Re: additional transformers [rotary gap]

From: 	Mad Coiler[SMTP:tesla_coiler-at-hotmail-dot-com]
Sent: 	Thursday, August 07, 1997 11:02 AM
To: 	tesla-at-pupman-dot-com
Subject: 	Re: additional transformers [rotary gap]

>From: 	Robert W. Stephens[SMTP:rwstephens-at-headwaters-dot-com]
>Reply To: 	rwstephens-at-headwaters-dot-com
>Sent: 	Thursday, August 07, 1997 12:21 AM
>To: 	Tesla List
>Subject: 	Re: additional transformers [rolled caps]
>> From: 	richard hull[SMTP:rhull-at-richmond.infi-dot-net]
>> Sent: 	Friday, August 01, 1997 5:52 PM
>> To: 	Tesla List
>> Subject: 	Re: additional transformers [rolled caps]
>> A
>> >> > >
>> >> > >Peter,
>> >> > 
>> >> > I recommended leaving a full 2" edge separation metal to edge of 
>> >> > in all rolled capacitors!
>> >> > 
>> >> > Richard Hull, TCBOR
>> >> 
>> >> Thanks for the info on that, I will go 2" on my future overlaps. 
>> >> seems strange to me that sparks seem to travel much further along 
>> >> surface of an insulator, no matter how clean it seems to be. Maybe 
>> >> is due to microscopic impurities on the surface of the plastic?
>> >> 
>> >> Another little trick that you probably have already figured out is 
>> >> insulate the input connections to the plates by rolling a few 
layers of
>> >> poly around them.
>> >> 
>> >> Cheers, Peter E.
>> >> 
>> >Peter, Richard, All,
>> >
>> >I had the same problem with a rolled poly cap I made once, and I 
>> >*was* using a 2 inch surround from the foil to the edge of the poly.  
>> >Dismantling the cap after the failure showed these burns distributed 
>> >all along the edge of the foil outwards into the poly.
>> >
>> >I had a chat with a capacitor engineer at Condesnser Products about 
>> >this phenomenon and was told that this is why HV capacitors are 
>> >generally not successful when one tries to apply more than 8-10 kV 
>> >across a single stage.  He explained that the energy exchange 
>> >the plate and the local surface of the dielectric becomes too 
>> >and just completely overstresses the dielectric causing it to 
>> >break down.  Placing additional thickness of poly does not 
>> >significantly reduce this violent surface area exchange so you will 
>> >still get failures no matter what you do if you try to run a single 
>> >stage cap at 15 or 20 kV.
>> >
>> >FWIW
>> >rwstephens
>> >
>> >
>> >
>> >Robert,
>> This is the very reason I have stated even in tape #3 where the big 
>> jobs are made that one should never run them at over 10KV.  Series 
for more
>> volts.  In tape #8 where we build another type of poly cap, I note 
that 7-8
>> KV is the max on the single unit.  Nonetheless,  many never headed my
>> warning and blew out there caps almost immediately.  Too many coilers 
>> to the 15,000 60ma neons and use a single capacitor unit.  They will 
lose it
>> sooner or later.  
>> The two inch boarder is minumum on caps used over 5KV per unit.  Once 
>> and all the air is out I have run my single, big, rolled oil caps 
with 12KV
>> neon transformers and luckily have never lost one.  When working on 
>> #1-8 from 1990-1995 I used two of the big rolled jobs in series with 
>> 14,400 volt potential transformer and never suffered a break down, 
but the
>> stress was reduced on each unit by series stringing them.
>> Since then I have used only professionally produced discharge caps.  
The old
>> 1990 built rolled caps are still kickin' and are often used in snap 
>> for visitors, etc.
>> Concomittant with the use of homemade caps is a sense of power input
>> limitation in the form of break rate.  Lots of folks kill these 
>> units with 15,800 rpm 24 point rotary gaps!!!!  Even 2 KV might blow 
them at
>> that rate of delivery.  Newbies always want the 20,000 volt 
transformers and
>> turbine speed rotaries and wonder at the ease of destruction of their
>> capacitors.
>> There is rarely a real viable need for break rate over 360/second 
>> can handle more).  If a rotary gap has more than 8 points, it will be 
a bear
>> to quench well with out super high speed and attendant cap 
>> I have no way of knowing, but I suspect a lot of Good CP caps fell to 
>> turbine rotary effect.
>> Richard Hull, TCBOR
>You have shared some valuable pointers again for newbies here and 
>safety reminders for the rest of us.  I can really appreciate how a 
>turbine break rate will destroy the best commercial capacitor but I 
>just wanted to say in reference to your 360 BPS suggestion that I 
>have personally found ~ 402.5 BPS (14 stud rotary wheel on a 1725 RPM 
>non-synchronous motor) to be really sweet.  A wheel with 12 studs 
>yielding ~345 BPS was significantly less impressive in my MTC unit, all 
>things else being identically equal.  I guess there is an ion channel 
>lifetime effect difference happening here that is better at the 
>slightly higher break rate of 400,  but suspect a supply sinewave 
>filling factor or synchronizing benefit also as the break pulses 'walk' 
>the 60 cycle mains phase in a slightly more concentrated manner.
>The Twin system which I have recently built really comes alive in 
>this  400 PPS regieme, and is noticeably less remarkable at slower 
>rates, including attempts to set the non-sync DC rotary break motor 
>to run synchronously at 120 BPS (due to large wheel inertia and 
>variac control I can successfully ride the crest of the sinewave peaks 
for a few
>seconds at a time).  I subsequently have no intention to operate the 
>Twin at 120 BPS synchronous,  nor any need to operate it's break rate 
>exceeding 402 PPS.

I am still a little fuzzy about the synch/non-synch rotary gaps. I 
understand the basics of the synch gap-but how is the non-synchronous 
gap advantageous? 

The confused, bewildered, and vexed

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