Thermistor fault

Hva betyr F29 ?

The thermistor input on the option board has detected an excessively high motor temperature. This fault can be caused by motor overheating or a broken thermistor cable. Continued operation with an overheated motor can lead to winding damage.

• Actual motor overheating due to sustained overload, inadequate cooling, or bearing issues.
• Open circuit in the motor thermistor cable or connections, causing an infinitely high resistance reading (e.g., broken wire).
• Short circuit in the motor thermistor cable, causing a very low resistance reading (e.g., short to ground or another wire).
• Incorrect thermistor type or resistance range configured in the drive parameters (e.g., P30-10 'Motor Thermistor Type').
• Faulty option board input for the thermistor, providing an incorrect resistance measurement.

Klikk på steg for å spore fremgangen.

1. 1

   Disconnect the motor thermistor wires from the drive option board terminals.

2. 2

   Measure the resistance of the motor thermistor directly at the motor terminal box using a multimeter. Compare the reading to the thermistor's datasheet at the current motor temperature.

3. 3

   If the thermistor resistance is normal, check the continuity and insulation of the thermistor extension cable from the motor to the drive terminals. Look for breaks or shorts.

4. 4

   Verify the motor thermistor parameters in the drive (e.g., P30-10 'Motor Thermistor Type', P30-11 'Thermistor trip limit') match the installed thermistor.

5. 5

   If the motor is genuinely hot, allow it to cool down and investigate mechanical causes for overheating (e.g., fan blockage, bearing wear, excessive load).

6. 6

   Temporarily connect a known good resistor (within the thermistor's normal operating range, e.g., 1kOhm for PTC) across the thermistor input terminals on the option board to test the drive's input circuit.