Lightning Protection

A wind turbine generator is the most exposed of all types of generators connected to electric utility systems.  Wind turbines are most often erected in hostile lightning environments.  Because of that, lightning damage to wind turbines can be costly in terms of repair and  replacement.  Lightning damage is the single largest cause of unplanned downtime in wind turbines and that downtime is responsible for the loss of countless megawatts of electrical power generation.  There is currently no international standard governing wind turbine lightning protection.


Blades - The blades are protected by copper lightning rods fitted close to the tip.  The rod projects slightly above the blade surface on both sides.  A flexible copper wire located inside the blade provides the conduction path from the rod to the rotor hub, which in turn is used as a conductor to the main shaft.  Electrical and hydraulic equipment located inside the hub is completely protected by the Faraday cage of the hub itself.


Controller - Metal oxide arrestors protect the turbine controller.




Tower - The steel tower acts as a conductor from the turbine to ground.  The ground connection is provided by several copper leads. 


Tower Grounding - A grounding resistance of less than 10 ohms is strongly recommended, using at least two deep copper electrodes and a copper ring ground surrounding the tower foundation.


Control Cable  -  Inside the tower, power cables are required from top to bottom.  But they are not ordinary power cables.  Because the turbines are constantly twisting and turning toward the direction of the wind, the cables that run the length of the tower must be designed to accommodate high torsional stresses.  A high-strength, torsion-resistant construction, which has highly flexible copper conductor strands, a specialty formulated EPR insulation, and an overall oil-resistant halogen-free sheath that provides the highest mechanical protection and personnel safety is typically used.