Addressing HV safety excursions: Oh Yikes what do I do?

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ian_krase
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Addressing HV safety excursions: Oh Yikes what do I do?

Post by ian_krase » Sun Aug 20, 2017 10:40 am

I've been running pretty successfully with an Oil Burner Ignition Transformer, but am trying to get set up with a real HV power supply (one of the Spellman 50kV ones that went for cheap recently).

I have my vacuum system, my ion gauge controller chassis, other controller chassis, and my power supply chassis all grounded together with substantial wire.

I also have a "chicken stick" (4 feet long) with a grounded end.

Anyway, when I've tried to run up voltage, I've had some scary stuff happen. I've managed to get discharges, but I've also had loud *snap* noises followed by every piece of microprocessor-controlled equipment resetting. In one terrifying case I had sparks appearing on the corners of the front panel of a piece of equipment that was grounded.

Oddly, simple arc-overs on feedthroughs seem not to be happening to me.


How should I attack this to make things safe again?

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Bob Reite
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Re: Addressing HV safety excursions: Oh Yikes what do I do?

Post by Bob Reite » Sun Aug 20, 2017 9:53 pm

What specific piece of equipment had sparks coming from the corners? Is your grounding arrangement a "Star Ground" with the fusor shell the star point? See article viewtopic.php?f=29&t=9968 for a detailed description of a star ground. Note that the diagram there shows a dedicated star point, I chose to define the fusor shell as my star point when I built my system. What you do not want is a "daisy chain" arrangement where the ground goes from one piece of equipment to the next.
The more reactive the materials, the more spectacular the failures.
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ian_krase
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Re: Addressing HV safety excursions: Oh Yikes what do I do?

Post by ian_krase » Sun Aug 20, 2017 10:38 pm

I have a star ground with my high vacuum pump as the star point.

Sparks were coming off of the outside of my ion gauge controller, which was sitting on top of my HV power supply.

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Re: Addressing HV safety excursions: Oh Yikes what do I do?

Post by John Futter » Mon Aug 21, 2017 3:33 am

Sounds like a suspect earth in your mains wiring

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Re: Addressing HV safety excursions: Oh Yikes what do I do?

Post by ian_krase » Mon Aug 21, 2017 6:10 am

Even with my star ground?

Oh boy.

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Re: Addressing HV safety excursions: Oh Yikes what do I do?

Post by John Futter » Mon Aug 21, 2017 9:21 am

it just means that the ion gauge controller is probably not earthed
suspect mains wire
do a continuity check between controller and star point ---beware of painted chassis earths lifting the chassis away from what you think it is

ian_krase
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Re: Addressing HV safety excursions: Oh Yikes what do I do?

Post by ian_krase » Mon Aug 21, 2017 7:37 pm

Ok, I'll look into that.

And I'm guessing that then at some point HV jumped to "ground" which wasn't really grounded and jumped between all the equipment, triggering resets of microprocessors?

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Dennis P Brown
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Re: Addressing HV safety excursions: Oh Yikes what do I do?

Post by Dennis P Brown » Tue Aug 22, 2017 12:54 pm

I have small copper screens over both my simple TC gauge and my ion gauge ports; discovered the hard way (not unlike you; and all my equipment has two independent ground points) that my plasma could see the grounds inside these gauge tubes - lucky, no costly failures.

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Richard Hull
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Re: Addressing HV safety excursions: Oh Yikes what do I do?

Post by Richard Hull » Tue Aug 22, 2017 3:34 pm

All gas discharge systems are electrically noisey! Arcing is even noisier! All modern microprocessor based electronics do not do well with electrical noise.

Once all grounds are verified to be good and solid, as mentioned above, if reseting of the micro's continues, look for a possible unshielded "antenna" entering the gear. These can be subtle and sometimes not obvious.

Richard Hull
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ian_krase
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Re: Addressing HV safety excursions: Oh Yikes what do I do?

Post by ian_krase » Wed Aug 23, 2017 8:36 am

I'm curious how you installed your metal screens. The easiest option would seem to be the weirdly expensive screened KF fitting rings.

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