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Re: current limiting choke
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To: tesla@pupman.com
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Subject: Re: current limiting choke
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From: "Harri \"Haba\" Suomalainen" <haba@cc.hut.fi>
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Date: Sun, 9 Jun 1996 11:41:08 +0300 (EET DST)
On Sat, 8 Jun 1996, Tesla List wrote:
> Start out smaller. It will get warm over several minutes, just let it
> cool. Mine weighs about 2kg +-.
Smaller core area means huge number of turns to wind. No fun. Making
a small core handle 10kW at 230VAC is not fun either!
> The 0.64mm wire got very hot very fast. To hot to touch in 2 minutes
> at 10A. I removed it and replaced it with bifilar #19/0.9mm SCE wire.
No wonder! 1.5mm^2 wire will heat to about 70 degr centigrade when you
put a constant 10A through it. The wire you used has a cross sectional
area of only some 0.32mm^2! That is for a single wire. For transformers
etc a good rule of thumb is to head for about 4.5A/mm^2 current density
in the wire. That is for heading towards constant power handling.
--
See "Malin Tunic: Chemistry of structure - function references in cheese" for
further details!
Harri.Suomalainen@hut.fi - PGP key available by fingering haba@alpha.hut.fi