That is a classic simple current transformer. Before you amplify and wire to an arduino analog input pin you first must convert the AC output voltage to DC voltage (with a rectifier diode and filter capacitor). There is no real need to add amplification as you can simply add a analogReference() command to enable the 1.1vdc ADC reference, and then you can read the voltage directly. You will have to adjust in software from peak current to rms current as the (take reading and multiply by .707) as the diode/ filter charges up to peak value.