LOAD MONITOR

PURPOSE:To accurately set without generating an error in a set value by setting a reference of monitoring on the basis of power consumption at actual normal operation time. CONSTITUTION:The maximum or minimum value of power consumption of a motor during the prescribed period is stored in a memory in a controller in a plurality of periods under normal operation state of a device prior to monitoring. The voltages and the currents of motors M1, M2 are detected and input to a power detector 3. Thus, a signal representing the power consumption of the motors M1, M2 is obtained. This is inputted through a peak holding circuit 5, an amplifier 6, and an A/D converter 7 to a controller 1. It is com pared with a monitoring reference value stored in the controller 1 to discrimi nate an overload or a light load.