PURPOSE: To provide a system for providing seal oil to a gland seal that surrounds the shaft of a generator under the conditions of minimizing the temperature difference between the seal oils, as well as maintaining it at the temperature higher than that of bearing lubricant oil supply system.

CONSTITUTION: The temperature of the air-side seal oil is used as a standard, and the difference between the air-side seal oil temperature and hydrogen-side oil temperature is used to control temperature of the hydrogen-side seal oil. The temperature of the air side seal oil is controlled by a separate controller using the bearing oil temperature as a reference. By this manner, the system has the advantages as the thermal difference expansion does not occur in the generator shaft 1 and the gland seal 12, and the need for operator attention for seal oil temperature regulation is eliminated.