These current sensors are a low cost solution for monitoring single phase AC loads, they contain an AC rectifier circuit to directly output a 0 to 5VDC signal and require no power supply. There are three full scale ranges which can be selected by simply moving the jumper on the device to switch between 10A, 20A and 50A sull scale. The output signal is proportional to the average current which will vary slightly from the results shown on an RMS measuring ammeter, depending on the load.
The new clamping / split core current transformer allows installation without interrupting the high voltage wiring. Add a second wrap of the high voltage cable to double the output signal for a given current.