Novel Partial Discharge Measurement Computer-Aided Measuremnet Systems

A computer-aided measurement system has enabled novel interpretation of partial discharge (PD) signals. We take into consideration voltage phase-angle at which each PD pulse takes place, and consequently need simultaneous measurement of the pulse height q and the phase angle ¿. According to the analysis of PD pulse signals, close relation between PD pulse signals and insulation degradation or defects was found. New PD characteristics such as 4-q distribution profile (average pulse height versus phase angle) can detect the growth of electrical trees in insulation caused by PDs. The skewness of the ¿-q distribution was found to be a good measure for insulation degradation by PDs and for electrical trees. The skewness of the ¿ -q distribution was found to be an indicator of the shape of a void in which PDs occur. A skewness plane or an S-plane is proposed to monitor electrical treeing degradation. Furthermore, an effective noise reduction system is devised for practical b application of the new profile for insulation diagnostics.