Characterization of Fiber Bragg Grating Sensor in a High Speed Rotating Pipe

摘要

The next generation generators will use high temperature superconductors (HTS) for its rotor construction replacing currently used conventional copper rotor. This will enhance the generator efficiency to a steep increase of 0.5% which results in saving of $ 3.8 M for 900 MVA Generator according to calculation done in 2007. The HTS rotor, rotates at 3600 rpm will be cooled by liquid Neon to 30 K using cooling channel arrangements. The temperature profile of the cooling channels has to be continuously monitored to ensure the sufficient cooling. But, it is a challenging task to identify a feasible sensing system and the associated signal transmission/processing unit. One of the possible sensing systems for the above-described application could be Fiber Bragg Grating. Gratings with different spatial period are arranged at various positions along a single mode fiber in the HTS Generator. Rotor temperature will vary the gratings' periods, which can be read out with a tunable laser in a wavelength division multiplexing (WDM) scheme. The spectral position of the reflections may be correlated with the spatial position of the gratings, and the shift of the gratings' maximum reflection indicates the change of the gratings' period,, which in turn measures temperature. In this paper, the initial experiments, which demonstrate the rotational effect on FBG sensor at room temperature is reported.