Physical interpretation of the floating electrode defect patterns under AC and DC stress conditions

Partial discharge is a prevalent phenomenon under high voltage (HV) where the discharge partially bridges the gap between two electrodes. At increasing voltage levels, physical dimensions and distances between the electrical parts become critical. Designing electrical components for such high voltages and planning of high voltage laboratories/tests need to deliberate this aspect as it could lead to possible complications such as partial discharges (PD) from the floating metal components. Floating electrodes under AC voltages are associated with a distinctive PRPD pattern. However, there is a lack of literature on the physical interpretation of this pattern. Likewise, under DC voltages, no consistent explanation towards the defect behavior has been reported. Therefore, this paper presents an in-depth study of the floating electrode defect configuration under AC and DC voltages. Subsequently, it provides the physical interpretation of the discharge patterns obtained through the stepwise description of the discharge stages under both conditions. By formulating criteria for repetitive discharges and presenting novel PD fingerprints for DC floating electrode configuration, the outcomes published in this paper contribute towards prospective PD defect identification tools under HVDC.