RE: [TCML] Primary # of turns on a 10KVA 14400 pole pig

["Phil Tuck (hvtesla)" <phil@xxxxxxxxxxx>]

Hello.
It is not Finn's page but mine . Finn's is at
http://home5.inet.tele.dk/f-hammer/tesla/museum/pig/porkchop.htm

The formula I give is a simplified version of  N = (E X 10^8) / (4.44 X F X
A X B) from http://home.att.net/~allencoilpage/ 

The above formula assumes a  magnetic flux (B) of  (it is assumed) 60,000  (
E = voltage,  A = core in sq inches, F = Freq) 
Most people don't know their cores specifications however and most sites on
the subject all seem to give different estimates!

I found the initial work of getting information on the number of turns,
current capacity of wire UNDER oil, and core materials the worse part. 

As a result my approach was very much 'suck it and see' as my own core size
made this feasible (or manageable). This was the main reason that in the end
I rewound my core using the same configuration and wire gauge as the
original.
 In your case that is a bit more difficult however. I would go to one of the
links I give:  http://mysite.du.edu/~jcalvert/tech/transfor.htm  and read
and, if your anything like me, 'try' to understand the full formulas and
methods that would be needed for a core of your size. 

If you have access to plenty of suitable gauge wire, based on size used in
other people's PIGS, then winding enough so as not to overfill the winding
wire will give you a rough idea, and then remove turns until the magnetising
current becomes too high. 
Monitoring the input current with a scope and current transformer is the
best way to make sure you don't saturate the core at the same time. There
are some scope traces from my own core at the bottom of my page. 
Basically the number of turns around your particular core size and material
should offer enough impedance to the incoming mains, while at the same time
induce enough voltage into a single turn on the secondary to make the normal
Pri turns : Sec turns ratio feasible.

Personally I would not wind something like a PIG for two reasons. First you
will need a pretty big jig to wind it on, and secondly a professionally
wound PIG will have a much higher BIL rating than anything ever made in a
garage by, in my case at least, an amateur.  Because of this fact, shortly
after winding my tranny, which performs well so far, a PIG came along which
I subsequently bought.

There's also another reason I nearly forgot, the cost of wire is
surprisingly high compared to buying a real PIG! 
It is an interesting and satisfying exercise though.

Regards

Phil
www.hvtesla.com

     



-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of Jim Mora
Sent: 20 July 2009 00:47
To: 'Tesla Coil Mailing List'
Subject: [TCML] Primary # of turns on a 10KVA 14400 pole pig

Hi All,

 

Does anyone know the usual primary turns (240v side) on a 10KVA pig and the
wire gauge? I have a dry core with 36.875"^2 area and am looking at Finn
Manner's transformer project page.
http://www.hvtesla.com/radartransformer.html This is a heavy core! According
to Finn, turns equal K=1.6 for 60hz (K* E)/Area so(1.6*240)/36.875" to fully
magnetize the core.  This would be only 10.41 turns. Yikes. Is that right?

 

Thanks,

Jim Mora

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