Suppression of Metal Particles by Coating for a ±550 kV DC GIS

Coating the inner surface of grounded enclosures has been used to inhibit metal particle motion inside AC GIS for many years. However, for DC GIS, only fundamental research has been performed, while very few attempts have been made on real DC GIS. This paper reviews the basic research into the inhibition of metal particles by coating at DC. On this basis, based on a ±550 kV DC GIS busbar, an inhibition test of metal particle motion using coating was performed. Four types of metal particles were used as samples to verify the inhibitory effect of the grounded enclosure coating. The results showed that the coating has a very good inhibitory effect on block and powder metal particles on real GIS, and there are rarely any metal particles moving again under the rated DC voltage. However, for wire and flake metal particles, the effectiveness of the coating depends on the way the particle contacts the ground electrode when they are still, and ~30% of wire and flake metal particles can be inhibited. The conclusion of this paper is of guiding significance for the research and development of stable and reliable DC gas-insulated equipment.