The product uses a special isolation module to monitor the AC current in the grid and circuit in real time, and when the AC current exceeds the set upper limit, the output exceeds the limit alarm signal, and the output signal is the action limit of the relay contact signal AC current. The value can be arbitrarily adjusted within ±20%. The input and output of the product are completely isolated, with high precision, high isolation and low drift. It Can be applied to motor overload monitoring, power loss detection, motion verification, signal isolation conversion, etc.