Abstract
Gas Insulated Switchgears (GIS) are widely used due to their many benefits. The reliability of GIS is challenged due to the presence of spacer defects and/or metallic particles. Free metallic particles can tremendously reduce the insulation strength of GIS especially when they enter the triple junction region (consisting of the spacer, the electrode and the gaseous medium interface) around the spacer. Therefore, there a need to investigate the effect of charged metallic particle on the field intensification produced along the spacer surface and its consequences on the Partial Discharge Inception Voltage (PDIV). In this study, simulation and experimental results are reported for metallic particles adhering to a cylindrical spacer. The effect of particle charging on the resulting field intensification, particle initiated partial discharge inception voltage as well as Phase Resolved Partial Discharge (PRPD) characteristics are presented in this study. The particle adversely affects the electric field uniformity in the area between the two electrodes. A particle in contact with the electrode causes the most severe intensification in the electric field, while the effect caused by the particle at the gap centre is the least severe.
Highlights
Gas Insulated Switchgears (GIS) due to their many advantages are widely used in electrical power industry
SF6 gas or its mixture with other gases used in GIS are highly sensitive to electric field intensification and the reliability of system (GIS) is challenged due to the presence of defects that cause microscopic regions at which the local electric field is enhanced resulting in partial discharge initiation, the intensification and development of which can lead to complete failure (CIGRE Working Group 01.03, 2004; Takuma et al, 2000; Srivastava and Moncos, 2001; Braun et al, 1993)
In order to investigate the dependence of PD magnitude and pattern on the particle position on the spacer surface, Phase Resolved Partial Discharge (PRPD) (φ-q characteristic) patterns for
Summary
Gas Insulated Switchgears (GIS) due to their many advantages are widely used in electrical power industry. In such equipments, spacers are used to support the High Voltage (HV) conductor and to maintain specified clearance between the HV conductor and the grounded enclosure. Field intensification occurs on spacer surface due to spacer design, system configuration or spacer defects. The breakdown strength of GIS is strongly influenced by the roughness of the spacer surface and defects/protrusions produced from improper manufacturing (Srivastava and Moncos, 2001). The knowledge of the electric field intensification around the conducting particles contributes towards a better understanding of the spacer surface flashover phenomenon
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