Fiber optic interferometric sensor for acoustic detection of partial discharges

Abstract

The detection of acoustic partial discharge signals produced in power transformers is reported. Detection is based on optic phase changes in an intrinsic Mach-Zehnder fiber optic interferometric sensor of high sensitivity. The sensor can be placed within transformers and is suitable for the detection of weak acoustic signals associated with the PD. The calibration of the interferometric fiber optic acoustic sensor at typical frequencies displayed by partial discharges is presented. Interferometric multi-fringe outputs are used for high-precision measurements during calibration. The demodulation of such signals is presented for obtaining the optical phase readout. Partial discharges are generated in laboratory conditions and are detected using the fiber optic sensor immersed in mineral oil.