Motor thermistor

What does 11 mean?

The motor is too hot, or the thermistor/thermistor connection is cut off. Parameter 128 allows choosing whether the drive issues a warning or an alarm. This fault indicates a thermal issue with the motor or a wiring problem with its temperature sensor.

• Motor overheating due to mechanical overload, insufficient cooling, or sustained operation at low speeds without forced ventilation.
• Open circuit in the motor thermistor wiring (e.g., broken wire, loose connection) from the motor to the drive's thermistor input terminals (e.g., 53, 54, or dedicated thermistor inputs).
• Short circuit in the motor thermistor wiring, causing the resistance to drop below the threshold for an 'open' fault.
• Faulty motor thermistor (PTC or NTC type) itself, providing incorrect resistance readings.
• Drive's thermistor input parameters (e.g., P3-08/P3-09 for analog input acting as thermistor, or specific thermistor parameters) incorrectly configured.

Click steps to track your progress.

1. 1

   1. Power off the drive and motor, then measure the resistance of the motor thermistor leads directly at the motor terminal box. Compare to the manufacturer's specified resistance at ambient temperature.

2. 2

   2. Verify the continuity and insulation of the thermistor cables from the motor terminal box to the drive's input terminals (e.g., 53/54, or specific thermistor input terminals).

3. 3

   3. Inspect motor cooling fins for obstruction and ensure the motor's fan is operating correctly.

4. 4

   4. Check parameter P1-28 (Motor thermal protection) is set to 'Motor PTC' or 'Motor NTC' if a thermistor is installed and connected.

5. 5

   5. If using an analog input (e.g., terminal 53) for thermistor feedback, verify scaling parameters (e.g., P3-08, P3-09) are correctly configured for the thermistor type.

6. 6

   6. Allow the motor to cool down to ambient temperature and then restart the drive to see if the fault clears.