Partial Discharge Fiber Grating Ultrasonic Sensor Based on Symmetric Double Diaphragm

A novel nonmetallic fibre optic acoustic sensor on the basis of a symmetric double-diaphragm structure and a fibre Bragg grating (FBG) is presented and demonstrated. The structural principle of the sensor and the optimization of its structural parameters are introduced. A detection system for the response characteristics of the FBG sensor in oil is built. Based on the edge filter demodulation method, the response characteristics of the FBG sensor to ultrasonic signals in oil are measured. The analysis results indicate that the FBG sensor can measure the ultrasonic signal of tens to hundreds of kilohertz in the oil sensitively, and the sensor has multiple resonant peak values, whose sensitivity is high. A partial discharge (PD) detection system is built. The designed FBG sensor is used to measure the ultrasonic signal generated by the actual PD. The PD detection performance of the sensor at different angles is tested. The results indicate that the designed FBG sensor can detect the PD ultrasonic signal in time domain sensitively.