High voltage transformer for neon bombarding.

[AndreasVE]

Hello everybody.

At the moment I'm looking into the neon craft. I've got everything figured out except for 1 transformer used in a process called "bombarding". It's a process in which a almost vacuum glass tube is bombarded with a very high voltage for the sake of cleaning it.

The instruction videos I have seen all use a pole like transformer (USA (I'm from Europe)). One transformer used is a 12.5Kva/20KV transformer, connected to 2 120V lines (USA). One video shows the current gauge when bombarding (0-400mA).

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So my question:

Are there any modern alternatives to such a transformer (heavy noisy pole transformer)?
If a high voltage, low current is drawn from the secundary side, does this mean primary has a very high current? If so does this mean that the transformer should be connected to a 3 phase net (Europe) instead of regular 230V AC and 10mm² +- wires should be used?

I know how a transformer works in theory, but I haven't really yet used one for real. Also, the bombarding process is kind of specific.
I hope that my questions are somewhat clear.

Kind regards from Belgium,
Andreas

[klugesmith]

Three phase is no good for what you are doing.  Here is one reference that gives electrical service requirements: https://www.egl-lighting.com/bombarders/

Regular bombarder transformers have core shunts, like NST's, to limit the current.

But they are designed for 15 to 30 times more current, to rapidly heat up the mostly evacuated glass tube.  Does your neon craft reference mention putting a bit of folded paper over the tube, which chars when the glass becomes hot enough?

As far as risk of lethal electric shock, neon bombarder transformers make MOT's look like safe playthings.   The electricity can jump much farther to get you.  These transformers have been essential tools of the neon trade for about 100 years.

[AndreasVE]

Yes I know that these transformers are very dangerous, that's why I was wondering if there are any alternatives.
I recently had a BA5 formation but still..

[klugesmith]

Thank you for mentioning BA5 electrical certification, a thing I had not heard of before.

There might be people on forums that have hints about DIY bombarders.
For example, maybe a used pole transformer combined with a ballast choke like some in arc welders.

As for safety:
I think the task requires short circuit current of 0.4 to 0.9 amps, which is as lethal as can be.
For short tubes you might get by with open circuit voltage much less than 20 kV.
Less likely to jump through air, or find pinhole or punch through an insulating glove.  But you should not be close when a tube is being bombarded. 
Beware of internal arc from one electrode into the gas manifold and/or the vacuum pump.

[msm22]

I have a technical problem in CT split core type installed in gantry of 380/132 KV substation in the bus duct of 132 KV.
the current in secondary not matching the primary after circuit energization but before energize and during the pre-commissioning tests while primary injection it was give correct values in secondary side so can any perfect experience engineer here advise us how to deal or solve this issue? CAN YOU HELP .
I WOULD BE VERY VERY THANKFUL IG YOU HELP MY PHONE +966509050475   moselhi@outlook.com

best regards

[klugesmith]

Good luck with that. Sincerely, if you are not here to troll for impassioned opinions.

It sounds like this is for a real working substation.
You need a qualified, experienced high voltage utility technician or engineer on site.

That might be a first-world view, but I wouldn't want my electricity maintained by people who depend on free advice from Internet hobby forums.  And I would be afraid if someone in my family were helping to fix or improve the substation.   What if some troll, far away, wanted to sound authoritative and invite damage or injury?

Back to the immediate question.   Some pictures or more words could clarify the problem for general readers.  Maybe you deliberately described things and procedures that make sense to people in the trade.  So you can identify responders who, unlike me, "get it" immediately.