Re: [TCML] Terry Filter Caps

["David Rieben" <drieben@xxxxxxxxxxx>]

Hi Phil,

My big coil once used an 18 kV rated distriubution arrester
acorss the 14.4 kV pole transformer for the "safety gap". Upon
firing the coil on a windy day a few years ago, some of the stream-
ers were "blown back" into the lower end of the secondary
coil and the primary circuit. This resulted in the arrester failing
as a dead short. I eventually replaced the defunct 18 kV
arrester with a 36 kV rated arrester. This one is nearly 30" long
but I have had not more problems like this since. Of course I
also now tend to avoid runs when the weather conditions are
marginal. It goes without saying that all runs with the Green
Monster, which throws 12 to 15 ft. sparks, are done out-
doors, since my "shop" is nothing more than a double car
garage with 8 ft. overhead ceilings!

David

----- Original Message ----- 
From: <FIFTYGUY@xxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Monday, August 25, 2008 8:40 PM
Subject: Re: [TCML] Terry Filter Caps


> In a message dated 8/24/08 11:39:19 P.M. Eastern Daylight Time,
> bartb@xxxxxxxxxxxxxxxx writes:
>
> > Hi Adam,
>
>
>
> Where was "Adam" in this part of the  discussion?
>
> > Did I get this right? Are you running a Terry Filter with a  pig?
> > Just curious about that. I personally don't use such a filter with a  pig
>
> > transformer. Only for NST's. Not that it hurts, but I'm not sure it's
>
> > necessary. NST's are voltage fragile. Transients are part of that.  The
>
> > filter helps some in that department.
>
>
> Bart, I just sent this post out:
>
> _http://www.pupman.com/listarchives/2008/Aug/msg00413.html_
> (http://www.pupman.com/listarchives/2008/Aug/msg00413.html)
>
>    I was surprised nobody commented at the time...  but it's in the
> archives, so I know ya'll got it!
>
> > Regardless, in this discussion, people should remember the MOV's  across
>
> > each cap/resistor circuit within the Terry filter. As long as the cap  is
>
> > of adequate voltage and the MOV's are designed for the "transformer",
>
> > then there is plenty of protection across each individual RC section
>
> > (beyond the cap or resistor ratings). But with a good design, those  are
>
> > last resort.
>
>
>
>    Yeah, and the MOV's are slow to respond to  transients at 1 MHz. But 
> they
> certainly are nice to have!
>    Some distribution arrestors use "combined  technology" with a spark gap
> in series with the MOV element, just to complicate  things. I think the 
> big one
> I've got sitting around is like that, since the last  time I tried it 
> across
> my pig on an untuned coil, hot metal sparks actually shot  out of it and
> rolled on the ground.... The two arrestors on my pig have done  just fine 
> at
> 15+kVA, even when the safety gap has been firing. I feel I've got  that 
> safety gap
> set pretty tight, but my arrestors are as tight on the MCOV  specs as I 
> dare go
> (even tighter than the specs for the "usual NST" Terry  Filter).
>
> -Phil LaBudde
> Center for the Advanced Study of Ballistic  Improbabilities
>
>
>
> **************It's only a deal if it's where you want to go. Find your 
> travel
> deal here.
> (http://information.travel.aol.com/deals?ncid=aoltrv00050000000047)
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla 

_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla