Techniques employed to detect and localize partial discharge in solid and liquid dielectrics

Partial Discharges (PD) are the electrical discharges occurring in the insulation of equipment’s, which are mainly caused because of the presence of voids within the insulation. When considering a high voltage system and if the voltage at the voids increases, the PD creates severe damages to the system. If the normal voltage in a system exceeds above the threshold level, then there occurs the partial discharge and it occurs in insulations of solids, liquids and gases. The resulting PD current completely relies on the form of discharge and also on the type of system leading to degradation in insulation materials. The PD in a system is measured either by On-line or Off-line techniques. The online technique aids in enhancing the reliability of the system; also protects the system from large damages and is performed at certain frequencies, while the offline techniques are performed at different frequencies. In this paper, a comparative study is carried out amidst the different online and offline techniques which employ various topologies to detect and localize the partial discharges occurring in a system with high accuracy, better sensitivity and with good clarity.