[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: failed cap
Original poster: Bert Hickman <bert.hickman-at-aquila-dot-net>
Hi Phil,
You can reduce the electrical stress concentration at the edges of aluminum
foil plates by folding the edges of the foil plates - the rounded edges
will help reduce the probability of corona formation at the edges of the
plates. Under high fields, corona will form under oil, since the oil begins
to break down liberating gases which then ionize. It doesn't take very long
to destroy the nearby dielectric. You can file/sand the edges of thicker
plates (such as aluminum flashing) to accomplish the same thing.
Best regards,
-- Bert --
--
--------------------------------------------------------------------
We specialize in UNIQUE items! Coins shrunk by Ultrastrong Fields,
Lichtenberg Figures (electrical discharges in acrylic), & Scarce OOP
Technical Books. Stoneridge Engineering -- http://www.teslamania-dot-com
--------------------------------------------------------------------
Tesla list wrote:
>Original poster: "philip barnes" <luck_phil87-at-hotmail-dot-com>
>I removed the bad layer and associated plates and stuck it back in oil
>(with who knows how much trapped air but anyway). After connecting it up
>to my TC is works! Perhaps only had 1 minutes total run time so far and
>really only seconds of on time each run and also using a slightly reduced
>gap but it is still working. wooohoooo. Wounder who long it will last this
>time lol. I use 16 layers of 4 mil poly btw. A rought burr on the end of
>one plate appears to be th reason that layer failed. punched a half inch
>hole in the poly to the plate above and below it.
>Phil
>
>>From: "Tesla list" <tesla-at-pupman-dot-com>
>>To: tesla-at-pupman-dot-com
>>Subject: Re: failed cap
>>Date: Mon, 01 Dec 2003 17:00:29 -0700
>>MIME-Version: 1.0
>>X-Sender: teslalist-at-twfpowerelectronics-dot-com
>>Received: from mc12-f42.hotmail-dot-com ([65.54.167.178]) by
>>mc12-s5.hotmail-dot-com with Microsoft SMTPSVC(5.0.2195.6713); Mon, 1 Dec
>>2003 16:14:11 -0800
>>Received: from hotlilpup.pupman-dot-com ([63.225.119.186]) by
>>mc12-f42.hotmail-dot-com with Microsoft SMTPSVC(5.0.2195.6713); Mon, 1 Dec
>>2003 16:11:46 -0800
>>Received: from poodle.pupman-dot-com (poodle.pupman-dot-com [63.225.119.188])by
>>hotlilpup.pupman-dot-com (8.11.6/8.11.6) with ESMTP id hB20VPX12497;Mon, 1
>>Dec 2003 17:31:25 -0700
>>Received: (from slist-at-localhost)by poodle.pupman-dot-com (8.9.3/8.9.3) id
>>RAA16001;Mon, 1 Dec 2003 17:09:33 -0700
>>X-Message-Info: 0jbW5ANosZJnWOr34Sni0a3NvGYhvpM0
>>Resent-Date: Mon, 1 Dec 2003 17:09:33 -0700
>>Message-Id: <6.0.0.22.2.20031201170027.02483548-at-twfpowerelectronics-dot-com>
>>X-Mailer: QUALCOMM Windows Eudora Version 6.0.0.22
>>Resent-Message-ID: <LfQYa.A.gdC.mc9y_-at-poodle>
>>Resent-From: tesla-at-pupman-dot-com
>>X-Mailing-List: <tesla-at-pupman-dot-com> archive/latest/17178
>>X-Loop: tesla-at-pupman-dot-com
>>Resent-Sender: tesla-request-at-pupman-dot-com
>>Return-Path: tesla-request-at-pupman-dot-com
>>X-OriginalArrivalTime: 02 Dec 2003 00:11:47.0559 (UTC)
>>FILETIME=[E04A6F70:01C3B868]
>>
>>Original poster: robert & june heidlebaugh <rheidlebaugh-at-desertgate-dot-com>
>>
>>Phill. My students and I have buitl over 12 low d. polyethylene/oil
>>capacitors with only one failier caused by not enough total thickness. we
>>use 12 layers of 4mill between plates with no problems. We use clear mineral
>>oil with no additives. Never tried to use thick poly. others have had
>>problems with thick poly, More layers less trouble.
>> Robert H
>>--
>>
>>
>> > From: "Tesla list" <tesla-at-pupman-dot-com>
>> > Date: Mon, 01 Dec 2003 08:02:07 -0700
>> > To: tesla-at-pupman-dot-com
>> > Subject: Re: failed cap
>> > Resent-From: tesla-at-pupman-dot-com
>> > Resent-Date: Mon, 1 Dec 2003 08:10:04 -0700
>> >
>> > Original poster: BunnyKiller <bunikllr-at-bellsouth-dot-net>
>> >
>> > Hi Phil...
>> >
>> > hmmmmmm building ones own cap... you didnt see my website did
>> you ?? ;)
>> >
>> > no matter how hard you try to build your own cap ( and yes Ive built 3 of
>> > them and all 3 failed eventually the plate cap lasted the longest
>> > but it was made from ultra clean PE sheeting 70thou thick with REAL
>> > transformer oil...) its best to buy a manufactured cap set be it an
>> > MMC or Maxwell's systems on Ebay ( best prices Ive seen as to date)
>> > .. I have done rolled caps plate caps glass caps and wasted alot of $
>> > doing so ( but hey it was a learning experience and ehhhhhh yes...
>> > it was expensive)
>> >
>> > definately sounds like you have blown a hole in the dielectric ( PE
>> > sheeting) and the oil is arcing out ( pull it apart and look for the
>> > black holes in the plastic) ...the spark gap at that setting is less of a
>> > resistive value than oil in the cap... yes most definately ..
>>without a
>> > secondary in place to "asorb" the energy the cap will arc out first....
>> >
>> >
>> > bite the bullet and buy a set of MMC caps or a set of Maxwells
>>dont do
>> > what I did and waste your money trying to build a home made cap...
>> > unless you like learning the hard way ......
>> >
>> > Scot D
>> >
>> >
>> > Tesla list wrote:
>> >
>> >> Original poster: "philip barnes" <luck_phil87-at-hotmail-dot-com>
>> >> Hi.
>> >> i built a cap with 1.6 mm or 64 mil thick PE dielectric and put the
>> >> whole thing in canola oil. It worked great for a while but while i had
>> >> just the cap across the nst ,,, with no tesla coil connected.. to test my
>> >> new mulitgap sparkgap... the PE between 2 of the plates broke down and
>> >> now it blows bubbles and hisses and only produces a spark in the gap if
>> >> the gap is 1 mm or 30 mil . Its pretty much had it and must be breaking
>> >> down at 1 or 2 thousand volts..IS it more stressfull on a cap with no
>> >> tesla coil connected and is it suprising my cap did not last in my
>> >> config. The plates are 1.75" clearance from each end and 1" along the
>> >> sides. !6 sheets of makes each layer
>> >>
>> >> Phil
>> >>
>> >>
>> >
>> >
>
>.