Applicable Systems
WJ200
Symptoms
Motor rotation error detected. The VFD has detected incorrect phase sequence or the motor is rotating in the wrong direction, causing immediate shutdown to prevent airend damage.
Possible Causes
- Supply phases wired incorrectly during installation or maintenance
- VFD output phase sequence corrupted after a parameter change or firmware update
- Motor encoder feedback reversed or encoder cable A/B channels swapped
- Mechanical coupling installed backwards between motor and airend (rare, but possible after rebuild)
Troubleshooting Steps
- Step 1: Check the supply phase sequence at the main disconnect with a phase rotation meter
If incorrect, swap any two supply phases at the disconnect. Do not swap at the motor terminals on a VFD-driven unit - Step 2: Access the VFD parameter menu and verify the motor rotation parameter (typically P1-01 or F0-08)
If the parameter was changed from factory default, restore the correct value and power cycle the VFD - Step 3: Check the encoder cable connections at the VFD and motor - verify A, B, and Z channel wires are in correct positions
Swap A and B wires if the encoder direction is reversed. Re-calibrate the encoder zero position if required - Step 4: With power locked out, mark the motor shaft and manually rotate in the direction indicated by the arrow on the airend housing
If the airend resists rotation in the correct direction but turns freely backwards, inspect the airend timing gears
How to Reset
Reset: Correct the phase sequence or encoder wiring, then power cycle the VFD and controller. The alarm clears after a successful 10-second test run with correct rotation confirmed.
Common Replacement Parts
- HIT-3030: Phase rotation indicator (Digital, for 3-phase 200-600V systems)
- HIT-3031: Motor encoder cable, 3 m (Shielded, 9-pin D-sub to terminal block)
- HIT-3032: Encoder calibration tool (For Hitachi VFDs, with software and USB cable)
Frequently Asked Questions
- Q: What happens if the motor runs backwards?
The airend will not build pressure and may pump oil backward into the intake, causing oil carryover and potential rotor contact. Shut down immediately if reverse rotation is suspected.
- Q: Can I swap motor leads on a VFD?
No. Always swap supply phases before the VFD input. Swapping VFD output phases can damage the drive encoder feedback circuit.
Comments (0)
Share your experience to help others facing the same problem.
Leave a Comment
Source: Hitachi DSP Series VFD Supplement, HIT-DSP-VFD-01
Category: Compressor
Published: 2026-10-17
No comments yet. Be the first to share your experience!