Statistical analysis of simultaneous partial sischarge measurements from IEC60270, HFCT and HFCT EMI methods

This paper investigates correlations of Partial Discharge (PD) measurements of associated statistical parameters from phase-charge-number Φ-q-n plots from IEC60270 PD measurements and High Frequency Current Transformer (HFCT) Φ-peak-n plot PD measurements. These are also compared with Electromagnetic Interference (EMI) Radio Frequency (RF) measurements. The three methods record simultaneously PD activity from 3 artificially created fault geometries on High Voltage cable sections, namely a semiconductor point fault, a large embedded particle fault and a smaller particle fault. One of the research aims is to demonstrate the potential for passive RF methods to show comparable results of fault characteristics with direct contact PD measurements. The ability to identify faults based on statistical analysis of IEC60270 Φ-q-n plot and HFCT Φ-peak-n plot deduced quantities, such as Skewness and Kurtosis is also highlighted. This is used in comparison with EMI energy in selected frequency bands to determine any related frequency characteristic changes. Comparisons for trended Skewness and Kurtosis measurements of IEC60270 vs HFCT peak measurements for the three faults are shown for the pulse count Hn(Φ)+ distribution.