Analysis of Thermo-Mechanical Stress in Fiber Bragg Grating used for Generator Rotor Temperature Monitoring

Reinaldo Corrêa Leite, Victor Dmitriev, C. Hudon, S. Gingras, J. Picard, L. Mydlarsky


Fiber Bragg gratings (FBGs) offer new possibilities to monitor accurately the rotor temperature. Dozens of sensors can be mounted in series in a single fiber and used to measure the temperature in several points of the rotor winding. Such sensors installed directly on the rotor winding surface are thermally isolated from the cooling air by a silicone layer. Because of the temperature gradient in this structure, the sensor is exposed to thermo-mechanical stresses and therefore can be deformed. Since the FBG probes are sensitive to both temperature and strain, the knowledge of each effect separately is necessary to ensure that the temperature readings are not affected by strain. Experimental results obtained in rotor winding mockup tests with thermistors and FBG sensors show that the temperature readings by the FBG are 4.5°C above the temperature defined by the thermistors which were used as references. Multi-physics simulations were carried out to calculate the strain and temperature in the FBG assembly. The theoretical and experimental results are in a good agreement.


Hydro generators;rotor;Fiber Bragg Gratings; Temperature Measurement

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Zawoysky, R. J., & Tornroos, K. C. (2001). GE Generator Rotor Design, Operational Issues, and Refurbishment Options. GE power System Report, GER, 4212(08), 01..

Hudon, C., Lévesque, M., Torriano, F., Gingras, S., Picard, J., & Petit, A. (2014, June). On-line rotor temperature measurements. In 2014 IEEE Electrical Insulation Conference (EIC) (pp. 373-377). IEEE.

Stone, G. C. (2013). Condition monitoring and diagnostics of motor and stator windings–A review. IEEE Transactions on Dielectrics and Electrical Insulation, 20(6), 2073-2080.

Rosolem, J. B., Floridia, C., Dini, D. C., Hortencio, C. A., Borin, F., Neto, J. B. D. M. A. & Sanz, J. P. M. (2010). Tecnologias de monitoração de hidrogeradores utilizando sensores ópticos. Cad. CPqD Tecnologia, 6(1), 21-30.

C. Hudon, S. Gingras, C. Guddemi, L. Mylarski and R. C. Leite. Rotor temperature monitoring using Fiber Bragg Gratings. In IEEE Electrical Insulation Conference (EIC)(pp. 456-459), IEEE

Dreyer, U., Sousa, K. D. M., Somenzi, J., Lourenço Junior, I. D., Silva, J. C. C. D., Oliveira, V. D., & Kalinowski, H. J. (2013). A technique to package Fiber Bragg Grating Sensors for Strain and Temperature Measurements.Journal of Microwaves, Optoelectronics and Electromagnetic Applications,12(2), 638-646.

Allil, R. C. S. B., Werneck, M. M., Ribeiro, B. A., & de Nazaré, F. V. (2013). Application of fiber Bragg grating sensors in power industry. Current Trends in Short-and Long-Period Fiber Gratings, 133-166.

Floridia, C., Rosolem, J. B., Borin, F., Bezerra, E. W., & Said, J. C. (2009, October). Asynchronous FBG interrogation system for temperature and strain monitoring on hydrogenerator rotors. In 20th International Conference on Optical Fibre Sensors (pp. 75033I-75033I). International Society for Optics and Photonics.

Stone, G. C., Boulter, E. A., Culbert, I., & Dhirani, H. (2004). Electrical insulation for rotating machines: design, evaluation, aging, testing, and repair(Vol. 21). John Wiley & Sons.

HEMERY, G. (2008). Alternateurs Hydrauliques et Compensateurs. Ed. Techniques Ingénieur.

Hill, K. O., & Meltz, G. (1997). Fiber Bragg grating technology fundamentals and overview. Journal of lightwave technology, 15(8), 1263-1276.

Othonos, A. (1997). Fiber bragg gratings. Review of scientific instruments,68(12), 4309-4341.

Rao, Y. J. (1999). Recent progress in applications of in-fibre Bragg grating sensors. Optics and lasers in Engineering, 31(4), 297-324.

Kersey, A. D., Davis, M. A., Patrick, H. J., LeBlanc, M., Koo, K. P., Askins, C. G., ... & Friebele, E. J. (1997). Fiber grating sensors. Journal of lightwave technology, 15(8), 1442-1463.

Jackson, J. D. (1999). Classical electrodynamics. Wiley..

Giallorenzi, T. G., Bucaro, J. A., Dandridge, A., Sigel, G. H., Cole, J. H., Rashleigh, S. C., & Priest, R. G. (1982). Optical fiber sensor technology.IEEE transactions on microwave theory and techniques, 30(4), 472-511.

PI1036; Corning SMF -28, Single Mode Optical Fiber, Product information, April 2002.

M. Chaaban, M. Lessard, "Analyse numérique et expérimentale de l'erreur potentielle commise lors de la mesure de témperature de surface," Institut de Recherche d'Hydro-Québec - IREQ, Montreal, QC, Canada, Jan. 2011.

COMSOL Multiphysics, Heat transfer module user's guide, October 2014.

Bergman, T. L., Incropera, F. P., DeWitt, D. P., & Lavine, A. S. (2011).Fundamentals of heat and mass transfer. John Wiley & Sons.

C. Hudon, M. Chaaban, S. Belanger, F. Torriano, A. Merkhouf. Detailed on-site measurements to validate generator numerical modeling. Colloquium on New Development of Rotating Electrical Machines - CIGRÉ, Beijing, September, 2011.

COMSOL Multiphysics, Reference Manual, October 2014.

MICRON OPTICS Inc, Grating Based Temperature Sensors - temperature calibration and thermal response, November 2008, retrieved from



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