ACOUSTIC DETECTION OF PARTIAL DISCHARGES WITH AN OPTICAL FIBER INTERFEROMETRIC SENSOR

摘要

An optical fiber interferometric sensor with intrinsic transducer along a coil of the fiber is presented for the acoustic detection of partial discharges (PD) within oil-filled power transformers. The sensor is designed for measurements of high sensitivity in a harsh environment of electrical discharges, temperature drift and in oil immersing. The partial discharges produce much attenuated ultrasonic signals (～1Pa) that are detected by the sensor immersed in oil with the purpose of localizing the source into the transformer. The transducer size is 28mm of diameter and 28mm of length. The ultrasonic frequencies are detected in the range of 20kHz - 200kHz. The results of characterization of the optical-fiber probe immersed in an acoustically isolated chamber are reported and compared with the response of piezoelectric ultrasonic transducers. First results in a controlled experiment of partial discharges generation (100pC - 1000pC) and acoustic detection are given. They show a direct acoustic detection of partial discharges with the optical fiber interferometer, instead of the indirect techniques available in the transformer walls.