How to use 3 pin current sensor
The sensor that you have chosen appears to be similar to the LEM series of closed-loop-servo Hall-Effect current sensors.  These are absolutely awesome sensors and are extremely easy to use.

Do note that the sensor is intended to be used with a bipolar DC power supply of plus minus 12-15 Vdc.  The output is a CURRENT which is directly proportional to the input current.

It looks as if this is a 1000:1 current sensor with a nominal input current range of up to 150 Amps.  The output current is 1/1000 of the input current.

You can interface this with your Arduino by connecting the sensor output pin to a burden resistor that gives you your desired sensitivity.  Do note that because the sensor will supply voltage above and below ground, the Arduino with pick up only positive current.

You can offset the output from the sensor if you capacitively-couple the output voltage from the burden resistor into the Arduino input, along with a 2:1 voltage divider from your Arduino supply rail to bias the analog input at the 1/2 Vdd point.