Re: MMC advice

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

Original poster: dhmccauley-at-spacecatlighting-dot-com 


I disagree with that advice.  It has been shown that you can properly run
MMC capacitors at an AC voltage rated to what their DC rated voltage is.  I
have a few MMCs that are rated for
only about 16kVDC and I run them perfectly fine with no problems on a
15kV/60mA NST.  My main MMCs i use are only rated at 20kVDC and I use them
for both my 15kV/60mA NST
coils and my 14.4kV Potential Transformer coils.

Dan


 > If you run the DC cap rating as the AC cap rating you will have trouble
and
 > problems --- as you are experiencing.
 >
 > Rate the AC cap string at least twice (preferably 2.5) times the DC cap
 > rating and you can get away with it on short duty cycles.  We rate our MMC
 > cap strings for AC rating at 3 times DC rating --- and we can run a coil
for
 > 15 minutes or more continuous without any failures.
 >
 > Once you start damaging a cap here and a cap there you really don't have
any
 > solid reference point because with several caps you would have to test the
 > leakage current on each cap at it's rating potential to find your problem
 > caps.  If you overrate them for AC use at least 2.5 times their DC rating
 > you should not have any future problems.
 >
 > I know many experimenters get away with less --- but, hey --- it's the
last
 > straw that breaks the camels back, and in this case --- you can't see it
 > happening.  Also, it always seems to happen when you want your system to
 > work to show off to someone --- that's when it will fail.
 >
 > Using new caps and good engineering to start with can save a lot of
 > headaches down the road.  At only $3.00 per cap it's the best cap bargain
 > going.
 >
 > Dr. Resonance
 >
 > Resonance Research Corporation
 > E11870 Shadylane Rd.
 > Baraboo   WI   53913
 >
 >  > Original poster: Thomas <tom-at-pwrcom-dot-com.au>
 >  >
 >  > Have you tried the MMC calculation spreadsheet?:
 >  >
 >  > http://www.pupman-dot-com/listarchives/2002/April/msg00146.html
 >  >
 >  >
 >  > I use identical capacitors (RS 114-468) in an 18 x 18 array with 10M
 >  > bleeders, this is (nearly) resonant with an 11kV 80mA NST (50Hz).
 >  >
 >  >
 >