RE: Filters for non - NST primary

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Lau, Gary" <Gary.Lau@xxxxxx>

Again, just because someone did it doesn't mean it was necessary.  We
hear all the time about NST's dying, but how often do you hear about
pigs dying?

NST's are manufactured to be as small and cheap as possible.  No extra
effort is made to make them durable.  If a sign quits, it's no big deal.
Pigs are built to last under the worst imaginable environmental and
electrical conditions.  If a pig fails in power utility service,
replacement costs are high and loss of utility power could be life
threatening.  They have to be tough.

Regards, Gary Lau
MA, USA


> Original poster: "MIKE HARDY" <MHARDY@xxxxxxxxxx>
>
> A while back this was somewhat discussed under the subject title "Pole
Pig
> Wiring". You might wan't to do a search. D.C. uses a  resistor/choke
combo.
> I paste his method bellow.
>
>
>
> 240 VAC across outer 2 low voltage lugs.  No connection to center lug.
>
> On HV side, ground one bushing to side of case.  Also connect 240VAC
ground
> to this lug.
>
> Use 10 pcs of 200 watt resistors x 250 Ohm connected in parallel and
then
> the bundle in series with output.  also a 4" ID PVC pipe x 3 ft long
> closewound with #18 AWG wire after the resistors to the spark gap.
Keep all
> of this on a cart away from the primary, sparkgap, and caps.  Use a 10
ft.
> long HV wire to connect.  Stripped coax works fine.
>
> Dr. Resonance
>   >
>   > Can someone tell me the correct setup for a two terminal 14.4KV
10KVA Pig
>   > in a primary LC circuit? Do i ground one of the terminals?
>   >
>
> ----- Original Message -----
> From: "Tesla list" <tesla@xxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Sent: Thursday, October 13, 2005 9:55 PM
> Subject: RE: Filters for non - NST primary
>
>
>  > Original poster: "Lau, Gary" <Gary.Lau@xxxxxx>
>  >
>  > Charging current is far higher from a pig and would probably fry
the
>  > resistors.  Also, should the cap selection or other variables cause
the
>  > charging voltage to go too high, the MOV's would quickly fry.
>  >
>  > As far as pigs on the web using chokes, all I can say is don't
believe
>  > everything you read on the web.  Pigs are bulletproof compared to
NST's
>  > and need no external protection, but you can add chokes if you
think
>  > they look nice.
>  >
>  > Regards, Gary Lau
>  > MA, USA
>  >
>  >
>  >  > Original poster: FIFTYGUY@xxxxxxx
>  >  >
>  >  > In a message dated 10/13/05 10:17:51 AM Eastern Daylight Time,
>  >  > tesla@xxxxxxxxxx writes:
>  >  >
>  >  >  > The Terry filter is only for NSTs.
>  >  >
>  >  >      How come? Why would it be unsuitable for a pig, MOT, PT,
etc.? I
>  >  > don't see how it could hurt.
>  >  >      IIRC the pig setups I've seen on the Web *do* use the
filtering
>  >  > chokes on the secondary lines. I understand weird resonances and
>  >  > other problems can occur with shunted transformers, such as
NSTs,
>  >  > when using filter chokes. Has anybody determined if they are of
>  >  > harm/benefit on the larger systems?
>  >  >
>  >  > -Phil LaBudde
>  >  >
>  >
>  >
>