<![CDATA[Steam turbines are essential components in steam power plants, converting thermal energy into mechanical energy to drive generators and produce electricity. Turbine blade damage can reduce efficiency and lead to plant trips, often accompanied by increased bearing vibration. This study investigates the root cause of low-pressure (LP) turbine blade failure at the Nagan Raya Steam Power Plant using the Root Cause Analysis (RCA) method. The results indicate that the failure was initiated by a 150 kV power system disturbance, which generated excessive blade vibration through the combined effects of backpressure and torsional resonance. The resulting cyclic stress exceeded the fatigue strength of the last-stage LP blade (L-0) on the generator side, causing blade fracture. Steam quality analysis confirmed abnormal operating conditions following the unit trip. Dye penetrant and magnetic particle inspections detected no surface cracks, while material composition analysis showed that the blade material met the specified standards. Scanning Electron Microscope (SEM) examination revealed clear evidence of high-cycle fatigue (HCF) at the fracture surface, confirming fatigue as the primary failure mechanism. These findings clarify the failure mechanism and provide recommendations to prevent similar incidents, thereby improving turbine reliability, operational stability, and maintenance strategies in steam power plants.]]>
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