WTT Hydraulic & Lubrication Systems 2

Question 1

What is the primary purpose of a hydraulic accumulator in a wind turbine pitch system?

Accepted Answer

To store pressurized fluid for emergency pitch feathering

Answer

Hydraulic accumulators store pressurized fluid so the pitch system can feather blades even during a grid loss or pump failure.

Question 2

Which type of hydraulic pump is most commonly used in wind turbine pitch control systems due to its variable displacement capability?

Accepted Answer

Axial piston pump

Answer

Axial piston pumps support variable displacement, allowing precise flow control needed for pitch regulation.

Question 3

A technician notices the hydraulic system pressure drops rapidly when the pump is off. What is the most likely cause?

Accepted Answer

Internal leakage in a hydraulic cylinder or valve

Answer

Rapid pressure drop with the pump off indicates internal leakage past cylinder seals or valve seats allowing fluid to bypass.

Question 4

What is the correct procedure for checking the nitrogen pre-charge pressure in a hydraulic accumulator?

Accepted Answer

Isolate and depressurize the hydraulic side before checking gas charge

Answer

The hydraulic side must be depressurized before checking nitrogen pre-charge to get an accurate gas pressure reading.

Question 5

ISO VG 46 hydraulic oil is specified for a turbine. Which alternative viscosity grade is acceptable in an emergency if VG 46 is unavailable?

Accepted Answer

ISO VG 32 or VG 68 within the OEM's approved range

Answer

Adjacent viscosity grades like VG 32 or VG 68 may be acceptable if approved by the OEM, but always verify the service manual.

(WTT) Wind Turbine Technician Certification Practice Test