RETARDING DEVICE FOR CORROSION OF HYDRAULIC MACHINERY

PURPOSE:To prolong the life of a cover storing a runner therein by providing the cover with plural electrodes, and generating chlorine gas as corrosive gas from sea water by means of a current passed between the electrodes, and detecting variations of the current value and the like so as to exhaust the chroline gas. CONSTITUTION:While a runner 3 is rotated by sea water 4 allowed to flow within a water passage the sea water 4 is allowed to flow also within back rooms 6, 7 in the direction indicated by the arrow. In this case chlorine gas 18 generated from the sea water 4 by a current passing between plural electrodes 8A to 8D is exhausted together with the sea water in the direction of a draft tube. When operation of a hydraulic turbine is stopped and the sea water 4 is stored in the upper side back room 6 the sea water 4 in the back room 6 generates chlorine gas 18 because of electrolysis and corrodes the inner surface of the back room 6. The value of a current passing through this corroded portion 18a is monitored by a monitoring device 14 and when the current value is lowered by corrosion a switching valve 16 is opened and also a pump P is driven so as to exhaust the chlorine gas.