4981 External Temperature 1 Fault in ABB ACS560 Drive
4981 External Temperature 1 Fault in the ABB ACS560 Drive indicates that the measured external temperature (Temperature 1) has exceeded the configured fault limit. The drive monitors an external temperature sensor connected to Measured Temperature 1, and when the measured value rises above the permitted threshold, it generates Fault 4981 to protect the motor or other monitored equipment from overheating.
This fault generally indicates a problem with the motor cooling system, external equipment cooling, or excessive operating temperature, rather than an internal drive hardware failure.
Possible Causes
- External temperature exceeds the configured fault limit.
- Motor overheating.
- Insufficient motor cooling.
- Cooling fan failure.
- Blocked ventilation passages.
- High ambient temperature.
- Excessive mechanical load.
- Faulty external temperature sensor.
- Loose or damaged temperature sensor wiring.
- Incorrect temperature monitoring parameter settings.
Solutions
- Check the value of Parameter 35.02 – Measured Temperature 1.
- Check the cooling of the motor (or other equipment whose temperature is being measured).
- Inspect the external temperature sensor and its wiring.
- Verify that the cooling fan is operating correctly.
- Remove any obstruction from the motor or equipment ventilation.
- Reduce the mechanical load if overheating is caused by overload.
- Allow the equipment to cool before resetting the fault.
Additional Information
The ABB ACS560 supports external temperature monitoring through analog temperature inputs. These inputs can be used to protect motors, gearboxes, bearings, or other equipment from excessive temperatures.
Fault 4981 is generated when the measured value of Temperature 1 exceeds the configured fault threshold.
According to ABB, the recommended corrective actions are to:
- Check Parameter 35.02 – Measured Temperature 1.
- Check the cooling of the motor or other monitored equipment.
Unlike an IGBT Temperature Fault, 4981 relates to an external temperature measurement, not the internal temperature of the drive.
Common Symptoms
- Drive displays 4981 External Temperature 1 Fault.
- Motor or monitored equipment becomes excessively hot.
- Drive trips to protect the equipment.
- High temperature reading is shown in Parameter 35.02.
- Cooling fan may not operate correctly.
- Reduced machine performance before the trip.
- Fault occurs during prolonged heavy-load operation.
- Drive cannot restart until the temperature returns to a safe level.
- Repeated trips if the overheating condition remains.
- External temperature monitoring alarm precedes the fault.
Recommended Troubleshooting Sequence
- Verify that the fault is 4981 External Temperature 1 Fault.
- Disconnect power and follow lockout/tagout procedures if maintenance is required.
- Check Parameter 35.02 – Measured Temperature 1.
- Inspect the motor or monitored equipment for overheating.
- Verify that cooling fans and ventilation are functioning properly.
- Inspect the external temperature sensor and its wiring.
- Reduce the mechanical load if necessary.
- Allow the equipment to cool.
- Reset the fault.
- Monitor the temperature during normal operation.
4981 External Temperature 1 Fault Check Table
| Check Point | Action |
|---|---|
| Parameter 35.02 | Check Measured Temperature 1 value |
| Motor cooling | Verify proper airflow and fan operation |
| External equipment | Check cooling of monitored equipment |
| Temperature sensor | Inspect sensor condition and wiring |
| Ventilation | Remove dust and obstructions |
| Mechanical load | Reduce if excessive |
| Ambient temperature | Ensure installation is within specification |
| Drive operation | Verify stable temperature after repair |
Preventive Maintenance Tips
- Regularly monitor Parameter 35.02 – Measured Temperature 1.
- Inspect motor cooling fans and ventilation openings.
- Clean dust from motors, heatsinks, and cooling passages.
- Verify proper operation of external temperature sensors.
- Inspect sensor wiring for loose or damaged connections.
- Avoid operating equipment continuously above its rated load.
- Maintain adequate airflow around the motor and monitored equipment.
- Record recurring 4981 External Temperature 1 faults to identify developing cooling issues.
- Perform periodic inspections of bearings and driven machinery that may contribute to overheating.
- Follow ABB preventive maintenance recommendations for the ACS560 drive and connected equipment.
Proper inspection of Parameter 35.02 – Measured Temperature 1, the external temperature sensor, motor or equipment cooling, ventilation, and mechanical load will help prevent recurring 4981 External Temperature 1 Fault conditions in ABB ACS560 drives, ensuring reliable thermal protection, safe operation, and long-term equipment reliability.
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