Three phase asynchronous motor maintenance from these aspect
Release time：2020-05-08 15:55Number of views：Originate：
There are many types of motor failure, the causes of motor failure may include: poor assembly with mechanical equipment; long-term high load operation; power supply out of phase, voltage or frequency mismatch. The winding is short circuited, open circuited or grounded, and the bearing is not working properly. The interior and exterior are not clean for a long time, the working environment is dirty or the ambient temperature is too high. There are great differences in the possibility of failure of each part of the motor. Therefore, we know that a thorough understanding of the composition and working principle of the motor can greatly help us to maintain and repair the motor. The principle of the motor is not repeated here. In order to attract the attention of the basic knowledge, the basic parts of the motor will be briefly described here. The motor is mainly composed of rotor, winding and insulating material, stator frame, bearing at both ends and end cover. It is estimated that more than 90% of motor damage is caused by inadequate routine maintenance and service by maintenance personnel. Follow the three-phase asynchronous motor manufacturers to see the three-phase asynchronous motor daily maintenance methods.
Basic methods of maintenance and repair of three-phase asynchronous motor;
Look: the normal operation of the motor has a lot to do with the surrounding environment. Therefore, in the daily inspection, it is necessary to check the water leakage and dripping around the motor (this will lead to low insulation of the motor, resulting in failure and burnout), and check whether there is any object outside the motor that affects its ventilation and cooling environment. At the same time, it is very important to monitor the working current of the motor regularly. In order to ensure the cooling and cooling effect of the motor, it seems that the high-frequency regular treatment of the dirt on the motor exterior, fan end cover and fan blade has little effect, but in fact it accounts for a large proportion of the daily maintenance of the motor.
Touch: an experienced mechanic can judge the operation of the motor by touching his hand. The accumulation of long-term experience is also an important part of motor routine inspection and maintenance. Touch the temperature around the motor with the back of your hand. If the overall temperature of the motor is higher than the normal working temperature, it is necessary to check the load, assembly and ventilation of the motor in combination with the working current of the motor. However, when the bearing is in good condition, the temperature of both ends is usually lower than that of the middle winding.
Test: when the motor stops working, the insulation resistance of motor phase to phase or phase to ground shall be measured regularly (preferably monthly) with insulation meter, and the insulation defects shall be found in time by comparing with the test results of last month. Taking a three-phase asynchronous motor as an example, the unbalance of the three-phase resistance measured cannot exceed 2%. When checking the insulation resistance, if it is lower than 5 ω, it is necessary to analyze the cause of this abnormal situation. Check whether the insulation is damped, or the grounding caused by poor winding insulation, etc. If there is no obvious problem in balancing the three-phase resistance through the bridge test, the insulation is completely affected by humidity. After drying, run the motor again to see if the condition returns to normal. If the three-phase resistance of the stator is unbalanced, the grounding point can be found through the three-phase grounding withstand voltage test and turn to turn test of the motor coil. Do not turn off the heating switch of the motor with moisture drying and electric heating functions unless there are special circumstances. If the motor is found to be immersed in water, remove the motor and pull it out of the rotor. After drying with compressed air, bake the motor from both ends of the motor stator with baking lamp until the motor insulation is normal.
Listen: the judgment of motor operation sound is also an important part of motor inspection and maintenance. Because the noise in the computer room is very high, it is very important to use auxiliary tools such as screwdriver or monitor stick. Close to both ends of the motor, through long-term experience accumulation, we can not only find the bad vibration of the motor and its driving equipment, but also judge the oil quantity inside the bearing. Measures such as adding oil bearing or replacing new oil bearing in time can obviously avoid locking, rounding and burning out of motor bearing due to lack of oil and dry grinding.
Do: some motor abnormalities may not be easily detected, and measures taken according to the maintenance cycle (usually one month), such as tightening, wiring fastening, disassembly and inspection, cleaning and maintenance, etc., often cause unexpected effects. If you don't look or do, or just look or don't do, it will eventually lead to failure or accidents. For example, the loose and virtual contact of the motor wiring stud leads to phase loss combustion, and the motor is burnt due to the failure of timely supplement of lubricating oil or replacement of bearing. Most mistakes can be prevented and avoided by observing, touching, measuring, doing and listening carefully. These basic maintenance methods are of great significance to motor maintenance and routine maintenance, but they are far from enough. As mentioned before, it is the premise for us to improve the efficiency and output of motor to accumulate experience, summarize and refine continuously, and improve the maintenance and repair ability of individual motor.