Non-invasive optical fibre acoustic monitoring of partial discharges within GIS

Although GIS were once thought to be maintenance free, there has been a number of reports of system failures throughout the world. These failures are reported to be caused by partial discharge activity within the GIS enclosure, Spaeren (1985). The authors report on a noninvasive fibre-optic technique which is shown to be sensitive enough to detect displacements of 10^-12 m and has a good response at 10 kHz but can respond to signals up to 40 kHz. This optical system is a portable interferometric fibre-dyne system and can be a cost-effective, retro-fittable solution for monitoring partial discharges in GIS. Comparison with a commercially available piezo-electric acoustic emission sensor is also made