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Re: transformer questions



In a message dated 95-10-24 20:53:46 EDT, tesla-at-grendel.objinc-dot-com writes:

>To: tesla
>Subject: transformer questions
>
>Greetings all,
>
>I'm looking for a pole pig now and have some questions that I would like
>to know the answers to.  
>
>1) Has/does anyone run a coil without any limiting ballast on the pig?
>   In other words, has anyone cut the welder and oven elements entirely
>   out of the circuit?
>
>2) Will these transformers blow up if they get shorted without any control?
>
>   I already have an arc welder that I am going to use, but I am asking 
>   because one of the guys that my wife contacted wanted to ask me some
>   saftey questions and I figured that I should know as many angles as
>   possible.  (It's not a surprise, but will be a great birthday gift :-))
>
>Chip

Chip,

I have not run my coil without any limiting ballast in series with the pole
pig.  I have a 5kva 14,400 v transformer.  I am running it with the welder
wide open and with 6000 watts of oven elements in parallel with the welder -
this is all in series with the input to the powerstat.  This achieves a
primary current of between 35 and 40 amps which is approximately 8.2 kva.  I
am comfortable there.  I have fuses and breakers that would allow me to go up
about another 10 amps.  I am concerned that if I fired it up with no ballast
I might get 50 or 60 or more amps in the primary.  My 10 guage wire and my
breakers could not handle that.  I would like to make a variable inductive
ballast to replace the welder so I could get the primary up to 40 to 45 amps.

The pole pigs are very conversatively rated.  I know you can run them at
twice their rated capacity for several minutes and they don't even get warm.
 If their outupt somehow gets shorted I am sure it would blow your breakers
or fuses before it harmed the pole pig.  It would sure dim the lights in your
house.

Ed Sonderman