Abstract: The quantity of make-up hydrogen is an important operation index of generator unit, too large quantity of hydrogen often appears in the double-ring oil sealing generator .By the analysis of the oil sealing system and the sealing bush construction, the problems and hidden troubles existing in system design and operation were treated and regulated, the speed of hydrogen purity lowering was controlled, the hydrogen exchange quantity of generator and the hydrogen consumption were reduced, so the purpose of energy-saving and consumption-reducing was achieved at last.

Key words: generator unit, double-ring sealing oil system, sealing bush construction