Danfoss FC 301/302 VFD showing ALARM 84, "No safety option"?
My Danfoss VLT AutomationDrive FC 301/302 VFD is showing ALARM 84. The display says "No safety option". What does this mean and what should I check first to clear it?
ALARM 84 on a Danfoss VLT AutomationDrive FC 301/302 indicates that a safety option, which was previously installed, has been removed without performing a general reset. The VFD expects the safety option to be present. To resolve this, you should first try reconnecting the safety option.
Likely causes and checks
1Safety option removed
- Points to it
- The VFD detected that a safety option, which was previously configured or present, is no longer connected. This typically happens if the option card was physically removed or became disconnected.
- Check
- Visually inspect the VFD to ensure that any safety option cards are securely seated in their slots. If an option was intentionally removed, it needs to be reconnected or a general reset performed.
2Loose or faulty connection
- Points to it
- Even if the safety option is present, a loose connection or a faulty card can trigger this alarm, as the VFD cannot properly communicate with it.
- Check
- Isolate and lock out power to the VFD. Carefully check the connections of the safety option card. Remove and re-insert the card to ensure it is properly seated. Inspect the card for any visible damage.
Next check: If reconnecting the safety option does not clear the alarm, you may need to perform a general reset of the VFD. According to the manual, "The safety option was removed without applying a general reset. Reconnect the safety option." If the option is confirmed to be present and connected, a reset might be necessary to re-initialize the VFD's configuration.
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