Filter system for hydrogen cooled dynamoelectric machines

A filter system 300 is provided for a hydrogen cooled dynamoelectric machine 110, such as a generator or a motor, and includes a float trap 320 fluidly connected to a component of the dynamoelectric machine via a first conduit 310; a filter 330 fluidly connected to the float trap via a second conduit 312; and a flow switch 340 fluidly connected to the filter via a third conduit 314 that is fluidly connected to a hydrogen control assembly 140. The float trap allows gas to flow but stops fluid flow if a predetermined amount of fluid such as oil enters it. The flow switch can raise an alarm if fluid flow suffers a blockage or interruption. Valves 325, 327 can connect the float trap to a drain 329 and valves 335, 337 can connect the filter to a drain 339. The filter can be a coalescing type. A valve 305 can be between the dynamoelectric machine component, which can be a generator or a seal oil drain enlargement (SODE) (fig 4, 130), and the hydrogen controller. There may be a valve 350 between the filter and the hydrogen control assembly. The filter system can be used to prevent gases or liquids such as lubricants from contaminating hydrogen purity sensors which monitor gas mixtures, which might render them inaccurate or inoperable.