Characterization of partial discharges from a protrusion in HVDC coaxial geometry

This paper aims at the detection and characterization of partial discharges (PD) in GIS under HVDC constraints in the presence of a protrusion/metallic particle on the high voltage conductor. It is shown that the use of the IEC 60270 standard does not allow for the detection of PDs. For that purpose, a very accurate steady-state current measurement and a high frequency measurement of the current and emitted light associated with the PDs are performed. The results evidence a close correlation between the PD and the steady-state current and light emission. The transition between pulse and pulseless forms of corona discharges is also evidenced.