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Fantastic new inductive ballast completed



Original poster: "Gregory Peters by way of Terry Fritz <twftesla-at-qwest-dot-net>" <s371034-at-student.uq.edu.au>

Hello all,

I have just completed a very efficient inductive ballast in the 
attempt to remove the two bulky welders I have previously been using.
I wound nearly 100m (about 200 turns) of 16mm2 wire on an old 10kW 
pole pig "c" core. The use of the "c" core makes the magnetic circuit 
very efficient. The inductance is variable from about 2mH (no core) 
to 0.29H with both "c" cores fully inserted. This corresponds to a 
minimum current limit of about 2.5 amps and a maximum of several 
hundred amps (though I wouldn't want to run continuously at over 60 
amps). The AC resistance is about 0.135 ohms. This corresponds to a 
voltage drop of only 6.75 volts at 50 amps (12kVA). Stated another 
way, the inductor will dissipate only ~338 watts at 12kVA, assuming 
no magnetic losses (obviously incorrect). The use of so many turns 
prevents saturation of the core (which probably wouldn't be a problem 
even with less turns because it is so big). I expect this unit to be 
very efficient at the power levels i will be using (8-12kVA)

Cheers,

Greg.