Vibration monitoring in electrical engines using an in-line fiber etalon

In this work a new scheme for condition monitoring of electrical engines using a fiber optic sensor is proposed. The in-line fiber etalon scheme, specifically designed for the detection of damages in large electrical machines, provides high robustness and stability. In general, these large systems are characterized by a low speed operation, and when a new mechanical or electrical fault appears, it can be monitored through the vibration spectrum in the low frequency range, with a maximum bandwidth of 500 Hz. The proposed sensor has been optimized to achieve minimum detectable acceleration amplitude of 0.05 g in the frequency range of interest, although the preliminary scheme can be customized to the specific motion system. The vibration sensor has been tested using laboratory induction motor test-rigs, showing a particularly good performance both in the detection of magnetic and mechanical nature vibrations.