Abstract: After the DC composite through-wall bushing in the converter station is covered with snow, flashover may occur, causing power outages. This article presents a horizontal arrangement of contaminated composite hollow bushing in a large artificial climate laboratory, and conducts snow-covering flashover tests under direct current voltage. The results show that 50% withstand voltoage (U₅₀) obtained by using a non-charged snow melting pressurization method is about 6.8% lower than U₅₀ obtained by using a charged snow melting pressurization method. The U₅₀ under the DC voltage of the snow-covered bushing decreases with the increase of salt density, but its characteristic index α is lower than the index obtained from the pollution test. When the salt density is 0.1mg/cm², the U₅₀ gradient under the horizontal arrangement of the snow-covering composite bushing is close to that under weak hydrophobicity of the contaminated bushing.

Key words: composite through-wall bushing, artificial snow-covering, salt density, DC voltage, flashover characteristics