Danfoss FC 302 Alarm 29: Heat Sink Temp after running loaded, what to check?
My Danfoss FC 302 drive is throwing an Alarm 29 (Heat Sink Temp) after running loaded for a while. It seems to happen more often on hot days. What should I check first?
Alarm 29 on a Danfoss VLT FC 302 indicates that the maximum heat sink temperature has been exceeded. This alarm will not reset until the heat sink cools down below a defined temperature, with trip and reset points varying by drive power size. Common causes include issues with the heat sink fan, blocked airflow, high ambient temperatures, or excessively long motor cables.
Likely causes and checks
1Heat sink fan damaged or not running
- Points to it
- A damaged or non-operational heat sink fan prevents proper cooling, leading to an overtemperature condition. This can be indicated by Warning 23 or 24 fan faults, or if the drive trips sooner than it used to.
- Check
- Cycle power to the frequency converter and observe if the fan operates briefly at start-up. Additionally, check for proper fan operation, which can be supervised using parameter 14-53 Fan Monitor.
2Dirty heat sink or blocked airflow
- Points to it
- Accumulated dust or debris on the heat sink fins, or insufficient clearance around the drive, can restrict airflow and reduce cooling efficiency, causing the heat sink temperature to rise.
- Check
- Inspect and clean the heat sink thoroughly. Verify that there is adequate airflow clearance both above and below the drive as specified in the operating guide.
3Ambient temperature too high
- Points to it
- If the surrounding air temperature within the cabinet exceeds the drive's rated ambient temperature, the drive's cooling system may not be able to dissipate enough heat, leading to an overtemperature alarm.
- Check
- Measure the air temperature inside the cabinet near the drive and compare it against the drive's specified maximum ambient operating temperature.
4Motor cables too long
- Points to it
- Excessively long motor cables can contribute to increased heat generation in the drive, even at moderate loads, potentially leading to the heat sink exceeding its temperature limits.
- Check
- Check the length of the motor cables against the maximum limits specified in the drive's Operating Guide.
Next check: Begin by checking the heat sink fan operation and ensuring the heat sink is clean and has proper airflow clearance. These are the most common and easily verifiable causes for Alarm 29.
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