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Re: Measuring HV capacitor voltage (fwd)

---------- Forwarded message ----------
Date: Fri, 20 Jul 2007 14:29:51 +0000
From: David Rieben <drieben@xxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Cc: drieben@xxxxxxxxxxx
Subject: Re: Measuring HV capacitor voltage (fwd)

Hi Bart,

Yes, a high voltage probe that plugs directly into your DVM
is the most convinient way to measure HV. I do already have 
one of these and was using it to try to calibrate my "attempts" 
at a voltage divider. However, I need a more permanent panel
mount meter for measuring the voltage across my huge quar-
ter shrinker caps so that I don't overvolt them. I'd really ra-
ther not have to be sticking that probe by hand onto the
"hot" terminal of a fully charged 20 kJ capacitor bank each 
tiem that I charge them up ;^() I need a safer and more per-
manent hardwired metering setup.

David Rieben

-------------- Original message -------------- 
From: "Tesla list" <tesla@xxxxxxxxxx> 

> ---------- Forwarded message ---------- 
> Date: Thu, 19 Jul 2007 01:21:24 -0700 
> From: Barton B. Anderson 
> To: Tesla list 
> Subject: Re: Measuring HV capacitor voltage (fwd) 
> Hi David, 
> A little while back I documented a hv divider: 
> http://www.classictesla.com/download/hvacdivider.pdf 
> I however broke one of the resistors and decided to simply buy some hv 
> resistors and give them a try. I ordered from Allied Electronics p/n = 
> 296-0171 (the manufacturer is Ohmite who's p/n is EX2G1006). I just 
> checked the website and it seems that part number is no longer listed? 
> Odd. It's a pc board mount type. If you can imagine a 10 pin sip 
> resistor with only pin 1 and pin 10 at their ends, this is what the 
> resistor looked like. Was good for a hefty 10kV however. I think it was 
> about 300M. It may not be available any longer? Anyway, something along 
> that line can be used. You just have to alter the center voltage divider 
> to suit. 
> Of course, the best way to measure is just to do an eBay search for a 
> high voltage measurement probe for high "AC" volts. Their out there. A 
> lot easier than building a divider and the cost is likely pretty similar 
> in the end. 
> Take care, 
> Bart 
> Tesla list wrote: 
> >---------- Forwarded message ---------- 
> >Date: Thu, 19 Jul 2007 15:15:51 +0000 
> >From: David Rieben 
> >To: Tesla list 
> >Cc: drieben@xxxxxxxxxx 
> >Subject: Measuring HV capacitor voltage 
> > 
> >Hi all, 
> > 
> >I'm having a little issue with measuring up to 10 kV across a capacitor 
> >on a standard panel mount, analog 0-15 VDC voltmeter from Radio 
> >Shack. Obviously, I was trying to make it read 1 volt for each measured 
> >1000 volts. I tried using a voltage divider of 10 seriesed 10 meg resistors 
> >and a 100 K pot but found that the 100 megs was just too much resist- 
> >ance to allow for sufficient current for reliable movement of the volt meter. 
> >I then tried a series-parallel arrangment of 10x10 of the 10 meg resistors 
> >for a total of 10 meg and then still used the 100 K pot and varied it to try 
> >to bring in the proper calibration. I was checking the voltage measurement 
> >with my HV probe and DVM. The resistors didn't like being bunched up 
> >10 at a time and started flashing over externally. Also, I was having trouble 
> >getting the analog meter readings to be accurate throughout the 0 - 15 volt 
> >range according to the measurement of the HV probe. I think the meter is 
> >designed for 10 meg impedance and it also comes with a 15 K resistor that 
> >is supposed to be in series with the voltage source. Anyone have any sug- 
> >gestions for reliable and reasonably accurate measurement of high voltage 
> >through a low voltage analog voltmeter via a voltage divider network? 
> > 
> >Thanks 
> >David Rieben 
> > 
> > 
> > 
> > 
> > 
> > 
> >