How to maintain the three-phase asynchronous ?
Monitoring in motor operation
After the three-phase asynchronous motor is put into operation, it should be monitored and maintained frequently to understand its working condition and find out the abnormal phenomenon in time to give reasonable treatment and eliminate the fault in the bud. In the process of operation monitoring, the on-site maintenance personnel can roughly judge the operation status of the motor by listening, watching, smelling and touching with working experience.
For example, when the sound issued during the operation of the motor is a regular crisp sound, commonly known as “machine music”, it means that the motor is running in light load or normal operation state; if a very dull sound is issued, it means that the motor is in heavy load operation state; if there is a burnt or pungent odor when the motor is running, it means that the temperature rise of the motor is too high. The motor should be stopped as soon as possible.
The monitoring work in motor operation mainly includes the following aspects.
(1) Monitor the change of power supply voltage. Normally, the fluctuation value of power supply voltage should not exceed ±10% of the rated voltage, and the difference between any two phase voltage should not exceed 5%. In order to monitor the power supply voltage, it is better to install a voltmeter and changeover switch on the motor power supply.
(2) Monitor the running current of the motor. Under normal condition, the running current of the motor should not exceed the rated current indicated on the nameplate. At the same time, you should also pay attention to whether the three-phase current is balanced. Normally, the difference between any two phases should not be more than 10% of the rated current. For motors with larger capacity, current meter should be installed to monitor; for motors with smaller capacity, clamp current meter should be used to measure at any time.
(3) Monitor the temperature of the motor. The temperature rise of the motor should not exceed the allowed temperature rise limit indicated on the nameplate. Check the temperature rise of motor can be measured by thermometer. The easiest way is to touch the motor shell with the back of hand, if the motor is hot, it means the motor is overheated, at this time, you can sprinkle some drops of water on the shell, if the water vaporizes sharply and there is “sizzling” sound, it means the motor is obviously overheated.
