Motor bearing temperature?
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Our facility has an explosion-proof asynchronous motor with a power rating of 55 kW. The bearings used in this motor are of the 6313 type. When the temperature inside the room was 42°C, the temperature at the front bearing of the motor was 80.2°C, while the temperature of the motor casing was 74.4°C. It felt hot to the touch. Is such a situation normal? What extent of damage is caused to the motor itself by long-term operation? Thank you!
Abnormal: the temperature of the motor’s front bearing is above 70 degrees, which can cause significant damage to the motor; it is recommended to shut down the machine for inspection
Generally, a bearing temperature exceeding 70 degrees Celsius is abnormal; it is recommended to conduct a check
Has the motor stator temperature been monitored? Is it a problem with the winding? Is there a standard for this question? Generally, what temperature threshold is considered abnormal? Like 100°C?
It’s abnormal; it should be checked. During mechanical operation, the areas where bearings are installed can reach a certain temperature; it is normal for the machine’s casing not to feel hot to the touch
I’m not sure what the insulation class of the motors you use is. Insulation class B can withstand a continuous operating temperature of 130°C, while class F can handle 155°C continuously. The allowable temperature for motor bearings (using either a thermometer or an embedded temperature sensor) should not exceed 95°C for rolling bearings.
Stop the machine immediately for inspection; check whether the bearings are worn, as well as the clearance between the shaft and the bearings
Determining high bearing temperatures: At present, motor manufacturers must check the bearing temperature of motors before they leave the factory. While there is a limit of a maximum temperature of 95°C for these tests, there is no unified standard regarding what level of temperature constitutes a high bearing temperature during operation. As a general rule, if the bearing temperature rises by no more than 35K after the motor has been running for 1.5 to 2 hours, it can be considered normal. However, if the temperature reaches 65°C after only a short operating time (such as 15 minutes), or if it remains above 65°C even after 1.5 hours of operation with no sign of decreasing, or if the stable temperature exceeds 75°C within less than 1.5 hours, all these situations can be regarded as high bearing temperatures. (The values of 65°C and 75°C apply in summer; in cold winters, 55°C and 65°C are more appropriate.) With your ambient temperature as high as 42 degrees, it is also possible for the motor bearings to reach high temperatures
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It’s abnormal; the machine should be shut down for inspection. It’s possible that the motor has been in use for many years, so it’s necessary to check the concentricity of the bearings
**The temperature of standard rolling bearings generally should not exceed 75 degrees Celsius, while that of sliding bearings generally should not exceed 70 degrees Celsius