[TCML] Ballast Inductor Question

["teslalabor@xxxxxxxxxxx" <teslalabor@xxxxxxxxxxx>]

Hi,

I want to build a new ballast inductor for my big coil. It runs on 400V
2phase at arround 60-80A, 50Hz (Germany) using a bank of 12 or
16 potential transformers, voltage controlled via variac.

I allready have a core for the inductor, but I'm concerned about it's
size. Is it big enough for that power? The core is an U-I type with
adjustable air gap. Its cross sectional size is: 3,15" x 2,36" = 7,4
square inch.

What is the general difference between a small core, which needs more
windings for a given voltage and a bigger core, which needs therefore
less windings? In both cases the current is nearly zero when the gap is
closed and rises, if opened. So why need big cores? I have allready read
here the tumb rule "1kW - 2,5 square inch" or the formula P =
(A/0,16)^2. Following this, for 400V / 60A I would need an VERY VERY BIG
core! So I wonder if I could use my "small" 7,4 sq.inch core.

Coiler Greets from Germany
Stefan



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