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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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In Reply to: Wrong measurement for OPT primary inductance ? posted by skyline on July 12, 2006 at 03:08:29:
Hi.To get correct H reading on a gapped SE O/P iron with laminated core, miniumum exciting current is needed to get the iron in the linear spot of the B/H curve of the iron, silicon or nickel steels regardless.
Most hand-held multi-meters just don't provide enough juices to the do the inductance measurement correctly. This explain why your meter read half value, meaning the exciting currents provided to the O/P iron primary winding was enough to move its operation point just at the fool of the 'hill' of the B/H curve.
Let me tell you how a leading O/P iron manufacturer tests the inductance of their products (silicon steel laminated)
Apply a 60Hz 240V to the primary of the SE O/P iron with speaker winding OPEN, the exciting current measured 17mA. (The manufacturer
gapped this iron for exciting current 15.2mA - 18.6mA range).So the impedance is calculated to be 14,117R.
So applying the basic formaula: X=2.TT.f.L, with X=14117R, f=60Hz,
the inductance L will be: 37.446H.Get it?
c-J
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Follow Ups
- You need enough exciting current to get it right. - cheap-Jack 13:05:22 07/12/06 (0)
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