Re: [TCML] Chinese made polystyrene caps

[DC Cox <resonance@xxxxxxxxxxxx>]

I've tested them.  They are not up to pole xmfr standards.  Perhaps good
below 5 kVA, but not above.

Our units are more expensive at $800, but still well below the $1,700
Maxwell price for the same unit.  Our are actually better for TC use since
the Q factor
is over 20,000 as compared with only 12,000 for the Maxwells.

Dr. Resonance




On Tue, May 12, 2009 at 5:42 PM, bartb <bartb@xxxxxxxxxxxxxxxx> wrote:

> Hi David,
>
> Ditto on Gary and Matts' comments. This cap has come up before on the list.
> Someones going to have to give them a try, but at $180 ea, well, someone
> with a money tree in the backyard will have to do it. I suspect due to it's
> small size rms currents are going to play a major role in it's limitation.
> There is also a high probability that these Chinese caps are not up to par
> in the derating area as is standard by major cap manufacturers. Too many
> unknowns.
>
> Take care,
> Bart
>
>
> David Rieben wrote:
>
>> Hey guys,
>>
>> I was just wondering if anyone has any experience
>> with these Chinese made capacitor types that are
>> absolutely flooding eBay these days:
>>
>>
>> http://cgi.ebay.com/30kV-0-2-F-High-Voltage-Polystyrene-capacitor-HAM-audio_W0QQitemZ360120565659QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item53d8dbbf9b&_trksid=p4634.c0.m14.l1262&_trkparms=%7C301%3A1%7C293%3A6%7C294%3A30
>>
>> My guess is that since this particular one is only
>> 80 mm x 120 mm long or appr. 3 1/8" x 6" long, and yet it has a very
>> significant energy capacity (90 J), there is no way that its internal
>> construction could render it competant to withstand the high RMS cur-
>> rents and tremendous peak currents encountered
>> in larger SG driven Tesla coil circuits, even though polystyrene is a
>> good, low loss dielectric. Likely of very fragile metallized film
>> construction. What are
>> your thoughts?
>>
>> David Rieben
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>>
>>
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