Field distribution on an HVDC wall bushing during laboratory rain tests

An efficient countermeasure to suppress flashovers across high-voltage DC (HVDC) wall bushings is to make their surfaces hydrophobic. The measured electric fields along such a bushing under different environmental conditions are reported. A significantly reduced radial field strength has been found for the hydrophobic bushing. Moreover, the total field strength distribution becomes almost independent of the prevailing dry zone. The flashover voltage for bushings with a hydrophobic surface is therefore significantly increased