Acoustic monitoring of partial discharges in gas insulated substations using optical sensors

A study has been made of the feasibility of applying optical fibre sensing technology to acoustic monitoring of partial discharges within gas insulated substations (GIS). A test rig has been constructed to simulate a section of GIS in which acoustic sources could be placed. This has been used to test the optical systems which showed greatest promise of having the capability of monitoring these partial discharges. Experimental results are presented which show that acousto-optical sensing, using fibredyne interferometry, of partial discharges within GIS is feasible in principle. However, further work is needed to extend the sensitivity range to acoustical amplitudes of about 10^-14 m which correspond to signals from the weakest discharges requiring detection.