Experimental verification of resonant frequencies and vibration behaviour of stators of electrical machines. Part 2: Experimental investigations and results

Results of experimental investigations conducted on the models described in Part 1 of this paper are presented here. The experimental results confirm several important aspects of the vibration behaviour of stators. Among these are; the actual existence of a new set of resonant frequencies which can play an important role (especially in large machines), the nature of both circumferential and axial mode shapes associated with the various resonant frequencies of stators, the phenomena of dual resonance and coupling between components of vibrations etc. Also, comparisons made between the experimental and analytical results indicate that the method of simulation of vibrations of the various components of a stator; namely, yoke, teeth, windings, frame and laminations, in the analysis presented in a companion paper is adequate and it delivers accurate values for first- and third-order resonant frequencies. The perfect agreement obtained between measured and calculated values of resonant frequencies of a smooth model proves that the experimental arrangement is sound and that the measuring procedure is correct.