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In order to ensure the safe and reliable operation of the three-phase asynchronous motor. We need to strengthen the monitoring and maintenance work. The editor of Dalan Motor has sorted out the matters needing attention for everyone to learn.
1. Temperature monitoring
If the motor is overheated (temperature exceeds the allowable value), it will damage the insulation, shorten the service life of the motor, or even burn the motor. Therefore, the motors in operation should pay close attention to the temperature and temperature of each component. Do not exceed the allowable value. The allowable temperature is + 40 ℃ in the surrounding environment, and the maximum allowable temperature of the external temperature of the motor should not exceed 75 ℃ (low-voltage motor)
2. The rated current value marked on the nameplate of the current monitoring motor refers to the value when the ambient temperature is + 40 ℃. When the ambient temperature rises and falls, the allowable current of the motor can be increased or decreased. The current of the motor in operation should not exceed the allowable current at the corresponding ambient temperature, otherwise the coil of the motor will be damaged due to overheating.
3. Voltage monitoring power supply
Voltage fluctuation is one of the reasons that affect the motor heating. If the power supply voltage is too high, the excitation current of the motor increases, the iron core will overheat, and the power supply voltage is too low. The electromagnetic torque of the motor will decrease by the square of the voltage (voltage reduction by 10% and torque by 19%). If the load of the motor is unchanged, the rotor current and stator current will increase, and the heating of the stator and rotor windings will increase.
Fourth, pay attention to the vibration, sound and smell of the motor
(1) Allowable vibration of the motor: speed (rev / min) 3000, vibration standard (mm) ≤ 0.06 1500 ≤ 0.10 1000 ≤ 0.13 750 ≤ 0.16 If the motor vibrates too much, it must be checked in detail whether the foundation is firm and the anchor screws are loose , Whether the pulley or coupling is loose or not. In addition, the axis of the motor and the dragged machine are not in a straight line, the rotor is eccentric, the bearing lacks oil or the copper ball is damaged, and the fan blade is defective, etc., can also cause vibration.
(2) Vibration can also be caused by electrical reasons, such as broken rotor bars, short circuit of stator windings, phase failure, wiring error, individual branch circuit breakage, etc. may cause vibration, the cause should be found and eliminated, in addition, attention The series movement of the motor in operation should not exceed 2-4 mm. Abnormal sound and smell are signs of motor failure.
(3) The sound of the motor should be uniform during normal operation, without noise and strange noise. When the motor is overloaded or lacks phase, it will emit a huge hum. When the shaft permanent ball is damaged, a grunt will be heard. When the rotor is fixed, the rotor will emit an uneven rubbing noise, and it will be emitted due to local overheat odor. When the motor is overloaded for a long time and the winding is overheated, a choking smell of insulating paint can be smelled. When the motor is found to have abnormal sound and smell, it should be stopped to find the cause.
----- Responsible Editor: Dalan Oil Pump Motor 02-Procurement Consultant
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