A skip-frequency function prevents steady operation in selected speed bands. It does not remove the mechanical resonance, and the drive may still pass through the band during acceleration or deceleration.
Base skip bands on measured response
Run a controlled speed sweep with vibration and speed recorded on the same timeline. Separate structural resonance from unbalance, misalignment, looseness or a process pulsation before programming exclusions.
Resonance record
| Item | Engineering purpose | Review action |
|---|---|---|
| Operating speed | Forcing frequency | Relate orders to shaft speed |
| Vibration point | Bearing, frame or structure | Keep sensor locations repeatable |
| Skip band | Lower and upper limits | Include measurement uncertainty |
| Ramp rate | Time through resonance | Check torque and process limits |
Evidence required before approval
Verify every normal operating point remains available and that PID control cannot dwell at a band edge. Record baseline vibration after commissioning and investigate any later shift in resonant speed.
Retain the equipment revision and test record. Name the reviewer. Keep open assumptions visible.
Commissioning decision
Never approve a copied setting. Confirm interface compatibility and operating limits. Exercise the intended response during a functional test.