Instructions and precautions for the use of three-phase asynchronous motors cover a wide range of aspects from pre-installation preparation to daily operation and maintenance, and the following are detailed instructions and precautions for use.

A. Operating Instructions

a) Preparation before installation

1. Check the package and appearance: Before opening the motor, check whether the package is intact and there is no moisture phenomenon. After unpacking, carefully remove the dust and antirust layer on the motor, and check whether the motor has been deformed or damaged during transportation.

2. Check the fastening parts: Check whether all the fastening bolts are tightened, whether the spring washers are missing, and whether the shell parts are properly connected.

3. Check the data on the nameplate: Compare the data shown on the nameplate, such as voltage, power, frequency, connection, speed, etc., with the power supply and load to make sure that they match each other.（To learn more about motor nameplates please click on the link. ）

4. Measure insulation resistance: Use 500V insulation resistance meter to determine the insulation resistance shall not be less than 0.5MΩ. After long-distance transportation or long-time unused motors, the insulation resistance between stator winding and casing should be checked, and its value shall not be lower than the specified value, otherwise the motor must be dried. For motors that have not been used for a long time or are stored in a humid environment, an electrician must be contacted to check whether the insulation is qualified before use.

5. Check the rotation situation: Trigger the rotor shaft of the motor to check whether the rotor can rotate freely, and whether there is any noise or jamming phenomenon when rotating.

6. Check ventilation and lubrication: Check whether the ventilation of the motor is good, make sure that the ventilation slots are not blocked by oil and other debris. Meanwhile, check the lubrication condition of the bearings, if the lubrication is insufficient, add suitable lubricant in time.

7. Special requirements: For motors with oil injection and discharge, make sure the grease injection pipe is free. For motors with bearing temperature measurement, make sure that the bearing monitoring device is well set up, and avoid the lead wire of the temperature measurement device at the fan end from touching the fan.

b) Installation

1. Select a well-ventilated, dry and clean place for installation to ensure air circulation and avoid installation in an environment susceptible to humidity and corrosive gases.

2. Select a solid and level foundation for installation, and the installation foundation should be firm enough to withstand the weight of the motor and the vibration generated during operation. There should be vibration isolation pads or elastic materials between the foundation and the ground, and the foundation dimensions should be designed according to the specifications and weight requirements of the motor.

3. If the motor and load are connected by coupling, the coupling should be installed correctly to ensure that the coaxiality of the two shafts is within the permissible range, so as to avoid excessive vibration or damage to the motor due to different shafts.

4. Installation should ensure that the centerline of the motor is the same as the centerline of the driven machine, check whether the screws and pins of the coupling or spur gear are tight, and whether the unit rotates flexibly.

5. Check whether the fastening bolts of the motor are tight and secure, whether the bearings are lacking oil, and whether the shell is reliably grounded or zeroed.

6. Check whether the motor protection device meets the requirements and whether it is installed firmly and reliably.

7. Check whether the wiring of the starting equipment is correct, whether the starting device is flexible, whether the contact is good, and whether the metal shell of the starting equipment is reliably grounded or zeroed.

c) Wiring

1. Select the power supply cable correctly according to the size of the motor current and conditions of use. 2.

2. The wiring method of the motor should be according to the wiring instruction diagram in the terminal box and the voltage on the nameplate. Be sure to follow the wiring method on the motor nameplate.

3. The phase sequence U, V, W of the motor should correspond to the phase sequence L1, L2, L3 of the connected external power supply.

4. When wiring, the cable core should be placed between two bow washers or crimp plates, and the grounding core should be placed between the bow washers of the grounding screw, and should be reliably connected.

5. After the wiring is completed, the box should be checked for debris, dust, and whether the connection is in accordance with the power supply voltage and the motor's nameplate data.

d) Starting and operation

1. Before starting, the power supply voltage, wiring and coupling should be checked again to see if they are normal. 2.

2. Limit the number of consecutive starts of the motor according to the technical requirements of the motor.

3. Monitor the power supply voltage: the range of voltage variation should not be more than or less than 10% of the rated voltage, if it is less than this range, the load should be reduced to run appropriately. At the same time, the three-phase voltage imbalance should not be too large, the difference between any two-phase voltage should not exceed 5%, otherwise the motor will heat up too quickly. (To learn more about motor overheating please click the link)

4. monitor the running current: under normal condition, the running should not exceed the rated value on the nameplate, meanwhile, it should also pay attention to whether the three-phase current is balanced or not, and the difference of current between any two phases should not be more than 10% of the rated current, otherwise, it indicates that there is a fault in the motor, especially pay attention to whether there is phase loss running.

5. Monitor the temperature: Check the temperature of the motor regularly, the temperature rise should not exceed the limit allowed on the motor nameplate. The method of checking the temperature rise can be carried out by installing a temperature measuring device on the motor, or touching the motor shell by hand (but be careful to prevent burns). Rolling bearings should not be allowed to heat up more than 95℃, and sliding bearings should not be allowed to heat up more than 80℃.

6. Listening to the sound and vibration: when the motor is running normally, the sound is even, the operation is smooth, and there is no smell of insulating paint and burnt odor. If abnormal sound, violent vibration, etc., that the motor overheating or other faults, should be immediately shut down for inspection. (To learn more about the abnormal sound of the motor please click the link)

7. Monitor the transmission device: pay attention to the pulley or coupling at any time whether there is any looseness, whether the transmission belt has any slipping phenomenon, whether the belt joint is intact.

8. Check the fuse: should always pay attention to

B. Precautions

1. power supply stability: three-phase asynchronous motors need stable and reliable power supply, excessive fluctuation of power supply voltage or frequent tripping should be avoided.

2. Load characteristics: Select the appropriate motor type and rated power according to the load characteristics to avoid overload operation.

3. operation temperature: three-phase asynchronous motor will generate some heat during operation, and it should be ensured that the temperature of the motor shell does not exceed the specified range. Usually, when there is no thermometer, you can use the back of your hand to test the temperature of the motor shell, if your hand can not stay on the shell, it means that the motor has been overheated.

4. Operation environment: In addition to the installation environment mentioned above, long-term operation of three-phase asynchronous motors should be avoided in harsh environments such as high temperature, humidity and corrosive gases.

5. Maintenance: Maintenance should be carried out in accordance with the specified cycle, clean dust and sundries in time, and check whether the wiring is loose and the insulation is damaged, etc. 6.

6. Stopping and parking: The motor should be stopped by deceleration to avoid damage caused by sudden cutting off the power supply. Parking location should be selected dry and clean place, and require appropriate temperature of the storage environment. If it needs to be parked for a long time, it should be treated with anti-rust treatment and rotated regularly to prevent the bearings from rusting.

In summary, the instructions and precautions for the use of three-phase asynchronous motors cover a variety of aspects such as pre-installation preparation, installation, wiring, startup and operation, as well as routine maintenance, etc. In the course of use, the instructions and precautions should be strictly observed. In the process of use, relevant regulations and precautions should be strictly observed to ensure the safe and reliable operation of the motor.