Re: Oil insulated secondaries (fwd) (Are they worth it?) (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Mon, 10 Sep 2007 21:11:57 -0700
From: huil888 <huil888@xxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Oil insulated secondaries (fwd) (Are they worth it?) (fwd)

Aaron -

I've got to disagree with your position that epoxy coatings don't provide
effective electrical insulation. I've been using epoxy to coat every
secondary I've wound over the last 8 years or so, and I can assure you that
a heavy (.050" or thicker) epoxy coating provides extremely effective
electrical insulation, as well as providing the mechanical protection you
mention.

Since I started using epoxy coatings, I have never had a secondary damaged
by external arcing or flashover, even when used with  helical primaries with
very high coupling factors. Exactly how much electrical insulation is
provided can be seen when there is a tiny pinhole or near-microscopic bubble
in the coating anywhere in the upper 1/2 of the secondary. Once the coil is
tuned and operating at near peak power, corona and thin spidery arcs will
flow out of the pinhole like a leak in a pressurized garden hose.

I fully agree that aside from the novelty factor, its hard to justify the
additional complexity and probability oil seepage with an oil-insulated
secondary for a conventional Tesla coil.. A correctly applied epoxy coating
will give the appearance that the secondary is encased in a perfect glass
sleeve, an effect that you just can't get with concentric acrylic tubes with
oil in between.

The only place that I can think of where this additional complexity is
likely to provide any real benefits is in a magnifier setup, where the
extremely tight pri-sec coupling makes it very hard to prevent corona and
flashover.

Regards,
Scott Hanson



----- Original Message ----- 
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Monday, September 10, 2007 7:37 PM
Subject: Re: Oil insulated secondaries (fwd) (Are they worth it?) (fwd)


>
> ---------- Forwarded message ----------
> Date: Mon, 10 Sep 2007 09:53:09 -0700 (PDT)
> From: J. Aaron Holmes <jaholmes@xxxxxxxxxxxxxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Re: Oil insulated secondaries (fwd) (Are they worth it?)
>
> Epoxy coating is not about electrically insulating,
> it's about physically protecting and preventing the
> windings from sliding off.  That's it, really.  Oil
> does neither of these things, and is instead all about
> electrical insulation.  HOWEVER, whether it's any
> advantage at all depends on what other aspects of your
> design you hold constant, and given that most of these
> other aspects are usually controllable in such a way
> as to avoid the necessity of oil insulation, I'd have
> to agree that oil insulated secondaries are moderately
> to extremely silly in most cases.  They are
> undoubtedly "interesting" and "cool", though.  I loved
> the look of Terry Blake's coil, and decided to add my
> own twist".
>
> All else being equal, I'd expect oil insulation would
> make the secondary less susceptible to secondary
> breakout, primary-secondary strikes, racing arcs, and
> internal arcing.  This, in turn, might permit the use
> of higher-than-average coupling, larger toploads
> (which would otherwise tend to encourage secondary
> breakout), and generally a bit more power, achieving a
> higher-than-average streamer-to-secondary length
> ratio.  But we'll see!!  Again, I doubt if it's a very
> practical way to accomplish these things, but it is
> nonetheless a fun twist.
>
> Cheers,
> Aaron, N7OE
>
> --- Tesla list <tesla@xxxxxxxxxx> wrote:
>
>>
>> ---------- Forwarded message ----------
>> Date: Sun, 9 Sep 2007 18:22:33 -0700 (PDT)
>> From: Yurtle Turtle <yurtle_t@xxxxxxxxx>
>> To: Tesla list <tesla@xxxxxxxxxx>
>> Subject: Re: Oil insulated secondaries (fwd)
>>
>> I'm just curious why oil would be better than simply
>> potting it in epoxy. I realize it would look cooler.
>> Seems like an oil tight seal would be harder to
>> accomplish than one that only needs to hold up until
>> the epoxy hardens.
>>
>> Adam
>>
>> --- Tesla list <tesla@xxxxxxxxxx> wrote:
>>
>> >
>> > ---------- Forwarded message ----------
>> > Date: Sat, 8 Sep 2007 16:22:58 -0700 (PDT)
>> > From: J. Aaron Holmes
>> <jaholmes@xxxxxxxxxxxxxxxxxx>
>> > To: Tesla list <tesla@xxxxxxxxxx>
>> > Subject: Re: Oil insulated secondaries (fwd)
>> >
>> > Hey there, Dave!  I'd be interested in any tips
>> > here,
>> > too, however I suspect the number of amateur
>> coilers
>> > who have built oil-insulated secondaries can be
>> > counted on one hand, maybe less ;-)  The only
>> > functioning amateur oil-insulated coil I've ever
>> > seen
>> > pictures of is Terry Blake's:
>> >
>>
> http://www.tb3.com/tesla/teslathon2003/tb_tc/tb_tc.htm
>> >
>> > It was his coil that inspired me to start building
>> > my
>> > own oil-insulated coil.
>> >
>> > I've also heard of a few oil-insulated research
>> > coils,
>> > and seen drawings illustrating their construction.
>> >
>> > For about the last year, I've been slowly
>> gathering
>> > the pieces for a medium-sized oil-filled
>> secondary.
>> > For lack of any real guidance on oil-insulated
>> > construction, I've decided to strike out in what
>> > seems
>> > like a new direction:  I'm building the secondary
>> > inside an oil-tight ceramic insulator that used to
>> > house a 115kV capacitor:
>> > http://silicon-arcana.com/cap/cap.jpg
>> > (on left)
>> >
>> > It's about 4' tall and will accomodate a 6" x 30"
>> > coil
>> > form quite nicely.
>> >
>> > The insulator has aluminum end caps with rubber
>> > seals.
>> >  If the end caps were steel, I'd worry about
>> losses,
>> > but aluminum should be fine.  The bottom of the
>> coil
>> > form will be stood off from the bottom cap, too.
>> >
>> > The secondary winding itself will also be
>> something
>> > unusual; a friend with a lathe has cut threads
>> into
>> > a
>> > piece of clear acrylic tubing, such that the
>> > secondary
>> > windings will actually lie in a groove, held very
>> > slightly apart so that the oil almost completely
>> > surrounds them.  I will not be coating the winding
>> > at
>> > all; the threaded form will keep the windings in
>> > place.  Within the ceramic insulator, the coil
>> form
>> > will be suspended from both ends by 2" OD copper
>> > tubing.  I'll also be installing a pressure
>> release
>> > valve on the top cap.  The top cap will then be
>> > completely hidden inside a 6"x24" spun toroid
>> which
>> > I've cut most of the center out of.  A larger
>> 8"x30"
>> > toroid will comprise the main topload above this.
>> >
>> > All this, it is hoped, will look extremely cool
>> when
>> > finished, not to mention being almost
>> > indestructible.
>> > The biggest missing piece right now is the time to
>> > actually finish it!  But as I have so little time
>> in
>> > general, I'm being patient about collecting all
>> the
>> > best stuff.  I can't bank on any second chances!
>> > We'll see what happens.  I'm hoping to actually
>> have
>> > something working by mid 2008.
>> >
>> > Cheers,
>> > Aaron, N7OE
>> >
>> >
>> > --- Tesla list <tesla@xxxxxxxxxx> wrote:
>> >
>> > >
>> > > ---------- Forwarded message ----------
>> > > Date: Sat, 08 Sep 2007 02:08:24 +0000
>> > > From: Sparktron01@xxxxxxxxxxx
>> > > To: Tesla List <Tesla@xxxxxxxxxx>
>> > > Subject: Oil insulated secondaries
>> > >
>> > > Folks
>> > >
>> > > Are there some links to construction techniques
>> to
>> > > build a oil insulated Tesla Coil or
>> > > Magnifier secondary (or extra coil)?  Please
>> > advise.
>> > >  Thanks
>> > >
>> > > Regards
>> > > Dave Sharpe, TCBOR/HEAS
>> > > Chesterfield, VA. USA
>> > >
>> > >
>> > >
>> > >
>> >
>> >
>> >
>> >
>>
>>
>>
>>
>>
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