Computer aided partial discharge evaluation about the surface material of the PD-source in gas-insulated substations

A PD (partial-discharge) diagnosis system is presented that gives information about the location of any detectable PD source in a GIS (gas-insulated-substation) testing unit. For every detected impulse the system measures and processes the apparent charge, impulse duration, phase angle, test voltage V/sub pp/, actual test voltage, impulse energy, and cycle number. A high-speed (60-MHz bandwidth) electronic system has been developed for online measuring and digital conversion. The data are transmitted to a personal computer by means of an electro-fiber-optic interface unit and analyzed by a statistical algorithm. This procedure runs automatically and provides information about the surface materials on which the partial discharges are active. Two types of defects representing sources of partial discharging have been implemented in gas-insulated switchgear. Some of the results are presented and discussed, showing the potential of computer-aided partial discharge evaluation.<>