Manufacturer
Vestas Series
Vestas designs are geared and use DFIG generators. The control system is mature and works well, but it needs tuning. The maintenance load concentrates in gearbox oil management and converter cooling.
The most decisive difference across the series is the gearbox layout: V110 uses parallel-axis, V126 planetary, V136 a planetary–helical hybrid. That single choice changes weight, noise, oil volume and the character of the faults you will chase.
3.0 MWVestas V110110 m rotor, parallel-axis gearbox, 700–750 L of oil. Shaft-seal oil leakage becomes the main topic after 8–12 years.
3.3 MWVestas V126126 m rotor, planetary gearbox, 850+ L of oil. Planetary gear pitting has to be caught early through metal analysis.
4.2 MWVestas V136136 m rotor, hybrid gearbox, ~1000 L of oil. Built for low-wind sites; vibration monitoring matters on the long blades.