Spar cap assembly for a wind turbine blade with a lightning protection system

A lightning protection system for a wind turbine blade including a pressure side and a suction side, and a leading edge and a trailing edge with a chord having a chord length extending therebetween, the wind turbine blade extending in a spanwise direction between a root end and a tip end, the lightning protection system comprising

• at least one tip end lightning receptor arranged at an outer surface of the blade and a down conductor extending within the blade,
• a first carbon fibre reinforced spar cap having a tip end and an opposing root end, the first spar cap being arranged inside the blade along the pressure side,
• a second carbon fibre reinforced spar cap having a tip end and an opposing root end, the second spar cap being arranged inside the blade along the suction side,
• a first electrically conductive mesh connecting the tip end of the first spar cap to the tip end lightning receptor,
• a second electrically conductive mesh connecting the root end of the first spar cap to the down conductor,
• a third electrically conductive mesh connecting the tip end of the second spar cap to the tip end lightning receptor, and
• a fourth electrically conductive mesh connecting the root end of the second spar cap to the down conductor.

A method of manufacturing a spar cap assembly for a wind turbine rotor blade, the method comprising the steps of

• laying a first plurality of carbon fibre rovings into a mould cavity of a mould to form a first carbon fibre lay-up, the first carbon fibre lay-up having a tip end and an opposing root end,
• arranging a first electrically conductive mesh on the first carbon fibre lay-up at the tip end of the first carbon fibre lay-up such that the first electrically conductive mesh extends beyond the tip end in a spanwise direction,
• arranging a second electrically conductive mesh on the first carbon fibre lay-up at the root end of the first carbon fibre lay-up such that the first electrically conductive mesh extends beyond the root end in a spanwise direction,
• laying a second plurality of carbon fibre rovings on top of the first carbon fibre lay-up and on top of at least part of the first and second electrically conductive meshes, to form a second carbon fibre lay-up, the second carbon fibre lay-up having a tip end and an opposing root end, wherein the first and the second electrically conductive meshes extend beyond the tip end and beyond the root end of the second carbon fibre lay-up,
• consolidating the first carbon fibre lay-up, the electrically conductive meshes, and the second carbon fibre lay-up to obtain the spar cap assembly.