[Prev][Next][Index][Thread]

Re: Source for Pole Pigs and metal spheres.

Tesla List wrote:
> 
> Subscriber: knardell-at-mailhost.accesscom-dot-net Sat Jan 11 10:51:54 1997
> Date: Fri, 10 Jan 1997 16:25:34 -0600
> From: Kevin <knardell-at-mailhost.accesscom-dot-net>
> To: tesla-at-pupman-dot-com
> Subject: Source for Pole Pigs and metal spheres.
> 
>         Well I went to the power company today and found the person in
> charge, I told him straight what I was looking for and why I needed it. He
> did not seem amused but took me seriously and also understood the budget I
> was on. We were looking at (Still in use and live) Corona balls, these are
> little aluminum balls about 5-6" dia. and are placed on the HV switches in
> the sub stations. Next we went to the yard and sized up the pigs!! those
> suckers were from 5KV-115KV (200lbs to ???HUGE), he put me in touch with the
> transformer shop and monday I get to go and pick out a pig! The best part is
> that I may be able to skate with it for 50 bucks! The corona balls are going
> to be another story, I have to find switches out of service for that but the
> good part is that they are free!
> 
> This fellow at the shop says they have alot of old NON-PCB transformers in
> the scrap pile, can I rewind or repair these? 

Not if you can get working one(s) for $50. You also want to check if
they have any old working potential transformers. These are precise
ratio transformers used for stepping down high voltages for measurement
and control purposes. They're smaller, lighter, are "dry" (not oil
immersed), and for low-moderate power levels can be used instead of a
pole pig. Many on this list use them instead. You're looking for ones in
the 12-15 KV range with 120 or 240 volt output - an example might be a
12 KV 100:1 ratio unit.
BTW, have you planned how you're going to control and ballast the pig? 

> Another thing I found was MONSTER capacitors, I don't know what they were > rated at but they are made to deal with those big pigs, would these be > > also something to try and get or look into? I tried to read a value but > there was nothing on the caps that said anything about voltage or > capacitance.

Utilities use Power Factor Correction (PFC) capacitors to counteract the
effects of inductive loads. These are rated in KiloVolt-Amperes Reactive
(KVAR) at a given line voltage instead of capacitance. However, if you
know the operating voltage (always AC), you can convert back to
microfarads:

       C = 2.653*K/(V^2) uF   (if rated for 60 Hz service)

                          OR

       C = 3.162*K/(V^2) uF   (if rated for 50 Hz service)  

      where: K = rating (in KVAR's)
             V = Operating Voltage (in Kilovolts)

   Example: a 20 KVAR rated for 4.2 KV 60 Hz service would be about 3
uF. 

Most PFC caps are not directly usable for Tesla Coil service (too high
capacitance, too low voltage, wrong construction, and wrong dielectric).
The older ones will probably contain PCB's. Polypropylene-paper types
can be dismantled and rebuilt to work as Tesla caps. Mylar types will
also work, but will be quite lossy, and oil-paper type are not worth the
effort. 

> 
> I hope I inspire some folks to visit their local power company and
> transformer shop as this can be rewarding, it sure made my week.
> 
> I think the oil in the out of service units might be good for poly caps, agree?

See if they'll sell you _new_ oil instead (hopefully cheaply!). Their
transformer shop already uses _lots_ of this. Old oil may be
contaminated with water or carbon (from flashovers/near lightning hits)
or partially oxidized from extended operation at high temperatures. If
you do decide to take the chance, the used oil should not smell burnt,
should be clear and light straw colored, and should only come out of
sealed units. I'd go with new...
 
>                                        Regards,
>                                             Kevin Nardelle
> 
>    ********************************************
>    * T   E   S   L   A      C   O   I   L   S *
>    ********************************************
> Kevin Nardelle   knardell-at-accesscom-dot-net
> My main web page IS UP all TESLA
> related with lotsa pictures and links.
> http://www.icorp-dot-net/users/kev/tesla
> http://www.accesscom-dot-net/nardell
> Non related sites I have
> The Louisiana Swamps Online (Under construction)
> http://www.icorp-dot-net/users/kev
> **********************************************