Overview of abnormal electric motor temperature

The common heating components of a motor are generally windings and bearings. The apparent temperature abnormalities are generally divided into the following categories: bearing temperature is too high, winding temperature is too high, housing temperature is too high, etc.

Bearing temperature is too high

The hazards of excessive bearing temperature

The motor bearing is the main component supporting the rotor. If the temperature is too high and it is not solved, it will cause the motor bearing loss to increase and the efficiency to decrease; it may even cause the motor bearing to seize and cause the motor to stall suddenly; finally, the entire traditional system Damaged. Therefore, it is very important to monitor the condition of the motor bearings.

Winding temperature is too high

The harm of high winding temperature

As the most important component for the conversion of electrical energy into mechanical energy, the monitoring of the status of motor windings is very important. Through monitoring of winding temperature, many problems can be reflected, such as excessive load caused by bearing problems, winding insulation damage, abnormal load end, etc. Will cause the winding temperature of the motor to be too high. Excessive temperature will damage the insulation of the winding, and will accelerate the loss of bearing grease when conducted to the bearing; therefore, monitoring the temperature of the winding is also essential.

Reasons for high winding temperature

The reasons that cause the winding temperature to be too high generally have the following categories:

Abnormal load: The user of the motor will select a suitable motor according to the actual use before purchasing the motor. A sudden change in the load during operation will cause the winding temperature of the motor to change significantly. Sudden changes in general load can also cause sudden changes in motor current.

Abnormal heat dissipation: various losses will occur during the operation of the motor. Among them, stator/rotor loss and iron loss are mainly reflected in the temperature of the winding, which requires components such as heat dissipation ribs on the casing to reduce the heat loss of this part. When the temperature of the winding is found to be too high, check whether the air inlet or outlet of the motor is blocked by dirt and whether the heat dissipation ribs are damaged.

Winding aging: The internal temperature of the normal running motor is generally high. For the inverter-powered motor, there are still harmonic problems. These problems will cause the aging of windings and magnets. When the aging reaches a certain level, it will As a result of the performance degradation of the motor, the temperature of the windings will rise significantly from the normal operating condition of the motor to overload operation. Generally, the temperature of the windings caused by this kind of problems changes slowly, and it is not prone to sudden temperature rises. The temperature of the winding is too high compared to the temperature of the motor bearing. It is a slower abnormal phenomenon. Generally, the temperature of the winding is too high will be accompanied by various other abnormalities. However, the temperature monitoring of the winding is compared with the monitoring of other values ​​(such as fan Abnormal vibration caused by damage is relatively simple, so the monitoring of winding temperature is currently the most common method for motor condition detection.

Case temperature is too high

The importance of case temperature monitoring:

For larger motors, the method of embedded temperature monitoring equipment is generally used to monitor the bearings or windings of the motor, but for smaller motors, the method of embedded temperature monitoring equipment is sometimes not easy to implement.

Similarly, some motors are not pre-embedded with temperature monitoring probes when they leave the factory. At this time, non-contact temperature measurement methods can be used to conduct inspections on the motors by professional staff on duty instead of pre-embedded temperature monitoring probes. Similarly, it can act as an early warning of excessive temperature.

Temperature limits of various parts of traditional motors

It can be seen from the above that in the actual use of the motor, many faults will cause the occurrence of abnormal temperature. Therefore, the monitoring of the temperature is very important in the actual use of the motor. In this regard, the national standard GB 14711 is for the safe use of the motor.