Stator End Winding Vibration and Temperature Rise Monitoring

In most turbine generators, excessive vibration and thermal cycling weaken the insulation on the windings causing stator bar to fracture and leading to partial discharge (PD), which ultimately results in fire. Therefore, PD becomes extremely dangerous for large hydrogen cooled turbines because it might lead to explosion in the plant. These risks can be mitigated by using VibroFibre(TM) fiber optic vibration sensors and the Integrated Signal Conditioning (ISC) system as condition monitoring solution. This solution prevents unplanned down time by obtaining a warning against arcing and fire resulting from the measurement and trending of vibration amplitudes in the stator end windings. The presence of an alarm stops the machine for repair before a disaster occurs, resulting in a life extension of critical power plant assets by at least 200%. Inside power generators, there are high voltages and strong electromagnetic fields, and such hostile environment makes the use of ordinary piezoelectric vibration sensors impossible. In this case, fiber optic vibration sensors are the most effective solution. Yet, until now, only single channel fiber optic sensors have been available. They are hard to manage and require one full week of down time to install. Using a bundle of fiber optic vibration sensors and an ISC unit, the architecture can be simplified. Moreover, one-day installation can be achieved by gluing the sensors onto the end cap with high temperature epoxy. This results in instantaneous return on investment.