Drive cooling fan
Common heat-related VFD and servo-drive failure point.
Yaskawa VFD Fault CF — What It Means
Yaskawa fault CF means control fault — the drive’s internal CPU detected a self-test failure, a parameter consistency error, or a control board malfunction. On Yaskawa A1000 and GA700 drives, CF can also indicate that an option card or communication card is communicating incorrectly or has failed. This is an internal drive fault, not a motor or load fault. CF does not point to external wiring or motor problems; it points to the drive’s control electronics or firmware.
Common Causes
- Parameter corruption — After a power surge, lightning strike, or improper power-down during a write operation, drive parameters stored in EEPROM can become corrupted, causing the control processor to detect inconsistencies.
- Failed option card — A communication card (DeviceNet, Profibus, EtherNet/IP) that has partially failed or is incorrectly seated can generate CF or a variant of it.
- Control board failure — The control PCB itself can fail due to electrostatic discharge, moisture, or component aging. If the self-test routine fails, CF is the result.
- Firmware issue — Some Yaskawa firmware versions have known CF triggers for edge-case parameter combinations. Check Yaskawa’s technical notes for your firmware version.
Step-by-Step Fix
- Perform a factory parameter reset — Initialize parameters to factory defaults (A1-03 = 2220 for 3-phase initialization on most Yaskawa models). This clears parameter corruption. Note: this erases all custom parameters — back them up first if possible.
- Remove and reseat option cards — With power off, remove any option cards (I/O, communication, encoder). Reseat them firmly or remove them entirely and test if CF clears.
- Check for static discharge sources — If the drive is installed in an environment with poor static control, the control board can be damaged by ESD. Ensure proper grounding of the drive and control panel.
- Update or verify firmware — Check the drive’s firmware version against Yaskawa’s latest bulletin for that model. Known CF bugs in certain firmware versions may have a patch.
- Reset the system — After a parameter reset, restore your motor nameplate data and any custom parameters. Run a motor ID run. If CF doesn’t return, the reset fixed it.
Parts Often Needed
| Part | Notes |
|---|---|
| Yaskawa control PCB | If parameter reset and card removal don’t resolve CF, board is suspect |
| Option card replacement | If a communication card is confirmed faulty |
| Ground cable (5mm² or larger) | Verify drive chassis is properly bonded to earth ground |
Technician Tips
When diagnosing VFD faults, always check the drive’s fault history before resetting. Modern drives store the last 5-10 faults with the drive state at the time (running, accelerating, decelerating, stopped). An overcurrent fault that occurs only during acceleration points to incorrect motor data or mechanical binding. The same fault during deceleration suggests regeneration issues. A ground fault that clears after disconnecting the motor and returns when reconnected means the motor or cable insulation has failed.
Prevention: Schedule annual infrared scanning of drive cabinets. Loose power connections and failing capacitors produce heat long before they cause faults. A 5-minute scan can prevent hours of unplanned downtime.
Need Replacement Parts?
Before ordering, match the drive part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
When to Call a Pro
A CF that persists after parameter reset and option card removal requires Yaskawa’s diagnostics software (DriveWizard) to read internal fault logs and test control board functions. This is a service-level task.