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Current amplifier, minimum current ?

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carpenter

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For example, a current transformer Talema AZ, primary current 0-25A.
What is the minimum current that can be "measured" with it?
Will there be any registrable voltage at the output, for example, at a current of 5mA on the primer? (R corresponds 1V on 25A)
 

Quality CT are basically linear down to very low currents, limited of course by the resolution of the amplifier. See the error curve of a 100 A VAC CT:

1641807220041.png


Cheap CT may have a performance drop at low currents due to lower magnetizing inductance and its current dependency. But I won't expect a detailed specification, it's suggested to make your own measurements.
 

you can easily measure down to 100mA on the pri - as long as your ckts on the sec side can discern the signal from any local noise ....
 

Low noise bipolar amplifier should be possible, as the input impedance will be reasonably low.
Also some kind of low pass filtering to reduce the bandwidth will help a lot with broad band noise.
 

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