Abnormal temperature of air compressor motor bearing
Thread Content
The Shanghai Bolite air compressor has been in use for over 7 years; each cycle of operation lasts around one to two months. The temperature of the motor’s front bearing remains below 70°C, indicating stable performance. The motor has not been maintained for over a year now. At noon on the 14th, the air compressor shut down due to a high temperature in the front bearing of the motor; it shut down when the temperature exceeded 95°C. The inspector was asked that around 11 o’clock, the temperature of the front bearing fluctuated between 81°C and 87°C, rising for about two minutes before dropping again. The bearing temperature is inside the motor; there are no temperature measurement points visible on the inner and outer end covers. The motor’s wiring box and PLC connection terminals are not loose. There are no obvious signs of corrosion or oxidation. There are no abnormalities detected in the electrical system or equipment. Upon being turned on again, the temperature rose steadily to 63°C, and it operated for nearly 3 hours. After that, about 200 ml of oil was added to the motor bearings; the bearing temperature increased slightly before dropping to 64°C, where it remained relatively stable. I’m seeking help from fellow professionals: what are the reasons for fluctuations in bearing temperature?
No maintenance for a year – that’s really serious. Do you keep those maintenance records every day just to show them during inspections? First, check whether there is a lack of lubricant or if it’s a problem with the cooler – its cooling capacity may be insufficient. If it’s not these two problems, then check the bearings; there’s nothing else to do
In terms of mechanics, check the bearings, lubricating oil, etc.; in terms of automatic control, examine the wiring of thermal resistors and the channels of PLC cards. Such issues often occur during actual production when a fault arises and it’s difficult to determine the cause. The automatic control team usually replaces the thermal resistors (which is a rather complicated process, especially for those that are embedded). If there is a certain trend, it’s possible to monitor the temperature rise to see whether it increases suddenly or gradually. If it increases suddenly, factors such as individual components, connection circuits, channel issues, and interference cannot be ruled out.
You need to keep observing this; if there are further fluctuations, it’s a problem with the measurements or the wiring. There are spare wires available in the motor’s junction box – use a multimeter to check them and replace them with another set of wires at different temperatures
Under normal circumstances, the motor needs to have its oil changed once a year and undergo major repairs every three to four years, which helps to prevent most problems
There is no trend; this is the PLC built into the air compressor, and trend querying is not available. In my opinion, issues with the connectors or wiring can be ruled out; if there are poor solder joints or faults in the components, such minor fluctuations should not occur. If there’s any interference, can you talk about it? There are no large motor devices available now
After reading your description, my suggestion is as follows: if it can still be used at the moment, it should be kept in use. If production allows for a pause, planned shutdown maintenance should be scheduled. Because motors require regular maintenance, such as inspection and lubrication of bearings, as well as maintenance checks on electrical components. There are many factors that cause fluctuations in bearing temperature, with mechanical factors being the most important and cannot be ignored. It is unlikely that an accurate conclusion can be drawn based solely on what has been discussed so far. In addition, samples of the oil also need to be taken for testing. For reference.
Measure the actual temperature of the motor casing and compare it before and after.