Development of Transformer Bushing Diagnosis System based on High Frequency PD Measurement

The transformer bushing failure occupies an over 30% or more of the transformer failure and it is categorized into a severe fault that can occur in a transformer because it causes a fire accident with a high probability of failure. With respect to a bushing failure prevention, a leakage current measuring using bushing tap adapter is adopted to diagnose the insulation condition of bushing. However, there are some problem that the conventional method can be determined only when a certain or more deterioration proceeds, and detection is difficult at the initial stage of the bushing defect. This paper deals with the development of bushing diagnosis system based on the high frequency (HF) partial discharge measurement technology. Based on the analysis result on the types of early-stage of bushing defect, the fault type that can occur in the transformer bushing was classified. In addition, the diagnostic system and new type of bushing sensor based on high-frequency partial discharge technology was developed. The performance verification of developed system was performed based on IEC-60270 partial discharge test.