Abstract: A device for monitoring the leakage of cooling gas for a turbogenerator stator into the stator water-cooling system is disclosed. The device is located next to the generator so that the operative elements are at the generator storage tank operating water level. As cooling accumulates in the storage tank together with cooling water, the gas displaces the water in the leak monitor until the water level rises to a predetermined, adjustable level. When this level is reached, the gas is vented and the water level is restored to equilibrium. Each cycle is recorded on a leak trip counter. When the leakage rate exceeds a predetermined value, an alarm is triggered.