To obtain an overexcitation protector capable of controlling the output voltage to fall within the overexcitation resistance range of a generator when the output voltage is controlled such that the generator is not overexcited due to voltage variation in a power system connected with the generator.
The overexcitation protector for controlling a generator 1 not to be overexcited is arranged such that the value of V/F falls within the overexcitation resistance range of the generator 1 where V is the ratio of the voltage set value of a voltage setter in the automatic voltage regulating means of an exciter 2 to the rated value of power generation voltage and F is the ratio of frequency to a rated frequency, and when the value of V/F does not fall within the overexcitation resistance range of th generator 1, tap of a transformer 4 is altered automatically to eliminate overexcited state.
Masuo Oiwa
Toshihide Kodama
Takenaka Ikuo
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