4981 External Temperature 1 in ABB ACS880 Drive

4981 External Temperature 1 in the ABB ACS880 Drive indicates that the measured external temperature connected to Temperature Input 1 has exceeded the configured fault limit. This fault is generated when the temperature monitored through an external temperature sensor (such as a motor winding sensor, bearing sensor, gearbox sensor, or other equipment) rises above the limit defined in the drive parameters. The ACS880 trips to protect the monitored equipment from overheating and prevent thermal damage.

Possible Causes

• Motor winding temperature exceeds the allowable limit.
• Motor bearing overheating.
• Gearbox or driven equipment overheating.
• Excessive motor load.
• Inadequate motor cooling.
• Cooling fan failure on the motor.
• Blocked motor ventilation openings.
• High ambient temperature around the motor.
• Motor operating continuously above rated current.
• Faulty external temperature sensor (PT100, PTC, KTY, etc.).
• Damaged or loose sensor wiring.
• Incorrect temperature sensor configuration.
• Temperature fault limit (Parameter 35.12) set too low.
• Incorrect scaling or configuration of the temperature input.
• External equipment overheating due to mechanical problems.

Solutions

• Check the value of Parameter 35.02 – Measured Temperature 1.
• Verify the actual temperature of the monitored equipment.
• Check the cooling system of the motor or monitored equipment.
• Ensure the motor cooling fan is operating correctly.
• Clean motor cooling fins and ventilation passages.
• Reduce the motor load if overheating occurs.
• Measure the motor current and compare it with the rated current.
• Inspect the external temperature sensor for proper operation.
• Check sensor wiring for loose, damaged, or broken connections.
• Verify the correct sensor type is configured in the drive.
• Check the value of Parameter 35.12 – Temperature 1 Fault Limit.
• Adjust the fault limit only if it is incorrectly configured and within safe operating limits.
• Repair or replace faulty sensors or cables if necessary.

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Additional Information

The ABB ACS880 allows monitoring of external temperatures using dedicated analog temperature inputs. These inputs can monitor:

• Motor winding temperature
• Motor bearing temperature
• Gearbox temperature
• Pump temperature
• Process equipment temperature
• Any external device equipped with a supported temperature sensor

The drive continuously compares the measured temperature (Parameter 35.02) with the configured fault limit (Parameter 35.12).

If the measured temperature exceeds the configured limit, the drive trips with:

4981 – External Temperature 1

This protection prevents overheating of motors and connected equipment, helping to avoid insulation damage, bearing failure, and unplanned downtime.

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Common Symptoms

• Drive trips during prolonged operation.
• Motor housing becomes unusually hot.
• Motor cooling fan runs continuously.
• Fault occurs under heavy mechanical load.
• High temperature value displayed in Parameter 35.02.
• Motor current remains close to or above the rated current.
• Equipment temperature increases during hot ambient conditions.
• Fault returns immediately after reset if overheating persists.

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Recommended Troubleshooting Sequence

1. Check the value of Parameter 35.02 – Measured Temperature 1.
2. Verify the actual temperature of the monitored equipment.
3. Inspect the motor cooling system.
4. Check motor cooling fan operation.
5. Clean motor ventilation openings and cooling fins.
6. Measure motor current during operation.
7. Reduce the mechanical load if necessary.
8. Inspect the external temperature sensor.
9. Check sensor wiring and connections.
10. Verify the configured sensor type.
11. Check Parameter 35.12 – Temperature 1 Fault Limit.
12. Replace the sensor if incorrect readings are confirmed.

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External Temperature Check Table

Check Point	Action
Parameter 35.02	Verify measured temperature value
Parameter 35.12	Confirm correct fault limit setting
Motor cooling	Ensure adequate cooling
Cooling fan	Verify proper operation
Motor ventilation	Clean cooling passages
Motor current	Verify within rated value
Mechanical load	Reduce if excessive
Temperature sensor	Inspect for proper operation
Sensor wiring	Check for loose or damaged connections
Sensor configuration	Verify correct sensor type and settings

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Preventive Maintenance Tips

• Regularly inspect motor cooling fans and ventilation paths.
• Clean motor cooling fins to maintain efficient heat dissipation.
• Monitor motor operating current during normal operation.
• Periodically inspect external temperature sensors and wiring.
• Verify temperature input calibration during scheduled maintenance.
• Ensure the monitored equipment operates within its rated temperature range.
• Inspect bearings and driven equipment for signs of overheating.
• Maintain proper ambient ventilation around the motor and equipment.
• Review temperature fault limits after commissioning or parameter changes.

Proper cooling, accurate temperature sensor configuration, routine inspection of sensors and wiring, and maintaining motor load within rated limits will help prevent recurring 4981 External Temperature 1 faults in ABB ACS880 drives, ensuring reliable operation and protecting the motor and other monitored equipment from overheating.