On the Use of the Instantaneous Angular Speed Measurement in Non Stationary Mechanism Monitoring

Power transmission faults are one important cause of machine downtime many production activities are working to prevail. Vibration monitoring tools have achieved this role on the assumption that the stationary condition hypothesis is maintained. Several industries, including wind energy production, are however demanding to observe mechanical or electrical rotating components behaviour at variable speeds. Instantaneous angular speed measurement has been recently proven able to detect localized faults in bearings using only an encoder close from the source of the defect. This paper presents the results obtained from a large span experiment on a 2MW wind turbine. The uniqueness of the sensor used to monitor the whole line shafting along with the continuous non stationary conditions are so many difficulties cumulated on this attempt. Two basic signal processing tools are theoretically defined and experimentally applied in an original way on the Instantaneous Angular Speed measurement to efficiently tackle these practical issues.