Leakage current measurements in Direct Current Gas Insulated Substations equipment

Charge accumulation on solid insulator in Gas Insulated Substation (GIS) is one of the major issues under Direct Current (DC). A specific device has been developed in order to assess the origin of such charges within SF
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, in a coaxial geometry. Current measurements have been performed at different pressures (0.2 – 0.5 MPa), using electric field ranging from 2 to 10 kV/mm and for various water content of gas. The results evidenced that non negligible current passes through the gas. It strongly suggests that charges are emitted from the high voltage electrode. Moreover, this emission is influenced by the water content in the device.