A non-invasive optical fibre sensor for detection of partial discharges in SF/sub 6/-GIS systems

Partial discharge (PD) activity is a localised high frequency stress mechanism which causes degradation of gaseous, liquid and solid electrical insulations. In an SF/sub 6/ gas-insulated system (GIS), partial discharge occurs due to the presence of electrode protrusions, fixed particles on insulating surfaces or moving particles, loose or floating electrodes, and voids in solid insulations. Due to the hermetically-sealed nature of GIS and the risk of introducing contaminants, noninvasive PD sensors are desirable for GIS systems. Fibre optic sensors have gained attention for their excellent sensitivity, and high reliability for applications in hostile environments, where there may be high EMI, corrosive materials and explosive hazards. Many fibre optic sensing methods have been demonstrated for sensing physical and chemical parameters since the late 1970s. In this paper, a noninvasive fibre sensor has been used for the detection of ultrasonic pressure waves produced by partial discharges within an SF/sub 6/ glass chamber. The fibre sensor was tested in the laboratory environment and shows a high sensitivity which make it a potential monitor for PDs in GIS.