This product adopts special isolation module to monitor AC current in power grid and circuit in real time. When AC current exceeds the set upper limit, it outputs alarm signal of exceeding limit, and output signal is relay contact signal. Within the range of the input range, the action limits of alternating current can be set arbitrarily. The product is completely isolated from input and output, and has the characteristics of high precision, high isolation and low drift. It can be applied to motor overload monitoring, power loss detection, action verification, signal isolation and conversion.