How to measure current in high voltage (kV)???help please

how to measure kv

hi all,
I wonder how to measure current in high voltage power supply without special measure tool?is it possible to use general voltagemeter. because the output about 200 kV(DC). actually, i want to know is the power suply is working. so how to make it measureable using general voltagemeter( max about 100V dcV). Please...I need your help

thanks
Elits

how to measure kv

hi

As long as I know you can NOT even attemp to do it, DO NOT mess up with high voltage.

Sal

Re: How to measure current in high voltage (kV)???help pleas

DONT EVEN TRY USING A SIMPLE VOLTMETER.

so how i measure it? is there anyway to do it?
thanks

Re: How to measure current in high voltage (kV)???help pleas

You can do something like this .. see attached picture ..

Each resistor has to be rated for at least > 1 kV ..

Regards
IanP

Re: How to measure current in high voltage (kV)???help pleas

IanP said:

You can do something like this .. see attached picture ..

Each resistor has to be rated for at least > 1 kV ..

Regards
IanP

Click to expand...

IanP !
You should thing that when R = 500*10M, with Ohm law : I = U/R (U = 200KVDC) current is very small so may be it bellow the sensitive of the VOLTMETER !!!
Good luck for U !

Re: How to measure current in high voltage (kV)???help pleas

Hi, Normally voltages like this are measured in a completely different way, I will try to explain. You have two metal butterfly shaped plates, one is connected to you 200kV and the other connected to a desistor with a 100uA meter. The two plates are mounted above each other (take 1Kv/mm for dry air) keep in mind that the plates are not allowed to have sharp edges since they will give flashovers. OK. Now if you connect the butterfly shaped plate that is connected to your 100uA meter, to a motor so its rotating you will see a sin wave on the resistor which is having an amplitude which is the same as the voltage on your 200Kv line. I mean its proportional !. This is the only way you can savely measure these voltage levels any direct connection even with 500 resistors will not work . You will get a bang and all your things are broken.

Re: How to measure current in high voltage (kV)???help pleas

HI,

If you want to know current, why not put some low resistance in the ground side and measure the drop across that. Don't even go to the high side. If this is just to see if the supply is working and then remove it when you are through.

Good Luck

dfullmer

Re: How to measure current in high voltage (kV)???help pleas

IanP said:

You can do something like this .. see attached picture ..

Each resistor has to be rated for at least > 1 kV ..

Regards
IanP

Click to expand...

This would measure very well the voltage not the current.

On 200KV (if it's AC) the standardised way is current transformer.
On 200KV DC, the standardised way to measure current is using the shunt (a resitor) on the side connected to ground (the COLD side).

WARNING: the ground (or COLD side) becomes a WARM side as long the connection is interrupted, being so dangerous as the WARM side. So take care.

Rarely it could be used an optoisolated amplifier on the WARM side, but 200KV optoisolation is difficult to get.

Sorry for bumping in. I have to measure DC current going in the load attached to 60 volts and display it on lcd. I have seen AN105 "current sense circuit collection".But Alas LT Op-amps aren't available in my Area. So plz recommend so op-amp like LM series or so which support Voltage supply > 60v thanks.

200KV measurement issue requires information on the current capability of source. If the current capability is not too low to drive measuring instruments like meters, a suitable series resistor chains as advised by others could be resorted too. Leakage through mounting and even air is to be taken care. I have used similar arrangement successfully for years in measuring up to 40KV dc in driving circuit for a nitrogen laser.