An ultra-sensitive optical MEMS sensor for partial discharge detection

A diaphragm-based interferometric fiber optical microelectromechanical system sensor with high sensitivity is designed and tested for on-line detection of the acoustic waves generated by partial discharges (PD) inside high-voltage power transformers. In principle, the sensor is made according to Fabry Perot interference, which is placed on a micro-machined rectangular silicon membrane as a pressure-sensitive element. A fiber-optic readout scheme has been used to monitor sensor membrane deflection. Sensor design, fabrication, characterization, and application in PD acoustic detection are described. Test results indicate that the fiber optical sensor is capable of detecting PD acoustic signals propagating inside transformer oil with high sensitivity. (Some figures in this article are in colour only in the electronic version)