High Voltage Capacitor Safety :{

For posts specifically relating to fusor design, construction, and operation.
Post Reply
3l
Posts: 1866
Joined: Sat Jul 07, 2001 7:51 pm
Real name:

High Voltage Capacitor Safety :{

Post by 3l » Sat Jan 04, 2003 4:35 pm

So you want to do pulsed work huh?

High energy capacitors are kinda tricky and need special measures.
Let's say you get one charged and want to get it safe again....what do you do?

#1 Don't be crazy and try to short discharge the caps.
They can blow apart for one.
The caps I'm using in the 33uf @10kv can take off
an arm.
It has enough energy to vaporize a straight blade
screw driver.
Use a bleed resistor tied from pole to pole on
the capacitor....don't bleed to ground.
A small cap it would be ok..but it would be an
invitation to disaster for your charging supply if it
is grounded.....capacitors will eat up a power
supply in nothing flat. Bleed resistors will have to
be sized in order not to explode or to exceed
the rated Di/Dt of the cap.

#2 Stay away from them
Sounds silly right?
could be fatal.....no rings chains ect.

#3 Charge them up slowly
increases the lifetime of the caps.
By breaking them in by escallating the voltage in steps of say 100 volts
Also any defect in the capacitor will
malfunction with less juice (if you are lucky)

#4 Don't use a discharge hoop over 200J.
molten sparks will shower from the shorting
cane. All those pictures you see are of personel
using the wand with small caps.

#5. Put them in plastic containers always.
If one pops or has a leak... you won't have
a mess or potential accident or fire hazard.
Also hot power leads won't just flop down
at your feet.

#6 Keep a halon fire extinguisher handy.

#7 Keep a discharge journal.
Most caps won't last over 100,000 discharges.
Dielectric failure becomes more of a worry as caps get used more.

Fusion is fun!
Larry Leins
Fusion Tech

Post Reply