Spark Discharge Distributed Detection Based on Coherent Optical Time-Domain Reflectometer

Distributed detection of cable insulation defects is a difficult problem in engineering, and traditional methods cannot perform distributed detection over the entire cable. In this paper, based on the principle of coherent optical time domain reflectometer (COTDR), the distributed broadband measurement and localization of weak spark discharge acoustic signals were realized. The principle of optical fiber distributed acoustic sensing based on COTDR was introduced firstly, and the sensing system was improved to expand the sensing frequency band. Then, the sensing performance of the system was calibrated with a Piezoelectric vibrating tube. Finally, spark discharges with 1 mm gap length were detected by the proposed sensing system over a 1.1 km long sensing fiber. The upper limit of the sensing frequency band reached 90kHz. The sensing method proposed in this paper provided a novel solution for the distributed detection of cable insulation defect.