F0021 fault in WEG CFW701 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 or phase loss.
Cause:
The input voltage is too low and the DC link voltage dropped below the minimum permitted value (monitor the parameter P0004):
- Ud < 223 V: For 200 / 240 V three-phase input voltage.
- Ud < 170 V: For 200 / 240 V single-phase input voltage (models CFW701XXXXS2 or CFW701XXXXB2, P0296 = 0).
- Ud < 385 V: For 380 V input voltage (P0296 = 1).
- Ud < 405 V: For 400 / 415 V input voltage (P0296 = 2).
- Ud < 446 V: For 440 / 460 V input voltage (P0296 = 3).
- Ud < 487 V: For 480 V input voltage (P0296 = 4).
- Ud < 530 V: Input voltage 500 / 525 V (P0296 = 5).
- Ud < 580 V: Input voltage 550 / 575 V (P0296 = 6).
- Ud < 605 V: Input voltage 600 V (P0296 = 7).
- Phase loss at the inverter input.
- Pre-charge circuit failure.
- Parameter P0296 was set to a value higher than the power supply rated voltage.
Remedy:
Monitor parameter P0004. Check physical input terminals. Ensure correct configuration of parameter P0296 to match incoming rated mains voltage. Check pre-charge circuit paths.
