Characterization of temperature and vibrations in a medium-power transformer using an optical-fiber interferometer

We investigate the measurement of vibrations at the core and windings of the transformer, as well as the differential temperature between. zones. We present first results of vibrations measurements at the magnetic core of an oil-filled power transformer. The sensor is based on an intrinsic transducer of the dynamic strain at the surface into changes of the optical path of a segment of fiber. The sensing length is bonded to the core, immersing in oil and inside the transformer environment. Interferometric sensing is accomplished for high sensitivity because the vibrations are due to dynamic strain. up to a few mu epsilon. It allows short probe lengths to be used, though an increase of the length could be used for enhancing the sensitivity. A common accessing of the fibers of the interferometer is used for reducing the common disturbance. The spectral decomposition of the output signals is shown and it is related to the electric reference and the behavior of the transformer.