A variable frequency electromagnetic compensating device for protecting wind tower blades or other mobile or static structures includes two conductive adapters of connection (1, 2) charged, one (1) of the connections of the device with the external collectors of the element to be protected on the one hand and another (2) of the connections with the earth, on the other hand; and two elements of high reactance to the passage of high frequency current and absorbers of energy in form of heat (3, 4) connected on both sides of a frequency resonator composed of a dielectric insulator (9) located between a first and a second conductive elements (7, 8) and respectively to the two adapters (1, 2), generating a force against electromotive to the passage of initial high frequency current, lowering the frequency and absorbing a part of the energy generated in heat.