Re: pole xmfr protection circuit

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>

Hi all,

I think that I have mentioned this before in the time past, but
one of the best pole xmfr protection devices that I have been
able to come up with is a properly rated distribution arrester
in parallel with the HV output of the pole xmfr. Think about it-
the utility power companies place these across the HV input
bushings (output for us) to protect the transformer from line
voltage spikes caused by switching transients, sudden load
changes, lightning strikes, ect. Protection from sudden voltage
spikes is exactly what we're looking for, too. I was using an
18 kV rated arrester across the bushings of the 14,400 volt,
15 kVA pig that I power my "Green Monster" with. This worked
great until I fired it off outside on a windy day and the wind blew
the streamer sparks back into the side of the secondary coil. This
sent the RF nasties back into the primary circuit, which ended
up smokin' the arrester to a dead short! I guess it's a good
thing that the arrester was there or it may very well have been
the pig itself that "bit the dust" instead. Fortunately, it did not
smoke my primary capacitor, either ;^0 I finally found a 36 kV
rated arrester and replaced the dead 18 kV arrester with it.
36 kV may seem a bit high of rating for a 14.4 kV pig, but I think
it would still clamp the voltage spikes before they reached
"pig killing" levels, as most 14.4 kV pigs are rated at 110 kV
biL. Also, I won't be able to smoke this arrester quite so easily.

BTW, I have yet to ever "smoke" a pole "pig" xmfr, with or without
protection in 7 years of "piggie" coiling. I think a very few may have,
but I'm telling you that compared to fragile NSTs, pole pigs are virtu-
ally bullet proof. If you decide not to use any type of protection circuit
with your piggie, it will probably still live as long as you, even in Tesla
coil service ;^) As a matter of fact, I'd be far more concerned about the
pig smokin' me (from getting a little too careless with it) than me smokin'
it ;^0

David



----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Monday, April 16, 2007 1:56 PM
Subject: Re: pole xmfr protection circuit


> Original poster: <donwb@xxxxxxxxxxxxx>
>
> I would like to have a copy please.
> Thanks.
>  >
>  > From: "Tesla list" <tesla@xxxxxxxxxx>
>  > Date: 2007/04/15 Sun PM 09:05:26 EST
>  > To: tesla@xxxxxxxxxx
>  > Subject: pole xmfr protection circuit
>  >
>  > Original poster: "D.C. Cox" <resonance@xxxxxxxxxxxx>
>  >
>  >
>  >
>  > Note to those experimenters who have purchased pole xmfrs from me in
>  > the past year:
>  >
>  > I have a pole xmfr protection circuit in my files.  Contact me
>  > off-list and I will email the circuit to you.
>  >
>  > Gerry --- also sending a copy to you if you wish to add it to the
archives.
>  >
>  >
>  > Dr. Resonance
>  >
>  >
>  >
>  >
>  >
>