How to connect equipotential bonding devices to wind turbine blades

Equipotential bonding is a measure to ensure electrical safety by electrically connecting different conductive parts (e.g. metal structures, pipes, electrical equipment cases, etc.) to maintain the same potential (voltage) .

This will prevent potential differences between various metal parts or external conductive elements within an electrical installation, significantly reducing the risk of electric shock or electrical damage .
Equipotential bonding, unlike grounding, is a direct connection between metal conductors within a building, structure, or facility, and plays an important role in preventing risks that may occur in special situations such as leakage current, lightning, or ground faults by ensuring that all connected parts have approximately the same potential.

Things to check when connecting the blade and lightning conductor

• Inside the blade, a down conductor is installed for lightning protection. This conductor must extend to the root of the blade (where it connects to the hub) and is connected to a metal insert or a dedicated terminal.

• Connect the equipotential bonding conductor to the lightning conductor or metal insert of the blade root. At this time, the connection must be electrically secure and use appropriate terminals (e.g. copper wire, aluminum terminal, etc.) to prevent corrosion .

• The equipotential bonding conductor is connected from the blade root to the equipotential bonding bar (EBB) inside the hub or to the grounding conductor of the generator body. At this time, the KEC (Korean Electrical Installation Code) 153.2 and 341.15 regulations must be followed, and the conductor size, material, and connection method (bolt fastening, welding, etc.) must comply with the regulations .

• Bonding conductors are connected equally to all blades and are then gathered into the EBB within the hub. The EBB must then be connected to the main grounding system within the tower .

• The connecting parts should be inspected regularly to ensure that the contact resistance does not increase, and should be repaired immediately if corroded or damaged.

• The potential difference breaker is connected in parallel to the ground wire and bonding conductor, or in parallel with the inductor if inductance is secured.

Inspection and Notes

• Equipotential bonding must be performed during blade installation or maintenance, and safety procedures (power off, electric shock prevention, etc.) must be followed before work.

• The connection between the lightning conductor and the bonding conductor inside the blade must be maintained to withstand mechanical vibration and environmental changes (moisture, salt, etc.).

• Equipotential bonding conductors must be consistently connected to all metal structures, including the inside and outside of the blade, hub, nacelle, and tower, and care must be taken to avoid open circuits or poor connections .

It is necessary to ensure that the metal structures and grounding conductors within the wind turbine are connected to the equipotential busbar (EBB) to maintain individual integrated grounding and equipotential bonding .

 

• Connect the equipotential bonding conductor to the lightning conductor or metal insert at the blade root.

• Gather the bonding wires into an equipotential bonding bar (EBB) within the hub.

• EBB is connected to the tower main grounding system.

• Comply with conductor material, thickness, and connection method according to KEC regulations

• Regular inspection and maintenance are required

Effectively prevents damage from lightning and abnormal voltage by minimizing the potential difference between the blades and the entire generator.