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Inductor question
TL>I am still leaning towards the classic induction coil method of
TL>purchasing a spool of soft iron bailing wire, cutting the wire
TL>into sections, coating them, and tightly binding the cut sections
TL>into a bundled core.
TL>Any additional information by other experimenters would be
TL>appreciated.
TL>Richard Quick
I recommend using an old variac. If you cut the windings off an 8A
variac, you then have a long magnetic path length which is easily
utilised. You can hacksaw through the core in around 5-10 minutes. When
you have done so it is an easy task to open up the sawcut with a bolster
chisel, to give you a gap that is, say, half an inch wide.
It is then easy to wind a load of suitable enamelled Cu wire onto the
core: you will end up with a core that will not saturate and has minimal
eddy current losses. You can make it multilayer, or you can do what I am
doing, and wind three inductors which can then be switched in
series/parallel combinations to provide a variety of reactances. In my
case, each one will be approx 18 ohms which will give me switchable VAs
of approx. 1kVA, 1.6kVA, ... upto 10kVA with three 57mH chokes in
parallel.
One other method is to cut the variac core into two equal halves: the
one half can have the windings whilst the other can be moved towards and
away from the winding half. Or you could make a 1:1 transformer like a
variometer whereby coupling between separate coils is performed by
proximity to a common core. The neatest way, however (this was metioned
sometime over the last week or so by someone on the list whose name I
forget-sorry) is to use a DC current through a separate control winding.
The problem with this is that you will saturate the core (seeing as the
devise is a saturable reactor) so the 2nd harmonic powers will be
significant. This will limit the charging ability of the pole
transformer.
Richard Craven
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CMPQwk #1.42 UNREGISTERED EVALUATION COPY