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September 2, 2020
Overhaul of hydraulic turbines in hydropower stations and preparations for first start-up
1. General matters concerning overhaul of turbines in hydropower stations
1.1 Overhaul and maintenance of hydraulic turbines in hydropower stations include prevention and repair. The common purpose of preventive and restorative maintenance is to identify the causes of damage and wear and eliminate them. The purpose of preventive maintenance is to reduce the possibility of damage and wear or failure. Repairable maintenance The purpose is to repair the damaged and worn parts to the best condition.
1.2 During the overhaul and maintenance of the turbine, the work ticket system must be strictly observed.
1.3 The inlet gate should be closed every time the machine is shut down for a long time.
1.4 When shutting down, the oil valve switch cavity of the oil pipeline of the servomotor is turned on, and the maintenance seal of the turbine should be turned on.
2. Preparation work before the first start-up of the turbine of a hydropower station
2.1 Clean and inspect all parts of the runner through the turbine.
2.2 All instrument tubes should be blown clean, and check whether the valve under the instrument is open.
2.3 All moving joints of the turbine should be filled with lubricant. All ancillary pipelines of the water machine should be tested by hydraulic or pneumatic pressure according to their working pressure. There should be no foreign objects in the pipes and the connections should be correct and smooth.
2.4 The turbine runner shall be subjected to sealing test and action test, and there shall be no oil leakage everywhere. Detect the working and oil leakage of the oil receiver, and detect the clearance between the runner blades and the runner chamber at different rotation angles.
2.5 Check the action of the motor and oil pump of the hydraulic pump station. Set the liquid level signal device to make the oil pump start or stop when the oil level reaches the specified height.
2.6 Check the level indicator of the gravity oil tank. When the oil level reaches the lowest oil level, the oil pump of the hydraulic pump station will start.
2.7 Check the hydraulic load shedding device pipeline, high-pressure oil pump and motor operation. Adjust the corresponding automation components to start and stop the oil pump. The capillary restrictor should be adjusted in advance, and check whether it can lift the spindle.
2.8 Check whether the main shaft sealing water source is unblocked and the corresponding signal device.
2.9 Check the bolts and nuts at the joints of important parts for looseness. In particular, pay attention to whether the coupling bolts and cylindrical pins of the main shaft and the runner are all spot welded firmly.
2.10 Check the action of the guide vane servomotor and whether the water guide mechanism can close the guide vane under the action of the heavy hammer.
2.11 Check whether the guide vane is stuck with the seat ring, outer water guide ring, and inner water guide ring in the maximum opening and closed state.
2.12 When checking that the guide vane is closed, the clearance between the inner and outer end faces of the water guide and the elevation should meet the design requirements.
2.13 Check the relationship between the guide vane and the stroke of the servomotor under various rotation angles. From fully closed to fully open, there should be no less than 8 measuring points.
2.14 Check and test the action of the contacts of each mechanical measuring device of the turbine.
2.15 The front and rear drain valves should be closed before the flow channel is filled with water.
2.16 The entrance door of draft tube φ650 should be closed firmly.
2.17 Check the following items after filling with water:
a. Whether there is water leakage at each combined surface.
b. Whether there is water leakage at the outer sleeve of the water guiding mechanism and the water guiding shaft.
c. Whether there is water leakage at the expansion joint.
d. Check that the main shaft seal does not leak.
e. Detect the deformation of outer water ring and runner chamber.
f. Check whether the actions of each instrument are correct.