Measuring Voltage with Kelvin Water Dropper: Device Options and Combos

[Blaze_409]

I ve seen some answers to this issue of measuring the voltage of a low current high voltage system such as the kelvin water dropper. We have buolt the device and it functions properly. However once we attach any kind of meters to the device it no longer sparks and no longer charges.

Devices we have:
Oscilloscope
Highvoltage probe
Electrometer
Digital multimeter
MicroAmmeter

What kind of combo can i use to measure the voltage

 

[Blaze_409]

Measuring High Voltage(a.k.a)

As you can see this is the kelvin water dropper and i need to measure the voltage buildup of the device before it discharges. Its very low current and very high voltage(15kV-20kV)


Digital mutimeter's don't work by them selves. Digital multimeter's and a high voltagge rpobe either don't work. ( the multimer loads down the system too much. It draws all the current. An oscillosope also draws all the current.

Could some explain how i could use a breadboard and resistors in combination with an oscilloscope or mutimeter or voltage probe to measure the voltage. We need to measure that voltage

I will be sure to mention you in the credits for my project and i will even send you the video link to the live webcast of our project.

 

[sophiecentaur]

I could suggest (very carefully) charging a very large high voltage capacitor, connected across the two cans. This would take some time to charge up but there could well be enough charge for you to be able to measure the initial voltage before the charge is all used up. The capacity of the basic system can only be a few tens of pF at most. Could be a bit deadly if you don't take care, though.

 

[Blaze_409]

what would you say to running a potential through the sytem. Would that give it enough current to be read by a voltmeter.

the original issue is that the voltmeter loads down the generator because the generator has such low current.

Thereofr giving it current could help possibly?

does that even make sense

 

[sophiecentaur]

What do you mean by that?
The problem is that the capacity of the system is very low. There is too little charge for your equipment to measure with. Did you understand my comment?

 

[Blaze_409]

What do you mean by that?
The problem is that the capacity of the system is very low. There is too little charge for your equipment to measure with. Did you understand my comment?

The electrometer is the only thing that actually measure the potential of the system beacuse the input resistance is virtually infinite, 10^14 ohms.(It has no effect and does not put a load on the generator) very good for ultra low current devices The issue is the pasco eleectrometer only reads to a max +/-100V. And on a school budget a 40kV electrometer is not reasonable. There has to be a cheaper alternative.



Right now we have the dropper connected to a variable parallel plate capacitor. The spark gap is only 5cm right now. i suspect we could reach 1cm on a very dry day. Its been very rainy in New Jersey for the last few days. Not thunderstormy

 

[sophiecentaur]

So why not try charging a large capacitor with your Kelvin Dropper?
Do you understand what I meant by that suggestion?
The capacitor should not be a variable air gap capacitor as it is only designed for signal levels - not high voltage. Get a range of 10kV capacitors (1000pF, 10,000pF or thereabouts, I suggest) and see if the charges that they collects can give you an instantaneous voltage reading with your high voltage meter).. (Be very careful with charged HV capacitors- they can be deadly).

A fan heater can improve local humidity if you are plagued with leakage.