Partial discharge characteristics of typical defect of SF₆ gas insulation under impulse voltage

It is well known that the power frequency withstand voltage test and its corresponding partial discharge (PD) measurement are inadequate for the detection of all the hidden flaws in GIS with the continuous improvement of the voltage level of the power grid. Such inadequacy can be compensated by the oscillating impulse withstand voltage (OIV) test and its PD detection measurement which are recommended by IEC. In order to study the difference of impact on insulation between the OIV and the double exponential impulse voltage, an OIV generator is designed and built to produce the voltage waveforms in accordance with the IEC 60060-3-2006 standard, and the partial discharge (PD) measurement system is also developed. Then PD characteristics of typical defect in GIS under double exponential impulse voltage and OIV are studied and compared. The results show that the number of partial discharge pulses under OIV more than that under double exponential impulse voltage, and so that it is better to detect metal protrusion defect in GIS. This study may provide a basis for PD detection under OIV test.