3. Conclusions
Proper operation of turbine-generator bearings in hydroelectric power
plants is of great importance for the unit to continue energy
production. Therefore, it is necessary to periodically inspect the
sliding bearings during the energy production by predictive maintenance
methods and to measure and evaluate the factors such as vibration,
balance and temperature. In this study, the causes of the fracture
formed in the generator guide bearing shell of a hydroelectric power
plant are investigated metallographically. When we examine the
metallographic sample taken in the region near the fractured area near
sliding bearing with the help of optical microscope, SEM images and EDS
analysis, Ferrite and Perlite structures found in low carbon steels in
the sample are seen and these structures have the least risk of
fractures in the steel materials due to the formation of fractures So
other factors that will affect the structure of this material have been
focused. Variable loads and oil temperature changes as a result of this
material working together with the shaft can cause fracture formation
due to fatigue strength in the material. Not being able to apply
necessary heat treatment in order to remove internal stresses that
appear in the production stage of the ring when it becomes a cylinder
due to the large size of ring causes fractures. Such fractures can occur
frequently in the sliding bearing shells of hydroelectric power plants.
The only way to prevent these fractures from damaging the sliding
bearing is to follow the vibration changes in the bed well and to be
interpreted by the experienced technical staff. Because vibration
changes in sliding bearings can be caused by many reasons such as
magnetic, dynamic and hydraulic imbalances.