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Temperature Sensor for Hydro Generator Bearings using Thermally Regenerated Fiber Bragg Gratings

Authors:
Erlon Vagner da Silva
Uilian José Dreyer
Kleiton de Moraes Souza
Cicero Martelli
Valmir de Oliveira
Hypolito Kalinowski
Jean Carlos Cardozo da Silva

Keywords: Electrical generator bearing; Optical Regenerated Fiber Bragg Gratings; Temperature measurement

Abstract:
This work presents the design and experimental results of a temperature sensor based on quasi-distributed thermally regenerated Fiber Bragg gratings (RFBG) applied to the bearings of hydro generators. The temperature increase in the bearing is generally due to excessive shaft misalignment, low oil level or dirt in the lubricant oil. Expensive and time-consuming damage can be caused to the generator if the temperature sensors are not able to detect the fault in time and accurately. The proposed sensor has three wavelength multiplexed RFBG to monitor the vertical temperature gradient in the lubricant oil. The developed package is designed to avoid the cross sensitivity of the RFBG with mechanical of forces. Thermally treated Fiber Bragg Grating (FBG) is heated till about 900 C far away the temperature range in which the power plant operates, making its use suitable to obtain thermal stability for many years. Temperature stability tests were carried out for over fourteen hours in laboratory. The uncertainties were evaluated considering the sample dispersion and equipment characteristics used during the sensor temperature calibration. The experimental results show that the uncertainty associated to each FBG matches the power plant metrological requirements. The developed package for bearing temperature measurement proved to be robust both mechanically and thermally.

Pages: 35 to 40

Copyright: Copyright (c) IARIA, 2015

Publication date: August 23, 2015

Published in: conference

ISSN: 2308-4405

ISBN: 978-1-61208-425-1

Location: Venice, Italy

Dates: from August 23, 2015 to August 28, 2015