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Re: Capacitor Help Needed
Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>
Hi,
guys - why do you use 942C20P15K? it`s more than 2 times worse in
C*U/$ than 942C16P68K for example, it has smaller peak & rms current.
i know that dU/dt is almost 3 times higher, but for 100-200 khz coils
942C16P68K should be fine, and then we just can increase number of
caps per string.
Let's see... For a 15/60 NST in the LTR mode we want:
http://hot-streamer.com/temp/MMCcapSales.gif
http://catalog.rell.com/scripts/SkuPage.asp?SKU=162589
27.3nF 22kV which is two strings of 11 of the 150nF caps. At $2.45
each that is $53.90.
From the data sheet:
http://www.cornell-dubilier.com/film/9422000.htm
864 amps peak and 27 amps RMS.
Now for the 942C16P68K
http://catalog.rell.com/scripts/SkuPage.asp?SKU=165330
$4.15 Each
http://www.cornell-dubilier.com/film/9421600.htm
680nF 1600V 781 amps peak 16 amps RMS
To get 27.3nF we would need to put 25 in series which would give use
25 x 1600 = 40kV The cost would be 25 x 4.15 = $103.75..
To get 22kV like we want, we would need 14 caps. 14 x 27.3nF =
382.2nF/cap... We could try the 942C16P33K at 330nF and use 12 caps
to get to 27.3nF. The little extra voltage will not hurt them. So
we need 12 of the 942C16P33K caps:
http://catalog.rell.com/scripts/SkuPage.asp?SKU=159547
$2.52 x 12 = $30.24 :-)))
We have to buy 27 of them though at $68.00 but maybe we could sell
the extras here on the list ;-) They are back ordered, but Rell gets
them in about a week. The peak current is 633 amps and the RMS
current is 13.3 amps. We loose a good amount on the RMS
current... "maybe" that is ok...
So If one shops around you might save some money. We like the
942C20P15K since it is one nice cap that we can order in giant
quantities to get big discounts. But there are certainly other possibilites...
The Geek Group was also selling the 100nF 2000V caps since they
matched many situations better for NSTs...
Cheers,
Terry