Three important indices for ensuring safe operation of the hydrogen cooled turbo-generator sets are as follows:having no hydrogen leakage to the outside;keeping purity of hydrogen in the generator;and avoiding oil entering into the generator.The reliability of oil-replenishing and oil-dicharging device for seal-oil tank in the seal-oil supplying sysrem

however

is the guarantee to realize the above-mentioned three indices.Directing against the problems existing in the device of replenishing and discharging oil for seal-oil tank of generator no.4 in Shajiao A Power Plant

such as discharging oil occurred at the same time of replenishing oil into the seal-oil tank

decreasing control quality of oil-level in the seal-oil tank

etc.

the retrofit of floating-ball valves for replenishing oil into the tank and for discharging oil out from the tank has been carried out.Practical application shows that the oil-level in seal-oil tank after retrofit can accurately and automatically be controlled to the desired situation

realizing control automation of oil-level in the seal-oil tank

enhancing greatly the safety and reliability in operation of the unit.