Split Casing Pump Motor Bearing Temperature: Regulations, Causes of Abnormality, and Troubleshooting
1. Introduction
The operating temperature of motor bearings in a split casing pump is critical for reliable performance and long service life. Bearings are the most vulnerable components of the pump motor, and excessive temperatures can lead to premature wear, leakage, or mechanical failure. Proper monitoring, maintenance, and adherence to regulations are essential.
2. Temperature Regulations
| Component | Maximum Temperature | Maximum Temperature Rise | Notes |
| Rolling Bearings | 95°C | ≤55°C | Temperature rise = bearing temperature − ambient temperature |
| Sliding Bearings | 80°C | ≤55°C | — |
Definitions:
Temperature Rise: The difference between bearing temperature and the ambient temperature during operation or testing.
Ambient Temperature: Typically 40°C considered in standard calculations.
3. Measurement Methods
Use a calibrated infrared thermometer to measure the outer surface temperature of the bearing.
For a 4-pole motor, the highest bearing point should not exceed 70°C.
Motor body monitoring is generally not required, as the motor’s temperature rise is stable after manufacturing. Bearings, however, require continuous attention.
4. Abnormal Causes and Troubleshooting
| Reason | Possible Consequence | Troubleshooting |
| Shaft bent or misaligned | Bearing load imbalance, premature wear | Re-center the shaft |
| Loose foundation screws | Vibration, misalignment | Tighten the foundation screws |
| Contaminated lubricating oil | Increased friction, wear | Replace lubricating oil |
| Oil used for too long without replacement | Bearing wear, overheating | Clean bearings and replace oil |
| Damaged ball or roller in the bearing | Bearing failure | Replace with a new bearing |
5. Motor Temperature Limits and Standards
Insulation: F-class
Temperature Assessment: B-class
Motor Temperature Rise Limits: 80 K (resistance method), 90 K (component method)
Considering an ambient temperature of 40°C, maximum operating temperature of the motor should not exceed 120–130°C.
Maximum bearing temperature: 95°C
6. Additional Notes
Bearings are the most vulnerable parts and must be inspected regularly.
Ensure proper lubrication, alignment, and foundation stability to maintain normal operating temperatures.
Following national standards and manufacturer guidelines ensures long-term reliability and prevents unexpected failures.
7. Conclusion
Proper monitoring and maintenance of motor bearings are critical for the safe and efficient operation of split casing pumps. By adhering to temperature regulations, performing regular inspections, and addressing abnormal conditions promptly, operators can minimize downtime, extend equipment life, and maintain optimal pump performance.
