An Analysis of Partial Discharge Characteristics due to Transformer Bushing Failure

Among the failures of transformers, the main component of power plants, bushing-related failures consist of about 40% of the total failures, excluding the failure of electric/mechanical protective relays and human errors. In addition, bushing failures are generally accompanied by fire, which is why it is classified as a critical failure. In this article, we will consider the implementation of partial discharge diagnosis technologies to identify bushing failures in their early stage as a means of bushing failure prevention and examine the feasibility of implementing those technologies. The categories of bushing faults that can occur at transformer bushings were selected and simulated on a 154kV bushing removed from an actual electrical substation, and partial discharge measurements were taken according to the IEC-60270 and IEC-62478 standards. From the results, electrical characteristics of partial discharge signals generated within the transformer bushings were identified, and the optimal requirements for the implementation of partial discharge diagnosis technologies were derived.