# Re: [TCML] Fixing secondary strikes Re: Bad strike to a 12 inch traditional coil (somewhat terminal)

The radio transmitter sends out propagating electromagnetic waves which are no longer coupled to the transmitter after they are more than 1/3 of a wavelength away, therefore the transmitter is unaffected no matter how many receivers there are.  This is called the far field. With the TC, the frequency is so low that 1/3 of a wavelength is a few kilometers.  Within this distance, the coupling is through the magnetic field or the electric field, which are still attached to the TC.  This is called the near field. The arc ring is majorly inside the near field, so it can eat power from the primary.
```
--- Carl

On 7/8/2018 3:57 PM, Tedd Dillard wrote:
```
```Thank you sirs for the explanation.
Just one of the many things I hope to understand about TCs.
Teddy

On Jul 8, 2018 6:26 PM, "David Rieben" <drieben@xxxxxxx> wrote:

```
```Hi Tedd,

One must also consider that the flux density of radiant energy intercepted
on a perpendicular plane from a transmitter source is inversely
proportional to the square of the distance between the "transmitter" and
the "receiver". In light of this well established physical science, as well
as the fact that a closed (i.e. short circuited) strike ring intercepts a
significant portion of the MAGNETIC flux energy of the primary coil, the
transmitter/receiver analogy is not really a valid comparison to the
relatively very "up close and personal" closed strike ring scenario.

David
----- Original Message ----- From: "Tedd Dillard" <tedd.dillard@xxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Sunday, July 08, 2018 3:06 PM
Subject: Re: [TCML] Fixing secondary strikes Re: Bad strike to a 12 inch

Gentlemen permit me a follpw up question.
```
```I understand that the heating of a closed loop rail is absorbing energy.
But is the energy that which would other wise be going into the primary
such that the power into the primary is being reduced?
This may be a false example but a radio transmitter transmits the same
by one does not affect that of other receivers
Teddy

On Jul 8, 2018 12:00 PM, "phil" <pip@xxxxxxxxxxx> wrote:

Teddy.
```
```Your question makes a good point, and the explanation is as Garry states;
I was simply drawing attention to the fact that the coil's owner had
remembered to place a gap in the ring. I'll add something in the
description.

PS: I'm not aware of situations where you would have a closed loop (maybe
others are?)

Phil T

On 08/07/18 00:45, Tedd Dillard wrote:

Gentlemen the reasons for my question are;
```
```1. I am new at this so am trying to understand how these things work.
They
are obviously complicated so getting into details is important.
2. In reading past post I remember some discussion on strike rings that
included some reference to open and closed loop rings but I was not
clear
on the issue.
3. In the video of the damage to the secondary one of the captions
indicated an open loop strike ring so I wondered if there was any
significance to specifying that it was open loop. If no one runs closed
loop why say it was open?
Teddy

On Jul 6, 2018 5:22 PM, "Steve White" <steve.white1@xxxxxxxxx> wrote:

If it is heating then it is absorbing energy. Heat takes energy to

```
```generate. A closed loop that is grounded would be just as effective as
an
open loop that is grounded but why would you even want to consider that
unless this is just casual interest? It is simple enough to cut a gap
in
the ring.

Steve

----- Original Message -----
From: "Tedd Dillard" <tedd.dillard@xxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Friday, July 6, 2018 8:16:04 AM
Subject: Re: [TCML] Fixing secondary strikes Re: Bad strike to a 12
inch

Carl thank you for your quick response.
In a closed loop does the energy going in to heating the loop detrack
from
the energy going into the primary or is the heating the only issue?
Is there any effect on the effectiveness of the loop to protect the
primary
if it is an open loop.
Teddy

On Jul 5, 2018 10:15 PM, "Carl Noggle" <cn8@xxxxxxx> wrote:

Hey--

A closed loop ring will act like a single shorted turn coupled to the
primary.  If it has a much bigger radius than the primary, it probably
won't absorb too much power.  But is it's close, it will absorb a lot
of
power just heating up the ring. Putting a small gap in the ring
eliminates
this problem.

--- Carl

On 7/5/2018 5:51 PM, Tedd Dillard wrote:

Gentlemen this may not be best place to ask this question but I noticed

```
```in
```
```the vedio that it was an open loop strike ring. Comments on the
```
```difference
```
```in an open loop vs closed loop strike ring please.
```
```Teddy

On Jul 5, 2018 1:31 PM, "Bert Hickman" <bert@xxxxxxxxxxxxxxxxxxxxx>

wrote:
```
```Phil, Steve, and all,
```
```Sorry for the damage to your secondary, Phil. The videos were
```
```excellent
and will hopefully lead to good discussion here and effective

preventative
```
```measures for higher power systems.
```
```A thick coating of 2-part epoxy or polyester may accomplish a similar
function as PMMA tubing at significantly lower cost. When uniformly
coated,
errant strikes to the secondary will "splash" outward across a

relatively
```
```wide area of the outer surface of the coated secondary. The coating
```
```dissipates spark energy by spreading it out and capacitively
conducting

it
```
```to the secondary without creating damaging hot spots. In practice, I've
```
```seen hot primary-secondary flashovers that left NO permanent or
visible
effect on thickly-coated secondaries. These would have undoubtedly

caused
```
```melting and turn-turn shorts on an unprotected secondary.
```
```Your system also has a comparatively large topload OD compared to

primary
```
```OD. You may want to consider adding one or two additional,
```
```larger-diameter,
strike rails to spread out the E-field "footprint" of the base. These

will
```
```alter the E-field between the topload and base, making it more vertical
```
```(in
the space between the two) helping to reduce strikes to the
secondary.

The
```
```larger strike rails could be an add-on that can be removed before
```
```transporting the coil, and they would would require any changes to
your
existing primary winding.

You may also want to consider adding a smaller toroid under the top
toroid. By elevating the top toroid, you'll increase the outward
"throw"
of
sparks while further reducing hits to the strike rail. In the latest

video
```
```there were a number of hits to the strike rail that came quite close to
```
```flashing over to the lower half of the secondary even at 100 BPS. The
hotter 200 BPS strikes combined with thermal rise seems to have
tipped

the
```
```balance, unfortunately.
```
```Good luck and best wishes,

Bert

Steve White wrote:

I have also had this idea for some time. I would love for somebody to

try
```
```this but even if it works I don't know if any of us could stand the
```
```expense.
```
```Steve

----- Original Message -----
From: "Phillip Strauss via Tesla" <tesla@xxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Wednesday, July 4, 2018 4:02:13 PM
Subject: Re: [TCML] Fixing secondary strikes Re: Bad strike to a 12

inch
```
```traditional coil (somewhat terminal)
```
```
Hello Jim,
Although very costly in the UK, I was considering a 350mm diam cast
acrylic 1 metre long tube (that's how it comes) with 5mm wall
thickness
to
go over my 300mm (12") diam secondary, it would cover about the
first

two
```
```thirds of the tube, a good few inches higher than the previous strikes.
```
```Your comment on a dissipative tube caught my eye for that particular
```
```reason
but I don't understand the concept of loading or that my idea would

work,
```
```any explanation and/or prediction would be much appreciated.I'm
```
```contemplating your other suggestions (which are totally novel
```
```<https://maps.google.com/?q=her+suggestions+(which+are+

totally+novel&entry=gmail&source=g>
```
```to me) with
```
```interest.
```
```Regards,Phillip.

____________________________________________________________
_________________

14 Broad Street, Stamford, Lincs PE9 1PG

Tel: 01780 753008

On Wednesday, 4 July 2018 21:26:39 BST, jimlux <
jimlux@xxxxxxxxxxxxx>
wrote:
On 7/4/18 11:40 AM, David Rieben wrote:

Hi Phil,

My deepest condolences for your loss. I know it's JUST a secondary
```
```coil,
```
```but as a fellow coiler, I most assuredly feel your pain. On the bright
```
```side, at least you did manage to capture some truly spectacular
```
```footage
```
```of this secondary coil mishap. I have had this happen on rare occasion
```
```with the operation of my big coil, though fortunately, none of my
```
```mishaps turned out quite that severe! Only once did I actually have
to
repair some damage to the side of my coil and was able to get it
back
into full functioning mode via the repair. Since I must operate
mine
outside, I did have one occasion where the wind actully "blew" one
of
the streamers back into the side of my secondary coil, too. Lesson
learned - although refraining from outdoor operation during
rainfall

is
```
```an obvious good rule, non-starters in windy conditions are also well
```
```advised.
```
```I suppose this is a risk, that although may be small with a
well-tuned
and efficiently operating coil, is never completely absent. :^/

I wonder if we could figure out a way to segment a large coil

```
```vertically, so if a segment gets damaged, you can just rewind that
segment. Just off the top of my head, I'm thinking about something
like
segments with a hundred turns or so. Could we come up with a way of
making the connections in a "good" way. I'm almost thinking about
how
you using field grading rings on a Van de Graaff. You don't want a
complete shorted turn, but you could terminate the winding in some
sort
of flat terminal on the "mating face" of a segment. You'd stack the
segments, and then put some compression on it (threaded fiberglass

rod?)
```
```The other idea that comes to mind is if there is some way to "spread"
```
```the energy of the secondary strike.. Say your secondary were coated
```
```with
```
```a resistive (but still conductive) coating. Would that spread the
```
```current density enough to prevent burning through the insulation? Or
```
```a
dissipative tube covering the secondary - not enough to "load" the
secondary, but enough to "take the hit".

OR, what about a second helix, space wound, that extends the length
of
the secondary, with some suitable resistive conductor, so the
voltage
profile matches that of the secondary (so no protective helix to
secondary arcs), but so it doesn't enter into the resonant circuit.
The
protective helix would be mostly capacitively coupled to the
secondary,
establishing the voltage.

What about something like a helix wound with wire, but with small
gaps
along the length.. the gaps don't break down normally, but if a

streamer
```
```strikes, the gaps break down and provide a conductive (but lossy) path
```
```to the base.
```
```

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```--
Regards Phil www.hvtesla.com
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