F021 fault in WEG CFW900 Drive indicates a DC Link Undervoltage. This means the internal DC bus voltage has dropped below the safe operating minimum, usually due to an input power dip.
Cause:
Supply voltage is too low, producing voltage on the DC link (S2.7.1) below the minimum value:
- Ud < 203 V: Supply voltage 200 V.
- Ud < 210 V: Supply voltage 208-240 V.
- Ud < 385 V: Supply voltage 380 V.
- Ud < 405 V: Supply voltage 400-415 V.
- Ud < 446 V: Supply voltage 440-460 V.
- Ud < 487 V: Supply voltage 480 V.
- Ud < 507 V: Supply voltage 500-525 V.
- Ud < 557 V: Supply voltage 550-600 V.
- Ud < 669 V: Supply voltage 660-690 V.
- Phase loss at the input.
- Fault on the pre-charge circuit.
- Parameter C1.1.2 is configured with a value above the rated line voltage.
Remedy:
Verify incoming mains supply. Check input terminals and check for missing phases. Check the pre-charge circuit. Verify the configuration value of parameter C1.1.2.
