Re: [TCML] MMC failure / question or advice.

[Mddeming@xxxxxxx]

In a message dated 12/2/07 8:51:55 A.M. Eastern Standard Time,  
teslatech@xxxxxxxxxxx writes:

Hello  people

Recently I have been running into some trouble with my coil and  what I 
believe to be an MMC failure
but not sure what's causing it.
I am  running 8 series CDE 942C20P15-F .15 MFD 2000 VDC caps in my MMC. First 
 failure burned a hole
through two of these caps. I replaced the two bad  caps with the same type 
and did two more 20 second
runs which resulted in a  loud snap. No visible damage this time but I could 
still hear a loud snap or  arc 
even after the coil stopped functioning. One bleeder resistor on one  of my 
caps looks to have heated quite
a bit but it doesn't look burnt.  Primary power input is 2 12/30 NST's and a 
RQ style gap. This  functioned
great for years but it seems somewhere something is breaking  down now. 
Does anyone have an ideas what could be happening. I am thinking  maybe it's 
time to build complete new MMC.
Would anyone know if there is a  better more robust MMC solution for my  
setup?

Thanks

Vinnie
_______________________________________________


Ayyyy Vinnie,
 
    Ya, your system killed your MMC because it was  under-designed. Your peak 
voltage from a 12/60 system is 16,970 Volts. Now 8 x  2KV = 16KV, so your MMC 
was over-volted by almost 1 KV, 120 times  each second. It should be at least 
twice that rating, and for your  pair of NSTs, you should have at least 2 
strings for the current. To keep the  same capacitance, you should have two 
strings of 16 each (~$100), or for a  better safety margin, 3 strings of 
24,(~$225),  etc.  Beyond  that, you're getting into the custom-made Maxwell-type cap 
range.
 
Hope this helps,



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