[Amps] Using an oil capacitor

[Vic K2VCO]

I have an oil capacitor rated at 53 uf 3.5kv. I would like to use it in a power supply 
with a transformer delivering 2.4 kVAC. The peak voltage is thus close to 3400V.

I've never used an oil capacitor before. My line voltage is pretty constant at 240V, but 
if it were to rise to 250V, the voltage rating of the capacitor would be exceeded. What 
kind of safety factor do capacitors like this have?

The capacitor is 4-1/2" x 4" x 10" and is marked CSI 4W308T. The CSI website 
<http://www.csicapacitors.com/csite/cms/149.htm> doesn't list this particular one, but 
other 3.5kV capacitors have similar part numbers. There's no detailed spec. There is this 
statement:

"The WM series of capacitors is designed for general purpose pulse applications in power 
supplies for lasers, flash tubes and other capacitor discharge circuits where moderate to 
long life is required."

I'm not sure if this is appropriate for power supply filter application. Anybody familiar 
with these?
-- 
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/