Intrinsic fiber optic ultrasound sensor for oil immersed detection of partial discharges

A fiber-optic ultrasound sensor is presented for acoustic detection of partial discharges in oil immersed set-ups. Its specifications are similar to R15i (optimized sensor for the detection on the walls of transformers) but for internal installation. It consists of an intrinsic fiber-optic sensing probe, an all-fiber interferometer, homodyne demodulation and an optoelectronic specific conditioning for detecting ultrasounds in the range of 100 kHz - 300 kHz. It is characterized in water and tested with real partial discharges in oil. The sensing probe is based on a multilayer coil that is customized to a specific sensitivity. It is a cost-effective solution useful for a multichannel configuration.