Representative case · 07
Blade vibration: 1P or 3P?
Nacelle vibration only in one wind band; no visible blade damage.
Representative case. This page describes a fault pattern that is common in the field, as a diagnostic sequence. It does not describe a specific wind farm, turbine or date; numbers are examples only and limits vary by turbine type. On your own turbine the OEM instructions, LOTO procedure and safety rules apply; work near energised equipment is for authorised personnel only.
Symptom
Nacelle vibration only in one wind band; no visible blade damage.
What was measured
Spectrum dominated by 1P with normal 3P; a physical measurement found one blade at a different angle.
Root cause
After an earlier encoder replacement the blade angle reference had not been calibrated correctly.
Fix and verification
All three blade angle references reset to the physical marks with the OEM method; 1P dropped.
Lesson
Look at the spectrum before calling a blade inspection.
Full version
The complete diagnostic sequence — possible causes table, step-by-step checks, maintenance checklist and common mistakes — is in the Turkish version of this case.