| 摘要 |
PURPOSE:To supply shaft sealing oil of high quality by providing a sensor for measuring as the variation in the resistance the conductivity for detecting the variation in the density of the sealing oil in a vacuum tank and opening or closing a control valve which is provided at the vacuum evacuating pipe inlet with the signal from the sensor, thereby preventing the cavitation of a shaft sealing oil pump. CONSTITUTION:A vacuum tank 10 which contains shaft sealing oil communicates via a suction tube 11 with an ordinary shaft sealing oil pump 4 and via a vacuum evacuation tube 12 with the interior of a turbine generator. A conductivity measuring sensor 17 is movably at the mounting position provided in the tank 10 to detect as the variation in the resistance the variation in the density of the shaft sealing oil in the tank, and the resistance value is converted via a converter 18 to a current value. The electric signal is converted via an electric/air converter 19 to an air signal, and an automatic vacuum control valve 20 which is provided in the tube 12 is opened or closed by the air in response to the magnitude of the air signal. |
