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
traditional coil (somewhat terminal)
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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