Re: New Pole Pig user
At 08:39 PM 1/16/99 -0700, Tesla List wrote:
>Original Poster: Matthew Wenger <m-wenger-at-uiuc.edu>
>I am a new subscriber to this list and I am building my first coil over
>1KVA. I have been searching the archives for information on using and
>maintaining pole pigs, but I still have a few questions I was hoping
>someone could answer. I recently obtained two (15KVA and a 10KVA, one is
>my backup) surplus transformers (110V in - 14,400V out) and need to limit
>them to 2.5 or 3KVA for my current coil project. I have seen many systems
>that are anywhere from 7.5 to 100KVA. My first question is: where do
>people get the power to run these large systems? In order to run my coil I
>will probably have to plug it into plain old 110V plugs and in order to get
>3KVA that means drawing 27.27 amps, not possible as far as I can tell. I
>MAY be able to hook up to 220V, but I still would like to know how people
>build large systems at their homes. I am also concerned about limiting the
>current to my pig.
>As I said earlier, I need to limit the input power to my coil to 3KVA. I
>would like some suggestions for the best way to do this. I'd like to use a
>welder to do the job, but I don't know where to get an inexpensive one. If
>I plug it into a 110V outlet that means It has to limit the draw to 27 amps
>(13A for 220V). I can find a welder that does that, but it's only 10% duty
>cycle. What kind of ratings do I need to have for my coil to be on for a
>few minutes at a time?
>I would like to learn how to do accurate calculations for tesla coil
>systems. I was wondering if there is a way I can find the appropriate
>equations and information to relate these to real systems (ie. calculation
>for impedence of a transformer; how to relate that to the value I need for
>the capacitor, and other such things). Can anyone suggest any good sources
>for this information? I would like to try using a synchronous rotary gap
>for this coil and since the components all need to be fairly well matched
>(since the gap speed cannot be adjusted) I need to calculate for and use
>well matched pieces.
>Thanks in advance for any help!
Your home must have very old wiring. Most houses in the US nowadays
have120-0-120 3-wire entrances, giving 240V across the two "hot" wires.
Your should check the current rating of your service; 100A or higher is
pretty much standard, though older 60A installations are still around. The
old 110V services were commonly 30A, but beware of trying to draw anything
like that from a domestic wall receptacle, particularly if you don't know
the age or condition of the wiring: you could burn your place down! Run a
separate line from your entrance with at least #10 cable and terminate with
a 30A breaker.
This assumes that your local code permits you to do your own wiring;
otherwise (and probably preferably)
get a licensed electrician.
A half-century ago I lived in houses with 110V services, and ran them
pretty close to 30A for brief periods; once when the meter was being read.
The alarmed reader came to the door to warn me that I needed a heftier
service. Those old houses had #14 knob and tube wiring which was more
tolerant of overloads than cable. Even so, it was fool's luck that kept me
out of trouble.
By the way, if in fact you don't have 220V available, I do have a 3KVA
110V to 220V pig (just that; no HV winding) which you could have for the
cost of shipping. E-mail me privately if interested.