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Current Transformers



Original poster: "Gary Johnson by way of Terry Fritz <twftesla-at-uswest-dot-net>" <gjohnson-at-ksu.edu>

James T

A current transformer (CT) will be quite linear if the load impedance is
below some specified value.  The output current will be exactly 5/60 of the
input current if the load impedance is zero, but will be acceptable if the
load impedance is below some value like 0.5 ohm.  Therefore, if you try to
draw more than 2.5 V from the 5 A winding, you will start to see
nonlinearity, even if the currents are within rating.

If you are trying to convert a 0-2.5 V ac waveform to a dc value using
diodes, then the mostly fixed drop across each diode will add considerably
to the nonlinearity. There are op amp circuits that act as ideal diodes, if
this is what you need.

Gary Johnson