Classification of Fault and Failure Types Determined by Dissolved Gas Analysis for Transformers

In this study, the locations of fault and failure that can be visually identified during internal inspection are determined by classifying the fault and failure types by dissolved gas analysis (DGA). The fault types are classified by analyzing 195 internal inspected transformers that faults were identified, and the failure types are classified by analyzing 338 failed transformers of Korea Electric Power Corporation. The fault types that affected DGA in oil are classified as winding, core, clamp, bushing, on load tap changer (OLTC), and oil. The faults are classified into 18 types according to subcomponent and fault cause. The failure types that affected DGA in oil are classified as winding, bushing, and OLTC. The failures are classified into 21 types according to subcomponent and failure cause. The failure results are classified as turn-to-turn breakdown, breakdown, and oil leakage. The phenomena caused by faults and failures that can be identified by visual during internal inspection are classified as carbon, discharge, and overheat traces.