Current transformer for current sensing at Low Voltage AC
Measuring the current on the secondary side of the transformer can be accomplished in three possible ways.


place a small resistor (less then 1 ohm) in series with the transformer connection and measure the AC voltage drop across the same. Thereafter it is simply Ohms law (I = V/R).
The other way is placing a miniature current transformer (see picture) and measure the voltage across the transformer load resistor ( Do not use such a transformer without a load resistor). Look at the data and application sheet of such transformers for further information.





A third way could be to use a hall effect sensor with corresponding electronics such as the NA25 or NAP25 both from FW BELL.