Motion of conducting particles causing inadvertent outages in GIS

Inadvertent failure of a HV gas-insulated system (GIS) is traced to a seemingly innocuous mechanism in particle-induced breakdown. Impending dangers from inconspicuous conducting particles in a large physical system are quite intriguing. The dynamic behavior of the particle due to electric field/particle/fluid medium interaction is a complex phenomenon. To understand this interaction a credible database has been generated for the field-induced motion of the particles on a physical prototype model. Induced surface charge acquired by the particle is calculated based on the proposed model (field calculations) and by considering it to be a prolate ellipsoid. Methods for deactivating potentially dynamic particles using dielectric coated active parts and grounded enclosures, and a novel technique called reverse polarity charging have been suggested. Performance of GIS in the presence of metallic particles has been studied with bare electrodes and with dielectric coatings of different conductivities with a view to obtain an optimal value of the conductivity.