Troubleshooting
Motor runs hot
Separate overload, voltage, phase, cooling, cycling, and mechanical causes.
Temperature is a symptom. Compare actual load, voltage/phase balance, duty, cooling, ambient conditions, cycling, and mechanical condition.
Likely causes
- Overload or excessive starts.
- Voltage/phase imbalance or single phasing.
- Blocked airflow, high ambient, or low-speed operation.
- Bearing, alignment, or driven-load problems.
Tests
- Record current on every phase and compare to nameplate/service factor.
- Measure voltage balance, inspect cooling paths, and review start frequency/duty.
- Check bearings, alignment, and load condition while de-energized.
Corrective action
- Correct supply, load, cooling, duty, or mechanical cause; do not simply increase overload settings.
Verification
- Trend current and temperature under representative load and confirm protective-device operation.