The experimental research, whose most important segments are described in this paper, is one of the first attempts to determine the influence of wind turbine blade rotation on likelihood of getting struck by lightning. The tests were conducted in the high-voltage laboratory, applying the up-and-down method for determination of the 50% flashover standard switching voltage. The impulse voltage waves were applied between the specially designed arching electrode and the blades of a reduced-size wind turbine model, driven by a frequency controlled motor. Two types of lightning protection systems and the case of absent protection system were examined. According to the theory of similarity this paper discusses the characteristics of direct atmospheric discharges for the following typical rotational speeds of the wind turbine: w = 0 r/min (when the wind turbine is idle), w = 250 r/min (for the winds of moderate strength), and w = 400 r/min (rated rotor speed).