OPERATING DEVICE FOR COOLER OF ELECTRIC APPARATUS

PURPOSE:To hardly receive the influence of noise by providing a level comparator and an adequate frequency signal setter, thereby constructing a structure without using a microcomputer and reducing the size. CONSTITUTION:Signals corresponding to respective stage points are compared with a signal detected by a detector 4 in the operating frequency characteristic of a cooler of stepwise state having a hysteresis corresponding to the load of a transformer obtained in advance for each transformer by a level comparator 14, and a level comparison signal considered for the hysteresis in stepwise state is outputted to an adequate frequency signal setter 15. The setter 15 converts the signal inputted by the comparator 14 into a frequency set signal, and outputs to a variable frequency inverter 7.