Partial Discharge Ultrasonic Detection based on Sagnac Interferometer with High Noise Suppression

Partial discharge detection is very important for the insulation properties evaluation of power equipment. As an ultrasonic detection method, the Sagnac interferometer has received extensive attention due to its many advantages. Because the partial discharge signal is very weak, it is easily affected by external low-frequency noise and the noise of the optical polarization. In order to overcome this problem, a high noise suppression Sagnac interferometer system for ultrasonic detection of partial discharge is proposed. Firstly, it summarizes the advantages and disadvantages in recent years of Sagnac interferometer in measurement of partial discharge, and the Fundamental of Sagnac interferometer and fabrication of the sensor probe. On this basis, the principle of high noise suppression Sagnac interferometer system is described in detail. The Faraday mirror is introduced to form a symmetrical structure to eliminate the noise in the Sagnac sensing system. The results show that the Sagnac sensing system has a good suppression effect on low frequency and polarization noise, in agreement with the theory.