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Re: Pig questions

Subject: 
           Re: Pig questions
      Date: 
           Sat, 29 Mar 1997 11:38:25 -0500
      From: 
           "Edward J. Wingate" <ewing7-at-frontiernet-dot-net>
        To: 
           Tesla List <tesla-at-pupman-dot-com>
(snip)
> 
> << Hi guys,
>          The recent forays into semi-suitable transformers, and the fact
>  that this is the income tax season, have got me thinking about buying a
>  pole pig.  I have some questions, though.
>          With the current limiting arc welder in place, what is the
>  typical
>  current that you pig coilers are using in your setups?
>          Am I correct in assuming that with a 5kVA pig operating at
> rated
>  voltage is delivering just under 400 mA into the circuit, or am I
>  reading
>  the power ratings wrong?
>          What is the reasonable amount that one can overdrive a pig in
>  terms of input current?
>          What current capacity should my lab have?
> 
>          I'm sure that the answers to these questions will only generate
>  new ones, but that's all I have for now.
> 
>          Thanks,
>          Stan Harle
>          Alamogordo, NM
>   >>
> Stan,
> 
> I use a 14,400 volt 5kva pole pig.  Yes, the current output should be
> about
> 350 ma at 14,400 volts when running at 5 kva.  I have ran mine up to
> about 8
> kva and it doesn't even get warm.  I think you could probably push them
> to
> double the faceplate rating for 5 or 10 minutes at a time with no
> problem.
>  At 5 kva, it should draw 23 amps from the mains.  I have had my primary
> current up to almost 40 amps.  I am using 40 amp breakers with 30 amp
> fuses
> in series.
> 
> Ed Sonderman

Ed & Stan,

The power companies regularly run pole transformers up to 180% of
nameplate ratings in normal service conditions before changeing them out
for a larger nameplate KVA rating. The reason being that they don't like
to pay for the extra energy losses incured by having to energize the
core of a larger KVA rated transformer if it isn't necessary. The power
company has to pay to keep the transformer energized 24 hours a day even
if the customer is only drawing power from it for a small fraction of
that time. Larger core equals higher current to energize the core. These
babies are designed to put out full rated power day in and day out for
years in hot weather or cold, and to take short term overloads far
exceding their nameplate ratings, so anything we can draw, in Tesla coil
service, right up to the point of core saturation, has little effect on
them. A 5 KVA distribution transformer has a chart rating of 20.8 amps
at 240 volts single phase and I have personally run a 5 KVA transformer
between 60 and 70 amps for 15 to 20 minutes at a time. That translates
to over 1000 MA on the high voltage side! I have yet to hear of anyone
blowing a pole transformer in Tesla use, so, wail away and don't worry,
they can take the abuse. Just be careful, the shock from a neon
transformer hurts ( personal experience), but with a pole transformer
you won't get a second chance!! They are not for newbies.

Happy and safe coiling,

Ed Wingate