Danfoss FC 302 Alarm 10: Motor ETR Overtemp, what to check?
I'm getting Alarm 10 (Motor ETR Overtemp) on my Danfoss FC 302 drive. The motor feels hot to the touch and the current is high. What should I check first?
Alarm 10 on a Danfoss VLT FC 302 indicates that the drive's electronic thermal protection (ETR) calculates the motor is too hot, likely due to running with more than 100% overload for an extended period. This can be configured as a warning or a trip via parameter 1-90. It's a calculated temperature, distinct from Alarm 11 which uses a physical thermistor.
Likely causes and checks
1Motor mechanically overloaded
- Points to it
- The motor is running with a load exceeding its design capacity, causing it to draw excessive current and overheat.
- Check
- Inspect the driven machine for any issues that could increase mechanical resistance. Compare the actual motor current with the motor's rating plate data.
2Motor current or motor data set wrong
- Points to it
- Incorrect motor parameters in the drive can lead to inaccurate ETR calculations, causing a false alarm or improper protection.
- Check
- Verify that parameter 1-24 Motor Current and parameters 1-20 to 1-25 (motor data) are correctly set according to the motor's rating plate.
3External motor fan not declared
- Points to it
- If the motor uses a separately powered external fan for cooling, but this is not configured in the drive, the ETR may incorrectly calculate an overtemperature, especially at low speeds.
- Check
- If an external fan is present, ensure it is selected in parameter 1-91 Motor External Fan.
4Drive not tuned to the motor
- Points to it
- Without proper tuning, the drive may not accurately control the motor, potentially leading to increased thermal loading and premature ETR alarms.
- Check
- Run Automatic Motor Adaptation (AMA) in parameter 1-29. Danfoss notes that AMA reduces thermal loading.
Next check: Given the motor feels hot and current is high, start by checking for mechanical overload on the driven machine and comparing the motor current to its rating plate. This is the most common cause for these symptoms.
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