Abstract: An electric generator is operated under conditions in which rapid off-loading may occur. A generator control unit (GCU) employs a detector to detect rates of change of output of the generator. In response to a rapid change of output, e.g. an off-loading, an overvoltage protection system is activated. Excess energy stored in an excited winding is directed into an impedance circuit thus precluding overvoltage that may have been produced by the excess energy.

Abstract: An electric generator is operated under conditions in which rapid off-loading may occur. A generator control unit (GCU) employs a detector to detect rates of change of output of the generator. In response to a rapid change of output, e.g. an off-loading, an overvoltage protection system is activated. Excess energy stored is an excited winding is directed into an impedance circuit thus precluding overvoltage that may have been produced by the excess energy.

Abstract: A generator control unit (200) includes a field current modulator (212) that repeatedly switches between an ON state and an OFF state to control the flow of field current to the generator (20), a free-wheeling path (216) that feeds excitation current from the generator (20) back to the generator (20) as a field current component when the field current modulator (212) is in the OFF state, and an impedance circuit (220) that selectively and temporarily absorbs excitation current in the free-wheeling path (216) to reduce voltage overshoot of the generator (20) upon occurrence of an operating transition, such as a transition from high load to low load. In one implementation, the impedance circuit (220) is an RC circuit and a by-pass switch (222) is provided across the RC circuit. When excitation current in the free-wheeling path (216) is not to be absorbed by the RC circuit, the by-pass switch (222) is ON, thereby providing a low-impedance path for the excitation current.

Abstract: A generator control unit (200) includes a field current modulator (212) that repeatedly switches between an ON state and an OFF state to control the flow of field current to the generator (20), a free-wheeling path (216) that feeds excitation current from the generator (20) back to the generator (20) as a field current component when the field current modulator (212) is in the OFF state, and an impedance circuit (220) that selectively and temporarily absorbs excitation current in the free-wheeling path (216) to reduce voltage overshoot of the generator (20) upon occurrence of an operating transition, such as a transition from high load to low load. In one implementation, the impedance circuit (220) is an RC circuit and a by-pass switch (222) is provided across the RC circuit. When excitation current in the free-wheeling path (216) is not to be absorbed by the RC circuit, the by-pass switch (222) is ON, thereby providing a lowe impedance path for the excitation current.