Patent ID: 8624563

Claim:
A static exciter of a field winding of an electric generator comprising: 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; a further switch disposed electrically between the unidirectional electronic switch and the capacitor bank; a control unit connected to the further switch and configured to close the further switch when a voltage indicative of a grid voltage drops below a first prefixed voltage value so as to connect the capacitor bank to the field winding so as to supply energy to the field winding from the capacitor bank and configured to interrupt current flowing between the capacitor bank and the field winding by opening the further switch when the voltage indicative of the grid voltage exceeds a second prefixed voltage value so as to disconnect the capacitor bank from the field winding, such that the capacitor bank supplies energy to the field winding only for the time needed, wherein the control unit is configured to open or control the further switch with a prefixed delay, and wherein the control unit includes at least one voltage drop band associated with a prefixed closing delay time for the further switch, wherein the closing delay time is zero for a voltage lower than the first prefixed voltage value, and wherein the control unit includes at least one voltage rise band associated with a prefixed opening delay time for the further switch, wherein the opening delay time is zero for a voltage greater than the second prefixed voltage value.