Characterization of Partial Discharges in a Gas Insulated System Using an Acoustic Emission Technique

Abstract

The major cause of failure of GIS is the presence of foreign particles causing partial discharges/corona in the insulation structure. In the present work, partial discharge activity in GIS under AC, DC, and the composite voltage formed by AC and DC voltages, was studied using the acoustic emission technique. It is observed that the magnitude of the acoustic emission (AE) signal produced due to partial discharges under positive DC is high compared to negative DC and AC voltage. Under the composite voltages, it is observed that superimposing AC voltage over positive DC enhances the partial discharge activity, and superimposing the AC voltage over the negative DC voltage could limit the partial discharge activity. The rate of rise and the duration of the AE signal indicates that partial discharge activity under positive DC voltage is severe compared to AC and negative DC voltages. The measured counts and energy content of the AE signal produced due to partial discharges under positive DC is high compared to the negative and AC voltages. It is also realized, based on a partial power analysis, that the maximum energy content of the AE signal lies in the range 125–250 kHz, for the signals generated under AC/DC/composite voltage formed by AC and DC voltage.