Genset having at least one generator for generating electrical energy, which can be driven by a drive device, with: - a detection device for detecting the presence of a grid fault in at least one phase of a power grid, - a device for determining an operating state of the generator immediately before or upon detection of a grid fault and - a regulating device, to which the signals of the detection device and of the device for determining the operating state can be fed, characterized in that the regulating device is formed, after detection of a grid fault, to regulate a power of the drive device in dependence on the operating state of the generator which was determined immediately before or upon detection of the grid fault, wherein - the regulating device is formed to carry out a reduction of the power of the drive device for a predetermined time period (Δt), - the regulating device is formed to select the predetermined time period (Δt), for which the reduction of the power of the drive device is carried out, in dependence on the operating state of the generator and/or the configuration of the genset immediately before or upon detection of the grid fault, - the regulating device is formed to select a longer time period, the further last-measured values with respect to the operating state of the generator and/or the configuration of the generator before or upon detection of the grid fault deviate from predefined target values, and - the regulating device comprises a lookup table which contains the predetermined time periods for various possible operating states of the generator and/or configurations of the genset immediately before or upon detection of the grid fault. - a detection device for detecting the presence of a grid fault in at least one phase of a power grid, - a device for determining an operating state of the generator immediately before or upon detection of a grid fault and - a regulating device, to which the signals of the detection device and of the device for determining the operating state can be fed, characterized in that the regulating device is formed, after detection of a grid fault, to regulate a power of the drive device in dependence on the operating state of the generator which was determined immediately before or upon detection of the grid fault, wherein - the regulating device is formed to carry out a reduction of the power of the drive device for a predetermined time period (Δt), - the regulating device is formed to select the predetermined time period (Δt), for which the reduction of the power of the drive device is carried out, in dependence on the operating state of the generator and/or the configuration of the genset immediately before or upon detection of the grid fault, - the regulating device is formed to select a longer time period, the further last-measured values with respect to the operating state of the generator and/or the configuration of the generator before or upon detection of the grid fault deviate from predefined target values, and - the regulating device comprises a lookup table which contains the predetermined time periods for various possible operating states of the generator and/or configurations of the genset immediately before or upon detection of the grid fault.