Re: More MMC qustions

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

Original poster: "Mike Tucknott by way of Terry Fritz <teslalist-at-qwest-dot-net>" <michael.tucknott-at-virgin-dot-net>

Big Big snip-ola (got to keep the moderator happy)


 > Hi Mike,
 >
 > dV/dT is the voltage change in volts per microsecond that caps can take.
 >
 > In our case, suppose we have 2000V across each cap and our coil runs at
 > 250kHz.  During a single cycle, the voltage goes to +2000 to -2000 volts
in
 > 1/2 cycle which is 2uS in this case (1/250000 x 1/2).  So we have 4000V in
 > 2uS or 2000 V/uS.
 >
 > This value determines the peak current the caps will see.  Thus, it is an
 > indictor if the caps are going to get torn apart by current spikes (like
 > full metalized caps do).  If we have a 50nF cap in this case, the peak
 > current can be found.
 >

Thanks Terry as ever your explanations are clear and once read over a few
times sink in and are well recived, I`ll get the old note pad and pencil out
later
and see what figures I come up with, using our caps.

I must say when I read the peak current figure for a dead shorted cap I was
somewhat taken aback, I never thought it would be so high...

Cheers Mike (pencil in hand) Tucknott