Abstract: In 2×600MW hydrogencooled unit of Huaneng Tongchuan Power Plant, the singlering seal oil system is adopted. In this system, the phenomenon of oil hammer, which is similar to the water hammer, occurred many times; and large fluctuation of the outlet pressure of seal oil pump and the pressure difference of oil and hydrogen occurred in the same frequency. The reasons of the faults were analyzed; and some improvement measures were put forward.

Key words: hydrogen-cooled generator, seal oil system, oil hammer, vacuum oil tank, float valve