Earthing of wind farms

Wind farms are now being constructed in England and Wales in considerable numbers and it is anticipated that some 140 MW of capacity will have been commissioned by the end of 1993. The power in the wind is proportional to the cube of the wind speed and so, for effective operation, it is necessary to locate the turbines in areas of high mean wind speed. This has resulted in many wind farms being located on exposed, upland areas of Wales and the west of England. It is common for these sites to have rocky ground conditions which give high earth resistivity values as well as making the use of vertically driven rod electrodes impractical. Here, the authors show the ground conditions and values of mean earth resistivity of three sites which have been examined in detail