Abstract: The analysis on the abrasion and corrosion phenomenon of slip-ring in large hydrogenerators is conducted, and it concludes that this phenomenon is mainly caused by the mechanical wear, electric spark corrosion and electrochemical corrosion. Therefore, the prevention and mitigation measures are proposed as follows. Firstly, choose natural graphite carbon brush; secondly, eliminate the brush sparking in time; thirdly, strengthen the shutdown protection; fourthly, improve the running environment of the ring room; and finally, keep the ring surface smooth. These measures have been applied to the 125-MW units of Gezhouba Hydropower Plant. It demonstrates that the operating state of slip-ring in the hydrogenerators gets improved substantially, and the sparking and overheating caused by the abrasion and corrosion are eliminated.

Key words: hydrogenerator, slip ring, abrasion and corrosion, carbon brush