Blades

BLADES

Overview

Blade damage typically occurs as a result of lightning strikes, design/material defects, or wear and tear.

Leading edge erosion is the most common form of wear and tear damage and can cause a significant drop in energy production.

Depending on the severity of the issue, blades can either be repaired in situ using rope access or lowered to the ground using a crane for more complex repairs.

In extreme cases the entire blade has to be replaced.

Inspections can be carried out using drones and new approaches to
in situ repairs have been developed, for example using maintenance robots.

BLADES - TYPES OF DAMAGE

Leading edge erosion

Leading edge erosion is caused by the impact of rain, dust, sand and salt on the front (leading) edge of the blade. This reduces the aerodynamic efficiency of the blade and reduces energy production.

Longer blades spin faster therefore the erosion is worse on larger WTGs.

Leading edge erosion is repaired by applying composite materials to the affected areas.

BLADES - TYPES OF DAMAGE

Lightning damage

Lightning damage can be mitigated through an adequate Lightning Protection System (LPS), which runs from the tip of the blade to the ground.

If incorrectly designed or installed, the LPS may fail to route the strike
to ground.

Carbon fibre within WTG blades is highly conductive, and can
‘compete’ with the copper elements of the LPS, causing damage
to the blades.

BLADES - TYPES OF DAMAGE

Delamination

Delamination affects the shells of the blade, which are made of laminates bonded together with resin (the matrix).

Manufacturing defects in the matrix can cause the laminates to pull apart when put under bending stresses from wind.

The placement of the reinforcing elements, that help to hold the blade together, is also critical to blade integrity. These defects can be identified during quality control at the factory.