Abstract
Most of wind turbines have metallic receptors at the tip of their blades as lightning protection. Recently, aluminum tip receptors of some large wind turbines have dropped out accidentally. After the investigation, it is expected the following phenomena caused dropout accidents. At first, they were struck by lightning through the blade skin and the internal air and moisture expanded explosively by arc heat. Subsequently, bonded part around the tip receptor was fractured by pressure, and then holding force of the receptor was lost. To prevent similar accidents, the authors revised the tip receptor and its bonding structure. High-current arc tests and tensile strength tests were carried out on blade specimens which equipped the revised receptors. As a result, it was confirmed that the revised receptor can endure electric charge amount as high as 1500 C and sixteen times as much as the extreme tensile force.
