From the field

Field Notes

These are not from a book; they came out of the tower. Each one follows a single fault from start to finish: what the alarm said, what I thought it was, which measurement I took, which possibilities it ruled out, what the root cause turned out to be and how we closed it. The point is not the answer — it is the order of the diagnosis.

A fault tree gives you a fast route from symptom to cause; these pages show you what it is like inside one case. The two complement each other: narrow it down with the tree first, then read the closest case here.

Note: these are field experience, not a substitute for the manufacturer's service documentation. Your own turbine's OEM instructions, LOTO procedure and site safety rules govern every intervention.

Case 01Pitch Motor High CurrentPitch motor drawing 18 A instead of 12 A on a Nordex N117. Six-step diagnosis; root cause was a gearbox oil leak. Case 02Gearbox Temperature RiseOil temperature at 78–82 °C on a Vestas V126. Eight-month trend analysis; oil loss through a failing shaft seal. Case 03Yaw HuntingNacelle oscillating ±18° on an Enercon E92. Bearing drag, sensor jitter and a drifted PLC parameter. Case 04Generator Temperature AlarmA 116 °C alarm on a Vestas V126. A 41 °C gap between the IR thermometer and SCADA: sensor calibration drift. Case 05Converter OvercurrentAn intermittent fault on a Vestas V110 that only tripped above 2.3 MW. A loosened DC busbar joint, found by chasing the condition. Case 06Yaw Bearing WearDamage caught with no alarm on an Enercon E92. A blocked lubrication line starved one sector of the race. Case 07Blade VibrationVibration in a narrow 7–9 m/s band on a Vestas V126. 1P harmonic, 2.5° pitch asymmetry — calibration, not the blade.

Frequently asked

What should you do first when a turbine faults?

Before you read the alarm, make it safe: stop the turbine, apply LOTO, isolate the system you are going to touch. Then pull the OEM fault log and the SCADA trend. The trend tells you far more than a single instantaneous reading: did this start today, or has it been growing for weeks?

Why does a SCADA value differ from what you measure on site?

The most common reason is sensor calibration drift. RTD temperature sensors in particular change resistance over the years and SCADA then reports a value that does not exist. That is why the first move on a temperature alarm is to take a physical reading with an IR thermometer and compare: a large gap tells you the fault is in the sensor.