Regular maintenance of asynchronous motors is an important measure to eliminate hidden troubles and prevent failures. Regular maintenance can be divided into two types: regular minor maintenance and regular overhaul. The former does not disassemble the motor, while the latter requires the entire motor to be disassembled for maintenance.

1. Regular minor repairs Periodic minor repairs are general cleaning and inspection of the motor and should be carried out frequently. Minor repairs include:

① Clean the motor casing to remove dirt accumulated during operation.

② Measure the insulation resistance of the motor. After the measurement, be sure to reconnect the wires and tighten the terminal screws.

③ Check whether the motor end cover and anchor bolts are tight.

④ Check whether the motor grounding wire is reliable.

⑤ Check whether the transmission device between the motor and the load machinery is in good condition.

⑥ Remove the bearing cover, check whether the lubricating oil is dirty or dry, and refuel or change the oil in time. After the processing is completed, pay attention to the end caps and fastening screws.

⑦ Check whether the attached starting and protection equipment of the motor is intact.

2. Regular overhaul: Regular overhaul of asynchronous motors should be carried out in conjunction with the overhaul of load machinery. Agricultural electric motors can be carried out once every winter in conjunction with the farming season. During overhaul, the motor should be disassembled for inspection and repair of the following items:

① Check whether there is mechanical damage to each component of the motor. If so, repair it accordingly.

②Clean the disassembled motor and starting equipment to remove all sludge and dirt. During cleaning, pay attention to the insulation condition of the windings. If the insulation is dark brown or dark brown, it means that the insulation has aged. Pay special attention to this insulation so that it does not fall off due to collision. If any peeling is found, local insulation repair and painting should be carried out.

③ Remove the bearing and clean it thoroughly by immersing it in kerosene or gasoline. After washing away the remaining grease and dirt between the bearing frame and the steel balls, clean it again with clean coal (gasoline) oil. The cleaned bearings should rotate flexibly and the bearing clearance should be measured. If the bearing surface is rough, it means the grease is unqualified; if the bearing surface is discolored (blue), it means it has been heated and annealed. According to the inspection results, the grease or bearings should be replaced, and the cause of the failure should be eliminated (such as removing sand, iron filings and other debris in the oil; installing the bearings correctly, etc.).

When the bearing is newly installed, oil should be added from one side. Grease only accounts for 1/2 to 2/3 of the bearing volume. If the oil is filled too full, it will heat up and flow out. Lubricating oil can be calcium-based grease, sodium-based grease or lithium-based grease.

④ Check whether there is any fault in the stator winding. Use a megohmmeter to measure the winding insulation resistance to determine whether the winding insulation is damp or has a short circuit. If so, it should be handled accordingly. Use a bridge to measure whether the three-phase resistance is balanced. If not, handle it accordingly.

⑤ Check the stator and rotor cores for wear and deformation. If any wear or bright spots are observed, it means there may be friction between the stator and rotor cores. Use a file or scraper to scrape down the bright spots. If there is any deformation, it should be repaired accordingly.

⑥After carrying out the above repairs and inspections, assemble and install the motor.

⑦The installed motor should be inspected after repair. After each test project is completed and the requirements are met, it can be operated with load.