Application of vacuum-changing method for large capacity transformer’s drying process

Moisture is the main factor for the infection of man-sized power transformer’s life-span, the atrophy of capillary of insulating layer is easily made by normal dry technology, so moisture of insulating deep layer is affected. The tuning of parameter of PID controller is quite difficult, because of the main vapor pressure and the vacuum degree and so on, big overshoot is often produced. The vacuum-changing method based on PLC is designed to solve the problems, configuration software is used in human interface station. Practical operation results show that the method is effective, this experience makes great reference for practical using.