Intricate aspects Of turbogenerator endwinding vibration monitoring based on data analysis

End winding vibrations of large turbogenerators are assuming a greater role in the reliability of the machines to avoid forced outages. So, on line monitoring during test run as well during operations have been given utmost importance in recent times. Electromagnetic forces, at double the operational frequency are responsible for overhang vibrations besides other mechanical phenomena. These vibrations depend on factors like type of insulation, slot fixing arrangement, overhang bracing and support system, dynamics of core with overhang and natural frequency of the end winding basket. This paper presents the comprehensive data generated over a period of two decades on end winding vibration on 200/210 MW turbogenerators and dwells on the analysis there on. The data collected have been studied to examine the various intricate aspects affecting these vibrations and the trends compared. In order to study the requirement of a robust slot-wedge system to contain the overhang vibrations and validate the adequacy of the adopted slot fixing system, the paper presents the experimentation done on a full-scale turbogenerator Slot Model. Special treatment has been made on the natural frequency test on overhang system and its significant bearing on the end winding vibration touching upon some corrective measures.