Motion of Metallic Particles in Gas Insulated Systems

Doktorsavhandling, 1997

The motion of a charged metallic particle subjected to an electric field in a gas insulated system is controlled by several parameters. The higher applied electric field, the better the individual parameters have to be mod eled in order to make satisfactory calculations of the motion. Statistical analysis of acoustic measurements can be used to identify different metallic particles moving in a GIS bus. Furthermore, measurement of dis charges generated from a moving particle show that they mostly appear when the particle comes close to the electrodes. However, for higher applied fields, discharges also occurred during flight when it was located between the electrodes. The number of discharges increased with increasing voltage. Models of the motion of the particle that traditionally are being used usually assume the charge to be constant between parti cle impacts. Since the discharges strongly influence the carried charge, an enhanced model of the motion has been suggested together with other improvements to enable a more accurate calculation of the motion to be performed. The influence of dielectric coatings on the electrodes on the voltage required to lift a particle off the surface has also been investigated.