High Voltage meter

I have been working on a viable meter to monitor the high voltage on my machine. After about 8 months of struggling with parts I have a ‘beta’ version on the machine and running.

I have posted a short description on the makers forum if you have any interest.



Not that this solves your problem, but having had to work with Hi Voltage during my working career (testing with up to 50 Kv. I have to ask what is your goal or purpose. Messing with the hi side of that kind of voltage is risky and unpleasant.

It’s really just to monitor the hv, out of curiosity. I don’t feel it’s dangerous if you understand it and take precautions. I think it’s more dangerous to not understand what’s going on. It’s all in a metal case, so it should be safe…

We’re always watching the current, that’s half the game. Maybe it’ll lead me to nowhere and maybe not.

As a radio person, monitoring the hv told you lots about what was going on. Maybe that’s my problem.

Thanks for asking…

Take care.


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Understood. I do some powdercoating, the HV supply of mine is around 17kv, enough to give an electrostatic attraction to make the powder stick to conductive surfaces. I have gottten bitten a couple of time in the past 10 year, certainly gets your attention.
With the electrostatic attraction, I wonder if there is a way to measure the voltage without actually being connected to the HV terminal.

I’ve seen them on a scope and they are very radical waveform, not what I’d call a ‘clean output’, but I really am comparing it to what I know of waveform.

I’m sure there is some ‘industrial’ way to measure this without a direct connection. That’s how a hall sensor works.

My mount is ‘odd’ since, it’s permanent and most of the tech people appear to use the handheld type to measure this in/out of the machine. Brings up questions about loading and so forth. I’m sure the factory has a way they test them also.

I can tell when I load it from 20% to 50%, the voltage drops as the power/ma increase. To be expected, but shows me there is some kind of ‘known’ loading taking place. I will see if I can tell if there is the same relative wattage with a volt/amp computation.

I got across 440 at a computer site once. Told me the installers didn’t ground it properly and it should have killed me. Should have sued them for future medical bills…

Bedtime for me…

Take care


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You should look into how an VT/voltage transmitter works. There used to measure the voltage in high voltage. It’s an transformer that steps the voltage down to an readable voltage. You then can work out the higher voltage by the turn ratio in the transformer. EXP. 100v on the input with a turn ratio of 5/1 will give you 20v. This might work for what your doing. :man_shrugging:

That may be a problem since we are working with dc voltages.


And although a pulsing DC acts a lot like AC, putting the HV and ground across the primary will not likely go well (even assuming you cn find a transformer rated for 20,000 volts.

Most of the transformers of that type appear to be for 60 hz. Maning they are resonant to the frequency they are designed. They are also very expensive…

The other problem is that the ‘pulsating’ dc has a frequency (probably based on the pwm frequency) that, if not resonant with the transformer it will be an issue and can effect the results.

I think it’s safe, it’s simply a resistor to a meter to ground. I’ve taken precautions to isolate the high voltage, multiple ways.

At 30kv there is 50ua of current. If the voltage went up 100 times ( to 3 Mv), I’d only be looking at 5ma…


Well :thinking: the tube it self is your resister. Just need to figure out the resistance of the tube. Would this work?

Or just buy this bad boy :wink: Fluke 80K-40 High Voltage Probe.

A lasing co2 lases in an area that causes it to exhibit ‘negative resistance’. What occurs is that there is an increase of voltage across 2 points, that causes a decrease in current. This can’t occur in passive components.

It didn’t fit in my case…

You have to attach directly to the wire. So you have to ‘break’ an area to get to it then repair it to ensure safety. These are OK where access to the hv is open and/or accessible, but not for this type of application. At least to use it frequently.