Sound detection monitoring in the transformer oil using fiber optic sensor

In this paper it is shown that a fundamental technology of hybrid system combining Sagnac interferometer and FBG. Fiber optic sensor array, i.e. two sensors in the Sagnac loop was suggested. Fiber optic sensor array was fabricated in the transformer oil and external sound applied to the sensor directly using by piezoelectric. Tunable laser source was used as a light source. Applied sound frequency range is from 5kHz to 90kHz. From this experiment it is confirmed that fiber optic sensor using Sagnac interferometer in the transformer oil can detect applied sound frequency. In real electric transformer system suggested fiber optic sensor array can be applied to monitoring physical quantities such as internal temperature, sound pressure and vibration due to partial discharge.