Re: Primary strikes

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

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi All,

I have done computer studies of arcs hitting various parts of Tesla coil
systems.  The arcs just don't have enough current to bother anything much.
Everything looks like a ground to the streamers and they just don't do much
to the normal low impedance parts of a Tesla coil.  I would try to keep
them from hitting AC line wiring since the RF may hurt sensitive equipment
on the circuit but that is about it.  I "was" going to caution about the
streamers hitting like the center of an MMC, but I guess Finn solved that ;-))

I still would "try" not to let a coil wildly arc to the electronics but not
a giant worry if it does.

Cheers,

	Terry
 

At 11:21 PM 6/1/2002 +0200, you wrote:
>Hello stephen!
>
>I was interested in the same question some time back, and performed the
>experiment shown on this picture:
>Http://home5.inet.tele.dk/f-hammer/caparc.jpg
>
>As you see, no harm was done. The coil is a quick MOT driven lashup.
>
>Since the energy that the cap receives from the arc originates from
>itself, and has been taxed by spark gap, and other losses, it should not
>be enough to create a voltage higher than that which was originally
>across it.
>
>So a primary strike is not bad for the cap, however it may still be a
>nuisance, because it can trigger the safety gap, with erretic firing as
>a result.
>
>That`s why I have strike rings on my coils anyway.
>
>Cheers, Finn Hammer
>
>
>Tesla list wrote:
>> 
>> Original poster: "Steven Ward by way of Terry Fritz <twftesla-at-qwest-dot-net>" 
><srward16-at-hotmail-dot-com>
>> 
>> Hi everyone,
>> 
>> I was just wondering what people think about primay strikes because my small
>> coil can arc nearly consistently to my primary coil.  I was wondering how
>> bad this can really be as i have seen no damage yet.  Here are my coil's
>> specs:
>> 
>> 9000v 50ma(modified)NST
>> 
>> .0136uf MMC made from 2 strings of 10 in series, GE yellow snubber type
>> caps.068uf each.  Each cap is 3kvdc, with the 10, i have a good 30kvdc
>> rating(i really over built it!) so its very tough with my power level.
>> 
>> 5 gap static gap.  Linear design of the Richard quick type.  Has a fan on
>> it, about .25" total width.
>> 
>> Flat spiral primary, 9 turns .25" cu tubing.  Inner diameter-4", outer
>> diameter-12", .25" spacing in between.
>> 
>> Secondary is 2.3" diameter x 10" wound with 28awg.  PVC form
>> 
>> Toroid- i have 2, 2" cord x 12" total diameter, stacked.
>> 
>> I can run the coil with a twin pri/sec setup, and have no problems with
>> primary arcs, and get a nice 23" spark.  But with a single coil setup, i get
>> strong primary arcs about 15" long(since they bow out a bit).
>> 
>> So are primary strikes really that bad?  I wanted to know because i may
>> de-rate my cap to about 21kvdc when i get my small SRSG to work so that i
>> have a bigger capacitance.  Since i do this, could i be putting my caps in
>> danger,  im sure that with a SRSG, this coil will really go nuts.  Also,
>> what parts of the primary circuit are at danger(if any) from primary
>> strikes?
>> 
>> Steve Ward.
>>