The problem of excessively high temperatures in motor bearings
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This post was last edited by WQC on 2015-8-17 at 16:18. I would like to ask everyone: We have a three-phase asynchronous motor whose vibration level is not high; the vibration speed at each point is only around 1 mm/s, and the acceleration is also low, with a maximum of around 0.3g； However, during operation, it was found that the temperature at the highest point on the outer surface of the bearing on the side closest to the coupling was around 87°C, while the temperature of the motor casing was around 65°C. In the speed spectrum, only the amplitude at 2 times the frequency of the alternating current is relatively high (100 Hz). I’m not sure what causes the high temperature of the motor bearings (87°C) Can this temperature be maintained for a long time?
This problem is likely due to an issue with the quality of the motor; our company also has motors that suffer from the same problem.
This temperature allows for long-term operation. . . Observe again
First, top up the grease to check if there is a lack of it, and then observe whether there is any change in the bearing temperature. If it decreases, it indicates a lack of fat; if there is no decrease and instead a gradual increase, you need to pay closer attention. Parameters such as vibration and sound are also those that require heightened attention.
If it is the external temperature of the end cover that is being measured, then 87 degrees is a bit high, increasing the risk of bearing damage over time. Regarding the motor housing temperature, measure it on both the front and back sides. If the difference is not significant, it indicates that the temperature rise is generated by the stator itself; if it is higher on the side closest to the bearing with a high temperature, then the heat is being transferred from the bearing. Just to confirm, what is the motor load? Is it a high-temperature pump?
The problem with this motor – did it arise right after maintenance, or after it had been in operation for some time? If it appeared right after maintenance, it might be due to an excessive amount of lubricant causing heat, poor assembly, or inferior quality bearings； After operating for a long time, there is a possibility of oil shortage; as for whether the double-frequency being high is due to poor alignment
What devices is the motor connected to?
Check the motor fan; dust removal from the motor is also important. Take another look at the working environment
This motor is connected to a centrifugal pump; it is not a high-temperature pump, with a power of 75KW. The motor bearing is a 2Z sealed bearing, which has just been overhauled.
This post was last edited by ZHANGZHANTJ on 2015-8-8 at 18:37. For 2z bearings, do the bearings at the motor drive end come with inner and outer bearing covers? If so, remove the dust covers on both sides of the bearing.