Re: [TCML] surge arrestor for pole pig

["J. Aaron Holmes" <jaholmes@xxxxxxxxxxxxxxxxxx>]

Hi David:  Figured you'd chime in on this one ;-)  Are you sure about the construction?  I'm pretty sure the new rubberized arresters are wayyyyyy different inside than the old percelain ones, being MOV-based rather than silicon carbide-based.  SiC is far more linear than MOV technology, so I'd expect more dissapation and less effective clipping of high-frequency transients than with modern MOV arresters.  These arresters that Jim is asking about are dated 1971 (!), so I'm going to go out on a limb and say that they're SiC and not MOV.  I'd wait for something modern, m'self.

Cheers,
Aaron, N7OE

--- On Wed, 9/17/08, David Rieben <drieben@xxxxxxxxxxx> wrote:

> From: David Rieben <drieben@xxxxxxxxxxx>
> Subject: Re: [TCML] surge arrestor for pole pig
> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> Date: Wednesday, September 17, 2008, 1:46 PM
> Hi Jim,
> 
> I originally had a single 18 kV rated arrestor on my big
> coil.
> On one occasion, I was firing the coil outdoors on a windy
> day
> and the wind actually "blew" some of the
> streamers/sparks
> back into the lower third of the secondary coil and into
> the primary
> circuit. The output almost immediately died and further
> inves-
> tigation revealed that the arrestor had failed as a short
> circuit.
> However, nothing else in the system died so I guess the
> arrestor
> did its job by sacrificing itself to protect the
> transformer and the
> capacitor. I eventually replaced the 18 kV arrestor with a
> 36
> kV arrestor, which would be in the same
> "ballpark" rating as
> your proposed (2) seriesed 15 kV arrestors since my
> transformer
> is also rated at 14,400 volts on the high voltage side. I
> haven't had
> anymore problems since I added the 36 kV arrestor but then
> again, I have also since tried to avoid firing the coil
> during
> excessively windy conditions, too. BTW, my arrestor is one
> of the more modern butyl rubber exterior types instead of
> the
> porcelain exterior type. It's much lighter and less
> fragile, too.
> The exterior is the only difference though and the older
> por-
> celain style ones will work just as well.
> 
> David
> 

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