Experience with Partial Discharge detection at high voltage Gas Insulated Switchgear by ultra high frequency (UHF) method

The paper reviews the experience of Partial Discharge (PD) detection at 400kV and 132kV Gas Insulated Switchgear (GIS) by UHF method. It outlines the principle of UHF signal emission from possible PD inside HV GIS and relevant detection methods applied. Two real cases with detected incipient fault modes at 400kV and 132kV GIS are being discussed. Moreover, the shortcoming of UHF detection at metallic shielded GIS is identified and feasible solving through detection points at non-metallic secondary wiring terminals of Current Transformer (CT) and Voltage Transformer (VT) is described.