Acoustic fiber optic sensors for partial discharge monitoring

Partial discharge acoustic monitoring is an important tool in assessing the health of power equipment. Traditionally, the acoustic sensor is made of piezoelectric transducer (PZT), and is packaged in a metal tube. Recently, the advancement in fiber-optic sensor technology provides clear benefits in such applications, particularly because optical fiber is immune to electromagnetic interference. Additionally, fiber-optic sensor can be embedded in the power equipment for remote applications, offering high sensitivity because the sensor can be deployed closely to the partial discharge source. In this research, three typical discharging models, namely, the corona, the floating, and the gap models, were configured to test a single mode fiber Sagnac sensor and a multimode fiber speckle sensor in partial discharge monitoring. The results are compared with those from an off-the-shelf piezoelectric transducer. Both the single mode Sagnac sensor and the multimode speckle sensor display good sensitivity compared with the commercial piezoelectric transducer. It is expected that Sagnac and speckle optical fiber sensors can play an important role in the development of future PD monitoring instruments.