The air gap between the stator and the rotor of the motor is very small, which is easy to cause collision between the stator and the rotor; the abnormal vibration or noise of the motor can easily cause the motor to heat up; the bearing does not work properly, which will definitely cause the motor to heat up; the power supply voltage is too high, and the excitation When the current increases, the motor will overheat; the short circuit of the winding, the short circuit between turns, the short circuit between phases and the open circuit of the winding will cause the motor to be hot.
1. Abnormal vibration of the motor: If the motor is working, the bearing of the motor itself is worn, resulting in poor balance performance. In this case, the motor will generally become hot. If the parts of the motor are delivered, it will cause a different noise than before, and it will also cause the motor to become hot.
2. The voltage of the motor is unstable: if the motor is working, the voltage is relatively high or low, which will cause the motor to become hot to a certain extent. If the voltage is too high, it may also burn the motor or the insulation outside the motor. Therefore, when using the motor, try to choose an environment with a stable voltage to avoid fire caused by the motor being hot.
3. The air gap between the stator and the rotor of the motor is relatively small: if the air gap is small, it will easily cause the two to collide with each other and generate heat. These are the reasons that cause the motor to get hot. Generally, small or medium-sized motors have smaller air gaps, but some large motors have larger air gaps. Therefore, in general, the size of the air gap and the gap between the stator and the rotor are the main reasons for the motor to become hot.
4. Measure the current of the motor with a clamp meter to see if the current value is too large. If so, the motor may be damaged, or the load may be too heavy to carry.
5. You can disconnect the load of the motor to see if this happens under no-load conditions.
6. When the load is disconnected and the power is off, turn the motor rotor by hand to check whether the rotation is smooth and whether the bearing is damaged.
7. Measure whether the contactor signal that controls the motor is in place, whether the contactor is always closed, and whether the thermal relay has tripped and automatically reset. It is also possible that the starting capacitor of the motor is damaged, replace the starting capacitor.
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Precautions when starting the motor:
(1) When the motor is found to be on fire or the vibration is too large after starting, the brake should be opened immediately and the machine should be stopped for inspection.
(2) Under normal circumstances, the factory motor is allowed to start twice in a cold state, and the interval between each time is not less than 5 minutes; it is started once in a hot state. Only when dealing with accidents, and motors whose starting time does not exceed 2-3 seconds, can be started one more time.
(3) If it is found that the running direction is reversed after starting, the brake should be opened immediately, the power will be cut off, and the wiring of any two phases of the three-phase power supply should be exchanged and then restarted.
(4) If the power switch is turned on and the motor does not turn, the brake should be opened immediately, and the cause should be identified and the fault eliminated and then restarted.
When the motor is running under load, there is power loss in the motor, which will eventually become heat energy, which will increase the temperature of the motor and exceed the ambient temperature. The value by which the motor temperature is higher than the ambient temperature is called the ramp-up. Once the temperature rises, the motor will dissipate heat to the surroundings; the higher the temperature, the faster the heat dissipation. When the heat emitted by the motor per unit time is equal to the heat dissipated, the temperature of the motor will no longer increase, but maintain a stable temperature, that is, in a state of balance between heat generation and heat dissipation.
