Optical Fiber Sensor Encapsulated in Carbon Fiber Reinforced Polymer for Fault Detection in Rotating Electrical Machines

Abstract

This paper introduces a novel fiber-based sensor for dynamic strain and temperature measurements in the stator of rotating electrical machines. Fiber Bragg grating sensors were integrated into carbon fiber reinforced polymer. The encapsulation has appropriate mechanical energy transfer to measure dynamic strain and temperature. The proposed sensor is installed in the stator of the induction motor allowing to analyze the dynamic strain generated by the machine. The main failure in induction motors is attributed to bearing failures. In this work, the tests were performed operating at full load with new and defective bearings. The results show the main peaks of frequency caused by strain observed coincide with the electrical supply frequency (60 Hz) and mechanical bearing forces (30 Hz), with harmonic components at 120, 180, and 240 Hz. However, for the damaged bearings frequencies of 89.8, 116.5, 146.4, and 149.7 Hz were identified. These frequency components were generated by defects in the outer race, rolling element and inner race. The fundamental components of 30 and 60 Hz between the new and damaged bearings presents an increase of more than 75 %. Results show the potential of the proposed sensor in the monitoring of temperature and dynamic strain in electrical machines.