A static exciter of a field winding includes a rectifier connected to an electric grid and to the field winding; a unidirectional electronic switch connected in series with the rectifier; a capacitor bank; and a further switch disposed between the unidirectional electronic switch and the capacitor bank. Exciter also includes a control unit connected to the further switch and configured to close the further switch when a grid voltage drops below a first prefixed voltage value so as to connect the capacitor bank to the field winding and configured to open the further switch when the grid voltage exceeds a second prefixed voltage value so as to disconnect the capacitor bank from the field winding and so as to supply energy to the field winding from the capacitor bank for a time period.