I have a circuit at a high potential compared to ground, up to 30kV, in which I have to measure a current of like 2A. Because the whole circuit is at 30kV I could just measure it with a normal multimeter but my problem is that the whole thing should be in an isolated box for obvious safety reasons. So the "Display" needs to be connected to ground.

I know there are some wireless options like a current clamp or optocoupler but I don't know if they are isolated enough for 30kV compared to ground. The difficulties I see with a shunt and a voltage divider is that the voltage at the resistor would be much much smaller than the 30kV so the divider would need to be super precise. I hope someone has experience with stuff like this.

Thanks in advance

  • \$\begingroup\$ What about a battery powered bluetooth device? \$\endgroup\$ – PlasmaHH Jun 8 '17 at 8:34
  • \$\begingroup\$ I thought about something like that but couldn't find finished solutions \$\endgroup\$ – Niklas Jun 8 '17 at 8:37
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    \$\begingroup\$ It is dangerous to make something with advice by a forum for 30kV. If you don't have an expert that can help you, then you should stay away from 30kV. The solution is to make it wireless as @PlasmaHH wrote. Use batteries (perhaps with a solar cell) and use bluetooth or an other wireless communication or fiber optics. Even then the 30kV could spark into the antenna and electronics, or destroy the electronics due to ionization of particles in the air, so you still need an expert to help you. My experience is only with 1 and 2kV, and that caused me enough trouble already. \$\endgroup\$ – Jot Jun 8 '17 at 8:51
  • \$\begingroup\$ 30kV is just low enough to use a plastic insulating sleeve round the conductor to isolate a current transformer, but only if you really know what you're doing, it's too high for a first time novice, it's also far too high for IC opto-isolators. A stand-alone battery powered radio transmitting thing or fibre-optic would work well, arduino has options for easy-to-connect RF data links. \$\endgroup\$ – Neil_UK Jun 8 '17 at 8:51
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    \$\begingroup\$ Where is the 30Kv coming from, what is the circuit attached to it that draws 2A and how is it powered? How accurate does the current measurement need to be? \$\endgroup\$ – Bruce Abbott Jun 8 '17 at 20:09

I came up with a now working solution which is precise.

I used a shunt in the circuit and an Arduino with an 16-bit ADC (MC3426). The Arduino connects via a cheap wireless module to another Arduino which is connected to my display. By precisely measuring the shunt and testing the ADC the result is good enough for my purpose. The galvanic separation comes from the wireless connection between the two arduinos.

If someone wants more details, write me.


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