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Re: [TCML] Secondary coil strikes
Bert
You are correct. I don't see a corona just have that racing strike every once in a while. My secondary is 6.25" dia . My primary is an inverted cone @ 14.5 deg to which the inner most turn is only about one inch away from the secondary. Should I abandon the first turn that would make the primary 1.5 inches away from the secondary ? Or just go ahead, like you say, and raise it bit by bit ? How far away do most coolers make that first primary turn away from the secondary ?
You guys have been helpful, always learning something.
Thanks ,JM
On May 15, 2012, at 11:53 AM, Bert Hickman <bert.hickman@xxxxxxxxxx> wrote:
> Hi Jeff,
>
> If you were getting strikes from the top of your winding to the bottom, this sounds like "racing sparks". Racing sparks may occur as lower energy sparks between various portions of the secondary winding, or they may span the entire winding as a hot flashover. They are usually a sign that your primary:secondary coupling (k) is too high. Excessive coupling is often a problem when using an inverted conical primary. There can be other causes as well, These include using a bang size that is too large for your secondary's power handling capability, accumulated dust or debris on the secondary that abnormally increases the surface E-field, or using a toroid that has too large a minor diameter that doesn't break out on its own.
>
> Reliable operation of a simple two-coil spark-gap coil also becomes more challenging as you approach a 3:1 spark length to coil length ratio, especially if your secondary also has comparatively small diameter. A coil that seemingly operated just fine with an NST bank may become overpowered when migrating to a distribution transformer. Pig-powered coils generally perform better, and more reliably, with larger-diameter secondaries. Longer-term, consider migrating to an 8 - 10" diameter secondary.
>
> Near-term, try decreasing your coupling coefficient to prevent possible winding damage. Elevate the secondary (versus the primary) in increments of 1/4" until racing sparks stop. Also consider reducing bang size by either reducing spark-gap length or reducing your tank capacitance. Add a two-part coating (such as Envirotex Light) to increase voltage breakdown capability if your secondary winding is not already coated. Carefully inspect and clean your secondary with a dampened cloth and repair any damage. Coated coils often retain significant surface charges, making them powerful dust magnets after TC operation. When cleaning your secondary, remember to continually ground yourself to prevent charge building up on YOU. This will prevent you from getting bitten by a painful ESD event - a rite of passage for many coilers... :^)
>
> Carefully watch the coil in a darkened area as you ramp up power/ Look carefully for any abnormal corona off the top portion of the secondary winding, the primary, primary tap, or strike ring. Fix these problems, if necessary, before running at full power. If your toroid pair is too high, you'll see corona from the top of your secondary winding. Adding a small copper or aluminum tubing corona ring at the top of the winding, lowering your existing toroids, or increasing the outer diameter of your larger toroid will eliminate this.
>
> Good luck and safe coiling to you,
>
> Bert
>
> Jeff Miller wrote:
>> Where then should the ring be put ? Right below the Toroid or right
>> above the top last turn . There is about a 2.5 inch tall area where
>> it could be put. Again the strike were from the top of the winding to
>> the bottom
>>
>> Thanks ,JM
>>
>> On May 14, 2012, at 9:59 AM, Carl Noggle<cn@xxxxx> wrote:
>>
>>> You shouldn't lower your toroid, because if it is less than about
>>> half of the winding diameter away from the coil top, it will act as
>>> a shorted turn and reduce your performance. You can make a turn
>>> around the top of the coil with 1/2 inch copper tubing right next
>>> to the wire, but leave a break of 1/8 inch or so to avoid the
>>> shorted turn. Connect this tubing to the top of the secondary.
>>> Hopefully this will stop arcing from the top turns.
>>>
>>> Good luck---
>>>
>>> Carl
>>>
>>>
>>>
>>>
>>>
>>>> Hello everyone, Tried my tesla this weekend at our annual pig
>>>> roast. Work our great, was able to light up 20 4ft and one 8 ft
>>>> fluorescents. I did have an issue when I let it stand alone and
>>>> break out. Every once in a while I would get a secondary strike
>>>> from the top of the coil winding a few turns down to, it was
>>>> hard to tell either to the primary or to the very bottom of the
>>>> secondary where the lead goes to gnd. It is a 6.25" secondary
>>>> with two toroids, a 3x12 and a 6x24. If you were to look straight
>>>> at the coil the bottom of the 3x12 Toroid is about 2.25 inches
>>>> above the top of the sec winding. In your opinion could this be
>>>> the problem, the Toroid being too far above ? If so I could cut
>>>> it off, but a lot of work. What would happen if I wrapped 2" wide
>>>> foil tape around the top of the form, have it about 1/4" above
>>>> the top of the form, fold that 1/4" over the form, then put my
>>>> toroids back on . The folded in lip would then make contact the
>>>> the 12" Toroid .
>>>>
>>>> Need some help
>>>>
>>>> Thanks ,JM_______________________________________________ Tesla
>>>> mailing list Tesla@xxxxxxxxxx
>>>> http://www.pupman.com/mailman/listinfo/tesla
>>>>
>>>
>>>
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>>
>
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