Breakdown tests of glass fibre reinforced polymers (GFRP) as part of improved lightning protection of wind turbine blades

This paper addresses a need for analysing the interaction between electrical discharges and GFRP. A test method for evaluating the breakdown and withstand voltages for materials used in wind turbine blades has been developed. The method is based on IEC 243-3, methods of test for electrical strength of solid insulating materials, and simulates the situation in a wind turbine blade, where a lightning discharge penetrates an insulating layer towards an inner earth conductor. Different GFRP materials supplied by Danish wind turbine blade manufacturers have been tested. In the subsequent experiments, both the test methods and the results are evaluated. The different results are compared with respect to the GFRP materials' overall thicknesses, thickness of laminates and thickness of coatings. Finally, some general conclusions and different statements on how to manufacture specimens with minimum likelihood of breakdown are stated.