Since the appearance of commercial partial discharges analyzers, Copel is working to use this type of instrument to estimate the stator winding insulation condition in their larger hydro generators. For this purpose, Copel is working with three tools: PDA-H (a portable PD instrument), GenGuard (a continuous on-line PD instrument) and MICAA (expert system software for interpreting generator test data). The paper describes Copel's experience with partial discharge measurements in two power stations. The first one, with the GenGuard monitoring system; the other one, with the PDA-H system and with well-known endwinding discharges. The paper also describes Copel's experience using MICAA in both power stations. PD measurements are compared with visual inspections and other electrical tests to check MICAA diagnosis validity.
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