Troubleshooting
Motor runs backwards
Verify equipment direction, phase sequence, wiring, and safe correction steps.
Confirm the required equipment direction before changing phase sequence or leads; reversing the wrong machine can create an immediate hazard.
Likely causes
- Incoming phase sequence differs from expectation.
- Motor or drive output leads were changed.
- Drive direction command or parameter is inverted.
Safe tests
- Stop and isolate the equipment; confirm the driven machine can be reversed safely.
- Compare drawings, lead markings, phase sequence, and drive commands.
Corrective action
- For an across-line three-phase motor, interchange two phases at the approved point.
- For a VFD, follow drive/manufacturer direction logic; do not casually switch energized output leads.
Verification
- Bump-test uncoupled or under an approved safe method, mark direction, and confirm process interlocks.