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October 23, 2019
There are many reasons for the failure of the hydro turbine. The following is a description of the various faults related to the changes in the state quantities. Most faults occur, and some state quantities change. If you classify them, it is much more convenient to manage. These state quantities are called related state quantities. For the water supply and drainage device, it refers to the increase of water pressure, flow rate, vibration, etc. Similarly, for the turbine bearing, it refers to the amount of wear of the gold. Bearing temperature, vibration value, etc. J refers to noise, vibration, etc. for the casing, runner, and suction pipe. For oil pressure devices, it refers to oil pressure, oil level, deceleration valve operation time and number of times, etc. The device refers to an increase in the amount of the filler whistles, the amount of water leakage, and the like.
One of the important purposes of preventive maintenance is to use daily monitoring of temperature, vibration, etc., to predict the future. There are two ways to do this. One is to find out the trend from the highest daily or monthly value that has been advertised, and then predict when it will cross the given limit. Another way is to find the signs of anomalies from the changes in the above data. To effectively implement these methods, consider the following monitoring rules.
(1) Turbine bearing temperature
The turbine bearing temperature changes depending on whether the rotating part and the bearing itself are normal, as well as the amount of cooling water, water temperature, room temperature, oil temperature, and the like.
Before the bearing failure occurs, the temperature change rate is abnormal in most cases. The actual situation shows that the time change rate of the bearing temperature is mainly affected by the operating conditions (the uniformity of the oil temperature in the bearing oil tank, the rising rate of the unit speed, etc.). ) controlled. In the case of mixing water into the oil sump, the bearing temperature will be shorter.
(2) Turbine vibration (or acceleration)
The vibration level of a turbine bearing or the like changes in addition to a part of an abnormality such as rotation, and also changes due to the operating state of the turbine (for example, at the time of starting, stop, load, etc.), so the alarm limit is set. Depending on the various states, the measured value at the beginning of the operation is usually set to the initial value.
(3) Turbine indoor noise
Since the noise is transmitted by the vibration in the machine with air as the medium, the frequency component is the same as the basic component of the vibration. Therefore, if the frequency of the noise is analyzed and monitored, the abnormality can be detected early. In the event of a machine failure, there is not always a significant, large change in the positive amplitude. In many cases, although the sound pressure level is not high, the pitch changes in the frequency range.
The above is a brief description of the considerations and technical status of the turbine preventive maintenance system. These are new fields in the history of turbine development. In the future, with the advancement of hardware technology (sensors, etc.), software technology (for fault prediction) The computing system, etc.) will also be continuously improved.