Apparatus for pumping operation of a hydraulic machine having Francis type runner

摘要

An apparatus for operating a hydraulic machine having a Francis type runner provided with a multi-stage seal between the inner peripheral surface of the runner and the stationary part. The apparatus has a water extracting pipe opening at its one end to one of the seal stages of the multi-stage seal and to a draft tube at its other end. A valve disposed in the water extracting pipe is adapted to be opened when the water head has become greater than a predetermined level during the pumping operation of the hydraulic machine.