Maximum Partial Discharge Magnitude Hysteresis Curves as a Diagnostic Technique for Model Stator Bars

This paper proposes a method to diagnose the aging of model stator bars. Experiments have been performed in such bars, and the maximum partial discharge has been recorded as the applied voltage increases and then decreases. The resulting ldquohysteresisrdquo curve shows whether the stator bar is in a ldquogoodrdquo or ldquobadrdquo state. It is shown that the aging of the model bar influences the hysteresis curve, i.e., the latter presents a greater surface area with an aged bar than when the stator bar is not aged. The proposed method may render information as to whether a stator bar is aged or not, and it can also distinguish between a stator bar with a more serious aging problem and a stator bar with a less serious aging problem. A discussion on the merits of the proposed method follows. It is suggested that the proposed method can be used as a diagnostic tool for assessing the quality of a stator bar and for studying its aging.