Applicable Systems
Freedom Series
Symptoms
The motor bearing temperature has exceeded 90C (194F). The temperature monitoring system triggers a warning alarm to prevent bearing failure.
Possible Causes
- Bearing grease degraded or insufficient causing increased friction
- Motor cooling fan blocked or damaged reducing airflow
- Motor overloaded, causing the bearings to run at elevated temperature
- Bearing clearance incorrect due to wrong replacement bearing specification
Troubleshooting Steps
- Step 1: Use an infrared thermometer to measure the actual bearing housing temperature
Compare the reading to the controller sensor to verify the alarm is genuine - Step 2: Inspect the motor cooling fan for damage or blockage
Clear obstructions and replace broken fan blades - Step 3: Check the motor load current against the nameplate FLA
If current exceeds FLA, reduce the load or investigate the driven equipment - Step 4: Regrease the bearing with the correct grade and quantity of grease
Follow the manufacturer's greasing interval and quantity specification
How to Reset
Reset: The alarm clears automatically once the bearing temperature drops below 80C.
Common Replacement Parts
- Bearing grease: Polyurea or lithium complex, NLGI 2 (Do not mix grease types; clean thoroughly before switching)
- Motor cooling fan: Squirrel-cage or blade type (Match to motor frame size)
Frequently Asked Questions
- Q: How much grease should I add to a motor bearing?
Use the formula: Weight (g) = Bearing OD (mm) x Width (mm) x 0.005. Over-greasing causes as many failures as under-greasing.
- Q: What is the maximum motor bearing temperature?
For standard ball bearings with grease lubrication, the alarm threshold is 90C and shutdown is 100C. Consult the motor manual for specific limits.
- Q: How often should bearings be regreased?
Depends on motor frame size, speed, and operating conditions. Typical interval is 2000-6000 hours. Follow the manufacturer's table.
Source: OEM Technical Manual
Category: Electrical