Abstract
The electrical insulation quality of solid epoxy spacers in Gas Insulated Switchgear (GIS) is a vital issue to accomplish reliability and longevity of such hardware. Surface charge accumulation serves to be one of the prime issues that can deteriorate the insulation properties of the spacer. The variation in electric field on spacer surface due to charge accumulation can downgrade the insulation coordination on various sections of a GIS. In this work, variation of surface charge accumulation on epoxy spacer with time under AC and DC voltage application is found out and its effect on electric field and potential distribution is also analyzed. For this purpose, a 2D axisymmetric model of a gas insulated system has been considered. Electrostatic simulation studies neglecting and considering the surface charge accumulation were carried out and changes in surface charge density, field and potential were examined. All the simulations were performed in CO 2 medium considering it to have the potential to replace hazardous SF 6 gas as a dielectric medium. Also, variation in field and potential with the change in gas permittivity due to change in temperature were analyzed. It was observed that charge accumulation over the epoxy surface was more and slower for DC application but less and faster for AC application. The variation in charge accumulation with change in gas permittivity was negligible. Electric field showed significant variation with gas permittivity near the triple junction.
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