The output of the hydro-generator drops
Reason
In the case of constant water head, when the guide vane opening has reached the no-load opening, but the turbine has not reached the rated speed, or when the same output, the guide vane opening is larger than the original, it is considered that the output of the unit has decreased. The main reasons for the drop in output are: 1. Flow loss of water turbine; 2. Water conservancy loss of water turbine; 3. Mechanical loss of water turbine.
Processing
1. When the unit is running or shutting down, ensure that the draught tube submersion depth is not less than 300mm (except for the impact turbine). 2. Pay attention to the water inflow or outflow to keep the water flow in balance and unobstructed. 3. Keep the runner running in a normal state, and stop the machine for inspection if there is a noise. 4. For axial-flow fixed-blade turbines, if the output of the unit suddenly drops and the vibration increases, it should be shut down immediately for inspection.
The temperature of the bearing bush of the unit rises sharply
Reason
There are two types of turbine bearings: guide bearing and thrust bearing. The conditions to ensure the normal operation of the bearing are correct installation, good lubrication and normal supply of cooling water. There are usually three ways of lubrication: water lubrication, thin oil lubrication and dry lubrication. The reasons for the sharp rise in shaft temperature are: first, poor bearing installation quality or bearing wear; second, failure of the lubricating oil system; third, inconsistent lubricating oil label or poor oil quality; fourth, failure of the cooling water system; fifth, due to some reason Make the unit vibrate; Sixth, the bearing oil leaks and the oil level is too low.
Processing
1. Water-lubricated bearings. The lubricating water should be strictly filtered to ensure the water quality. The water should not contain a large amount of sand and oil to reduce the wear of the bearing and the aging of the rubber.
2. Thin oil lubricated bearings generally adopt self-circulation, adopting oil slinger and thrust plate, and self-circulating oil is supplied by the rotation of the unit. Pay close attention to the working conditions of the slinger ring. The slinger ring is not allowed to be stuck, the fuel supply to the thrust plate and the oil level of the fuel tank.
3. Lubricate the bearings with dry oil. Pay attention to whether the specifications of the dry oil are consistent with the bearing oil, and whether the oil quality is good, add oil regularly to ensure that the bearing clearance is 1/3~2/5.
4. The sealing device of the bearing and cooling water pipe is intact to prevent pressure water and dust from entering the bearing and destroying the normal lubrication of the bearing.
5. The installation clearance of the lubricated bearing is related to the unit pressure of the bearing bush, the linear speed of rotation, the lubrication method, the viscosity of the oil, the processing of the parts, the installation accuracy and the Baidu of the unit vibration.
Unit vibration
(1) Mechanical vibration, vibration caused by mechanical reasons.
Reasons: First, the hydraulic turbine is too heavy; second, the axis of the turbine and the generator is not right, and the connection is not good; third, the bearing is defective or the gap adjustment is improper, especially the gap is too large; fourth, there is friction between the rotating parts and the stationary parts. collision
(2) Hydraulic vibration, the vibration of the unit caused by the loss of balance of the water flowing into the runner.
Reasons: One is that the guide vane breaks the bolt and breaks, which makes the opening of the guide vane vary, so that the flow of water around the runner is uneven; the other is that there is debris in the volute or the runner is jammed, causing it to flow into the runner. The water flow around is uneven; thirdly, the water flow in the draft tube is unstable, which causes the water pressure of the draft tube to periodically change, or air enters the volute of the turbine, causing the vibration of the unit and the roar of the water flow.
(3) Electrical vibration, the vibration of the unit caused by the loss of balance or sudden change of electrical quantity.
Reasons: One is the serious imbalance of the three-phase current of the generator, which causes the imbalance of the three-phase electromagnetic force; the other is the instantaneous change of the current caused by the electrical accident, which causes the generator and the turbine to be unable to synchronize their speed instantly. ; Third, the gap between the stator and the rotor is not uniform, causing the instability of the rotating magnetic field.
(4) Cavitation vibration, the vibration of the unit caused by cavitation.
Reasons: First, the vibration caused by hydraulic imbalance, the amplitude of which increases with the increase of the flow; the second is the vibration caused by the unbalance caused by the heaviness of the runner, the poor connection of the unit, and the eccentricity, the amplitude of which increases with the increase of the speed. ; The third is the vibration caused by the electric surface, the amplitude increases with the increase of the excitation current, and the vibration can disappear when the excitation is removed; the fourth is the vibration caused by cavitation, whose amplitude is related to the regionality of the load, sometimes interrupted, sometimes severe, At the same time, knocking noise is generated in the draft tube, and there may be a swing phenomenon on the vacuum gauge.
The temperature of the bearing bush of the unit is increased or too high
Reason
1. Reasons for maintenance and installation: leakage of oil basin, incorrect installation position of piping tube, non-compliant tile gap, abnormal vibration of the unit caused by installation quality, etc.;
2. Reasons for operation: operating in the vibration zone, oversight of abnormal bearing oil quality and oil level, failure to replenish oil timely, interruption of cooling water, oversight of water shortage, and long-term low-speed operation of the unit.
Processing
1. When the tile temperature rises, first check the lubricating oil, add oil in time or contact to change the oil; adjust the cooling water pressure or switch the water supply mode; test whether the vibration of the unit exceeds the standard and stop the vibration if the vibration cannot be eliminated;
2. If the temperature protects the outlet, it should be monitored and shut down normally, and check whether the bearing bush is burnt out. Once the bearing bush is burnt, it should be replaced with a new tile or re-scraped.
Five, speed control failure
When the governor opening is fully closed, the runner cannot stop until the guide vane opening cannot be effectively controlled. This situation is called speed control failure. Reasons: First, the guide vane connection is bent, and the guide vane opening cannot be effectively controlled, causing the guide vane to close and the unit cannot be stopped. It should be noted that some small units do not have a brake device, and the unit cannot be stopped for a while under the action of inertia. At this time, don’t mistake it for being shut down. If you continue to close the guide vanes, the connecting rod will bend. The second is that the speed control fails due to the failure of the automatic speed governor. When the hydraulic turbine unit is operating abnormally, especially when the unit is in a crisis of safe operation, it should immediately try to shut down and deal with it. Reluctant operation will only amplify the failure. If the governor fails and the guide vane opening mechanism cannot be stopped, the main valve of the turbine should be used to cut off the water flow into the turbine.
Other treatment methods: 1. Regularly clean up the debris in the water guiding mechanism, keep it clean, and refuel the moving parts regularly; 2. The inlet water port must be equipped with trash racks and be cleared frequently; 3. The turbines of any vehicle installations should be replaced in time Brake pads, add brake fluid.
Post time: Jan-06-2022
