In agricultural production, all kinds of production machinery are widely used to drive the motor, and the correct selection of the motor supporting the mechanical load can make the motor run in the most economical and most reasonable way, so as to achieve the purpose of reducing energy consumption and improving efficiency. . First, the choice of motor motor selection, we must first understand the mechanical load characteristics of the motor, according to the type and characteristics of the mechanical load to select the motor rated capacity, rated speed, rated voltage and type. To select a motor for a production machine, the power of the motor must be selected first. The power of the motor is usually selected according to the needs of the production machine load. At the same time, the workload of the load must also be considered. That is to say, the selected motor should be adapted to the continuous, short-term or intermittent cycle operation of the mechanical load. When power is used, it cannot be too large or too small. Selecting a small one can not guarantee the normal operation of the motor and the production machinery. If the selection is large, it can ensure normal operation, but it is not economical. The motor capacity cannot be fully utilized, and the motor can not always be fully loaded, making the efficiency and power factor low. Secondly, according to the power supply voltage conditions, it is required that the rated voltage and frequency of the selected motor match the voltage and frequency of the power supply. The speed of the motor must be selected according to the requirements on the production machine nameplate, otherwise it may change the performance of the production machinery. In addition, the motor's structure, protection, cooling, and installation form should be adapted to the requirements of the use of environmental conditions, and must be installed, commissioned, and repaired to ensure that the motor can operate safely and reliably. Second, the maintenance of the motor Before starting the motor, you should first check whether the assembly of the motor is flexible, whether the insulation resistance of the winding meets the requirements, whether the rotating part is blocked, but also check whether the starting and protection equipment of the motor meets the requirements, such as whether the motor grounding device is In good condition, the selected low voltage circuit breakers, contactors, and fuses are correctly configured. When starting the motor, the number of starts can not be too much, otherwise the motor may be overheated and burned out. During motor operation, the voltage, current, and temperature should be closely monitored. The operating voltage of the motor should be strictly controlled within the range of change. Otherwise, the motor may overheat. Similarly, the current must not be too high or too low. Because the voltage is constant, the operating current is Reflects the load dragged by the motor. The mechanical load is too heavy. The motor will run for a long time and the current will increase. The motor will be overheated. If the motor load is too light, a “big horse-drawn car†will be formed and the motor capacity will not be able to Take advantage of. In routine maintenance, you should also closely monitor the motor for abnormal noises or vibrations, check whether the screws are loose or loose, and regularly check and maintain the motor to remove external dust in a timely manner and replace the oil regularly. Third, the common motor failures Common motor failures are mainly rotor broom, vibration, windings or inter-layer short circuit, winding grounding, stator winding phase operation, the stator windings end to end, three-phase current unbalanced, iron core silicon steel insulation Damage and so on. When the motor vibrates, it will generate noise and additional load, which may be caused by the transmission failure, or it may be caused by the motor itself. For example, the rotor has poor dynamic balance, the shaft is bent, the installation is not in place, and the fastener is loosened. The main reasons for the lack of operation of the motor are the fuse blowing of the line fuse or improper setting of the current, and the poor contact of the switch contacts. If the running time is too long, the motor will be burned. Unbalanced three-phase voltage of the power supply or short circuit between the windings will cause unbalance of the three-phase current. The reverse connection of the stator windings will cause the motor temperature to rise. The grounding or short circuit of the windings will cause the current to be too large. Insulation damage of the iron core silicon steel sheet will cause the motor Overheated and so on. In short, in actual operation, it is necessary to correctly analyze the causes of motor failures, strengthen inspections and maintenance, and identify and eliminate motor failures as soon as possible to ensure the safe operation of the motor. Author: Xinjiang Economic and Management College, Shihezi University, Xinjiang
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