ATOZ provides natural frequency test on turbine blades and stator winding.
Natural Frequency test on End Winding:
To measure the mechanical integrity of the Generator end winding, Natural frequency test is performed in order to determine the natural frequency response of individual loops in the radial and axial directions. If the measured natural frequency values are out of the resonance frequency band 95-100 Hz, it can be stated that the mechanical integrity of the stator end winding is in acceptable condition. If it is out of resonance frequency, end winding has to be strengthened till the measured frequency values are out of resonance frequency.
Natural Frequency test on Turbine Blades:
Any rotating component displays a natural frequency of motion at which offers minimum resistance to forces. Important components like Turbine Blades particularly the blades of larger lengths are so designed that the natural frequencies are away from the usual excitation frequencies during normal operating ranges of the machine. This is done for increasing the fatigue life of the component to avoid dangerous resonance conditions NFT testing is usually done on Turbine free standing blades every time when the blades are removed and refitted during over hauling period after long operation.