Analysis of partial discharges in stator windings

The analysis of partial discharges is a common tool for the diagnosis of electric equipment, whereby in most cases only the phase angles at which the discharges occur and the pulse heights are registered. If the voltage is applied to only one end of the stator winding and the opposite is left on free potential, the impulse height distributions may be different in dependence on what side is energized. The detailed analysis revealed that characteristically different pulse shapes may occur. The paper will deal with experimental results and discuss in how far the different pulse shapes of the output signal of the coupling impedance can be used to identify different defects located in different regions of the winding.