Large generator vibration monitoring

Two major generator incidents have resulted in unplanned and extensive outages in French nuclear power plants. A large action was launched to prevent this kind of incident. One part of this programme is improving on-line generator vibration monitoring. As far as the EDF Research and Development Division is concerned, the aim was to define end-winding stator vibration monitoring. Today, EDF nuclear power plants are equipped with on-line stator end-winding vibration monitoring. Previous studies, undertaken in EDF, enabled optimisation of the number and, above all, the location of sensors. The first goal of this monitoring is the protection of the machine, in order to avoid critical failure. But, the database which was created makes it possible to develop new methods, using vibration measurements, which are really interesting. So, the method described is a powerful tool to anticipate and to plan operation and maintenance actions. The on-line stator vibration monitoring is no more only a protection device but also a maintenance optimisation tool.