Technical reference
Pitch system
The pitch system turns each blade about its own axis. In low wind it holds the blade at the angle that captures energy best; as wind rises it changes the angle to limit power; when stopping it turns the blades out of the wind. Pitch is both power control and the turbine’s main aerodynamic brake.
General reference. Values, limits, intervals and torques vary by turbine type; the OEM documentation always governs.
Main parts
- Pitch bearing — connects the blade root to the hub
- Drive — electric (motor, gearbox, pinion) or hydraulic (cylinder)
- Motor brake — holds the blade when stopped
- Position feedback — reports the blade angle
- Emergency supply — batteries, capacitors or hydraulic accumulators that feather the blades when the grid is lost
- Pitch cabinet and slip ring — control, supply and communication
Common faults and where to look first
- High motor current on one axis: compare axes, check the motor brake, gearbox oil and bearing lubrication
- Angle difference between blades, 1P vibration: position feedback calibration, physical angle measurement
- Failed emergency supply test: battery or capacitor condition, charging circuit, accumulator pre-charge
Safety
Enter the hub only with the rotor locked. Move blades only in the OEM service mode. Pitch cabinets store energy in batteries or capacitors: apply LOTO, wait for discharge and verify zero voltage. Never test a motor by applying voltage directly to its terminals.
Full version
Parts tables, maintenance checklist and diagnostic tools are in the Turkish version of this page.