The behavior of charged conducting particles in electric fields

The presence of metal particles within gas insulated switchgear (GIS) might initiate a sparkover and lead to fatal failure of electric power transmission system. In order to investigate the behavior of a particle in GIS, model electrodes and a measuring system were constructed. The motion of a particle was investigated by using a CCD camera and a high-speed video camera. Different shapes of elongated particles were made from 0.1 mm and 0.25 mm diameter wires. The measured values of lift-off field strength of a particle lying on the electrode agreed quite well with the theoretical prediction. The initial raising up of particle usually started at the sharper edge as expected. There were two types of different mode of particle motions; one is bouncing motion between two electrodes or one electrode and the other the standing motion on the electrode. Interesting thing is that the standing motion on the upper electrode when a negative voltage is applied to the upper electrode. This phenomenon could be explained from the difference of positive and negative corona currents starting from both edges of a standing particle