Applicable Systems
FC-30
FC-51
FC-101
FC-202
FC-302
Symptoms
The drive shows a warning (not a trip). The display shows Alarm 29 as a warning, indicating that the heat sink temperature is approaching the trip limit. The drive is still running but may trip if temperature continues to rise.
Possible Causes
- Ambient temperature in the enclosure is high
- Drive cooling fan efficiency is degrading
- Drive operating near full load for extended periods
- Enclosure ventilation inadequate for the heat load
Troubleshooting Steps
- Step 1: Check the enclosure ventilation and ambient temperature
Ambient temperature is within the drive operating range - Step 2: Verify the drive cooling fan is running and airflow is unobstructed
Fan is operational and air flows freely through the heatsink - Step 3: Inspect the heatsink for dust buildup
Heatsink fins are clean - Step 4: Reduce the drive load or improve cooling if the warning persists
Heat sink temperature stabilizes below the warning threshold
How to Reset
To reset: This is a warning, not a trip. The warning clears automatically when the temperature drops below the warning threshold. Caution: Address the cooling issue promptly to prevent the drive from tripping on Alarm 12 (overtemperature trip).
Frequently Asked Questions
- Q: What is the difference between a warning and an alarm on Danfoss drives?
A warning does not trip the drive; it alerts the operator to a condition that may lead to a trip. An alarm (trip) stops the drive. Warnings should be addressed before they escalate to alarms.
- Q: What temperature triggers the heat sink warning?
The warning threshold varies by drive model but is typically set 5-10 degrees below the trip threshold. For most Danfoss drives, the warning triggers around 75-80 deg C and the trip at 85-90 deg C heat sink temperature.
Source: Danfoss VLT FC-51 Design Guide, 2023
Category: PLC & VFD