The Current Sensor Module ACS712 consists of a precise, low-offset, linear Hall circuit with a copper conduction path located near the surface of the die. Applied current flowing through this copper conduction path generates a magnetic field in which the Hall IC converts into a proportional voltage. Sensing and controlling current flow is a fundamental requirement in a wide variety of applications including, over-current protection circuits, battery chargers, switching mode power supplies, digital watt meters, programmable current sources, etc. This ACS721 current module is based on the ACS712 sensor, which can accurately detect AC or DC current. The maximum AC or DC that can be detected can reach 5A / 20A / 30A as per your model, and the present current signal can be read via analog I / O port of Arduino.