On-site partial discharge tools allow early detection before a breakdown occurs in any major part of a distribution system. The two key elements in any on-line partial discharge measurement scheme are the measuring system and the sensors themselves since using the right sensor can significantly enhance PD detection. This presentation reviews research involving on-site PD measurement at substations with 11 kV XLPE power cables to access condition of the insulation based on IEC 60270. It will also explain how characterization of PD in terms of rise time, zero-crossing and resonant frequency was statistically performed in a MATLAB software environment based on real data measured on-line.