Abstract: Rotor cracks may lead to turbine-generator shaft broken accident, causing the unit to be destroyed and producing great losses. Therefore, how to timely detect rotor cracks to ensure the safe and stable operation of the unit is significantly and practically important. Based on the summarization of the research results of the vibration characteristics of cracked rotors and combined with the experience of field vibration fault diagnoses, a practical method of identifying cracked rotors with abnormal vibration analysis is proposed. Through analyzing the abnormal vibration of two 600-MW units, the process of detecting the rotor crack is introduced. Because the diagnosis is accurate, the unit is timely stopped for check, and the defect is identified, thus avoiding catastrophic accidents if the unit continues running.

Key words: turbine-generator set, rotor crack, abnormal vibration, fault identification