Characterization of an Ultrasonic Low Frequency Fibre Optic Interferometric Sensor for Partial Discharges Detection in Transformers

Partial Discharges are one of the major sources and symptoms of the deterioration of the dielectric material in power transformers. Such discharges are shown to emit weak acoustic signals in a wide ultrasonic range. A fibre optic sensor based on a Mach-Zender interferometer has been developed to detect these weak signals. It will be demonstrated that fibre optic sensors (FOS), placed within the harsh environment of typical power transformers are the best choice for partial discharge detection. This paper presents a calibrated fibre optic sensor with a high precision at 20kHz, this being a typical partial discharge signal within power transformers. The sensor has been first characterised in a laboratory environment which mimics the real life application proposed for future work