{"$comment":"Fault types the condition monitoring can see. Costs for a 4.2 MW onshore turbine in Germany, 2024–2026 prices, from the sources listed in the report footer (WindGuard, Nordex, EPRI, Wind Systems, Donnelly et al., CORDIS, Festo/Siemens price lists). Where no published price exists the value is a labelled proxy. severity 0 = new, 1 = failure.","faults":[{"id":"hss_bearing","component":"gearbox","name":"Gearbox high-speed shaft bearing, outer race damage","plain":"A damaged rolling path in the fast-turning bearing at the gearbox output. Each ball that rolls over the damage gives a small knock; the knocks repeat at the bearing's outer-race frequency (BPFO) and grow as the crack spreads.","signature":["bpfo_hss","bpfo_hss2","bpfo_hss3","sb_hss"],"sync":"Knocks at 6.1 × shaft speed, not locked to the gear teeth","gain":17,"grows":true,"repair":{"label":"Exchange the HSS bearing up-tower","skill":"drivetrain","crew":3,"hours":14,"windLimit":15,"crane":"service","parts":[{"id":"hss_bearing_kit","qty":1}],"tools":["induction_heater","bearing_puller","borescope","torque_set","laser_alignment"],"partsCost":9000,"extraCost":2000},"failure":{"label":"Bearing seizes and damages the gear stage: gearbox exchange","cost":550000,"crane":"crawler750","downtimeDays":90,"note":"Gearbox exchange on a 4.2 MW turbine: new gearbox about €530k, large crane about €100k (€8k a day plus €50k mobilisation), 3–6 months downtime waiting for the gearbox and the crane. Planned up-tower bearing job: about €18k (Wind Systems 2024)."}},{"id":"main_bearing","component":"mainbearing","name":"Main bearing wear","plain":"The large bearing that carries the rotor wears in its rolling path. The rise is slow and shows at low frequency, about 8 knocks per rotor turn.","signature":["bpfo_main","bpfo_main2","p1"],"sync":"Low-frequency knocks at 7.9 × rotor speed","gain":13,"grows":true,"repair":{"label":"Replace the main bearing (rotor lift)","skill":"drivetrain","crew":4,"hours":40,"windLimit":10,"crane":"crawler750","parts":[{"id":"main_bearing_unit","qty":1}],"tools":["induction_heater","hydraulic_tensioner","torque_set","laser_alignment"],"partsCost":120000,"extraCost":25000},"failure":{"label":"Bearing failure damages main shaft and housing","cost":300000,"crane":"crawler750","downtimeDays":120,"note":"Planned main-bearing exchange: €200k–360k including the crane (EPRI 2024). After a failure the main shaft and housing need replacing too; main-shaft lead times reach 9 months (RES)."}},{"id":"gen_bearing","component":"generator","name":"Generator bearing, early damage","plain":"The generator's drive-end bearing shows first damage. Its knocks repeat at 3.6 × generator speed.","signature":["bpfo_gen","bpfo_gen2","g1"],"sync":"Knocks at 3.6 × generator speed","gain":40,"grows":true,"repair":{"label":"Replace the generator bearing up-tower","skill":"drivetrain","crew":2,"hours":10,"windLimit":15,"crane":"service","parts":[{"id":"gen_bearing_kit","qty":1}],"tools":["induction_heater","bearing_puller","torque_set","laser_alignment"],"partsCost":7000,"extraCost":2000},"failure":{"label":"Bearing failure damages the generator: generator exchange","cost":165000,"crane":"crawler750","downtimeDays":60,"note":"Generator exchange: generator about €150k (Donnelly et al. 2024: £151k for a 3 MW unit), large crane about €100k, crew; about 2 months downtime. Planned bearing exchange up-tower: about €11k–15k."}},{"id":"gen_misalignment","component":"generator","name":"Gearbox–generator shaft misalignment","plain":"The shafts of gearbox and generator no longer line up. The coupling bends each turn, which shows as a strong peak at 2 × generator speed and wears the generator bearings.","signature":["g2","g1","g3"],"sync":"Strong 2 × generator speed: the two shafts run out of line","gain":24,"grows":true,"repair":{"label":"Re-align the generator, new coupling insert","skill":"mech","crew":2,"hours":8,"windLimit":15,"crane":"none","parts":[{"id":"coupling_insert","qty":1}],"tools":["laser_alignment","torque_set","vibration_analyzer"],"partsCost":1500,"extraCost":300},"failure":{"label":"Coupling breaks, generator bearings damaged","cost":30000,"crane":"service","downtimeDays":10,"note":"Broken coupling and damaged generator bearings, repaired up-tower: coupling plus a bearing job (proxy from published up-tower bearing costs)."},"power":{"shape":"uniform","loss":0.004}},{"id":"mass_imbalance","component":"rotor","name":"Rotor mass imbalance","plain":"One blade is heavier than the others (water ingress or repair material). The rotor wobbles once per turn: a strong 1P peak, exactly in sync with rotor speed.","signature":["p1"],"sync":"1P peak, locked to rotor speed","gain":1.3,"grows":true,"repair":{"label":"Balance the rotor (weights in the blade root)","skill":"rope","crew":3,"hours":8,"windLimit":12,"crane":"none","parts":[{"id":"balancing_weights","qty":2}],"tools":["rope_access_kit","vibration_analyzer","laser_pitch_gauge"],"partsCost":800,"extraCost":2500},"failure":{"label":"Fatigue damage at blade root bolts and main bearing","cost":60000,"crane":"none","downtimeDays":10,"note":"No published price for balancing: technician day plus a balancing measurement (proxy). Imbalance rarely breaks things within days; it shortens the life of bolts and bearings."},"power":{"shape":"uniform","loss":0.003}},{"id":"pitch_offset","component":"pitch","name":"Pitch angle offset on blade B","plain":"Blade B sits 4° off the angle of blades A and C (encoder offset after a pitch-motor exchange). The rotor is out of aerodynamic sync: 1P vibration rises, and the power curve is shifted to the right: the turbine needs about 0.5 m/s more wind for the same power and reaches full power late.","signature":["p1","p3"],"sync":"Blade B 4° off: aerodynamic 1P, power curve shifted right","gain":0.3,"grows":false,"repair":{"label":"Calibrate the pitch angles","skill":"elec","crew":2,"hours":4,"windLimit":15,"crane":"none","parts":[{"id":"pitch_encoder","qty":0}],"tools":["laser_pitch_gauge","service_laptop"],"partsCost":0,"extraCost":1500},"failure":{"label":"No failure within days: yield loss continues","cost":0,"crane":"none","downtimeDays":0,"note":""},"power":{"shape":"shift","ms":0.5},"deg":4},{"id":"yaw_misalignment","component":"yaw","name":"Yaw misalignment 7°","plain":"The nacelle points 7° beside the wind because the wind vane is offset. No damage within days, but the rotor sees less wind: yield falls with the cosine of the angle.","signature":[],"sync":"Nacelle 7° off the wind","gain":0,"grows":false,"repair":{"label":"Recalibrate the wind vane (spinner anemometer check)","skill":"elec","crew":2,"hours":3,"windLimit":15,"crane":"none","parts":[{"id":"yaw_sensor","qty":0}],"tools":["service_laptop","lidar_kit"],"partsCost":0,"extraCost":3000},"failure":{"label":"No failure within days: yield loss continues","cost":0,"crane":"none","downtimeDays":0,"note":""},"power":{"shape":"uniform","loss":0.022},"deg":7},{"id":"leading_edge","component":"rotor","name":"Leading-edge erosion","plain":"Rain and dust have roughened the blade tips. The airfoil loses lift: about 2 % less yield (up to 5 % when the erosion is severe). The coating repair needs dry air (humidity below 80 %) and at least 5 °C.","signature":[],"sync":"Aerodynamic loss, no vibration","gain":0,"grows":false,"repair":{"label":"Leading-edge protection repair (rope access)","skill":"rope","crew":3,"hours":40,"windLimit":10,"rhMax":80,"tempMin":5,"crane":"none","parts":[{"id":"lep_kit","qty":1}],"tools":["rope_access_kit","platform","hygrometer"],"partsCost":4000,"extraCost":6000},"failure":{"label":"No failure within days: yield loss continues","cost":0,"crane":"none","downtimeDays":0,"note":""},"power":{"shape":"partial","loss":0.025}},{"id":"tower_resonance","component":"tower","name":"Tower resonance near 3P","plain":"At low wind the blades pass the tower at 3 × rotor speed, close to the tower's own swing frequency (0.22 Hz). The controller's speed-exclusion window is set too narrow, so the tower sways more than it should.","signature":["tower","p3"],"sync":"3P meets the tower frequency","gain":1.4,"grows":false,"repair":{"label":"Widen the speed-exclusion window (software)","skill":"elec","crew":1,"hours":2,"windLimit":25,"crane":"none","parts":[],"tools":["service_laptop"],"partsCost":0,"extraCost":500},"failure":{"label":"Faster fatigue of tower bolts","cost":40000,"crane":"none","downtimeDays":3,"note":"Illustrative: re-tensioning and inspecting the tower bolts."},"power":{"shape":"uniform","loss":0.002}},{"id":"power_limit","component":"generator","name":"Power limit stuck at 3.0 MW","plain":"After a grid-code test the converter's active-power limit was left at 3.0 MW instead of 4.2 MW. The turbine runs smoothly and shows no vibration, so condition monitoring cannot see it. Only the power curve shows it: a flat top at 3.0 MW. Every hour with more than about 10.5 m/s loses up to 1.2 MW. The fix is a parameter reset from the remote service centre, then a check that the turbine reaches 4.2 MW.","signature":[],"sync":"No vibration: a control setting","gain":0,"power":{"shape":"cap","kw":3000},"grows":false,"repair":{"label":"Reset the active-power limit remotely and check full load","skill":"elec","crew":1,"hours":1,"windLimit":20,"crane":"none","parts":[],"tools":["service_laptop"],"partsCost":0,"extraCost":500,"remote":true},"failure":{"label":"No failure: yield loss continues","cost":0,"crane":"none","downtimeDays":0,"note":""}}],"cranes":{"none":{"name":"No crane","cost":0},"service":{"name":"On-board service crane","cost":0},"mobile130":{"name":"Mobile crane 200 t","cost":14000},"crawler750":{"name":"Large crawler crane (800 t class)","cost":100000}}}