Development of the On-line PD Diagnosis Device for Mold Transformers

An on-line PD diagnosis device for mold transformers has been developed, which consists of a ceramic capacitive coupling sensor, the PD monitoring system and diagnosis algorithms. For a performance test for the device, a lot of defects of mold transformer were tested in models and in the field. The devices have been installed and monitored in the mold transformers in S.M., a subway company in Korea which has been using a lot of old mold transformers. A defect of a mold transformer was found. The developed device will contribute to the reliability and the quality level of the mold transformer and minimize economical damage and provide a solution that will help to maintain public confidence by preventing unexpected power failure.