Vibration measurement of the generator stator end windings and precautions against insulation wearing

In this paper, detailed stress analysis and calculations on generator stator bars are presented. It points out that the electromagnetic force applied on the stator winding is confirmed as a 100 Hz alternative force. When the intrinsic frequency of the stator bars is equal or is close to 100 Hz, resonance of stator bars will occur. This resonance will cause serious damage to stator insulation. For serious vibrating conditions, this can lead to generator accidents such as internal short circuits or broken stator bars. Examples of stator end winding accidents which are caused by resonance frequency at 100 Hz are also presented and analyzed in the paper. A measuring method of stator bars intrinsic resonance frequency at 100 Hz is also introduced.