Re: Homemade Voltage Divider

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Mike" <induction@xxxxxxxxxxx>

Hi David,
                At work we usually use 1 meg ohm per KV.
Typical machine has three 5 meg resistor banks in 
series with a 1 MA DC meter. Full scale on meter 
face is 15 KV, many of the machines run 12 KV or 
so where we red line the meter at.
Here I have a couple of dividers, the one I use the most is the 10 KV supply.
We also have a large bank of ten 100 microfarad 
caps at 25 KV each and a 3 phase 0 to 25 KV 
charging supply rated at 250 MA to drive the bank.
Makes much noise when that gap fires but you can 
do all sorts of cool stuff with it. Good luck and 
have fun with you expanded bank.
Mike


----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Monday, January 23, 2006 11:16 PM
Subject: Homemade Voltage Divider


Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>

Hi all,

I am pondering a way to reliably measure 10 KVDC
across the terminals of (2) 100 µFd energy dis-
charge caps that I plan to build a quarter shrinker/
can crusher project with. I will have up to a total
of 450 µFd at 10 kV when I get 2 other 120
µFd, 10 kV caps added to my collection. Anyway,
I was originally going to just use my Beckman HV
probe in combo with one of my DVMs to monitor
the voltage at the cap terminals to insure that I
do not overvolt the caps, since my HVDC supply
can go up to about 20 kVDC. However, I believe
the HV probe isn't desinged to be used like this
as its ergonomics lends it for hand held operation
so I was thinking of getting some 10K or 100K
carbon resistors and building a 100 resistor di-
vider to get a 100:1 reduction to safely
read 10 kV on my DVM as 100 volts. What
are the best resistance values to go for 10 K
or 100 K? A 1 Meg total with 10K(X100) would
still allow 10 mA of current flow at 10 kV and that
would translate to 100 watts (WOW)! I suppose
that I just answered my own question- don't think
(100) 1/4 resistors would take much of that! Better go
for 100 K per resistor, that would only allow up to 1 mA
of current flow at 10 kV and 10 watts. I believe 10
watts spread over (100) 1/4 watt resistors would work ;^)
Any comments or suggestions?

David Rieben