Metallic particle effect on the gas PD in co-axial cylinder electrodes

High voltage apparatus, for example GIS, insulated in a gas dielectric easily show partial discharge (in short PD), because of particle impurities, particularly some kinds of metallic particles. The PD failures are very dangerous and detrimental, because they could destroy the insulating system of the high voltage apparatus, result in a great deal of economic damage and imperil personal safety. Co-axial cylinder electrodes have been made to simulate the high voltage apparatus structure and service conditions under various applied voltages and existence of some types of metallic particles of different materials (for instance, copper, stainless steel, steel) with variable diameters, lengths and geometry. Through practical experiments in the laboratory, the relationships between PD inception voltage, PD quantities, length, materials and geometry have been obtained. Meanwhile the PD signals have been recorded by the measurement systems. The position of the particles shows different waveform and behavior, so that it could provide a way to detect the PD failure characteristics, location and attribution, and help to analyze, judge and assess the service conditions.