Measure high voltage

[aryan_hr]

Hi,
How can I mreasure 2000V (2KV) whit my A/D ( its range is 1V)?

Thanks,
Aryan

 

[Ubergeek63]

resistor divider

 

[Papabravo]

Is the 2KV AC or DC?
If AC then what frequency?
If AC an isolation transformer would be a capital idea.
Leakage currents and arcing can be substantial problems in any case.

 

[aryan_hr]

It is DC.
Which resistor should I use? The voltage rating for resistor is 200V!

 

[Mikebits]

You should have a read here.
Basics of High Voltage Probe Design

 

[Leftyretro]

It is DC.
Which resistor should I use? The voltage rating for resistor is 200V!

In practice many resistors is series are used to stay within the maximum voltage rating of any single resistor.

Lefty

 

[spitso]

best thing to do if you enjoy and commonly do work with high voltage is purchase a HV tester, or an eletric fence tester. I've purchased one for about $50 which is slightly expensive but is very usefull.

Who knows you might be able to find a schematic on how to make a HV tester.

 

[aryan_hr]

Hi All,
Thanks for your comments. I try them.
spitso, I want to measure HV through my program.

 

[Ubergeek63]

It is DC.
Which resistor should I use? The voltage rating for resistor is 200V!

well if you are of a mind to spend more than you need to to be cool, you can buy a HV precision resistor, but you would be better off putting 10 resistors in series minding the power dissipation.

Think in terms of at least 10M total resistance...

Dan

 

[swoel]

You can buy a HV DMM probe. It is not very expensive and you can use with any DMM.

 

[tcmtech]

what are you using 2kv for?
and at what amps?
I just dont see that in these threads that often.

 

[Willbe]

If the probe ground opens you will have a resistive divider of quite a different ratio.

 

[Sceadwian]

Yeah, probe ground will be critical. Typical resistors are rated for around 200V's? They're not usually marked, so you use 10 maybe 15 of those in series, with one more to ground with a 2000/1 ratio. Coating with wax or some other basic insulator of the leads will be required as 2kv can arc through about 2cm's of open air.

 

[funktek]

ouch!

...Coating with wax or some other basic insulator of the leads will be required as 2kv can arc through about 2cm's of open air.

Yup, and that's enough to arc right around each of the resistors so either that insulation has to be good (silicon tubing is recommended) or the resistors have to be long enough to prevent arc-over.

But, as someone else already advised, a HV probe can be had cheap enough and is better than waking up on the other side of the room.

Another word of advice (I have spent a lot of time probing 1+kv circuits) is to keep one hand behind your back or in your pocket. This prevents an unintended ground path that goes through your heart. The other bit of advice is to not wear any jewelry.

 

[aryan_hr]

what are you using 2kv for?
and at what amps?
I just dont see that in these threads that often.

I use it as electroplating and the current is around 600 to 800 mA.

 

[Willbe]

". . .at an electric field gradient of about 10 kV/cm, which is just below the nominal breakdown voltage of air between two sharp points, . . ."

10 ea. +/- 10% resistors in series will give you a composite +/- 3% resistor. 100 ea. will give you a +/- 1% resistor.

 

[Sceadwian]

Umm Aryan, I worked at a electroplating shop for 10 years, typical voltages are between 6 to 12 volts... If you're using 2KV it's not 'electroplating' it's powder coating?

 

[aryan_hr]

Umm Aryan, I worked at a electroplating shop for 10 years, typical voltages are between 6 to 12 volts... If you're using 2KV it's not 'electroplating' it's powder coating?

Dear Sceadwian,
Thanks for the reply. You are right, in some experiments we use 6-12 V for electroplating and in some experiments we use 2000V for high voltage anodizing.
Thanks for your reply.

 

[Sceadwian]

I'm still confused, anodizing uses voltages in the 15-20 volt range. You really need to clarify what you're doing. You can't put that kind of voltage through a fluid, it'll explode.

 

[aryan_hr]

I'm still confused, anodizing uses voltages in the 15-20 volt range. You really need to clarify what you're doing. You can't put that kind of voltage through a fluid, it'll explode.

Yeah exactly, for this reason the solution should be put in ice bath and one can see spark on the anode. This is because the layer (oxide film or other layers) is non conductive and has high resistance. The experiment is done at constant current, therefore during the experiment the voltage is increasing up to 600-700 V.