In a device and a method for regulating an alternator increased alternator output is achieved either in that the exciter current can have a value above the nominal exciter current or in that the alternator control parameters are fixed in such a way that overheating could occur under unfavorable circumstances. In order to prevent this overheating even under unfavorable circumstances, the temperature is measured preferably in the regulator and the temperature at critical locations is determined from this temperature while taking into account typical parameters. This can be effected in that the temperature or temperatures which would occur in stationary operation are first determined. When an impermissible temperature is detected, the exciter current is reduced by suitable steps until the allowable maximum temperature is not exceeded.