cost was roughly the same. Although there is a satisfaction from winding
transformers and ballasts.
Phil
P Strauss's coil, similar sized
https://www.flickr.com/photos/33962508@N03/albums/72157687370041666
On 09.12.2018 19:54, Jan Ohlsson wrote:
> Yes Steve,
> it is an underground bomb shelter, formed as a tunnel. It is huge, two
> stories, made to shelter 1800 people, but limited in height and width. I
> will move the flourescent lighting from the wires that hangs from the roof,
> to a position closer to the walls, to gain some space for the coil. And I
> will experiment with toroid height and the breakout point (if I need one).
>
> The coil design is pretty much standard for the size, I think. ARSG is a 300
> mm FR4 disc, on a 2.2 kW 3 phase 3000 rpm motor. Six flying 3/8 inch
> tungsten electrodes in brass bolts. Stationary electrodes are 1/2 inch
> tungsten, clamped in very large Al cooling fins (7 kg each). VFD motor
> drive.
>
> Tank cap is a MMC, based on the usual CornelDubilier caps, 18 in series, 36
> such strings in parallell, for a total of 300 nF. The caps are housed in
> cable channels. It was an insane project to solder these together, will not
> do it again, I hope. Primary is 1/2 inch Cu tubing, tapped at a little less
> than four turns.
>
> Secondary form is a 315 mm polypropylene tube, wound with 1.06 mm Cu, about
> 900 turns. Main toroid is 315 mm vent duct, outside diameter 1.5 m, height
> above floor about 2.2 m.
>
> The 12 kV HV transformer is home wound on a 55 kg core, in an oil tank. Tha
> ballast core is very large, about 130 kg with 2 x 12 mm air gap, with six
> switched taps for a current of 10 - 50 amps at 400 V. The ballast is very
> well behaved and soft starting, I dont have a variac so that is important.
>
> So far I have only run the coil at half power, for very short runs. I have
> to move the lighting fixtures before I can allow the coil to strike
> sideways, so I have no idea of the coils potential at the moment.
>
> Here are some rather badly lit photos:
>
> https://photos.google.com/share/AF1QipMGIjbFcuhcW-ygtbhLNYTcdZIP-cKCiFdsglUP
> 2CICWzJj2jLL5XnpTIZ5SZeLLg?key=VVR2dks0OHpVOUcwb3FWR3VQTzJfQ1hmOHBlR3dB
>
> Jan
> Stockholm, Sweden
>
> ----------------------------------------------------------------------------
> --
> Is that underground?
>
> On Sat, Dec 8, 2018, 12:30 PM G Hunter via Tesla <tesla@xxxxxxxxxx wrote:
>
>> You may be able to crudely adjust the breakout angle by changing the
>> height of the toroid. I found that if I placed the toroid very close
>> to the top turn of the secondary, the streamers tended to curve
>> downward. If I raised it a bit, they broke out horizonally. If I
>> raised it a lot, I
> had
>
>> serious top turn corona and the streamers tended to curve upwards. By
>> experimenting with toroid height and breakout point location, you may
>> be able to reduce ceiling strikes. This is only rough adjustment of
> course.
>
>> Some streamers are just wild and there's no controlling them.
>> Greg
>
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