Safely testing 22 kV capacitors
 

On Thu, 30 Mar 2006 19:19:12 GMT, Ignoramus27088
wrote:

Got myself some capacitors for $10 apiece.

http://cgi.ebay.com/ws/eBayISAPI.dll...tem=7603382621

The specs are 22 kV, 1 uF, discharge capacitor. See

http://igor.chudov.com/tmp/cap.jpg

The seller was wrong in describing them as 22 VOLT capacitors. They
are 22 KILO volt capacitors. (the seller is Fermilab).

They are similar to this one:

http://cgi.ebay.com/ws/eBayISAPI.dll...tem=7598631638

but have twice more capacitance.

Anyway, here is my question. I have a 9 kV DC power supply. (a
Franceformer). How can I safely test these caps before selling
them. At 22 kV, they can store about as much energy as a .22 bullet,
according to my calculations.

It would be less at 9 kV, but still, obviously, very deadly.

Certainly unpleasant, in the ballpark of a defrib.


So. What is a safe way to charge them, verify that they hold the
charge, and then DIScharge them at 9 kV.

Well, you need a HV supply: neon sign xfmr + HV doubler, or a
flyback/rectifier from a color TV set. Read it on a DVM with a HV
probe, and then just leave the probe on there until it's mostly
drained, and kill the last few hundred volts with a resistor.

No big deal.

But if it was a 22KV cap, and it behaves like a 1 uF cap at low
voltages, it's very likely fine to sell.

John