Re: A few questions and thanks

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Hollmike-at-aol-dot-com>

In a message dated 7/12/01 10:17:14 PM Mountain Daylight Time, 
tesla-at-pupman-dot-com writes:

<< http://www.teslacoils-dot-org/rcs1000/index.html >>
Hi Chris,
   Since you are going to place the four caps in parallel, you will have 
.08uF -at- 45kv.  The energy(per bang)  will be 0.5*(0.08*10^-6)* the charging 
voltage squared.  The formula is 0.5*C*V^2 Joules/bang.  Now if you multiply 
that by the break rate(bangs per second) you will get a fair estimate of the 
power handling capability in Joules/second, or Watts.  I say estimate, 
because there may be some reactive power involved with this which would alter 
the result a bit, but this will at least give you a ballpark figure if 
nothing else.   I think as long as your cap bank can take up all the power 
from your transformer(or more), there should be no problem with running it.
   If your caps have oil fill ports, I would not run them on their sides.  
They might leak oil for one thing.  The biggest concern I would have is that 
an air pocket might lead to failure of a cap.  The reaction with oxygen in 
the air will form corona which can break down the oil and/or your capacitor 
dielectric.
    As far as discharging the caps,  you should have a high resistance, like 
10 megaohm or more to limit the discharge current.  45000V/ 10,000,000 would 
be discharged at a rate of 4.5 milliamps(max - the current drops as the 
voltage).  The power rating on the resistor would need to be a little over 
200W to handle this(I squared times R).  If you simply put a 100megaohm 
resistor across the bank,  it would not likely consume too much of your power 
(about 20 Watts - use one rated for 25 to be safe) and would discharge the 
bank each time you shut down.  People do this with the MMC banks 
presently-partly to equalize the voltage across the caps, but it also bleeds 
the energy away after shutdown.
Hope this helps,
Mike